Potential Origins of Acute Surgical Site Infections in Non-Traumatic Orthopedic Surgery - a Single-Center Prospective Evaluation

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Lüer, David Albrecht, Pascal R. Furrer, Alexandre Ansorge, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6541947/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 Background: In orthopedic surgery, we overlook the proportion of surgical site infections (SSI) acquired Intra- versus postoperative. A better overview would help to allocate resources for infection control instead of solely aiming for the perioperative period. Methods: We make use of prospective our database composed of four prospective-randomized clinical interventional trials and surveillance registers and concentrate on acute SSIs. We evaluate each SSIs clinically by searching medical and nursing notes for potential postoperative events that could plausibly cause a postoperative acquisition of bacteria. Results: Among 370 cases, we estimated 241 SSIs (65%) to be acquired intraoperatively, and 129 (35%) postoperatively. There was a clear gradient from the shoulder to the (diabetic) foot, with the shoulder yielding the highest plausible part of intraoperative SSIs (93%) and the foot the least (29%). By excluding foot SSIs, the proportion of estimated intraoperative SSIs rose to 83% (204/242 cases). The three most frequent reasons for postoperative SSIs were wound debridement immediately preceding infection, skin breakdowns and local surgical complications of various reasons (hematoma, dehiscence), and necrosis with a high proportion of polymicrobial foot SSIs among the postoperative origins. In contrast, hematogenous SSIs were rare (3%) and intraoperative SSIs were more often due to skin commensals. Conclusions: According to our prospective clinical evaluation, one-third of acute orthopedic SSIs were related with a postoperative complication that could potentially be the cause of SSI. By excluding adult (diabetic) foot surgeries, this postoperative proportion is reduced to one-sixth. Aside from reviewing the initial surgical justifications in high-risk patients and promoting (hand) hygiene, we require additional preventative treatments for the initial postoperative period. Clinical Trial Numbers: NCT05502380, NCT04081792, NCT05647252, NCT04048304. surgical site infection orthopedic surgery origin postoperative care prospective Figures Figure 1 Introduction The incidence of SSIs in adult elective orthopedic surgery is approximately 1-3% [1]. Among many measures to prevent SSI, only some are based on strong evidence [1]. These few measures apply to "standard" patients and primarily target SSIs that are acquired intraoperatively. Until now, the bulk of SSI pathogens is believed to be acquired during the index surgery [1]. At the same time, our patient population is changing. We witness a steadily increase of multi-morbid, immune-suppressed, malnourished, elder and frail patients undergoing (revision) surgeries [2]. These patients usually yield multiple chronic co-morbidities and additional risks for other HAIs, including UTIs and PNEUs [3]; together with a potentially higher risk of more antibiotic-resistant infections among the causative pathogens [4]. Additional entry ports of bacteria are not only of academic interests. Infection control teams might more frequently allocate resources towards the postoperative period; especially when the multimodal "bundled" interventions targeting the perioperative period have been implemented and maintained. To cite examples, post-anesthesiologic urinary catheters can be associated with postsurgical UTI and (Gram-negative) SSIs after lumbar surgery (regardless of concomitant symptomatic UTI) [5]. Secondary SSIs can also be caused by wound dehiscence, ischemia [6], material failures, steroid administration, blood transfusions, hematoma, lack of patient's compliance (e.g. regarding off-loading and wound care), bacterial pneumonia or even systemic viral infections such as nosocomial SARS-CoV-2 [7]. Almost every substantial post-operative complication indirectly rises the risk for SSIs [1]. However, most of this experience remain unreported or bases on retrospective trials. In this study, we are interested in the plausible origins and the postoperative epidemiology of adult orthopedic SSIs; nota bene to diverse our interventions instead of merely focusing on the operation theatre. Methods Setting and study period The Balgrist University Hospital is a tertiary orthopedic center with a prospective surveillance of all infections since July 2018. For this study, we included the last SSI episode on 1 July 2014 and closed the composite database on 31 December 2024. During this study, five major interventions occurred in our wards which might interfere with the origins of SSI. These were the official Covid-19 lockdown in spring 2020 [8], a large hand hygiene campaign 2023-2024 [9], a prospective-randomized trial targeting the preoperative nasal and skin decolonization in high-risk patients [10] (February 2023 to November 2024), a trial on perioperative broad-spectrum antibiotic prophylaxis (October 2022 to November 2024) [11], and a computer-based intervention to reduce the use of urinary catheters and UTIs since March 2023 [12]. Throughout the study period, the routine perioperative antibiotic prophylaxis consisted of cefuroxime 1.5 g parentally (double-dose in obesity) [13]. So far, we do not use negative-pressure devices for preventive purposes [14]. There was no trial for dressings [15] or antibiotic-containing devices. Study definitions, criteria and identification of surgical site infections An orthopedic surgeon (PSL) and an ID physician specialized in orthopedic infections (IU) reviewed all SSIs in a composite Excel ™ database. We identified SSIs on clinical, radiological and microbiological criteria [3,5,10,11,16-20] that were crosschecked by members of the Infection Control Team (NBH, DB, TS) and by research nurses of the Unit for Clinical and Applied Research, who run several prospective-randomized trials [10,11,16-18]. Many patients also participate in the SwissNOSO surveillance and in the SIRIS (Swiss Implant) register that served as controls. We excluded episodes due to a factitious disorder or similar psychological entities and SSI due to very unusual pathogen groups such as mycobacteria, virus or fungi. The definition of antibiotic (multi)-resistance was in line with the requirement of contact isolation according to SwissNOSO recommendations [21]. Interpretation of the origin of surgical site infections The clinical interpretation of the patient’s individual history was the most important parameter of interpretation, followed by the microbiological results. Plausibility primed on formal SSI definitions (i.e. SSIs for soft tissue surgeries within thirty days and one year for implants [18-21]). We divided our certainty into two degrees: “sure” and “probably”. If we failed to find a plausible postoperative origin, we classified the SSI as intraoperatively-acquired by default. For example, when an arthroplasty witnessed urosepsis one month after implantation (e.g., because of urinary catheterization), we considered the origin as postoperatively acquired (urinary/hematogenous), if the pathogens were Gram-negative, or intraoperatively acquired if the microorganisms of SSIs were coagulase-negative staphylococci. Likewise, steroid injections in the operated spine with consecutive local infection would count as a "postoperative SSIs", even if surgery was recent. An infection due to patients' malcompliance (e.g., sabotage of off-loading), would be attributed to a postoperative origin. Regarding the special group of SSIs occurring after diabetic foot surgery, we focused on the last intervention before the immediate onset of SSI. We considered SSI that immediately occurring after invasive wound debridement as possibly postoperatively-acquired, while those without invasive immediate prior debridement were classified as intraoperative SSIs. Statistical analyses The primary objective was the plausible origins of various SSIs. The Pearson-ꭓ 2 -test compared between possible intra- and postoperative SSI origins. Few missing data were not imputated. Episodes with substantial missing data were excluded. We used STATA ™ software (Version. 18, College Station, USA) and considered p -values ≤0.05 (two-tailed) as significant. Results Surgical site infections Among 2816 infection episodes reported during the study period 2018 to 2024, we kept 370 as acute (deep) SSIs and proceeded with further analyses. The rest of the reported infections did not concern orthopedic surgery, were community-acquired, or represented contaminations, colonization, or SSI episodes with incomplete or divergent histories, or were attributed to other centers. Among the remaining 370 SSI episodes in our database, 38 involved orthopedic foot surgery, 90 diabetic foot surgery, 40 hip, 54 knee, and 45 spine-related surgeries. The rest involved other interventions, including hand, shoulder, extremity surgery or combined surgeries, e.g. with SSIs of the iliac crest harvesting site [22] or of flaps. Half of the SSIs (174/370; 47%) were predominantly implant-related with lesser degree of soft-tissue infections, of which 77 were PJIs. Regarding the other half, the soft-tissue and bone involvement clinically predominated over the implant contamination. The median time delay between index surgery and the first surgical debridement was 29 days (interquartile range, 15-56 d). Our final study population primarily consisted of acute, pyogenic SSIs, whereas late or low-grade SSI have been excluded by our study criteria due to lack of sufficient documentation or patient's history. Pathogens We retrieved 136 microbiological SSI constellations; with 96 (26%) polymicrobial SSIs and 78 (21%) primarily due to Gram-negative bacteria. Among the 246 (66%) predominant Gram-positive SSIs, we noticed 123(..%) Staphylococcus aureus SSIs and associated 103(..5) episodes with skin commensals (e.g. cutibacteria, coagulase-negative staphylococci or corynebacteria). Overall, 28 SSIs (8%) were bacteremic, 134 (36%) resistant to the prior antibiotic prophylaxis (cefuroxime), and 13 (4%) multidrug-resistant. Figure 1 resumes the ten frequent pathogens. Epidemiology of the origins We were certain in 212 episodes (57%) or estimated the SSI origin with less probability in 43%. Overall, we would classify 241 SSI episodes (241/375; 65%) as intraoperatively-acquired, and 129 (35%) cases as postoperative. We were more certain regarding intraoperative SSIs (171/241 (71%) vs. 41/129 (32%); p <0.001). Anatomically, we noted postoperative-related SSI in lower body parts. There was a clear gradient from the shoulder to the diabetic foot, with the shoulder yielding the highest part of intraoperative SSIs (13/14; 93%), and foot surgery the least (29%). Especially for the (ischemic) diabetic foot, the proportion of postoperative SSI was four times higher than the presumed intraoperative origins (81% vs. 19%, respectively). By excluding all foot SSIs, the overall proportion of estimated intraoperative SSIs rose to 83% (204/242 cases). Table 1 summarizes our plausible origins, while Table 2 compares them. The Supplementary Appendix 1 separately provides the most important variables. The three most frequent origins of postoperative SSI were wound debridement, new ulcers, and/or wound (flap) necrosis (Table 1). The comparison between these two origin groups revealed a significant predominance of foot and polymicrobial infections among postoperative origins, whereas intraoperative SSIs typically yield skin commensals as the causal pathogens (Table 2). Lastly, we saw 14 SSI episodes with a significant complication in the postoperative period, which we attributed to an intraoperative origin, mostly because of history and pathogens were incompatible with a plausible postoperative origin: dental intervention (n=1), postoperative debridement (2), urosepsis (2), open fractures (2), intravenous drug abuse (1), pneumonia (1), wound discharge (1), trauma (1), necrosis (1), and oncologic chemotherapy (1). Table 1. Plausible origins of SSIs. Descriptive statistics with frequencies . Intraoperative origin of SSI 241 (65%) Postoperative origin of SSI 129 (35%) - Iterative debridement of (yet) uninfected wound 61 (16%) - New foot ulcers 14 (3%) - Secondary wound or flap necrosis 10 (3%) - Hematogenous from gastrointestinal source 10 (3%) - Hematogenous from urinary (catheter) source 3 (1%) - Hematogenous from cutaneous source (decubitus) 1 (0.3%) - PIN-tract infection spreading into deep layers 9 (2%) - Mechanical postoperative wound trauma 6 (2%) - Wound dehiscence and scar problems 6 (2%) - Large hematoma 5 (2%) - Large seroma 2 (1%) Table 2. Differences between intra- and postoperative SSIs stratified upon infections. Pearson-ꭓ 2 -tests*. Probably postoperative n = 129 Groups (strata) analyzed Probably intraoperative n = 241 p -values* median 34 days Time since index surgery median 28 days 0.68 22 (17%) Arthroplasties 55 (23%) 0.19 91 (71%) Foot surgery 37 (15%) 0.01 9 (7%) Bacteremia-associated 19 (8%) 0.75 42 (41%) Polymicrobial infections 54 (24%) 0.01 74 (72%) Gram-positive pathogens 172 (78%) 0.24 17 (17%) Skin commensals° 86 (39%) 0.01 29 (28%) Gram-negative pathogens 49 (22%) 0.24 3 (3%) Multidrug-resistance 10 (5%) 0.49 44 (43%) Prophylaxis-resistant (Cefuroxime-resistance) 90 (41%) 0.73 ° Skin commensals: e.g. coagulase-negative staphylococci, cutibacteria, corynebacteria, clostridia, Bacillus spp. Discussion In our single-center for elective adult orthopedic surgery, we plausibly estimate one-third of all formal acute SSIs being acquired (originating) during surgery. When excluding with (diabetic) foot surgery, this postoperative proportion becomes one-sixth and the intraoperative part 83%. We thus confirm the expert opinion stating that the majority of SSI are presumably acquired intraoperatively; but maybe to a lesser extent than we previously anticipated. Existing literature concentrates on intraoperative risks and perioperative interventions. Even recent publications and preventive trials prefer to target pre- and risks. Clinically, the antibiotic prophylaxis [11,23], the self-reported compliance of surgeons (only pre- and intraoperatively) [24], the increasing number of surgical skill labs, or the preoperative decolonization [10,25,26], all concentrate on the peri-, or preoperative period. Indeed, prospective trials on decolonization do not extend beyond the postoperative phase, although postoperative new wound problems would occur frequently in orthopedic surgery [27]. Similarly, bundled interventions often neglect the postoperative period [28]. Regarding the postoperative period, guidelines [18-20] and expert opinions are often limited to improve hand hygiene [9,29] and to enhance “asepsis” during dressing change [15]. Exceptionally, some research groups report a protective benefit of negative-pressure technology for preventive purposes in selected patients [14]. International guidelines state by resigning that " There is a lack of high-quality studies comparing various strategies of postoperative wound management…. This is an area for further research " [19]. Pre- or perioperative prevention might not be enough, especially when “intraoperative” measures [1] have been maxed out, and the clinicians would only expect a slight improvement of prevention just by adding supplementary efforts into the “intraoperative“ axis. We think that our relatively high proportion of postoperative SSIs needs further attention. However, and theoretically, the various aspects of postoperative prevention are more resource--consuming than only focusing on perioperative measures. They will involve a higher number of HCWs and medical disciplines, and a longer intervention compared to the relatively short duration of the surgical intervention. Moreover, postoperative interventions take place in environments that cannot compete with the “aseptic” operation theatre in terms of infection control. The literature on postoperative orthopedic SSIs is sparse. Originally and according to early expert opinion, this literature mostly consisted of hematogenous PJIs representing up to one-quarter of all arthroplasty SSIs in selected studies [30]. Hematogenous hip PJI might occur earlier than hematogenous knee PJIs [31]. Other (smaller) implants, such as plates or nails, are quasi exempt from a hematogenous seeding from a remote infection source. In recent literature, the risk of hematogenous seeding is much lower than the risk of “intraoperative” PJIs becoming bacteremic. A retrospective cohort identified that only 1 of 79 severe remote infections would become bacteremic and seed to total joint arthroplasties [31]. A Swedish study assessed the incidence for hematogenous PJI in case of Gram-positive bacteremia . This risk was only 6% [32]. Sometimes the origin of hematogenous PJIS may remain occult. If the origin cannot be elucidated through history, a blind (radiological) and laboratory search is ineffective and costly [33]. The majority of the postoperative SSI acquisitions occur locally and are due to two major groups of postsurgical problems: wound breakdowns (ischemia [6], trauma, hematoma, dehiscence, seroma [27]) and patient’s malcompliance in its various forms (e.g. unrest against medical order [34], smoking [35], or malnutrition [36,37]). A wound breakdown is frequent. According to a prospective observation during one year in Geneva, only 40% of freshly operated orthopedic wounds yielded no clinical problems [27]. In that study, among 1,073 adult orthopedic patients, 630 operated episodes (59%) showed relevant postoperative wound complications, leading to a significantly longer hospital stay compared to patients without complications. The most frequent wound complications were serous discharge with dehiscence (41%) and hematoma (35%) [27]. Wound dehiscence due to malcompliance remains a major problem. To cite an own example, a study randomizing operation techniques for septic bursitis, identified the lack of compliance (together with psychiatric conditions) as an important reason for failure (and infection recurrence) [34]. Other breakdowns occur after postsurgical debridement or because of wound necrosis in ischemic patients such as in diabetic foot syndromes. Finally, there are PIN-tract [1] infections in orthopedic surgery of the lower extremities, especially on the toes. PINs and wires cross the skin and are kept in place during weeks. In these situations, the reason for SSI could be a wrong surgical indication for elective surgery, or, most likely, unintended shortcomings in hand hygiene [29] during professional (or less experienced) wound care [15]. Our observation study has strengths and limitations. The main strength is a prospective work-up of each attributed SSI case by judging upon playabilities of the individual patient's histories. The main limitations are multiple: i) The subjective evolution of the origins. ii) Mild superficial and late (low-grade) SSIs, which were not revised, might have gone unnoticed. iii) This is a pilot observation. We do not report intervention. Infection Control encompasses many other HAI groups and antibiotic resistances [38], which we could not evaluate in this study with very few multidrug-resistant pathogens. Indeed, operated patients reveal the same proportion of other HAIs as non-operated patients, with 5% SSIs in addition [3]. v) Lastly, our observation only concerns adult orthopedic surgery. In other disciplines with less superficial wounds, e.g. abdominal laparoscopy, the epidemiology of postoperative SSIs might be completely different. Conclusions When prospectively investigating the origin of adult orthopedic SSIs, between 17% and 35% of postoperative infections were presumably acquired after the surgical intervention; especially after (diabetic) foot surgery. In terms of prevention, pre- and intra-operative measures remain should be addressed first. But not exclusively. The proportion of postoperatively-acquired SSI is substantial and needs attention. Their preventions are diverse and include clinical teams not involved in the first treatment of the patient. Revising the indication for index surgery, a better wound care, and improved compliance among patients and HCWs regarding all aspects of HAIs, are probably most likely to be beneficiary for the postoperative SSI prevention. Abbreviations SSI Surgical site infections HAI Healthcare-associated infections PJI Prosthetic joint infections UTI Urinary tract infection PNEU Healthcare-associated bacterial pneumonia HCW Healthcare workers GP General practitioner ID Infectious Diseases Declarations Ethics approval and consent to participate This project (Wissenschaftsnummer 1070) bases on a composite database from the following active prospective-randomized trials at the Balgrist University Hospital: BASEC 2022-00800 [11], 2019-00778 [17], 2021-00137 [5], 2023–00095 [10], and 2019-00646 [16]. The corresponding Clinical Trial Numbers (ClinicalTrials.gov) are NCT05502380, NCT04081792, NCT05647252, and NCT04048304, respectively. Additionally, participating patients signed an Institutional General Informed Consent validated by the Ethical Committee of Zurich Canton. Consent for publication Patients consented for publication of this side study by participating in prospective-randomized trials and by signing a General Informed Consent Form providing their medical data. Availability of data and materials We may provide anonymized key data upon reasonable scientific request to the corresponding author. Supplementary Appendix 1 is a summary of the study database. Competing interests All authors declare no competing interests. Funding This research received no external funding. Author Contributions Conceptualization: NK, PLS, and IU. Methodology: PLS, NK, TG, LSB, and IU. Validation: PLS, LSB, AA and IU. Data collection: PLS, DB, DA, PRF, AV, NK, TG, AA, and IU. Data analysis: PLS. LSB, DB and IU; Analysis verification: DA, AA, DB and IU. Writing: original draft preparation, PLS and IU. Writing- review and editing: IU and MF. Supervision: NK, TG, IU, and MF. All authors have agreed to the published version of the manuscript. Doctor thesis This research is part of a Doctoral Thesis (PLS), supervised by IU and MF. Acknowledgements We thank to all colleagues of the Institut für Medizinische Mikrobiologie (IMM) at the University of Zurich and to the Unit of Clinical and Applied Research of the Balgrist University Hospital. We are indebted to Ms. Jasna Plesko Martinelli and Ms. Nadja Bragatto-Hess from Infection Control Unit for their invaluable help during the surveillance period. References Uçkay I, Harbarth S, Peter R, Lew D, Hoffmeyer P, Pittet D. Preventing surgical site infections. Expert Rev Anti Infect Ther. 2010;8(6):657-70. Uçkay I, Holy D, Betz M, Sauer R, Huber T, Burkhard J. Osteoarticular infections: a specific program for older patients? 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Sax H, Uçkay I, Richet H, Allegranzi B, Pittet D. Determinants of good adherence to hand hygiene among healthcare workers who have extensive exposure to hand hygiene campaigns. Infect Control Hosp Epidemiol. 2007;28(11):1267-74. Vu DL, Uçkay I, Gonzalez A, Rohner P, Hoffmeyer P, Lübbeke A. Factors related to outcome of early and delayed prosthetic joint infections. J Infect. 2016;72(2):255-7. Uçkay I, Lübbeke A, Emonet S, Tovmirzaeva L, Stern R, Ferry T, Assal M, Bernard L, Lew D, Hoffmeyer P. Low incidence of haematogenous seeding to total hip and knee prostheses in patients with remote infections. J Infect. 2009;59(5):337-45. Thompson O, Påhlman LI. Frequency of haematogenous periprosthetic joint infection due to bacteraemia caused by gram-positive cocci. Infect Dis (Lond). 2025:1-7. Bouvet C, Tchernin D, Seirafi M, Stern R, Lew D, Hoffmeyer P, Uçkay I. No need to search for the source of haematogenous arthroplasty infections. Swiss Med Wkly. 2011:141:13306. Uçkay I, von Dach E, Perez C, Agostinho A, Garnerin P, Lipsky BA, Hoffmeyer P, Pittet D. One- vs 2-Stage Bursectomy for Septic Olecranon and Prepatellar Bursitis: A Prospective Randomized Trial. Mayo Clin Proc. 2017;92(7):1061-9. Gonzalez AI, Luime JJ, Uçkay I, Hannouche D, Hoffmeyer P, Lübbeke A. Is There an Association Between Smoking Status and Prosthetic Joint Infection After Primary Total Joint Arthroplasty? J Arthroplasty. 2018;33(7):2218-24. Zhang D, Zhang X. Effect of serologic malnutrition on postoperative wound infection problems after total joint arthroplasty: A meta‐analysis. Int Wound J. 2022;20(2):261-8. Uçkay I, Yogarasa V, Waibel FWA, Seiler-Bänziger A, Kuhn M, Sahli M, Berli MC, Lipsky BA, Schöni M. Nutritional Interventions May Improve Outcomes of Patients Operated on for Diabetic Foot Infections: A Single-Center Case-Control Study. J Diabetes Res. 2022: 2022:9546144. Muhamad AN, Teh CSJ, Draman MR, Adnan YK, Abbas AA, Khong TL, Narayanan V, Tang SN, Karunakaran R, Manan NA, Kukreja A, Razali SZM, Cham CY, Hontz RD, Gregory MJ, Selariu A, Nguyen HC, Letizia AG, Ponnampalavanar SSS. High incidence of multidrug-resistant organisms and modifiable risk factors associated with surgical site infections: a cohort study in a tertiary medical center in Kuala Lumpur, Malaysia from 2020 to 2023. Antimicrob Resist Infect Control. 2025;14(1):22. Additional Declarations No competing interests reported. Supplementary Files SupplementaryAppendix1.pdf 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-6541947","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":517940880,"identity":"a63a1e92-9a4c-4985-a3cc-3ccd03823cf5","order_by":0,"name":"Philipp S. Lüer","email":"","orcid":"","institution":"Balgrist University Hospital","correspondingAuthor":false,"prefix":"","firstName":"Philipp","middleName":"S.","lastName":"Lüer","suffix":""},{"id":517940881,"identity":"7d793b73-a990-4393-9ad0-489990b6096e","order_by":1,"name":"David Albrecht","email":"","orcid":"","institution":"Balgrist University Hospital","correspondingAuthor":false,"prefix":"","firstName":"David","middleName":"","lastName":"Albrecht","suffix":""},{"id":517940882,"identity":"19f71719-0a86-42db-8c60-3d583c387102","order_by":2,"name":"Pascal R. Furrer","email":"","orcid":"","institution":"Balgrist University Hospital","correspondingAuthor":false,"prefix":"","firstName":"Pascal","middleName":"R.","lastName":"Furrer","suffix":""},{"id":517940883,"identity":"3fb4bfeb-8b59-4c43-aa4f-62264442e490","order_by":3,"name":"Alexandre Ansorge","email":"","orcid":"","institution":"Balgrist University Hospital","correspondingAuthor":false,"prefix":"","firstName":"Alexandre","middleName":"","lastName":"Ansorge","suffix":""},{"id":517940884,"identity":"dd44e97e-ea87-4e17-ac98-44b779a09356","order_by":4,"name":"Nathalie Kühne","email":"","orcid":"","institution":"Balgrist University Hospital","correspondingAuthor":false,"prefix":"","firstName":"Nathalie","middleName":"","lastName":"Kühne","suffix":""},{"id":517940885,"identity":"5c85b57f-027d-4b33-97b1-dac59e7650f0","order_by":5,"name":"Denise Baumgartner","email":"","orcid":"","institution":"Balgrist University Hospital","correspondingAuthor":false,"prefix":"","firstName":"Denise","middleName":"","lastName":"Baumgartner","suffix":""},{"id":517940886,"identity":"c406f29b-a69d-4107-9c58-a58c7c7496d1","order_by":6,"name":"Mazda Farshad","email":"","orcid":"","institution":"Balgrist University Hospital","correspondingAuthor":false,"prefix":"","firstName":"Mazda","middleName":"","lastName":"Farshad","suffix":""},{"id":517940887,"identity":"dd992cdd-91e7-4859-b8cd-2c2272321241","order_by":7,"name":"Ilker Uçkay","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABBElEQVRIiWNgGAWjYBACNnY2CEOCgYHxMQODBQMDM5h/ALcWZoQWZmMIxcDYgE8LA5IWNmkwxUBACx8zW+LjCobD8pLtZ8yqC2ok7La3sz9/wFBzB5/DDhueYThsOJsnx+z2jGMSyXMO8xg2MBx7hkcLe5tkA8PhBDkGoBYeNolkCWYexgbGhsP4tLT/BGvhf2NWzPMPpIX9IQEtbMcYQVqkJXLMmHnbJOwkmBkMCWlJlmwwSDecOeNZsfTMPokEoMMMZyQcw61Fvr3N8GNDhbW8xPnkjZ8LvtnYS/Aff/DhQw1uLRBgACI4wGRiA4hMIKABCtgfgEh74hSPglEwCkbBSAIAu9pJayKFWA0AAAAASUVORK5CYII=","orcid":"","institution":"Balgrist University Hospital","correspondingAuthor":true,"prefix":"","firstName":"Ilker","middleName":"","lastName":"Uçkay","suffix":""}],"badges":[],"createdAt":"2025-04-27 18:08:14","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6541947/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6541947/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":91960676,"identity":"f4cb7568-5ee2-4577-99da-0a768ea81236","added_by":"auto","created_at":"2025-09-23 07:47:55","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":71703,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ePredominant pathogens of orthopedic surgical site infections.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-6541947/v1/4aad612b76bc857f78c89c46.png"},{"id":100951489,"identity":"f9d1194e-f774-41d2-8082-9da7b08093d8","added_by":"auto","created_at":"2026-01-23 07:10:40","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":666347,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6541947/v1/c35482fa-9dab-4aca-99b9-e2efc54dfaa4.pdf"},{"id":91960677,"identity":"13667b81-53e7-43e7-b7e2-6501d00398ac","added_by":"auto","created_at":"2025-09-23 07:47:55","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":172286,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementaryAppendix1.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6541947/v1/8642c9aa12e2b14a7713a528.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Potential Origins of Acute Surgical Site Infections in Non-Traumatic Orthopedic Surgery - a Single-Center Prospective Evaluation","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe incidence of SSIs in adult elective orthopedic surgery\u0026nbsp;is approximately 1-3% [1]. Among many measures to prevent SSI, only some are based on strong evidence [1]. These few measures apply to \"standard\" patients and primarily target SSIs that are acquired intraoperatively. Until now, the bulk of SSI pathogens is believed to be acquired during the index surgery [1]. At the same time, our patient population is changing. We witness a steadily increase of multi-morbid, immune-suppressed, malnourished, elder and frail patients undergoing (revision) surgeries [2]. These patients usually yield multiple chronic co-morbidities and additional risks for other HAIs, including UTIs and PNEUs [3]; together with a potentially higher risk of more antibiotic-resistant infections among the causative pathogens [4].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAdditional entry ports of bacteria are not only of academic interests. Infection control teams might more frequently allocate resources towards the postoperative period; especially when the multimodal \"bundled\" interventions targeting the perioperative period have been implemented and maintained. To cite examples, post-anesthesiologic urinary catheters can be associated with postsurgical UTI and (Gram-negative) SSIs after lumbar surgery (regardless of concomitant symptomatic UTI) [5]. Secondary SSIs can also be caused by wound dehiscence, ischemia [6], material failures, steroid administration, blood transfusions, hematoma, lack of patient's compliance (e.g. regarding off-loading and wound care), bacterial pneumonia or even systemic viral infections such as nosocomial SARS-CoV-2 [7]. Almost every substantial post-operative complication indirectly rises the risk for SSIs [1]. However, most of this experience remain unreported or bases on retrospective trials. In this study, we are interested in the plausible origins and the postoperative epidemiology of adult orthopedic SSIs; \u003cem\u003enota bene\u0026nbsp;\u003c/em\u003eto diverse our interventions instead of merely focusing on the operation theatre.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e\u003cem\u003eSetting and study period\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe Balgrist University Hospital is a tertiary orthopedic center with a prospective surveillance of all infections since July 2018. For this study, we included the last SSI episode on 1 July 2014 and closed the composite database on 31 December 2024. During this study, five major interventions occurred in our wards which might interfere with the origins of SSI. These were the official Covid-19 lockdown in spring 2020 [8], a large hand hygiene campaign 2023-2024 [9], a prospective-randomized trial targeting the preoperative nasal and skin decolonization in high-risk patients [10] (February 2023 to November 2024), a trial on perioperative broad-spectrum antibiotic prophylaxis (October 2022 to November 2024) [11], and a computer-based intervention to reduce the use of urinary catheters and UTIs since March 2023 [12]. Throughout the study period, the routine perioperative antibiotic prophylaxis consisted of cefuroxime 1.5 g parentally (double-dose in obesity) [13]. So far, we do not use negative-pressure devices for preventive purposes [14]. There was no trial for dressings [15] or antibiotic-containing devices.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eStudy definitions, criteria and identification of surgical site infections\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eAn orthopedic surgeon (PSL) and an ID physician specialized in orthopedic infections (IU) reviewed all SSIs in a composite Excel\u003csup\u003e™\u003c/sup\u003e database. We identified SSIs on clinical, radiological and microbiological criteria [3,5,10,11,16-20] that were crosschecked by members of the Infection Control Team (NBH, DB, TS) and by research nurses of the Unit for Clinical and Applied Research, who run several prospective-randomized trials [10,11,16-18]. Many patients also participate in the \u003cem\u003eSwissNOSO\u003c/em\u003e surveillance and in the SIRIS (Swiss Implant) register that served as controls. We excluded episodes due to a factitious disorder or similar psychological entities and SSI due to very unusual pathogen groups such as mycobacteria, virus or fungi. The definition of antibiotic (multi)-resistance was in line with the requirement of contact isolation according to \u003cem\u003eSwissNOSO\u003c/em\u003e recommendations [21].\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eInterpretation of the origin of surgical site infections\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe clinical interpretation of the patient’s individual history was the most important parameter of interpretation, followed by the microbiological results. Plausibility primed on formal SSI definitions (i.e. SSIs for soft tissue surgeries within thirty days and one year for implants [18-21]). We divided our certainty into two degrees: “sure” and “probably”. If we failed to find a plausible postoperative origin, we classified the SSI as intraoperatively-acquired by default. For example, when an arthroplasty witnessed urosepsis one month after implantation (e.g., because of urinary catheterization), we considered the origin as postoperatively acquired (urinary/hematogenous), if the pathogens were Gram-negative, or intraoperatively acquired if the microorganisms of SSIs were coagulase-negative staphylococci. Likewise, steroid injections in the operated spine with consecutive local infection would count as a \"postoperative SSIs\", even if surgery was recent. An infection due to patients' malcompliance (e.g., sabotage of off-loading), would be attributed to a postoperative origin. Regarding the special group of SSIs occurring after diabetic foot surgery, we focused on the last intervention before the immediate onset of SSI. We considered SSI that immediately occurring after invasive wound debridement as possibly postoperatively-acquired, while those without invasive immediate prior debridement were classified as intraoperative SSIs.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eStatistical analyses\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe primary objective was the plausible origins of various SSIs. The Pearson-ꭓ\u003csup\u003e2\u003c/sup\u003e-test compared between possible intra- and postoperative SSI origins. Few missing data were not imputated. Episodes with substantial missing data were excluded. We used STATA\u003csup\u003e™\u003c/sup\u003e software (Version. 18, College Station, USA) and considered \u003cem\u003ep\u003c/em\u003e-values ≤0.05 (two-tailed) as significant.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cem\u003eSurgical site infections\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eAmong 2816 infection episodes reported during the study period 2018 to 2024, we kept 370 as acute (deep) SSIs and proceeded with further analyses. The rest of the reported infections did not concern orthopedic surgery, were community-acquired, or represented contaminations, colonization, or SSI episodes with incomplete or divergent histories, or were attributed to other centers. Among the remaining 370 SSI episodes in our database, 38 involved orthopedic foot surgery, 90 diabetic foot surgery, 40 hip, 54 knee, and 45 spine-related surgeries. The rest involved other interventions, including hand, shoulder, extremity surgery or combined surgeries, e.g. with SSIs of the iliac crest harvesting site [22] or of flaps. Half of the SSIs (174/370; 47%) were predominantly implant-related with lesser degree of soft-tissue infections, of which 77 were PJIs. Regarding the other half, the soft-tissue and bone involvement clinically predominated over the implant contamination. The median time delay between index surgery and the first surgical debridement was 29 days (interquartile range, 15-56 d). Our final study population primarily consisted of acute, pyogenic SSIs, whereas late or low-grade SSI have been excluded by our study criteria due to lack of sufficient documentation or patient\u0026apos;s history.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003ePathogens\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eWe retrieved 136 microbiological SSI constellations; with 96 (26%) polymicrobial SSIs and 78 (21%) primarily due to Gram-negative bacteria. Among the 246 (66%) predominant Gram-positive SSIs, we noticed 123(..%) \u003cem\u003eStaphylococcus aureus\u003c/em\u003e SSIs and associated 103(..5) episodes with skin commensals (e.g. cutibacteria, coagulase-negative staphylococci or corynebacteria). Overall, 28 SSIs (8%) were bacteremic, 134 (36%) resistant to the prior antibiotic prophylaxis (cefuroxime), and 13 (4%) multidrug-resistant. Figure 1 resumes the ten frequent pathogens.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eEpidemiology of the origins\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eWe were certain in 212 episodes (57%) or estimated the SSI origin with less probability in 43%. Overall, we would classify 241 SSI episodes (241/375; 65%) as intraoperatively-acquired, and 129 (35%) cases as postoperative. We were more certain regarding intraoperative SSIs (171/241 (71%) vs. 41/129 (32%); \u003cem\u003ep\u003c/em\u003e\u0026lt;0.001). Anatomically, we noted postoperative-related SSI in lower body parts. There was a clear gradient from the shoulder to the diabetic foot, with the shoulder yielding the highest part of intraoperative SSIs (13/14; 93%), and foot surgery the least (29%). Especially for the (ischemic) diabetic foot, the proportion of postoperative SSI was four times higher than the presumed intraoperative origins (81% vs. 19%, respectively). By excluding all foot SSIs, the overall proportion of estimated intraoperative SSIs rose to 83% (204/242 cases).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTable 1 summarizes our plausible origins, while Table 2 compares them. The Supplementary Appendix 1 separately provides the most important variables. The three most frequent origins of postoperative SSI were wound debridement, new ulcers, and/or wound (flap) necrosis (Table 1). The comparison between these two origin groups revealed a significant predominance of foot and polymicrobial infections among postoperative origins, whereas intraoperative SSIs typically yield skin commensals as the causal pathogens (Table 2). Lastly, we saw 14 SSI episodes with a significant complication in the postoperative period, which we attributed to an intraoperative origin, mostly because of history and pathogens were incompatible with a plausible postoperative origin: dental intervention (n=1), postoperative debridement (2), urosepsis (2), open fractures (2), intravenous drug abuse (1), pneumonia (1), wound discharge (1), trauma (1), necrosis (1), and oncologic chemotherapy (1).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 1. Plausible origins of SSIs. Descriptive statistics with frequencies\u003c/strong\u003e.\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 406px;\"\u003e\n \u003cp\u003eIntraoperative origin of SSI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003e241 (65%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 406px;\"\u003e\n \u003cp\u003ePostoperative origin of SSI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003e129 (35%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 406px;\"\u003e\n \u003cp\u003e- \u0026nbsp; \u0026nbsp; Iterative debridement of (yet) uninfected wound\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003e61 (16%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 406px;\"\u003e\n \u003cp\u003e- \u0026nbsp; \u0026nbsp; New foot ulcers\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003e14 (3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 406px;\"\u003e\n \u003cp\u003e- \u0026nbsp; \u0026nbsp; Secondary wound or flap necrosis\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003e10 (3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 406px;\"\u003e\n \u003cp\u003e- \u0026nbsp; \u0026nbsp; Hematogenous from gastrointestinal source\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003e10 (3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 406px;\"\u003e\n \u003cp\u003e- \u0026nbsp; \u0026nbsp; Hematogenous from urinary (catheter) source\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003e3 (1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 406px;\"\u003e\n \u003cp\u003e- \u0026nbsp; \u0026nbsp; Hematogenous from cutaneous source (decubitus)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003e1 (0.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 406px;\"\u003e\n \u003cp\u003e- \u0026nbsp; \u0026nbsp; PIN-tract infection spreading into deep layers\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003e9 (2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 406px;\"\u003e\n \u003cp\u003e- \u0026nbsp; \u0026nbsp; Mechanical postoperative wound trauma\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003e6 (2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 406px;\"\u003e\n \u003cp\u003e- \u0026nbsp; \u0026nbsp; Wound dehiscence and scar problems\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003e6 (2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 406px;\"\u003e\n \u003cp\u003e- \u0026nbsp; \u0026nbsp; Large hematoma\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003e5 (2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 406px;\"\u003e\n \u003cp\u003e- \u0026nbsp; \u0026nbsp; Large seroma\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003e2 (1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2. Differences between intra- and postoperative SSIs stratified upon infections.\u003c/strong\u003e Pearson-ꭓ\u003csup\u003e2\u003c/sup\u003e-tests*.\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"623\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 171px;\"\u003e\n \u003cp\u003eProbably postoperative\u003c/p\u003e\n \u003cp\u003en = 129\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 187px;\"\u003e\n \u003cp\u003eGroups (strata) analyzed\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 171px;\"\u003e\n \u003cp\u003eProbably intraoperative\u003c/p\u003e\n \u003cp\u003en = 241\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e\u003cem\u003ep\u003c/em\u003e-values*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 171px;\"\u003e\n \u003cp\u003emedian 34 days\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 187px;\"\u003e\n \u003cp\u003eTime since index surgery\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 171px;\"\u003e\n \u003cp\u003emedian 28 days\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0.68\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 171px;\"\u003e\n \u003cp\u003e22 (17%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 187px;\"\u003e\n \u003cp\u003eArthroplasties\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 171px;\"\u003e\n \u003cp\u003e55 (23%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0.19\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 171px;\"\u003e\n \u003cp\u003e91 (71%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 187px;\"\u003e\n \u003cp\u003eFoot surgery\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 171px;\"\u003e\n \u003cp\u003e37 (15%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003e0.01\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 171px;\"\u003e\n \u003cp\u003e9 (7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 187px;\"\u003e\n \u003cp\u003eBacteremia-associated\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 171px;\"\u003e\n \u003cp\u003e19 (8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0.75\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 171px;\"\u003e\n \u003cp\u003e42 (41%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 187px;\"\u003e\n \u003cp\u003e\u003cem\u003ePolymicrobial infections\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 171px;\"\u003e\n \u003cp\u003e54 (24%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003e0.01\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 171px;\"\u003e\n \u003cp\u003e74 (72%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 187px;\"\u003e\n \u003cp\u003e\u003cem\u003eGram-positive pathogens\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 171px;\"\u003e\n \u003cp\u003e172 (78%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0.24\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 171px;\"\u003e\n \u003cp\u003e17 (17%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 187px;\"\u003e\n \u003cp\u003e\u003cem\u003eSkin commensals\u0026deg;\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 171px;\"\u003e\n \u003cp\u003e86 (39%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003e0.01\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 171px;\"\u003e\n \u003cp\u003e29 (28%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 187px;\"\u003e\n \u003cp\u003e\u003cem\u003eGram-negative pathogens\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 171px;\"\u003e\n \u003cp\u003e49 (22%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0.24\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 171px;\"\u003e\n \u003cp\u003e3 (3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 187px;\"\u003e\n \u003cp\u003e\u003cem\u003eMultidrug-resistance\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 171px;\"\u003e\n \u003cp\u003e10 (5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0.49\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 171px;\"\u003e\n \u003cp\u003e44 (43%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 187px;\"\u003e\n \u003cp\u003e\u003cem\u003eProphylaxis-resistant\u003c/em\u003e\u003c/p\u003e\n \u003cp\u003e\u003cem\u003e(Cefuroxime-resistance)\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 171px;\"\u003e\n \u003cp\u003e90 (41%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e0.73\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u0026deg; Skin commensals: e.g. coagulase-negative staphylococci, cutibacteria, corynebacteria, clostridia, \u003cem\u003eBacillus\u003c/em\u003e spp.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eIn our single-center for elective adult orthopedic surgery, we plausibly estimate one-third of all formal acute SSIs being acquired (originating) during surgery. When excluding with (diabetic) foot surgery, this postoperative proportion becomes one-sixth and the intraoperative part 83%. We thus confirm the expert opinion stating that the majority of SSI are presumably acquired intraoperatively; but maybe to a lesser extent than we previously anticipated.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eExisting literature concentrates on intraoperative risks and perioperative interventions. Even recent publications and preventive trials prefer to target pre- and risks. Clinically, the antibiotic prophylaxis [11,23], the self-reported compliance of surgeons (only pre- and intraoperatively) [24], the increasing number of surgical skill labs, or the preoperative decolonization [10,25,26], all concentrate on the peri-, or preoperative period. Indeed, prospective trials on decolonization do not extend beyond the postoperative phase, although postoperative new wound problems would occur frequently in orthopedic surgery [27]. Similarly, bundled interventions often neglect the postoperative period [28]. Regarding the postoperative period, guidelines [18-20] and expert opinions are often limited to improve hand hygiene [9,29] and to enhance “asepsis” during dressing change [15]. Exceptionally, some research groups report a protective benefit of negative-pressure technology for preventive purposes in selected patients [14]. International guidelines state by resigning that \"\u003cem\u003eThere is a lack of high-quality studies comparing various strategies of postoperative wound management…. This is an area for further research\u003c/em\u003e\" [19].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003ePre- or perioperative prevention might not be enough, especially when “intraoperative” measures [1] have been maxed out, and the clinicians would only expect a slight improvement of prevention just by adding supplementary efforts into the “intraoperative“ axis. We think that our relatively high proportion of postoperative SSIs needs further attention. However, and theoretically, the various aspects of postoperative prevention are more resource--consuming than only focusing on perioperative measures. They will involve a higher number of HCWs and medical disciplines, and a longer intervention compared to the relatively short duration of the surgical intervention. Moreover, postoperative interventions take place in environments that cannot compete with the “aseptic” operation theatre in terms of infection control.\u003c/p\u003e\n\u003cp\u003eThe literature on postoperative orthopedic SSIs is sparse. Originally and according to early expert opinion, this literature mostly consisted of hematogenous PJIs representing up to one-quarter of all arthroplasty SSIs in selected studies [30]. Hematogenous hip PJI might occur earlier than hematogenous knee PJIs [31]. Other (smaller) implants, such as plates or nails, are quasi exempt from a hematogenous seeding from a remote infection source. In recent literature, the risk of hematogenous seeding is much lower than the risk of “intraoperative” PJIs becoming bacteremic. A retrospective cohort identified that only 1 of 79 severe remote infections would become bacteremic and seed to total joint arthroplasties [31]. A Swedish study assessed the incidence for hematogenous PJI in case of Gram-positive bacteremia\u003cem\u003e.\u003c/em\u003e This risk was only 6% [32]. Sometimes the origin of hematogenous PJIS may remain occult. If the origin cannot be elucidated through history, a blind (radiological) and laboratory search is ineffective and costly [33].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe majority of the postoperative SSI acquisitions occur locally and are due to two major groups of postsurgical problems: wound breakdowns (ischemia [6], trauma, hematoma, dehiscence, seroma [27]) and patient’s malcompliance in its various forms (e.g. unrest against medical order [34], smoking [35], or malnutrition [36,37]). A wound breakdown is frequent. According to a prospective observation during one year in Geneva, only 40% of freshly operated orthopedic wounds yielded no clinical problems [27]. In that study, among 1,073 adult orthopedic patients, 630 operated episodes (59%) showed relevant postoperative wound complications, leading to a significantly longer hospital stay compared to patients without complications. The most frequent wound complications were serous discharge with dehiscence (41%) and hematoma (35%) [27]. Wound dehiscence due to malcompliance remains a major problem. To cite an own example, a study randomizing operation techniques for septic bursitis, identified the lack of compliance (together with psychiatric conditions) as an important reason for failure (and infection recurrence) [34]. Other breakdowns occur after postsurgical debridement or because of wound necrosis in ischemic patients such as in diabetic foot syndromes. Finally, there are PIN-tract [1] infections in orthopedic surgery of the lower extremities, especially on the toes. PINs and wires cross the skin and are kept in place during weeks. In these situations, the reason for SSI could be a wrong surgical indication for elective surgery, or, most likely, unintended shortcomings in hand hygiene [29] during professional (or less experienced) wound care [15].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eOur observation study has strengths and limitations. The main strength is a prospective work-up of each attributed SSI case by judging upon playabilities of the individual patient's histories. The main limitations are multiple: i) The subjective evolution of the origins. ii) Mild superficial and late (low-grade) SSIs, which were not revised, might have gone unnoticed. iii) This is a pilot observation. We do not report intervention. Infection Control encompasses many other HAI groups and antibiotic resistances [38], which we could not evaluate in this study with very few multidrug-resistant pathogens. Indeed, operated patients reveal the same proportion of other HAIs as non-operated patients, with 5% SSIs in addition [3]. v) Lastly, our observation only concerns adult orthopedic surgery. In other disciplines with less superficial wounds, e.g. abdominal laparoscopy, the epidemiology of postoperative SSIs might be completely different.\u0026nbsp;\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eWhen prospectively investigating the origin of adult orthopedic SSIs, between 17% and 35% of postoperative infections were presumably acquired after the surgical intervention; especially after (diabetic) foot surgery. In terms of prevention, pre- and intra-operative measures remain should be addressed first. But not exclusively. The proportion of postoperatively-acquired SSI is substantial and needs attention. Their preventions are diverse and include clinical teams not involved in the first treatment of the patient. Revising the indication for index surgery, a better wound care, and improved compliance among patients and HCWs regarding all aspects of HAIs, are probably most likely to be beneficiary for the postoperative SSI prevention.\u0026nbsp;\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eSSI\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Surgical site infections\u003c/p\u003e\n\u003cp\u003eHAI\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Healthcare-associated infections\u003c/p\u003e\n\u003cp\u003ePJI\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Prosthetic joint infections\u003c/p\u003e\n\u003cp\u003eUTI\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Urinary tract infection\u003c/p\u003e\n\u003cp\u003ePNEU\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Healthcare-associated bacterial pneumonia\u003c/p\u003e\n\u003cp\u003eHCW\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Healthcare workers\u003c/p\u003e\n\u003cp\u003eGP\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;General practitioner\u003c/p\u003e\n\u003cp\u003eID \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;Infectious Diseases\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003e\u003cem\u003eEthics approval and consent to participate\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis project (Wissenschaftsnummer 1070) bases on a composite database from the following active prospective-randomized trials at the Balgrist University Hospital: BASEC 2022-00800 [11],\u0026nbsp;2019-00778 [17], 2021-00137 [5], 2023–00095 [10], and 2019-00646 [16]. The corresponding Clinical Trial Numbers (ClinicalTrials.gov) are NCT05502380, NCT04081792, NCT05647252, and NCT04048304, respectively. Additionally, participating patients signed an Institutional General Informed Consent validated by the Ethical Committee of Zurich Canton.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eConsent for publication\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePatients consented for publication of this side study by participating in prospective-randomized trials and by signing a General Informed Consent Form providing their medical data.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eAvailability of data and materials\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe may provide anonymized key data upon reasonable scientific request to the corresponding author. Supplementary Appendix 1 is a summary of the study database.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eCompeting interests\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll authors declare no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eFunding\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis research received no external funding.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eAuthor Contributions\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eConceptualization: NK, PLS, and IU. Methodology: PLS, NK, TG, LSB, and IU. Validation: PLS, LSB, AA and IU. Data collection: PLS, DB, DA, PRF, AV, NK, TG, AA, and IU. Data analysis: PLS. LSB, DB and IU; Analysis verification: DA, AA, DB and IU. Writing: original draft preparation, PLS and IU. Writing- review and editing: IU and MF. Supervision: NK, TG, IU, and MF. All authors have agreed to the published version of the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eDoctor thesis\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis research is part of a Doctoral Thesis (PLS), supervised by IU and MF.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe thank to all colleagues of the Institut für Medizinische Mikrobiologie (IMM) at the University of Zurich and to the Unit of Clinical and Applied Research of the Balgrist University Hospital. We are indebted to Ms. Jasna Plesko Martinelli and Ms. Nadja Bragatto-Hess from Infection Control Unit for their invaluable help during the surveillance period.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eU\u0026ccedil;kay I, Harbarth S, Peter R, Lew D, Hoffmeyer P, Pittet D. Preventing surgical site infections. 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Trials. 2020;21(1):54.\u003c/li\u003e\n\u003cli\u003eWorld Health Organization. Global guidelines for the prevention of surgical site infection. WHO. 2018; https://www.who.int/publications/i/item/9789241550475 (last assessed 14.3.25).\u003c/li\u003e\n\u003cli\u003eLing ML, Apisarnthanarak A, Abbas A, Morikane K, Lee KY, Warrier A, Yamada K. APSIC guidelines for the prevention of surgical site infections. Antimicrob Resist Infect Control. 2019:8:174.\u003c/li\u003e\n\u003cli\u003eMangram AJ, Horan TC, Pearson ML, Silver LC, Jarvis WR. Guideline for prevention of surgical site infection, 1999. Infect Control Hosp Epidemiol. 1999;20:250-78.\u003c/li\u003e\n\u003cli\u003eTroillet N, Berthod D, Perdrieu C; on behalf of \u003cem\u003eSwissNOSO\u003c/em\u003e (Swiss National Centre for Infection Prevention). Modul SSI Surveillance. 2025. https://www.swissnoso.ch/module/ssi-surveillance/ueber-ssi-surveillance/das-modul/ (last assessed 14.3.25).\u003c/li\u003e\n\u003cli\u003eUnterfrauner I, Olthof M, Jans P, Sch\u0026uuml;pbach R, Betz M, U\u0026ccedil;kay I. Surgical Site Infections at Donor and Recipient Sites in Patients with Iliac Crest Harvesting For Autologous Bone Grafting - A Pilot Evaluation. Ann Case Report. 2022;7:1087.\u003c/li\u003e\n\u003cli\u003eDavat M, Wuarin L, Stafylakis D, Abbas M, Harbarth S, Hannouche D, U\u0026ccedil;kay I. Should antibiotic prophylaxis before orthopedic implant surgery depend on the duration of pre-surgical hospital stay? Antimicrob Resist Infect Control. 2018;7:131.\u003c/li\u003e\n\u003cli\u003eTomsic I, Ebadi E, Goss\u0026eacute; F, Hartlep I, Schipper P, Krauth C, Schock B, Chaberny IF, von Lengerke T. Determinants of orthopedic physicians\u0026apos; self-reported compliance with surgical site infection prevention: results of the WACH-trial\u0026apos;s pilot survey on COM-B factors in a German university hospital. Antimicrob Resist Infect Control. 2021;10(1):67.\u003c/li\u003e\n\u003cli\u003eWandhoff B, Schr\u0026ouml;der C, N\u0026ouml;th U, Krause R, Schmidt B, David S, Scheller EE, Jahn F, Behnke M, Gastmeier P, Kramer TS. Efficacy of universal preoperative decolonization with Polyhexanide in primary joint arthroplasty on surgical site infections. A multicenter before-and after-study. Antimicrob Resist Infect Control. 2020;9(1):188.\u003c/li\u003e\n\u003cli\u003ePortais A, Gallouche M, Pavese P, Caspar Y, Bosson JL, Astagneau P, Pailh\u0026eacute; R, Tonetti J, Duval BR, Landelle C. \u003cem\u003eStaphylococcus aureus\u003c/em\u003e screening and preoperative decolonisation with Mupirocin and Chlorhexidine to reduce the risk of surgical site infections in orthopaedic surgery: a pre-post study. Antimicrob Resist Infect Control. 2024;13(1):75.\u003c/li\u003e\n\u003cli\u003eU\u0026ccedil;kay I, Agostinho A, Belaieff W, Toutous-Trellu L, Scherer-Pietramaggiori S, Andres A, Bernard L, Vuagnat H, Hoffmeyer P, Wyssa B. Noninfectious wound complications in clean surgery: epidemiology, risk factors, and association with antibiotic use. World J Surg. 2011;35(5):973-80.\u003c/li\u003e\n\u003cli\u003eEder M, Sommerstein R, Szelecsenyi A, Schweiger A, Schlegel M, Atkinson A, Kuster SP, Vuichard-Gysin D, Troillet N, Widmer AF; for\u003cem\u003e SwissNoso\u003c/em\u003e. Association between the introduction of a national targeted intervention program and the incidence of surgical site infections in Swiss acute care hospitals. Antimicrob Resist Infect Control. 2023;12(1):134.\u003c/li\u003e\n\u003cli\u003eSax H, U\u0026ccedil;kay I, Richet H, Allegranzi B, Pittet D. Determinants of good adherence to hand hygiene among healthcare workers who have extensive exposure to hand hygiene campaigns. Infect Control Hosp Epidemiol. 2007;28(11):1267-74.\u003c/li\u003e\n\u003cli\u003eVu DL, U\u0026ccedil;kay I, Gonzalez A, Rohner P, Hoffmeyer P, L\u0026uuml;bbeke A. Factors related to outcome of early and delayed prosthetic joint infections. J Infect. 2016;72(2):255-7.\u003c/li\u003e\n\u003cli\u003eU\u0026ccedil;kay I, L\u0026uuml;bbeke A, Emonet S, Tovmirzaeva L, Stern R, Ferry T, Assal M, Bernard L, Lew D, Hoffmeyer P. Low incidence of haematogenous seeding to total hip and knee prostheses in patients with remote infections. J Infect. 2009;59(5):337-45.\u003c/li\u003e\n\u003cli\u003eThompson O, P\u0026aring;hlman LI. Frequency of haematogenous periprosthetic joint infection due to bacteraemia caused by gram-positive cocci. Infect Dis (Lond). 2025:1-7.\u003c/li\u003e\n\u003cli\u003eBouvet C, Tchernin D, Seirafi M, Stern R, Lew D, Hoffmeyer P, U\u0026ccedil;kay I. No need to search for the source of haematogenous arthroplasty infections. Swiss Med Wkly. 2011:141:13306.\u003c/li\u003e\n\u003cli\u003eU\u0026ccedil;kay I, von Dach E, Perez C, Agostinho A, Garnerin P, Lipsky BA, Hoffmeyer P, Pittet D. One- vs 2-Stage Bursectomy for Septic Olecranon and Prepatellar Bursitis: A Prospective Randomized Trial. Mayo Clin Proc. 2017;92(7):1061-9.\u003c/li\u003e\n\u003cli\u003eGonzalez AI, Luime JJ, U\u0026ccedil;kay I, Hannouche D, Hoffmeyer P, L\u0026uuml;bbeke A. Is There an Association Between Smoking Status and Prosthetic Joint Infection After Primary Total Joint Arthroplasty? J Arthroplasty. 2018;33(7):2218-24.\u003c/li\u003e\n\u003cli\u003eZhang D, Zhang X. Effect of serologic malnutrition on postoperative wound infection problems after total joint arthroplasty: A meta‐analysis. Int Wound J. 2022;20(2):261-8.\u003c/li\u003e\n\u003cli\u003eU\u0026ccedil;kay I, Yogarasa V, Waibel FWA, Seiler-B\u0026auml;nziger A, Kuhn M, Sahli M, Berli MC, Lipsky BA, Sch\u0026ouml;ni M. Nutritional Interventions May Improve Outcomes of Patients Operated on for Diabetic Foot Infections: A Single-Center Case-Control Study. J Diabetes Res. 2022: 2022:9546144.\u003c/li\u003e\n\u003cli\u003eMuhamad AN, Teh CSJ, Draman MR, Adnan YK, Abbas AA, Khong TL, Narayanan V, Tang SN, Karunakaran R, Manan NA, Kukreja A, Razali SZM, Cham CY, Hontz RD, Gregory MJ, Selariu A, Nguyen HC, Letizia AG, Ponnampalavanar SSS. High incidence of multidrug-resistant organisms and modifiable risk factors associated with surgical site infections: a cohort study in a tertiary medical center in Kuala Lumpur, Malaysia from 2020 to 2023. Antimicrob Resist Infect Control. 2025;14(1):22.\u003c/li\u003e\n\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":"surgical site infection, orthopedic surgery, origin, postoperative care, prospective ","lastPublishedDoi":"10.21203/rs.3.rs-6541947/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6541947/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground:\u003c/strong\u003e In orthopedic surgery, we overlook the proportion of surgical site infections (SSI) acquired Intra- versus postoperative. A better overview would help to allocate resources for infection control instead of solely aiming for the perioperative period.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods:\u003c/strong\u003e We make use of prospective our database composed of four prospective-randomized clinical interventional trials and surveillance registers and concentrate on acute SSIs. We evaluate each SSIs clinically by searching medical and nursing notes for potential postoperative events that could plausibly cause a postoperative acquisition of bacteria.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults:\u003c/strong\u003e Among 370 cases, we estimated 241 SSIs (65%) to be acquired intraoperatively, and 129 (35%) postoperatively. There was a clear gradient from the shoulder to the (diabetic) foot, with the shoulder yielding the highest plausible part of intraoperative SSIs (93%) and the foot the least (29%). By excluding foot SSIs, the proportion of estimated intraoperative SSIs rose to 83% (204/242 cases). The three most frequent reasons for postoperative SSIs were wound debridement immediately preceding infection, skin breakdowns and local surgical complications of various reasons (hematoma, dehiscence), and necrosis with a high proportion of polymicrobial foot SSIs among the postoperative origins. In contrast, hematogenous SSIs were rare (3%) and intraoperative SSIs were more often due to skin commensals.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions:\u003c/strong\u003e According to our prospective clinical evaluation, one-third of acute orthopedic SSIs were related with a postoperative complication that could potentially be the cause of SSI. By excluding adult (diabetic) foot surgeries, this postoperative proportion is reduced to one-sixth. Aside from reviewing the initial surgical justifications in high-risk patients and promoting (hand) hygiene, we require additional preventative treatments for the initial postoperative period.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eClinical Trial Numbers:\u003c/strong\u003e NCT05502380, NCT04081792, NCT05647252, NCT04048304.\u003c/p\u003e","manuscriptTitle":"Potential Origins of Acute Surgical Site Infections in Non-Traumatic Orthopedic Surgery - a Single-Center Prospective Evaluation","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-23 07:47:51","doi":"10.21203/rs.3.rs-6541947/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":"5868e884-f7e6-4dfe-8810-e0e071eecfe8","owner":[],"postedDate":"September 23rd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-01-23T02:40:12+00:00","versionOfRecord":[],"versionCreatedAt":"2025-09-23 07:47:51","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6541947","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6541947","identity":"rs-6541947","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}