Strategies to overcome intrinsic resistance in Stenotrophomonas maltophilia: In vitro activity of aztreonam/avibactam, cefiderocol, and cefepime–zidebactam

Strategies to overcome intrinsic resistance in Stenotrophomonas maltophilia: In vitro activity of aztreonam/avibactam, cefiderocol, and cefepime–zidebactam | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Strategies to overcome intrinsic resistance in Stenotrophomonas maltophilia: In vitro activity of aztreonam/avibactam, cefiderocol, and cefepime–zidebactam Vishnukumar Ramesh, Boomiga Rathakrishnan, Yamuna Devi Bakthavatchalam, and 7 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8927701/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Purpose: To evaluate the in vitro activity of cefiderocol, aztreonam/avibactam, and cefepime/zidebactam against contemporary clinical Stenotrophomonas maltophilia isolates and to assess bactericidal activity using time-kill analyses. Methods: A total of 216 nonduplicate clinical S. maltophilia isolates collected between 2018 and 2024 from five tertiary care hospitals in India, were studied. MICs of trimethoprim/sulfamethoxazole (TMP-SMX), levofloxacin, minocycline, cefiderocol, aztreonam/avibactam, and cefepime/zidebactam were determined by broth microdilution according to CLSI guidelines. Cefiderocol was tested in iron-depleted cation-adjusted Mueller–Hinton broth. Aztreonam/avibactam was tested with avibactam at 4 mg/L, and cefepime/zidebactam at a 1:1 ratio. PK/PD breakpoints of ≤ 8 mg/L and ≤ 64 mg/L were applied for aztreonam/avibactam and cefepime/zidebactam, respectively. Time–kill assays were performed at 1× MIC against two representative isolates and ten additional isolates spanning cefepime/zidebactam MICs of 4–64 mg/L. Results: Cefiderocol inhibited 96.8% of isolates at MICs ≤ 1 mg/L (MIC50/MIC90 ≤ 0.12/1 mg/L). Susceptibility rates were 95.8% for aztreonam/avibactam and 99.5% for cefepime/zidebactam. TMP-SMX and levofloxacin each inhibited 91.7% of isolates, while minocycline susceptibility was 92.6%. The three novel agents retained activity against most isolates non-susceptible to comparators. In time–kill assays, cefiderocol, aztreonam/avibactam, and cefepime/zidebactam achieved ≥ 3-log10 CFU/mL reductions, including isolates with cefepime/zidebactam MICs up to 64 mg/L. Minocycline did not demonstrate bactericidal activity. Conclusions: Cefiderocol, aztreonam/avibactam, and cefepime/zidebactam demonstrated potent in vitro activity against contemporary S. maltophilia isolates. These findings support further PK/PD-informed clinical evaluation of these agents for difficult-to-treat S. maltophilia infections. Stenotrophomonas maltophilia Antimicrobial Resistance Cefepime/zidebactam Azteronam/avibactam Cefiderocol PK/PD Clinical Failures Figures Figure 1 Figure 2 Introduction Stenotrophomonas maltophilia is an increasingly important nosocomial pathogen, particularly among immunocompromised patients and those with indwelling medical devices. Prior carbapenem exposure is a well-established risk factor for S. maltophilia infection ( 1 ). Bacteremia due to this pathogen is associated with mortality rates ranging from 13% to 70% ( 2 ). Treatment is complicated by extensive intrinsic resistance mediated primarily by the L1 metallo beta-lactamase (MBL) and L2 serine beta-lactamase, which together confer resistance to most beta-lactams ( 3 , 4 ). In addition, recently approved beta-lactam/beta-lactamase inhibitor (BL/BLI) combinations lack activity against the L1 MBL, with the notable exception of aztreonam/avibactam. Trimethoprim-sulfamethoxazole is the preferred first-line agent for invasive S. maltophilia infections. However, emerging data indicate limited bactericidal activity against contemporary strains and a lack of robust pharmacokinetic/pharmacodynamic (PK/PD) data to guide dose optimization, raising concerns about its clinical utility ( 5 , 6 ). Levofloxacin and minocycline are commonly used alternatives, yet high-quality preclinical and clinical data supporting their use are limited ( 7 ). Moreover, interpretation of clinical outcome data is further confounded by frequent polymicrobial infections and the absence of robust PK/PD data to guide dose optimization. Collectively, these limitations underscore the need for additional agents with consistent and reliable activity against S. maltophilia . Cefiderocol and aztreonam/avibactam demonstrate potent in vitro activity against S. maltophilia ( 8 , 9 ). Zidebactam is a novel bicyclo-acyl hydrazide beta-lactam enhancer that selectively binds penicillin-binding protein 2 (PBP2) and also inhibits class A, C and some D beta-lactamases ( 10 ). In combination with the PBP3-targeting cephalosporin cefepime, zidebactam produces synergistic antibacterial activity through complementary dual PBP engagement. Although zidebactam does not inhibit MBLs, activity is retained due to stable and unhindered PBP2 binding ( 10 ). Cefepime/zidebactam is currently in phase 3 clinical development for the treatment of complicated urinary tract infections and acute pyelonephritis (ClinicalTrials.gov identifier NCT04979806). In this study, we compared the in vitro activity of cefiderocol, aztreonam/avibactam, and cefepime/zidebactam against clinical S. maltophilia isolates using broth microdilution and time-kill analyses. Methods Bacterial isolates A total of 216 clinical S. maltophilia isolates collected between 2018 and 2024 were included from five tertiary care hospitals in India, including Christian Medical College, Vellore. Non duplicate isolates (one isolate per patient) were recovered from blood cultures and respiratory specimens as part of routine diagnostic testing. Only clinically significant isolates considered causative of infection were included. Species identification was confirmed using matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) (bioMérieux, Marcy-l’Etoile, France). Minimum inhibitory concentration: Minimum inhibitory concentrations (MICs) of trimethoprim/sulfamethoxazole, levofloxacin, minocycline, aztreonam/avibactam, cefiderocol and cefepime/zidebactam were determined by broth microdilution using the same 0.5 McFarland adjusted inoculum in accordance with Clinical and Laboratory Standards Institute (CLSI) guidelines (M07-A9) ( 11 ). Cefiderocol MICs were determined using iron-depleted cation-adjusted Mueller–Hinton broth (ID-CAMHB). Aztreonam/avibactam was tested with avibactam at a fixed concentration of 4 mg/L, and cefepime/zidebactam was tested at a fixed 1:1 ratio. Analytical-grade ceftazidime, cefepime, sulfamethoxazole, trimethoprim, levofloxacin, minocycline, aztreonam, avibactam, and cefiderocol were obtained commercially (MedChemExpress, New Jersey, USA). Zidebactam powder was provided by the manufacturer (Wockhardt Ltd., Mumbai, India). Quality control testing was performed concurrently using Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853. Susceptibility to aztreonam/avibactam was interpreted using a PK/PD susceptibility breakpoint of ≤ 8 mg/L, and cefepime/zidebactam susceptibility was interpreted using the proposed PK/PD breakpoint of ≤ 64 mg/L. For all other comparator agents, CLSI 2025 (M100-Ed35) breakpoints were applied ( 12 ). Time-kill assays Time-kill experiments were performed on two representative S. maltophilia isolates and an additional subset of ten isolates selected to represent a range of cefepime/zidebactam MIC values. Experiments were performed according to CLSI guidelines ( 13 ). Briefly, a starting inoculum of approximately 10⁶ CFU/mL was prepared from 3 to 4 isolated colonies of a pure overnight culture adjusted to a 0.5 McFarland standard. The suspension was incubated with agitation to achieve log-phase growth and then diluted 1:100 in cation-adjusted Mueller–Hinton broth (CAMHB). Final inoculum densities were verified by colony enumeration. Antimicrobial agents were tested at 1× MIC, and growth controls without antibiotic were included for each experiment. All cefiderocol-containing experiments were performed using ID-CAMHB. At predefined time points of 0, 2, 4, 6, and 24 h, 100-µL aliquots were withdrawn and serially diluted in log10 dilutions. A 10 µL aliquot of each dilution was spotted in duplicate onto Mueller–Hinton agar plates, which were incubated at 35°C for 24 h prior to enumeration. Colony counts from duplicate spots were averaged, and time-kill curves were generated by plotting mean CFU/mL versus time. Bactericidal activity was defined as a ≥ 3-log₁₀ CFU/mL reduction from the starting inoculum at 24 h. Results The MIC distributions and MIC 50 /MIC 90 values for all agents tested against S. maltophilia isolates are shown in Table 1 . Cefiderocol inhibited 96.8% of isolates at MICs of ≤ 1 mg/L, with MIC 50 /MIC 90 values of ≤ 0.12/1 mg/L. Applying the PK/PD susceptibility breakpoint of ≤ 8 mg/L, 95.8% of isolates were susceptible to aztreonam/avibactam. Cefepime/zidebactam exhibited potent in-vitro activity by inhibiting 99.5% of isolates at the proposed PK/PD susceptibility breakpoint of ≤ 64 mg/L. Notably, cefiderocol, aztreonam/avibactam, and cefepime/zidebactam retained activity against the majority of isolates that were non-susceptible to trimethoprim-sulfamethoxazole (TMP-SMX), levofloxacin, and minocycline (Supplementary Table S1 ). TMP-SMX and levofloxacin each inhibited 91.7% of isolates, with MIC 50 /MIC 90 values of 0.5/2 mg/L and 1/2 mg/L, respectively. Minocycline susceptibility was 92.6%. MICs of agents tested against Stenotrophomonas maltophilia isolates selected for time–kill analyses are shown in Supplementary Table S2. Against isolates SM-1 and SM-2, cefiderocol, aztreonam/avibactam, and cefepime/zidebactam achieved ≥ 3 log 10 CFU/mL reductions at 8 h (Fig. 1 ). Minocycline did not demonstrate bactericidal activity against any isolate at 1× MIC (1 mg/L) (Fig. 1 ). Time–kill results for isolates tested with cefepime/zidebactam, with MICs ranging from 4 to 64 mg/L, are presented in Fig. 2 . Cefepime/zidebactam consistently produced ≥ 3 log 10 CFU/mL reductions across isolates with MICs at or below the proposed PK/PD susceptibility breakpoint of 64 mg/L. In contrast, minocycline did not exhibit bactericidal activity against this subset of isolates. Table 1 Antimicrobial activity of newer agents and comparator antibiotics against S. maltophilia clinical isolates (n = 216) Antimicrobial Agents MIC (mg/L) No. of isolates (cumulative % of inhibition) % of Susceptibility MIC50 MIC90 ≤ 0.12 0.25 0.5 1 2 4 8 16 32 64 128 > 128 TMP-SMX 31 [14.3] 27 [26.8] 52 [50.9] 56 [76.8] 32 [91.7] 10 [96.3] 5 [98.6] 1 [99.1] 1 [99.5] 1 [100] 91.7 0.5 2 Levofloxacin 21 [9.7] 60 [37.5] 80 [74.5] 37 [91.7] 6 [94.4] 9 [98.6] 2 [99.5] 1 [100] 91.7 1 2 Minocycline 38 [17.6] 38 [35.2] 81 [72.7] 43 [92.6] 10 [97.2] 2 [98.1] 1 [98.6] 2 [99.5] 1 [100] 92.6 0.5 1 Aztreonam/avibactam 3 [1.4] 16 [8.8] 91 [50.9] 80 [88.0] 17 [95.8] 3 [97.2] 1 [97.7] 3 [99.1] 2 [100] 95.8 2 8 Cefiderocol 125 [57.9] 31 [72.2] 36 [88.9] 17 [96.8] 5 [99.1] 1 [99.5] 1 [100] 96.8 ≤ 0.12 1 Cefepime+ zidebactam 1 [0.5] 14 [6.9] 32 [21.8] 69 [53.7] 66 [84.3] 19 [93.1] 9 [97.2] 5 [99.5] 1 [100] 99.54 4 16 Discussion The absence of standardized treatment guidelines for Stenotrophomonas maltophilia reflects persistent gaps in high-quality clinical evidence, including the lack of randomized comparative trials and heterogeneity in infection syndromes. Therapeutic options remain limited. Given that most S. maltophilia infections involve the respiratory tract, where epithelial lining fluid is relatively acidic, site-specific drug exposure and antibacterial activity warrant careful consideration. In this context, we evaluated newer agents with activity against MBL producing gram negative pathogens. In the present study, cefiderocol, aztreonam/avibactam, and cefepime/zidebactam demonstrated activity against > 95% of isolates, with cefiderocol exhibiting the lowest MIC 50 /MIC 90 values. Consistent with previous reports, cefiderocol demonstrated potent in vitro bactericidal activity, achieving ≥ 3 log 10 CFU reductions in time–kill experiments ( 14 , 15 ). In a neutropenic murine lung model, cefiderocol achieved 2–4 log 10 CFU/lung reductions against isolates resistant to TMP-SMX, levofloxacin, and minocycline ( 9 ). Clinical data, however, remain limited and largely confined to case reports ( 16 – 20 ). In a randomized trial evaluating cefiderocol for carbapenem-resistant infections, five patients with S. maltophilia infection received cefiderocol. However, none achieved clinical cure or microbiological eradication, despite the isolates demonstrating low MICs of ≤ 0.03 to 0.25 mg/L ( 21 ). This may be due to limited pulmonary penetration, estimated at approximately 24% for cefiderocol ( 22 ). Clinical failure can occur despite in vitro susceptibility, underscoring the importance of PK/PD optimization. The combination of aztreonam with avibactam represents a rational strategy given the presence of L1 (MBL) and L2 (serine β-lactamase). Aztreonam is stable to hydrolysis by L1, while avibactam inhibits L2, thereby protecting aztreonam and restoring PBP3 binding ( 23 , 24 ). In the present study, aztreonam/avibactam exhibited potent in vitro activity with 3 log 10 kill. Notably, this combination demonstrated ≥ 2 log 10 CFU/mL reductions at 24 h in the majority of isolates non-susceptible to TMP-SMX and levofloxacin ( 8 ). However, the PK/PD target required to achieve a ≥ 1 log bacterial kill has not yet been defined. Clinical experience remains limited to small numbers of patients in trials and case reports ( 25 – 27 ). Although aztreonam/avibactam is now approved in Europe and the United States for certain indications, it is not specifically approved for S. maltophilia infections. There are several documented cases of the clinical use of the combination of ceftazidime/avibactam with aztreonam to treat S. maltophilia infections ( 28 , 29 ). Importantly, the aztreonam/ avibactam combination requires a loading dose and has a greater 24-hour dose of avibactam (2 g vs 1.5 g daily) compared with combining ceftazidime/avibactam and aztreonam. Cefepime/zidebactam also demonstrated substantial in vitro activity, with MIC 50 /MIC 90 values consistent with prior reports ( 30 ). Although cefepime is susceptible to L1 hydrolysis, activity likely reflects the β-lactam enhancer effect of zidebactam through high-affinity PBP2 binding. In the present study, cefepime/zidebactam achieved ≥ 3 log 10 CFU reductions in time kill kinetic experiment against isolates with MICs ranging from 4 to 64 mg/L. PK/PD studies indicate that zidebactam-mediated reduction in the requirement of %fT > MIC of cefepime enables coverage of high-MIC strains (up to 64 mg/L) with 2 to 3 log 10 kill ( 31 ). Although not yet approved for clinical use, these findings support continued clinical development of cefepime/zidebactam for difficult-to-treat S. maltophilia infections. In conclusion, cefiderocol and the combinations of aztreonam/avibactam and cefepime/zidebactam demonstrated promising in vitro activity against contemporary S. maltophilia clinical isolates, suggesting their potential as alternative therapeutic options, for this difficult-to-treat pathogen. This study also demonstrated that cefepime/zidebactam exhibits potent in vitro bactericidal activity against S. maltophilia producing L1 metallo-β-lactamase, likely attributable to the beta-lactam enhancer effect of zidebactam rather than direct inhibition of L1. Further clinical evaluation and PK/PD-informed investigations are warranted to define the optimal role of these agents in the management of S. maltophilia infections. Declarations Disclosure Statement: No potential conflict of interest was reported by the author(s). Ethics Statement This study was approved by the Institutional Review Board (IRB) of Christian Medical College, Vellore (IRB Min No. 2506123 dated 25.06.2025) Funding: None Author Contribution Conceived and designed the analysis: V.R., Y.D.B., B.V. Wrote the paper: V.R., Y.D.B., B.V. Performed the analysis: V.R., Y.D.B., B.A.S., B.R., reviewed the manuscript: V.R., Y.D.B., B.R., B.L., A.M., B.A.S., R.J., E.R.S., K.W., B.V. All authors reviewed the results and approved the final version of the manuscript. Acknowledgments: The authors thank the Department of Clinical Microbiology, Christian Medical College and Hospital, Vellore, for providing us with all the necessary facilities to conduct our study. Data availability statement: NA References Aitken SL, Sahasrabhojane PV, Kontoyiannis DP, Savidge TC, Arias CA, Ajami NJ, Shelburne SA, Galloway-Peña JR (2021) Alterations of the Oral Microbiome and Cumulative Carbapenem Exposure Are Associated With Stenotrophomonas maltophilia Infection in Patients With Acute Myeloid Leukemia Receiving Chemotherapy. Clin Infect Dis 72(9):1507–1513 Dadashi M, Hajikhani B, Nazarinejad N, Noorisepehr N, Yazdani S, Hashemi A, Hashemizadeh Z, Goudarzi M, Fatemeh S (2023) Global prevalence and distribution of antibiotic resistance among clinical isolates of Stenotrophomonas maltophilia: A systematic review and meta-analysis. J Glob Antimicrob Resist 34:253–267 Brooke JS (2012) Stenotrophomonas maltophilia: an emerging global opportunistic pathogen. Clin Microbiol Rev 25(1):2–41 Brooke JS, Di Bonaventura G, Berg G, Martinez JL (2017) Editorial: A Multidisciplinary Look at Stenotrophomonas maltophilia : An Emerging Multi-Drug-Resistant Global Opportunistic Pathogen. Front Microbiol 8:1511 Ko JH, Kang CI, Cornejo-Juárez P, Yeh KM, Wang CH, Cho SY, Gözel MG, Kim SH, Hsueh PR, Sekiya N, Matsumura Y, Lee DG, Cho SY, Shiratori S, Kim YJ, Chung DR, Peck KR (2019) Fluoroquinolones versus trimethoprim-sulfamethoxazole for the treatment of Stenotrophomonas maltophilia infections: a systematic review and meta-analysis. Clin Microbiol Infect 25(5):546–554 Chang YT, Lin CY, Chen YH, Hsueh PR (2015) Update on infections caused by Stenotrophomonas maltophilia with particular attention to resistance mechanisms and therapeutic options. Front Microbiol 6:893 Monardo R, Mojica MF, Ripa M, Aitken SL, Bonomo RA, van Duin D (2025) How do I manage a patient with Stenotrophomonas maltophilia infection? Clin Microbiol Infect 31(8):1291–1297 Biagi M, Lamm D, Meyer K, Vialichka A, Jurkovic M, Patel S, Mendes RE, Bulman ZP, Wenzler E (2020) Activity of Aztreonam in Combination with Avibactam, Clavulanate, Relebactam, and Vaborbactam against Multidrug-Resistant Stenotrophomonas maltophilia. Antimicrob Agents Chemother 64(12):e00297–e00220 Nakamura R, Oota M, Matsumoto S, Sato T, Yamano Y (2021) In Vitro Activity and In Vivo Efficacy of Cefiderocol against Stenotrophomonas maltophilia. Antimicrob Agents Chemother. ;65(4):e01436-20 Boattini M, Gaibani P, Comini S, Costa C, Cavallo R, Broccolo F, Bianco G (2025) In vitro activity and resistance mechanisms of novel antimicrobial agents against metallo-β-lactamase producers. Eur J Clin Microbiol Infect Dis 44(5):1041–1068 Clinical and Laboratory Standards Institute (2018) M-07- A10, 11th edn. Clinical and Laboratory Standards Institute, Wayne, PA, Methods for dilution antimicrobial susceptibility tests for bacteria that grow aerobically Clinical and Laboratory Standards Institute (2025) CLSI supplement M100, 35th edn. Clinical and Laboratory Standards Institute, Wayne, PA, Performance standards for antimicrobial testing Clinical and Laboratory Standards Institute. Methods for Determining Bactericidal Activity of Antimicrobial Agents (1999) ; 1st ed; CLSI M26-A. Clinical and Laboratory Standards Institute, Wayne, PA Biagi M, Vialichka A, Jurkovic M, Wu T, Shajee A, Lee M, Patel S, Mendes RE, Wenzler E (2020) Activity of Cefiderocol Alone and in Combination with Levofloxacin, Minocycline, Polymyxin B, or Trimethoprim-Sulfamethoxazole against Multidrug-Resistant Stenotrophomonas maltophilia. Antimicrob Agents Chemother 64(9):e00559–e00520 Sakoh T, Miyajima E, Endo Y, Baba M, Haraguchi M, Morishima M, Ogura S, Kimura M, Araoka H (2024) Cefiderocol susceptibility of 146 Stenotrophomonas maltophilia strains clinically isolated from blood in two Japanese hospitals over a 10-year period. Eur J Clin Microbiol Infect Dis 43(12):2485–2488 Fratoni AJ, Kuti JL, Nicolau DP (2021) Optimised cefiderocol exposures in a successfully treated critically ill patient with polymicrobial Stenotrophomonas maltophilia bacteraemia and pneumonia receiving continuous venovenous haemodiafiltration. Int J Antimicrob Agents 58(3):106395 Hsu AJ, Simner PJ, Bergman Y, Mathers AJ, Tamma PD (2023) Successful Treatment of Persistent Stenotrophomonas maltophilia Bacteremia With Cefiderocol in an Infant. Open Forum Infect Dis 10(4):ofad174 Imoto W, Abe J, Sakurai N, Kawamoto K, Yamada K, Kaneko Y, Kakeya H Efficacy of cefiderocol and levofloxacin against Stenotrophomonas maltophilia in a hemorrhagic pneumonia mouse model. Antimicrob Agents Chemother 2026 Jan 30:e0094425 Zappulo E, Grimaldi F, Paolillo R, Pinchera B, Buonomo AR, Picardi M, Catania MR, Pane F, Gentile I (2022) Successful treatment of MDR Stenotrophomonas maltophilia-associated pneumonia with cefiderocol-based regimen in a patient with hematological malignancy. Ann Hematol 101(12):2805–2806 Koirala A, Krishnappa B, Banh C, Brandenburg U, Findlay M, Williams PCM (2023) Successful Use of Cefiderocol to Treat a Multidrug-resistant Stenotrophomonas maltophilia Ventilator-associated Pneumonia in an Extremely Preterm Neonate. Pediatr Infect Dis J 42(11):1012–1016 Bassetti M, Echols R, Matsunaga Y, Ariyasu M, Doi Y, Ferrer R, Lodise TP, Naas T, Niki Y, Paterson DL, Portsmouth S, Torre-Cisneros J, Toyoizumi K, Wunderink RG, Nagata TD (2021) Efficacy and safety of cefiderocol or best available therapy for the treatment of serious infections caused by carbapenem-resistant Gram-negative bacteria (CREDIBLE-CR): a randomised, open-label, multicentre, pathogen-focused, descriptive, phase 3 trial. Lancet Infect Dis 21(2):226–240 Kullar R, Wenzler E, Alexander J, Goldstein EJC (2022) Overcoming Stenotrophomonas maltophilia Resistance for a More Rational Therapeutic Approach. Open Forum Infect Dis 9(5):ofsac095 Sader HS, Castanheira M, Arends SJR, Doyle TB (2025) Antimicrobial susceptibility of Stenotrophomonas maltophilia from United States medical centers (2019–2023). Antimicrob Agents Chemother 69(4):e0012425 Sader HS, Duncan LR, Arends SJR, Carvalhaes CG, Castanheira M (2020) Antimicrobial Activity of Aztreonam-Avibactam and Comparator Agents When Tested against a Large Collection of Contemporary Stenotrophomonas maltophilia Isolates from Medical Centers Worldwide. Antimicrob Agents Chemother 64(11):e01433–e01420 Carmeli Y, Cisneros JM, Paul M, Daikos GL, Wang M, Torre-Cisneros J, Singer G, Titov I, Gumenchuk I, Zhao Y, Jiménez-Rodríguez RM, Liang L, Chen G, Pyptiuk O, Aksoy F, Rogers H, Wible M, Arhin FF, Luckey A, Leaney JL, Pypstra R, Chow JW (2025) COMBACTE-CARE consortium REVISIT study group. Aztreonam-avibactam versus meropenem for the treatment of serious infections caused by Gram-negative bacteria (REVISIT): a descriptive, multinational, open-label, phase 3, randomised trial. Lancet Infect Dis 25(2):218–230 Mojica MF, Ouellette CP, Leber A, Becknell MB, Ardura MI, Perez F, Shimamura M, Bonomo RA, Aitken SL, Shelburne SA (2016) Successful Treatment of Bloodstream Infection Due to Metallo-β-Lactamase-Producing Stenotrophomonas maltophilia in a Renal Transplant Patient. Antimicrob Agents Chemother 60(9):5130–5134 Diarra A, Pascal L, Carpentier B, Baclet N, Cabaret P, Georgel AF, Dubreuil L, Weyrich P (2021) Successful use of avibactam and aztreonam combination for a multiresistant Stenotrophomonas maltophilia bloodstream infection in a patient with idiopathic medullary aplasia. Infect Dis Now 51(7):637–638 Alghamdi AO, Algethami AS, Aljuaeed MS, Alkhammash FM, Almalki FM, Alharthi SA, Aljaed NM, Abosabie SA, Abosabie SA, Kamal NM (2025) Successful dual therapy of aztreonam and ceftazidime-avibactam for multidrug-resistant Stenotrophomonas maltophilia infection in a preterm neonate: A life-saving approach. J Int Med Res 53(12):3000605251353486 Cowart MC, Ferguson CL (2021) Optimization of Aztreonam in Combination With Ceftazidime/Avibactam in a Cystic Fibrosis Patient With Chronic Stenotrophomonas maltophilia Pneumonia Using Therapeutic Drug Monitoring: A Case Study. Ther Drug Monit 43(2):146–149 Sader HS, Mendes RE, Duncan LR, Carvalhaes CG, Castanheria M (2022) Antimicrobial activity of cefepime/zidebactam (WCK 5222), a β-lactam/β-lactam enhancer combination, against clinical isolates of Gram-negative bacteria collected worldwide (2018-19). J Antimicrob Chemother 77(10):2642–2649 Kidd JM, Abdelraouf K, Nicolau DP (2020) Efficacy of human-simulated bronchopulmonary exposures of cefepime, zidebactam and the combination (WCK 5222) against MDR Pseudomonas aeruginosa in a neutropenic murine pneumonia model. J Antimicrob Chemother 75(1):149–155 Additional Declarations No competing interests reported. Supplementary Files TableS1.docx Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8927701","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":601170364,"identity":"27f8671f-c3b7-43c4-97aa-b4e209167ea6","order_by":0,"name":"Vishnukumar Ramesh","email":"","orcid":"","institution":"Christian Medical College","correspondingAuthor":false,"prefix":"","firstName":"Vishnukumar","middleName":"","lastName":"Ramesh","suffix":""},{"id":601170365,"identity":"b778f36b-9c2d-4829-8940-0924c3fbae38","order_by":1,"name":"Boomiga Rathakrishnan","email":"","orcid":"","institution":"Christian Medical College","correspondingAuthor":false,"prefix":"","firstName":"Boomiga","middleName":"","lastName":"Rathakrishnan","suffix":""},{"id":601170366,"identity":"87beb721-69a5-4405-8778-64f65fe455da","order_by":2,"name":"Yamuna Devi Bakthavatchalam","email":"","orcid":"","institution":"Christian Medical College","correspondingAuthor":false,"prefix":"","firstName":"Yamuna","middleName":"Devi","lastName":"Bakthavatchalam","suffix":""},{"id":601170367,"identity":"6a33fa2d-6f2f-4dbc-a2f1-7289928ec360","order_by":3,"name":"Binesh Lal","email":"","orcid":"","institution":"Christian Medical College","correspondingAuthor":false,"prefix":"","firstName":"Binesh","middleName":"","lastName":"Lal","suffix":""},{"id":601170368,"identity":"fc134060-c61e-4631-aed6-962ab9546708","order_by":4,"name":"Abi Manesh","email":"","orcid":"","institution":"Christian Medical College","correspondingAuthor":false,"prefix":"","firstName":"Abi","middleName":"","lastName":"Manesh","suffix":""},{"id":601170369,"identity":"a0e2291d-9cd9-4784-804c-1d1efdee3895","order_by":5,"name":"Baby Abirami Shankar","email":"","orcid":"","institution":"Christian Medical College","correspondingAuthor":false,"prefix":"","firstName":"Baby","middleName":"Abirami","lastName":"Shankar","suffix":""},{"id":601170370,"identity":"ec2c3652-03af-4e32-b88b-0389019af2ca","order_by":6,"name":"Rangineni Jayaprada","email":"","orcid":"","institution":"SriVenkateswara Institute of Medical Sciences","correspondingAuthor":false,"prefix":"","firstName":"Rangineni","middleName":"","lastName":"Jayaprada","suffix":""},{"id":601170371,"identity":"13206a85-babb-46c1-9835-a42c82f3459f","order_by":7,"name":"Ekadashi Rajni","email":"","orcid":"","institution":"Mahatma Gandhi Medical College","correspondingAuthor":false,"prefix":"","firstName":"Ekadashi","middleName":"","lastName":"Rajni","suffix":""},{"id":601170372,"identity":"6db9a04f-add6-4b8c-8633-c48d35f9f3fb","order_by":8,"name":"Kamini Walia","email":"","orcid":"","institution":"Indian Council of Medical Research","correspondingAuthor":false,"prefix":"","firstName":"Kamini","middleName":"","lastName":"Walia","suffix":""},{"id":601170373,"identity":"87908bc9-935c-48c8-a542-3dc25bb03016","order_by":9,"name":"Balaji Veeraraghavan","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABA0lEQVRIiWNgGAWjYDACCQbGAww8EnIQXoEFQhyPFgaQFmMIz0ACSRyvFgaGxAY0LbiBwe3mBwd+yFik9087/Ezig4GEnHl7A+OHHwwWeTi13DlmcLCHRyJ3xu00M8kZBhLGMmcOMEv2MEgU49IiOSPB4AAPUMsG6RxmYx4DicQZEgkM0kAHQ52KTUv6h4N/eCTSDUBa/oC0yD9g/o1PC79EjsFhoC0JQC2MjxnAtjCw4bWFX+ZMwWEZHglDoF8MH/YA/SLBk9hmCWTg1MIm3b7x4dueOnn+2cnAoKuwkZNgP3z4xo+KOpxawICxB5ULVGyATz0I/CCkYBSMglEwCkY0AADwkE2ThvrdPQAAAABJRU5ErkJggg==","orcid":"","institution":"Christian Medical College","correspondingAuthor":true,"prefix":"","firstName":"Balaji","middleName":"","lastName":"Veeraraghavan","suffix":""}],"badges":[],"createdAt":"2026-02-20 16:24:45","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8927701/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8927701/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":104268098,"identity":"be7e88e9-2631-46b3-bf43-8792ae83ed54","added_by":"auto","created_at":"2026-03-09 21:03:54","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":552387,"visible":true,"origin":"","legend":"\u003cp\u003eTime–kill curves depicting changes in log₁₀ CFU/mL over time against two representative \u003cem\u003eS. maltophilia\u003c/em\u003e isolates following exposure to minocycline, cefiderocol, aztreonam/avibactam, and cefepime/zidebactam (A and B).\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8927701/v1/1ef8d3feaf00b3ccbe670919.jpeg"},{"id":104268099,"identity":"b39db381-a861-41a3-90af-8b2ff07acf7e","added_by":"auto","created_at":"2026-03-09 21:03:54","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1329532,"visible":true,"origin":"","legend":"\u003cp\u003eTime–kill curves illustrating changes in log₁₀ CFU/mL over time against ten \u003cem\u003eS. maltophilia\u003c/em\u003e isolates treated with cefepime/zidebactam, with MICs ranging from 4 to 64 mg/L (A-J)\u003c/p\u003e","description":"","filename":"floatimage2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8927701/v1/697f2622dbe3da78a5cabf47.jpeg"},{"id":105563410,"identity":"e5ac18b1-ed33-4289-ba2c-9e9e65112f8b","added_by":"auto","created_at":"2026-03-27 12:46:55","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2526842,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8927701/v1/5247854c-876a-4414-8b11-b51b5a3e2931.pdf"},{"id":104268100,"identity":"4751c9d6-f3c5-4ec6-80a3-4fa27cba7fe3","added_by":"auto","created_at":"2026-03-09 21:03:54","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":26246,"visible":true,"origin":"","legend":"","description":"","filename":"TableS1.docx","url":"https://assets-eu.researchsquare.com/files/rs-8927701/v1/f785852a5630425ff391ce0c.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Strategies to overcome intrinsic resistance in Stenotrophomonas maltophilia: In vitro activity of aztreonam/avibactam, cefiderocol, and cefepime–zidebactam","fulltext":[{"header":"Introduction","content":"\u003cp\u003e \u003cem\u003eStenotrophomonas maltophilia\u003c/em\u003e is an increasingly important nosocomial pathogen, particularly among immunocompromised patients and those with indwelling medical devices. Prior carbapenem exposure is a well-established risk factor for \u003cem\u003eS. maltophilia\u003c/em\u003e infection (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e). Bacteremia due to this pathogen is associated with mortality rates ranging from 13% to 70% (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). Treatment is complicated by extensive intrinsic resistance mediated primarily by the L1 metallo beta-lactamase (MBL) and L2 serine beta-lactamase, which together confer resistance to most beta-lactams (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e). In addition, recently approved beta-lactam/beta-lactamase inhibitor (BL/BLI) combinations lack activity against the L1 MBL, with the notable exception of aztreonam/avibactam.\u003c/p\u003e \u003cp\u003eTrimethoprim-sulfamethoxazole is the preferred first-line agent for invasive \u003cem\u003eS. maltophilia\u003c/em\u003e infections. However, emerging data indicate limited bactericidal activity against contemporary strains and a lack of robust pharmacokinetic/pharmacodynamic (PK/PD) data to guide dose optimization, raising concerns about its clinical utility (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e). Levofloxacin and minocycline are commonly used alternatives, yet high-quality preclinical and clinical data supporting their use are limited (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e). Moreover, interpretation of clinical outcome data is further confounded by frequent polymicrobial infections and the absence of robust PK/PD data to guide dose optimization. Collectively, these limitations underscore the need for additional agents with consistent and reliable activity against \u003cem\u003eS. maltophilia\u003c/em\u003e.\u003c/p\u003e \u003cp\u003eCefiderocol and aztreonam/avibactam demonstrate potent in vitro activity against \u003cem\u003eS. maltophilia\u003c/em\u003e (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e). Zidebactam is a novel bicyclo-acyl hydrazide beta-lactam enhancer that selectively binds penicillin-binding protein 2 (PBP2) and also inhibits class A, C and some D beta-lactamases (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e). In combination with the PBP3-targeting cephalosporin cefepime, zidebactam produces synergistic antibacterial activity through complementary dual PBP engagement. Although zidebactam does not inhibit MBLs, activity is retained due to stable and unhindered PBP2 binding (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e). Cefepime/zidebactam is currently in phase 3 clinical development for the treatment of complicated urinary tract infections and acute pyelonephritis (ClinicalTrials.gov identifier NCT04979806). In this study, we compared the in vitro activity of cefiderocol, aztreonam/avibactam, and cefepime/zidebactam against clinical \u003cem\u003eS. maltophilia\u003c/em\u003e isolates using broth microdilution and time-kill analyses.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eBacterial isolates\u003c/h2\u003e \u003cp\u003eA total of 216 clinical \u003cem\u003eS. maltophilia\u003c/em\u003e isolates collected between 2018 and 2024 were included from five tertiary care hospitals in India, including Christian Medical College, Vellore. Non duplicate isolates (one isolate per patient) were recovered from blood cultures and respiratory specimens as part of routine diagnostic testing. Only clinically significant isolates considered causative of infection were included. Species identification was confirmed using matrix-assisted laser desorption ionization\u0026ndash;time of flight mass spectrometry (MALDI-TOF MS) (bioM\u0026eacute;rieux, Marcy-l\u0026rsquo;Etoile, France).\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eMinimum inhibitory concentration:\u003c/h3\u003e\n\u003cp\u003eMinimum inhibitory concentrations (MICs) of trimethoprim/sulfamethoxazole, levofloxacin, minocycline, aztreonam/avibactam, cefiderocol and cefepime/zidebactam were determined by broth microdilution using the same 0.5 McFarland adjusted inoculum in accordance with Clinical and Laboratory Standards Institute (CLSI) guidelines (M07-A9) (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e). Cefiderocol MICs were determined using iron-depleted cation-adjusted Mueller\u0026ndash;Hinton broth (ID-CAMHB). Aztreonam/avibactam was tested with avibactam at a fixed concentration of 4 mg/L, and cefepime/zidebactam was tested at a fixed 1:1 ratio. Analytical-grade ceftazidime, cefepime, sulfamethoxazole, trimethoprim, levofloxacin, minocycline, aztreonam, avibactam, and cefiderocol were obtained commercially (MedChemExpress, New Jersey, USA). Zidebactam powder was provided by the manufacturer (Wockhardt Ltd., Mumbai, India). Quality control testing was performed concurrently using \u003cem\u003eEscherichia coli\u003c/em\u003e ATCC 25922 and \u003cem\u003ePseudomonas aeruginosa\u003c/em\u003e ATCC 27853. Susceptibility to aztreonam/avibactam was interpreted using a PK/PD susceptibility breakpoint of \u0026le;\u0026thinsp;8 mg/L, and cefepime/zidebactam susceptibility was interpreted using the proposed PK/PD breakpoint of \u0026le;\u0026thinsp;64 mg/L. For all other comparator agents, CLSI 2025 (M100-Ed35) breakpoints were applied (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e).\u003c/p\u003e\n\u003ch3\u003eTime-kill assays\u003c/h3\u003e\n\u003cp\u003eTime-kill experiments were performed on two representative \u003cem\u003eS. maltophilia\u003c/em\u003e isolates and an additional subset of ten isolates selected to represent a range of cefepime/zidebactam MIC values. Experiments were performed according to CLSI guidelines (\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e). Briefly, a starting inoculum of approximately 10⁶ CFU/mL was prepared from 3 to 4 isolated colonies of a pure overnight culture adjusted to a 0.5 McFarland standard. The suspension was incubated with agitation to achieve log-phase growth and then diluted 1:100 in cation-adjusted Mueller\u0026ndash;Hinton broth (CAMHB). Final inoculum densities were verified by colony enumeration. Antimicrobial agents were tested at 1\u0026times; MIC, and growth controls without antibiotic were included for each experiment. All cefiderocol-containing experiments were performed using ID-CAMHB. At predefined time points of 0, 2, 4, 6, and 24 h, 100-\u0026micro;L aliquots were withdrawn and serially diluted in log10 dilutions. A 10 \u0026micro;L aliquot of each dilution was spotted in duplicate onto Mueller\u0026ndash;Hinton agar plates, which were incubated at 35\u0026deg;C for 24 h prior to enumeration. Colony counts from duplicate spots were averaged, and time-kill curves were generated by plotting mean CFU/mL versus time. Bactericidal activity was defined as a\u0026thinsp;\u0026ge;\u0026thinsp;3-log₁₀ CFU/mL reduction from the starting inoculum at 24 h.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eThe MIC distributions and MIC\u003csub\u003e50\u003c/sub\u003e/MIC\u003csub\u003e90\u003c/sub\u003e values for all agents tested against \u003cem\u003eS. maltophilia\u003c/em\u003e isolates are shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Cefiderocol inhibited 96.8% of isolates at MICs of \u0026le;\u0026thinsp;1 mg/L, with MIC\u003csub\u003e50\u003c/sub\u003e/MIC\u003csub\u003e90\u003c/sub\u003e values of \u0026le;\u0026thinsp;0.12/1 mg/L. Applying the PK/PD susceptibility breakpoint of \u0026le;\u0026thinsp;8 mg/L, 95.8% of isolates were susceptible to aztreonam/avibactam. Cefepime/zidebactam exhibited potent in-vitro activity by inhibiting 99.5% of isolates at the proposed PK/PD susceptibility breakpoint of \u0026le;\u0026thinsp;64 mg/L. Notably, cefiderocol, aztreonam/avibactam, and cefepime/zidebactam retained activity against the majority of isolates that were non-susceptible to trimethoprim-sulfamethoxazole (TMP-SMX), levofloxacin, and minocycline (Supplementary Table \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e). TMP-SMX and levofloxacin each inhibited 91.7% of isolates, with MIC\u003csub\u003e50\u003c/sub\u003e/MIC\u003csub\u003e90\u003c/sub\u003e values of 0.5/2 mg/L and 1/2 mg/L, respectively. Minocycline susceptibility was 92.6%.\u003c/p\u003e \u003cp\u003eMICs of agents tested against \u003cem\u003eStenotrophomonas maltophilia\u003c/em\u003e isolates selected for time\u0026ndash;kill analyses are shown in Supplementary Table S2. Against isolates SM-1 and SM-2, cefiderocol, aztreonam/avibactam, and cefepime/zidebactam achieved\u0026thinsp;\u0026ge;\u0026thinsp;3 log\u003csub\u003e10\u003c/sub\u003e CFU/mL reductions at 8 h (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Minocycline did not demonstrate bactericidal activity against any isolate at 1\u0026times; MIC (1 mg/L) (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Time\u0026ndash;kill results for isolates tested with cefepime/zidebactam, with MICs ranging from 4 to 64 mg/L, are presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. Cefepime/zidebactam consistently produced\u0026thinsp;\u0026ge;\u0026thinsp;3 log\u003csub\u003e10\u003c/sub\u003e CFU/mL reductions across isolates with MICs at or below the proposed PK/PD susceptibility breakpoint of 64 mg/L. In contrast, minocycline did not exhibit bactericidal activity against this subset of isolates.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eAntimicrobial activity of newer agents and comparator antibiotics against \u003cem\u003eS. maltophilia\u003c/em\u003e clinical isolates (n\u0026thinsp;=\u0026thinsp;216)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"17\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c13\" colnum=\"13\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c14\" colnum=\"14\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c15\" colnum=\"15\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c16\" colnum=\"16\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c17\" colnum=\"17\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eAntimicrobial Agents\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"12\" nameend=\"c13\" namest=\"c2\"\u003e \u003cp\u003eMIC (mg/L)\u003c/p\u003e \u003cp\u003eNo. of isolates (cumulative % of inhibition)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c14\"\u003e \u003cp\u003e% of Susceptibility\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c15\"\u003e \u003cp\u003eMIC50\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c17\" namest=\"c16\"\u003e \u003cp\u003eMIC90\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026le;\u0026thinsp;0.12\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.25\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.5\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003e16\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e \u003cp\u003e32\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c11\"\u003e \u003cp\u003e64\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c12\"\u003e \u003cp\u003e128\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c13\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;128\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c14\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c15\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c16\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"1\" nameend=\"c17\" namest=\"c17\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTMP-SMX\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e31\u003c/p\u003e \u003cp\u003e[14.3]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e27\u003c/p\u003e \u003cp\u003e[26.8]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e52\u003c/p\u003e \u003cp\u003e[50.9]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e56\u003c/p\u003e \u003cp\u003e[76.8]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e32\u003c/p\u003e \u003cp\u003e[91.7]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e10\u003c/p\u003e \u003cp\u003e[96.3]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e5\u003c/p\u003e \u003cp\u003e[98.6]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e1\u003c/p\u003e \u003cp\u003e[99.1]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e1\u003c/p\u003e \u003cp\u003e[99.5]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e1\u003c/p\u003e \u003cp\u003e[100]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e \u003cp\u003e91.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c15\"\u003e \u003cp\u003e0.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c16\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c17\" namest=\"c17\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLevofloxacin\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e21\u003c/p\u003e \u003cp\u003e[9.7]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e60\u003c/p\u003e \u003cp\u003e[37.5]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e80\u003c/p\u003e \u003cp\u003e[74.5]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e37\u003c/p\u003e \u003cp\u003e[91.7]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e6\u003c/p\u003e \u003cp\u003e[94.4]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e9\u003c/p\u003e \u003cp\u003e[98.6]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e2\u003c/p\u003e \u003cp\u003e[99.5]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e1\u003c/p\u003e \u003cp\u003e[100]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e \u003cp\u003e91.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c15\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c16\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c17\" namest=\"c17\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMinocycline\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e38\u003c/p\u003e \u003cp\u003e[17.6]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e38\u003c/p\u003e \u003cp\u003e[35.2]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e81\u003c/p\u003e \u003cp\u003e[72.7]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e43\u003c/p\u003e \u003cp\u003e[92.6]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e10\u003c/p\u003e \u003cp\u003e[97.2]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e2\u003c/p\u003e \u003cp\u003e[98.1]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e1\u003c/p\u003e \u003cp\u003e[98.6]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e2\u003c/p\u003e \u003cp\u003e[99.5]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e1\u003c/p\u003e \u003cp\u003e[100]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e \u003cp\u003e92.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c15\"\u003e \u003cp\u003e0.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c16\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c17\" namest=\"c17\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAztreonam/avibactam\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3\u003c/p\u003e \u003cp\u003e[1.4]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e16\u003c/p\u003e \u003cp\u003e[8.8]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e91\u003c/p\u003e \u003cp\u003e[50.9]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e80\u003c/p\u003e \u003cp\u003e[88.0]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e17\u003c/p\u003e \u003cp\u003e[95.8]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e3\u003c/p\u003e \u003cp\u003e[97.2]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e1\u003c/p\u003e \u003cp\u003e[97.7]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e3\u003c/p\u003e \u003cp\u003e[99.1]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e2\u003c/p\u003e \u003cp\u003e[100]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e \u003cp\u003e95.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c15\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c16\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c17\" namest=\"c17\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCefiderocol\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e125\u003c/p\u003e \u003cp\u003e[57.9]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e31\u003c/p\u003e \u003cp\u003e[72.2]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e36\u003c/p\u003e \u003cp\u003e[88.9]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e17\u003c/p\u003e \u003cp\u003e[96.8]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e5\u003c/p\u003e \u003cp\u003e[99.1]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1\u003c/p\u003e \u003cp\u003e[99.5]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e1\u003c/p\u003e \u003cp\u003e[100]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e \u003cp\u003e96.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c15\"\u003e \u003cp\u003e\u0026le;\u0026thinsp;0.12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c16\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c17\" namest=\"c17\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCefepime+ zidebactam\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1\u003c/p\u003e \u003cp\u003e[0.5]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e14\u003c/p\u003e \u003cp\u003e[6.9]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e32\u003c/p\u003e \u003cp\u003e[21.8]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e69\u003c/p\u003e \u003cp\u003e[53.7]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e66\u003c/p\u003e \u003cp\u003e[84.3]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e19\u003c/p\u003e \u003cp\u003e[93.1]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e9\u003c/p\u003e \u003cp\u003e[97.2]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e5\u003c/p\u003e \u003cp\u003e[99.5]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e1\u003c/p\u003e \u003cp\u003e[100]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e \u003cp\u003e99.54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c15\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c16\"\u003e \u003cp\u003e16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c17\" namest=\"c17\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe absence of standardized treatment guidelines for \u003cem\u003eStenotrophomonas maltophilia\u003c/em\u003e reflects persistent gaps in high-quality clinical evidence, including the lack of randomized comparative trials and heterogeneity in infection syndromes. Therapeutic options remain limited. Given that most \u003cem\u003eS. maltophilia\u003c/em\u003e infections involve the respiratory tract, where epithelial lining fluid is relatively acidic, site-specific drug exposure and antibacterial activity warrant careful consideration. In this context, we evaluated newer agents with activity against MBL producing gram negative pathogens. In the present study, cefiderocol, aztreonam/avibactam, and cefepime/zidebactam demonstrated activity against \u0026gt;\u0026thinsp;95% of isolates, with cefiderocol exhibiting the lowest MIC\u003csub\u003e50\u003c/sub\u003e/MIC\u003csub\u003e90\u003c/sub\u003e values.\u003c/p\u003e \u003cp\u003eConsistent with previous reports, cefiderocol demonstrated potent in vitro bactericidal activity, achieving\u0026thinsp;\u0026ge;\u0026thinsp;3 log\u003csub\u003e10\u003c/sub\u003e CFU reductions in time\u0026ndash;kill experiments (\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e). In a neutropenic murine lung model, cefiderocol achieved 2\u0026ndash;4 log\u003csub\u003e10\u003c/sub\u003e CFU/lung reductions against isolates resistant to TMP-SMX, levofloxacin, and minocycline (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e). Clinical data, however, remain limited and largely confined to case reports (\u003cspan additionalcitationids=\"CR17 CR18 CR19\" citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e). In a randomized trial evaluating cefiderocol for carbapenem-resistant infections, five patients with \u003cem\u003eS. maltophilia\u003c/em\u003e infection received cefiderocol. However, none achieved clinical cure or microbiological eradication, despite the isolates demonstrating low MICs of \u0026le;\u0026thinsp;0.03 to 0.25 mg/L (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e). This may be due to limited pulmonary penetration, estimated at approximately 24% for cefiderocol (\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e). Clinical failure can occur despite in vitro susceptibility, underscoring the importance of PK/PD optimization.\u003c/p\u003e \u003cp\u003eThe combination of aztreonam with avibactam represents a rational strategy given the presence of L1 (MBL) and L2 (serine β-lactamase). Aztreonam is stable to hydrolysis by L1, while avibactam inhibits L2, thereby protecting aztreonam and restoring PBP3 binding (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e). In the present study, aztreonam/avibactam exhibited potent in vitro activity with 3 log\u003csub\u003e10\u003c/sub\u003e kill. Notably, this combination demonstrated\u0026thinsp;\u0026ge;\u0026thinsp;2 log\u003csub\u003e10\u003c/sub\u003eCFU/mL reductions at 24 h in the majority of isolates non-susceptible to TMP-SMX and levofloxacin (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e). However, the PK/PD target required to achieve a\u0026thinsp;\u0026ge;\u0026thinsp;1 log bacterial kill has not yet been defined. Clinical experience remains limited to small numbers of patients in trials and case reports (\u003cspan additionalcitationids=\"CR26\" citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e). Although aztreonam/avibactam is now approved in Europe and the United States for certain indications, it is not specifically approved for \u003cem\u003eS. maltophilia\u003c/em\u003e infections. There are several documented cases of the clinical use of the combination of ceftazidime/avibactam with aztreonam to treat \u003cem\u003eS. maltophilia\u003c/em\u003e infections (\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e). Importantly, the aztreonam/ avibactam combination requires a loading dose and has a greater 24-hour dose of avibactam (2 g vs 1.5 g daily) compared with combining ceftazidime/avibactam and aztreonam.\u003c/p\u003e \u003cp\u003eCefepime/zidebactam also demonstrated substantial in vitro activity, with MIC\u003csub\u003e50\u003c/sub\u003e/MIC\u003csub\u003e90\u003c/sub\u003e values consistent with prior reports (\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e). Although cefepime is susceptible to L1 hydrolysis, activity likely reflects the β-lactam enhancer effect of zidebactam through high-affinity PBP2 binding. In the present study, cefepime/zidebactam achieved\u0026thinsp;\u0026ge;\u0026thinsp;3 log\u003csub\u003e10\u003c/sub\u003e CFU reductions in time kill kinetic experiment against isolates with MICs ranging from 4 to 64 mg/L. PK/PD studies indicate that zidebactam-mediated reduction in the requirement of %fT\u0026thinsp;\u0026gt;\u0026thinsp;MIC of cefepime enables coverage of high-MIC strains (up to 64 mg/L) with 2 to 3 log\u003csub\u003e10\u003c/sub\u003e kill (\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e). Although not yet approved for clinical use, these findings support continued clinical development of cefepime/zidebactam for difficult-to-treat \u003cem\u003eS. maltophilia\u003c/em\u003e infections.\u003c/p\u003e \u003cp\u003eIn conclusion, cefiderocol and the combinations of aztreonam/avibactam and cefepime/zidebactam demonstrated promising in vitro activity against contemporary \u003cem\u003eS. maltophilia\u003c/em\u003e clinical isolates, suggesting their potential as alternative therapeutic options, for this difficult-to-treat pathogen. This study also demonstrated that cefepime/zidebactam exhibits potent in vitro bactericidal activity against \u003cem\u003eS. maltophilia\u003c/em\u003e producing L1 metallo-β-lactamase, likely attributable to the beta-lactam enhancer effect of zidebactam rather than direct inhibition of L1. Further clinical evaluation and PK/PD-informed investigations are warranted to define the optimal role of these agents in the management of \u003cem\u003eS. maltophilia\u003c/em\u003e infections.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eDisclosure Statement:\u003c/h2\u003e \u003cp\u003e \u003cb\u003e\u003c/b\u003eNo potential conflict of interest was reported by the author(s).\u003c/p\u003e \u003c/p\u003e\u003cp\u003e \u003ch2\u003eEthics Statement\u003c/h2\u003e \u003cp\u003eThis study was approved by the Institutional Review Board (IRB) of Christian Medical College, Vellore (IRB Min No. 2506123 dated 25.06.2025)\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding:\u003c/h2\u003e \u003cp\u003eNone\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eConceived and designed the analysis: V.R., Y.D.B., B.V. Wrote the paper: V.R., Y.D.B., B.V. Performed the analysis: V.R., Y.D.B., B.A.S., B.R., reviewed the manuscript: V.R., Y.D.B., B.R., B.L., A.M., B.A.S., R.J., E.R.S., K.W., B.V. All authors reviewed the results and approved the final version of the manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgments:\u003c/h2\u003e \u003cp\u003eThe authors thank the Department of Clinical Microbiology, Christian Medical College and Hospital, Vellore, for providing us with all the necessary facilities to conduct our study.\u003c/p\u003e\u003ch2\u003eData availability statement:\u003c/h2\u003e \u003cp\u003eNA\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e \u003cli\u003e\u003cspan\u003eAitken SL, Sahasrabhojane PV, Kontoyiannis DP, Savidge TC, Arias CA, Ajami NJ, Shelburne SA, Galloway-Pe\u0026ntilde;a JR (2021) Alterations of the Oral Microbiome and Cumulative Carbapenem Exposure Are Associated With Stenotrophomonas maltophilia Infection in Patients With Acute Myeloid Leukemia Receiving Chemotherapy. Clin Infect Dis 72(9):1507\u0026ndash;1513\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDadashi M, Hajikhani B, Nazarinejad N, Noorisepehr N, Yazdani S, Hashemi A, Hashemizadeh Z, Goudarzi M, Fatemeh S (2023) Global prevalence and distribution of antibiotic resistance among clinical isolates of Stenotrophomonas maltophilia: A systematic review and meta-analysis. J Glob Antimicrob Resist 34:253\u0026ndash;267\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBrooke JS (2012) Stenotrophomonas maltophilia: an emerging global opportunistic pathogen. Clin Microbiol Rev 25(1):2\u0026ndash;41\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBrooke JS, Di Bonaventura G, Berg G, Martinez JL (2017) Editorial: A Multidisciplinary Look at \u003cem\u003eStenotrophomonas maltophilia\u003c/em\u003e: An Emerging Multi-Drug-Resistant Global Opportunistic Pathogen. Front Microbiol 8:1511\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKo JH, Kang CI, Cornejo-Ju\u0026aacute;rez P, Yeh KM, Wang CH, Cho SY, G\u0026ouml;zel MG, Kim SH, Hsueh PR, Sekiya N, Matsumura Y, Lee DG, Cho SY, Shiratori S, Kim YJ, Chung DR, Peck KR (2019) Fluoroquinolones versus trimethoprim-sulfamethoxazole for the treatment of Stenotrophomonas maltophilia infections: a systematic review and meta-analysis. Clin Microbiol Infect 25(5):546\u0026ndash;554\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChang YT, Lin CY, Chen YH, Hsueh PR (2015) Update on infections caused by Stenotrophomonas maltophilia with particular attention to resistance mechanisms and therapeutic options. Front Microbiol 6:893\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMonardo R, Mojica MF, Ripa M, Aitken SL, Bonomo RA, van Duin D (2025) How do I manage a patient with Stenotrophomonas maltophilia infection? Clin Microbiol Infect 31(8):1291\u0026ndash;1297\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBiagi M, Lamm D, Meyer K, Vialichka A, Jurkovic M, Patel S, Mendes RE, Bulman ZP, Wenzler E (2020) Activity of Aztreonam in Combination with Avibactam, Clavulanate, Relebactam, and Vaborbactam against Multidrug-Resistant Stenotrophomonas maltophilia. Antimicrob Agents Chemother 64(12):e00297\u0026ndash;e00220\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNakamura R, Oota M, Matsumoto S, Sato T, Yamano Y (2021) \u003cem\u003eIn Vitro\u003c/em\u003e Activity and \u003cem\u003eIn Vivo\u003c/em\u003e Efficacy of Cefiderocol against Stenotrophomonas maltophilia. Antimicrob Agents Chemother. ;65(4):e01436-20\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBoattini M, Gaibani P, Comini S, Costa C, Cavallo R, Broccolo F, Bianco G (2025) In vitro activity and resistance mechanisms of novel antimicrobial agents against metallo-β-lactamase producers. Eur J Clin Microbiol Infect Dis 44(5):1041\u0026ndash;1068\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eClinical and Laboratory Standards Institute (2018) M-07- A10, 11th edn. Clinical and Laboratory Standards Institute, Wayne, PA, Methods for dilution antimicrobial susceptibility tests for bacteria that grow aerobically\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eClinical and Laboratory Standards Institute (2025) CLSI supplement M100, 35th edn. Clinical and Laboratory Standards Institute, Wayne, PA, Performance standards for antimicrobial testing\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eClinical and Laboratory Standards Institute. Methods for Determining Bactericidal Activity of Antimicrobial Agents (1999) ; 1st ed; CLSI M26-A. Clinical and Laboratory Standards Institute, Wayne, PA\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBiagi M, Vialichka A, Jurkovic M, Wu T, Shajee A, Lee M, Patel S, Mendes RE, Wenzler E (2020) Activity of Cefiderocol Alone and in Combination with Levofloxacin, Minocycline, Polymyxin B, or Trimethoprim-Sulfamethoxazole against Multidrug-Resistant Stenotrophomonas maltophilia. Antimicrob Agents Chemother 64(9):e00559\u0026ndash;e00520\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSakoh T, Miyajima E, Endo Y, Baba M, Haraguchi M, Morishima M, Ogura S, Kimura M, Araoka H (2024) Cefiderocol susceptibility of 146 Stenotrophomonas maltophilia strains clinically isolated from blood in two Japanese hospitals over a 10-year period. Eur J Clin Microbiol Infect Dis 43(12):2485\u0026ndash;2488\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFratoni AJ, Kuti JL, Nicolau DP (2021) Optimised cefiderocol exposures in a successfully treated critically ill patient with polymicrobial Stenotrophomonas maltophilia bacteraemia and pneumonia receiving continuous venovenous haemodiafiltration. Int J Antimicrob Agents 58(3):106395\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHsu AJ, Simner PJ, Bergman Y, Mathers AJ, Tamma PD (2023) Successful Treatment of Persistent \u003cem\u003eStenotrophomonas maltophilia\u003c/em\u003e Bacteremia With Cefiderocol in an Infant. Open Forum Infect Dis 10(4):ofad174\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eImoto W, Abe J, Sakurai N, Kawamoto K, Yamada K, Kaneko Y, Kakeya H Efficacy of cefiderocol and levofloxacin against \u003cem\u003eStenotrophomonas maltophilia\u003c/em\u003e in a hemorrhagic pneumonia mouse model. Antimicrob Agents Chemother 2026 Jan 30:e0094425\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZappulo E, Grimaldi F, Paolillo R, Pinchera B, Buonomo AR, Picardi M, Catania MR, Pane F, Gentile I (2022) Successful treatment of MDR Stenotrophomonas maltophilia-associated pneumonia with cefiderocol-based regimen in a patient with hematological malignancy. Ann Hematol 101(12):2805\u0026ndash;2806\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKoirala A, Krishnappa B, Banh C, Brandenburg U, Findlay M, Williams PCM (2023) Successful Use of Cefiderocol to Treat a Multidrug-resistant Stenotrophomonas maltophilia Ventilator-associated Pneumonia in an Extremely Preterm Neonate. Pediatr Infect Dis J 42(11):1012\u0026ndash;1016\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBassetti M, Echols R, Matsunaga Y, Ariyasu M, Doi Y, Ferrer R, Lodise TP, Naas T, Niki Y, Paterson DL, Portsmouth S, Torre-Cisneros J, Toyoizumi K, Wunderink RG, Nagata TD (2021) Efficacy and safety of cefiderocol or best available therapy for the treatment of serious infections caused by carbapenem-resistant Gram-negative bacteria (CREDIBLE-CR): a randomised, open-label, multicentre, pathogen-focused, descriptive, phase 3 trial. Lancet Infect Dis 21(2):226\u0026ndash;240\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKullar R, Wenzler E, Alexander J, Goldstein EJC (2022) Overcoming \u003cem\u003eStenotrophomonas maltophilia\u003c/em\u003e Resistance for a More Rational Therapeutic Approach. Open Forum Infect Dis 9(5):ofsac095\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSader HS, Castanheira M, Arends SJR, Doyle TB (2025) Antimicrobial susceptibility of \u003cem\u003eStenotrophomonas maltophilia\u003c/em\u003e from United States medical centers (2019\u0026ndash;2023). Antimicrob Agents Chemother 69(4):e0012425\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSader HS, Duncan LR, Arends SJR, Carvalhaes CG, Castanheira M (2020) Antimicrobial Activity of Aztreonam-Avibactam and Comparator Agents When Tested against a Large Collection of Contemporary Stenotrophomonas maltophilia Isolates from Medical Centers Worldwide. Antimicrob Agents Chemother 64(11):e01433\u0026ndash;e01420\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCarmeli Y, Cisneros JM, Paul M, Daikos GL, Wang M, Torre-Cisneros J, Singer G, Titov I, Gumenchuk I, Zhao Y, Jim\u0026eacute;nez-Rodr\u0026iacute;guez RM, Liang L, Chen G, Pyptiuk O, Aksoy F, Rogers H, Wible M, Arhin FF, Luckey A, Leaney JL, Pypstra R, Chow JW (2025) COMBACTE-CARE consortium REVISIT study group. Aztreonam-avibactam versus meropenem for the treatment of serious infections caused by Gram-negative bacteria (REVISIT): a descriptive, multinational, open-label, phase 3, randomised trial. Lancet Infect Dis 25(2):218\u0026ndash;230\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMojica MF, Ouellette CP, Leber A, Becknell MB, Ardura MI, Perez F, Shimamura M, Bonomo RA, Aitken SL, Shelburne SA (2016) Successful Treatment of Bloodstream Infection Due to Metallo-β-Lactamase-Producing Stenotrophomonas maltophilia in a Renal Transplant Patient. Antimicrob Agents Chemother 60(9):5130\u0026ndash;5134\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDiarra A, Pascal L, Carpentier B, Baclet N, Cabaret P, Georgel AF, Dubreuil L, Weyrich P (2021) Successful use of avibactam and aztreonam combination for a multiresistant Stenotrophomonas maltophilia bloodstream infection in a patient with idiopathic medullary aplasia. Infect Dis Now 51(7):637\u0026ndash;638\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAlghamdi AO, Algethami AS, Aljuaeed MS, Alkhammash FM, Almalki FM, Alharthi SA, Aljaed NM, Abosabie SA, Abosabie SA, Kamal NM (2025) Successful dual therapy of aztreonam and ceftazidime-avibactam for multidrug-resistant \u003cem\u003eStenotrophomonas maltophilia\u003c/em\u003e infection in a preterm neonate: A life-saving approach. J Int Med Res 53(12):3000605251353486\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCowart MC, Ferguson CL (2021) Optimization of Aztreonam in Combination With Ceftazidime/Avibactam in a Cystic Fibrosis Patient With Chronic Stenotrophomonas maltophilia Pneumonia Using Therapeutic Drug Monitoring: A Case Study. Ther Drug Monit 43(2):146\u0026ndash;149\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSader HS, Mendes RE, Duncan LR, Carvalhaes CG, Castanheria M (2022) Antimicrobial activity of cefepime/zidebactam (WCK 5222), a β-lactam/β-lactam enhancer combination, against clinical isolates of Gram-negative bacteria collected worldwide (2018-19). J Antimicrob Chemother 77(10):2642\u0026ndash;2649\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKidd JM, Abdelraouf K, Nicolau DP (2020) Efficacy of human-simulated bronchopulmonary exposures of cefepime, zidebactam and the combination (WCK 5222) against MDR Pseudomonas aeruginosa in a neutropenic murine pneumonia model. J Antimicrob Chemother 75(1):149\u0026ndash;155\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Stenotrophomonas maltophilia, Antimicrobial Resistance, Cefepime/zidebactam, Azteronam/avibactam, Cefiderocol, PK/PD, Clinical Failures","lastPublishedDoi":"10.21203/rs.3.rs-8927701/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8927701/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003ePurpose:\u003c/h2\u003e \u003cp\u003eTo evaluate the in vitro activity of cefiderocol, aztreonam/avibactam, and cefepime/zidebactam against contemporary clinical \u003cem\u003eStenotrophomonas maltophilia\u003c/em\u003e isolates and to assess bactericidal activity using time-kill analyses.\u003c/p\u003e\u003ch2\u003eMethods:\u003c/h2\u003e \u003cp\u003eA total of 216 nonduplicate clinical \u003cem\u003eS. maltophilia\u003c/em\u003e isolates collected between 2018 and 2024 from five tertiary care hospitals in India, were studied. MICs of trimethoprim/sulfamethoxazole (TMP-SMX), levofloxacin, minocycline, cefiderocol, aztreonam/avibactam, and cefepime/zidebactam were determined by broth microdilution according to CLSI guidelines. Cefiderocol was tested in iron-depleted cation-adjusted Mueller\u0026ndash;Hinton broth. Aztreonam/avibactam was tested with avibactam at 4 mg/L, and cefepime/zidebactam at a 1:1 ratio. PK/PD breakpoints of \u0026le;\u0026thinsp;8 mg/L and \u0026le;\u0026thinsp;64 mg/L were applied for aztreonam/avibactam and cefepime/zidebactam, respectively. Time\u0026ndash;kill assays were performed at 1\u0026times; MIC against two representative isolates and ten additional isolates spanning cefepime/zidebactam MICs of 4\u0026ndash;64 mg/L.\u003c/p\u003e\u003ch2\u003eResults:\u003c/h2\u003e \u003cp\u003eCefiderocol inhibited 96.8% of isolates at MICs\u0026thinsp;\u0026le;\u0026thinsp;1 mg/L (MIC50/MIC90\u0026thinsp;\u0026le;\u0026thinsp;0.12/1 mg/L). Susceptibility rates were 95.8% for aztreonam/avibactam and 99.5% for cefepime/zidebactam. TMP-SMX and levofloxacin each inhibited 91.7% of isolates, while minocycline susceptibility was 92.6%. The three novel agents retained activity against most isolates non-susceptible to comparators. In time\u0026ndash;kill assays, cefiderocol, aztreonam/avibactam, and cefepime/zidebactam achieved\u0026thinsp;\u0026ge;\u0026thinsp;3-log10 CFU/mL reductions, including isolates with cefepime/zidebactam MICs up to 64 mg/L. Minocycline did not demonstrate bactericidal activity.\u003c/p\u003e\u003ch2\u003eConclusions:\u003c/h2\u003e \u003cp\u003eCefiderocol, aztreonam/avibactam, and cefepime/zidebactam demonstrated potent in vitro activity against contemporary \u003cem\u003eS. maltophilia\u003c/em\u003e isolates. These findings support further PK/PD-informed clinical evaluation of these agents for difficult-to-treat \u003cem\u003eS. maltophilia\u003c/em\u003e infections.\u003c/p\u003e","manuscriptTitle":"Strategies to overcome intrinsic resistance in Stenotrophomonas maltophilia: In vitro activity of aztreonam/avibactam, cefiderocol, and cefepime–zidebactam","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-09 21:03:49","doi":"10.21203/rs.3.rs-8927701/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"6eca0f77-8ca2-420c-a6a3-8ab3e47c2c35","owner":[],"postedDate":"March 9th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-03-22T17:39:33+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-09 21:03:49","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8927701","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8927701","identity":"rs-8927701","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}