Clinical relevance of urine cultures in febrile infants under 3 months of age with negative urine dipsticks

Clinical relevance of urine cultures in febrile infants under 3 months of age with negative urine dipsticks | 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 Clinical relevance of urine cultures in febrile infants under 3 months of age with negative urine dipsticks Hannah Sjöstedt, Clara Velander, Jimmy Celind This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7768006/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 23 Feb, 2026 Read the published version in Pediatric Nephrology → Version 1 posted 5 You are reading this latest preprint version Abstract Introduction The clinical significance of positive urine cultures in febrile infants with negative dipsticks remains debated. The aim of this study was to investigate the extent to which negative urine dipsticks in febrile infants <3 months of age correlate with clinically relevant urinary tract infections (UTI). Methods This prospective observational study included all febrile infants (<3 months of age, temperature ≥38.0 °C) visiting the emergency department between October 2022, and November 2023, who had a negative urine dipstick. Infants with a prior UTI or known susceptibility to UTI were excluded. Positive cultures were considered clinically irrelevant in cases of mixed growth, growth of 1000 cfu/ml, asymptomatic bacteriuria with the same bacteria and resistance pattern within 3 months, or negative inflammatory markers together with spontaneously resolved fever without antibiotic treatment. Results 111 infants were included. The median age was 1 month (IQR 1–2), and 42 (38%) were female. Positive urine cultures were found in 44 infants (40%), of which 24 (22%) showed mixed growth. Among the remaining 20 (18%) isolated positive cultures, 12 (11%) were of insignificant growth (1000 cfu/ml), 17 (15%) had fever that resolved spontaneously without antibiotic treatment, and 8 (7%) were asymptomatic bacteriuria. No infant had a clinically relevant UTI. Conclusion Clinically relevant UTIs are rare in febrile infants <3 months of age with negative urine dipsticks. Urine cultures should not be obtained in all febrile infants with fever, but be reserved for those with an indication of UTI or serious bacterial infection. Introduction Urinary tract infections (UTIs) are common in children, particularly in during the first months of life ( 1 ). UTI in this age group represents a potentially serious infection that may progress to sepsis or meningitis. Parents are generally advised to seek medical care if their infant presents with fever of unknown origin, even though most febrile infants do not have a serious bacterial infection ( 2 ). Consequently, febrile infants constitute a substantial proportion of patients at pediatric emergency departments (PEDs), and screening for UTI is a central component of the diagnostic evaluation ( 3 ). Urine dipstick analysis is a reliable screening method for the exclusion of UTI in older children and adults ( 1 ). Its reliability in infants, however, has been debated ( 4 – 9 ). According to the 2011 American Academy of Pediatrics (AAP) guidelines, the diagnosis of a clinically relevant UTI requires the presence of symptoms, pyuria, and a positive urine culture of a single bacterial strain with > 50,000 colony-forming units (cfu) per milliliter (ml) ( 3 ). Several research groups and local guidelines have questioned these recommendations and advocate urine culture in all febrile infants regardless of urine dipstick results ( 8 – 11 ). Because fever of unknown origin is common in infants < 3 months presenting to PEDs, universal urine culture testing would substantially increase workload and healthcare costs, as well as subject infants to unnecessary and painful procedures. The primary aim of the present study was to determine the prevalence of clinically relevant UTI in febrile infants under 3 months of age with negative dipstick tests. A secondary aim was to assess whether missed febrile UTIs could have been identified by clinical or laboratory characteristics other than routine urine cultures. Methods Study population The PED at Queen Silvia Children’s Hospital is the only PED in the Gothenburg metropolitan area, serving nine municipalities. With approximately 60,000 annual visits, it is the largest PED in the Nordic countries. All infants younger than 3 months presenting with fever between October 1, 2022, and November 11, 2023, were eligible if they had a negative dipstick test. Exclusion criteria were previous UTI or increased susceptibility to UTI (e.g., urinary tract reflux or other anomalies). At our PED, clean-catch urine is the first-line method for UTI screening. If the clinical history or symptoms suggest UTI, or if the initial sample indicates UTI, suprapubic aspiration is performed for culture. For participants in this study, who had neither a history nor a dipstick suggestive of UTI, most cultures were based on clean-catch samples. Study design This was a prospective, single-center observational study. Medical chart review included data on age, sex, temperature, symptoms, systemic inflammatory markers (C-reactive protein [CRP], interleukin-6), length of hospital stay, antibiotic treatment (agent and duration), urine culture results, and follow-up within 3 months. Definitions Fever was defined as ≥ 38.0°C measured at any site (rectal, ear, axillary, or forehead), either at home or in the PED. A dipstick was defined as negative if all of the following were absent: leukocytes, nitrite, erythrocytes, protein, glucose, and ketones. Strict criteria for clinically relevant FUTI were applied. Cultures were deemed clinically irrelevant if any of the following were present: growth of 1000 cfu/ml, mixed bacterial growth, negative inflammatory markers combined with spontaneous resolution of fever without antibiotics, or identical bacterial growth with the same resistance pattern in an asymptomatic period within 3 months. Statistical analysis Categorical variables were presented as counts and percentages. Continuous variables were presented as medians with interquartile ranges (IQR). Categorical comparisons were performed using Chi-square or Fisher’s exact test, and continuous variables using the Mann–Whitney U test. A two-tailed p < 0.05 was considered statistically significant. Analyses were performed with SPSS Statistics version 29 (IBM Corp., Armonk, NY, USA, 2025). The study was approved by the Swedish Ethical Review Authority, which waived the requirement for informed written consent. Results Study population A total of 111 infants were included over the study period. Twenty-three (21%) were younger than 1 month, while 44 (40%) each were 1 or 2 months of age. Forty-two infants (38%) were female (Table 1 ). Table 1 Characteristics of included participants (N = 111). Negative urinary cultures (N = 67) Positive urinary cultures (N = 44) P value Age, n (%) -0 months -1 month -2 months 16 (24%) 23 (34%) 28 (42%) 7 (16%) 21 (48%) 16 (36%) 0.3* Sex, n (%) -Girls -Boys 26 (39%) 41 (61%) 16 (36%) 28 (64%) 0.8** Symptoms (other than fever), n (%) -Upper respiratory symptoms -Vomiting -Diarrhea -Vomiting and diarrhea 40 (60%) 2 (3%) 0 0 23 (52%) 1 (2%) 1 (2%) 1 (2%) 0.5* Confirmed infection, n (%) -Otitis media -Respiratory viral infection 19 (28%) 8 (12%) 11 (16%) 14 (32%) 6 (14%) 8 (18%) 0.4* Inflammatory response, median (IQR) -C-reactive protein† -Interleukine-6 0 (0–5) 18 (10–36) 0 (0–6) 14 (5–40) 0.3*** 0.4*** Inpatient care -Admitted, n (%) -Days, median (IQR) 29 (43%) 1 (0.75–1.5) 17 (39%) 1 ( 1 – 1 ) 0.5* 0.96*** Bacterial strain (isolated cultures), n (%) -E.coli -Enterobacteria -Enterococcus -S.aureus NA NA NA NA 14 (32%) 1 (2%) 4 (9%) 1 (2%) † Values 0–4 were reported as < 5 in the lab system and recorded as 0 in the data collection. *Pearson Chi-square (2-sided) **Fishers exact test (2-sided) ***Mann-Whitney U test Presenting symptoms All infants presented with fever at some point. Sixty-three (57%) also had signs of viral upper respiratory tract infection, 3 (3%) had vomiting, 1 (1%) had diarrhea, and 1 (1%) had both vomiting and diarrhea. Urine cultures Positive cultures were obtained from 44 infants (40%), of which 24 (22%) showed mixed growth (Fig. 1). Among the remaining 20 (18%) isolated cultures, 14 (13%) grew Escherichia coli , 4 (4%) Enterococcus , 1 (1%) Enterobacteriaceae, and 1 (1%) Staphylococcus aureus . All isolates fulfilled criteria for being clinically irrelevant: 12 (11%) had low colony counts (1000 cfu/ml), 17 (15%) had fever that resolved without antibiotics before the urinary culture result, and 8 (7%) represented asymptomatic bacteriuria (Table 2 ). No clinically relevant UTI was identified. Table 2 Individual results for the 20 infants with isolated bacterial growth in the urinary cultures. Infant Antibiotic treatment 1 Asymptomatic bacteriuria 2 Spontaneously resolved 3 Insignificant growth 4 1 1 1 2 1 1 1 3 1 1 4 1 1 5 1 1 6 1 1 7 1 1 8 1 1 1 9 1 10 1 1 11 1 1 12 1 1 1 13 1 14 1 1 15 1 1 16 1 1 17 1 1 18 1 19 1 1 20 1 1 1 Antibiotic treatment that covers urinary tract infection pathogens, not including treatment with Phenoxymethylpenicillin for otitis media. 2 Renewed urinary culture in asymptomatic period within 3 months showed the same bacterial species and resistance pattern 3 Negative serum inflammatory reactants (CRP and IL-6) and resolved fever at the result of the urinary culture without antibiotic treatment. 4 Insignificant growth was defined as 1000 cfu/ml. Antibiotic treatment Eighty-four infants (76%) did not receive antibiotics. Of the 27 (24%) who were treated, 19 (17%) received phenoxymethylpenicillin for otitis, which does not cover typical urinary pathogens. The remaining 8 (7%) received agents active against urinary pathogens, most commonly trimethoprim–sulfamethoxazole; one infant with pneumonia was treated with cefotaxime. Inpatient care Thirty-six infants (32%) were admitted. Two were observed overnight in the PED without admission, and admission data were unavailable for two referred infants. Admission was more frequent among infants < 1 month (17/23, 74%) compared with those aged 1 month (23/44, 52%) and 2 months (6/42, 14%; p < 0.001). Median length of stay was 1 day (IQR 1–1). Infectious diagnoses Thirty-three infants (30%) were diagnosed with infections other than UTI. Acute otitis media was diagnosed in 14 (13%) based on clinical examination. Nineteen (17%) had viral respiratory infections confirmed by PCR, including 8 (7%) with COVID-19, 4 (4%) with RSV, and 7 (6%) with other viruses. One case of pneumonia with rhinovirus was considered a possible secondary bacterial infection. Discussion In this prospective cohort of 111 febrile infants < 3 months of age with negative urine dipsticks, positive urine cultures were common, but none were classified as clinically relevant UTI. These findings contribute to the ongoing debate balancing the need to detect serious infections against the imperative to avoid unnecessary, invasive, and potentially harmful investigations. Our results align with the 2011 AAP guidelines, which define clinically relevant UTI as the combination of symptoms, pyuria, and a single positive culture > 50,000 cfu/ml ( 3 ). The guidelines further state that in children 2 months to 2 years, a negative urine dipstick is a reasonable screen, allowing observation without urine culture or antimicrobial therapy. However, several studies have challenged this approach ( 9 , 12 , 13 ), citing reduced reliability of pyuria and nitrite in newborn infants due to frequent voiding, low dietary nitrate intake, and higher prevalence of pathogens that do not convert nitrate to nitrite ( 1 ). A retrospective study by Lasry et al. of positive urine cultures from admitted infants ≤ 2 months of age during 11 years of study, identified 2 cases of urosepsis and 32 cases of clinically relevant UTI among 308 children with positive cultures but negative dipsticks, concluding that cultures should be obtained in all febrile infants < 2 months ( 10 ). The controversy thus centers not on whether dipsticks are imperfect but whether the rare missed UTIs would be detected clinically regardless, or remain untreated with potential long-term consequences. We anticipated identifying a small number of clinically relevant UTIs in our cohort. However, no cases were detected, preventing secondary analyses of predictors of missed UTIs. This may partly reflect our strict definition of clinical relevance, which was narrower than that used in several prior studies ( 5 , 14 ). For example, definitions based solely on symptoms and colony count (> 10,000 or > 50,000 cfu/ml) ( 5 , 14 ), or combined with inflammatory markers would have classified several of our cases as UTI ( 10 ). Clinical practice in Gothenburg favors liberal watchful waiting in well-appearing febrile infants with negative tests. This approach allowed observation of the natural course of illness in many infants without antibiotics, strengthening the validity of distinguishing clinically relevant infections from benign bacteriuria. The key question remains how many urine cultures should be obtained to detect the few false negatives and whether these missed cases, if clinically relevant, would otherwise be identified. A multicenter study of 13,000 children by Glissmeyer et al. supports dipstick as an adequate stand-alone screen in febrile infants ( 5 ), consistent with our findings. Limitations include the restriction to infants with negative dipsticks, precluding sensitivity and specificity analysis. Data on circumcision status were unavailable, though unlikely to influence results in a Swedish setting. The use of clean-catch specimens likely increased contamination rates, though this did not affect the primary conclusion. Strengths include the prospective population-based design, limited antibiotic exposure enabling natural disease course assessment, and detailed participant data. Conclusion This prospective study demonstrates that clinically relevant UTIs are rare in febrile infants < 3 months of age with negative urine dipsticks. Routine urine cultures should not be obtained in all febrile infants at first presentation but reserved for those with clinical or laboratory indications of UTI or serious bacterial infection, thereby avoiding unnecessary testing, painful procedures, and inconclusive results. Declarations Acknowledgements The authors would like to thank the managing physicians of the pediatric emergency department for their assistance in identifying patients for inclusion in the study. We also extend our special gratitude to Associate Professor Per Brandström for his valuable support and guidance. References Brandstrom P, Hansson S (2022) Urinary Tract Infection in Children. Pediatr Clin North Am 69(6):1099–1114 Byington CL, Enriquez FR, Hoff C, Tuohy R, Taggart EW, Hillyard DR et al (2004) Serious bacterial infections in febrile infants 1 to 90 days old with and without viral infections. Pediatrics 113(6):1662–1666 Subcommittee on Urinary Tract Infection SCoQI, Management, Roberts KB (2011) Urinary tract infection: clinical practice guideline for the diagnosis and management of the initial UTI in febrile infants and children 2 to 24 months. Pediatrics 128(3):595–610 Herreros ML, Tagarro A, Garcia-Pose A, Sanchez A, Canete A, Gili P (2018) Performing a urine dipstick test with a clean-catch urine sample is an accurate screening method for urinary tract infections in young infants. Acta Paediatr 107(1):145–150 Glissmeyer EW, Korgenski EK, Wilkes J, Schunk JE, Sheng X, Blaschke AJ et al (2014) Dipstick screening for urinary tract infection in febrile infants. Pediatrics 133(5):e1121–e1127 Diviney J, Jaswon MS (2021) Urine collection methods and dipstick testing in non-toilet-trained children. Pediatr Nephrol 36(7):1697–1708 Coulthard MG (2019) Using urine nitrite sticks to test for urinary tract infection in children aged < 2 years: a meta-analysis. Pediatr Nephrol 34(7):1283–1288 Mori R, Yonemoto N, Fitzgerald A, Tullus K, Verrier-Jones K, Lakhanpaul M (2010) Diagnostic performance of urine dipstick testing in children with suspected UTI: a systematic review of relationship with age and comparison with microscopy. Acta Paediatr 99(4):581–584 Shaikh N, Shope TR, Hoberman A, Vigliotti A, Kurs-Lasky M, Martin JM (2016) Association Between Uropathogen and Pyuria. Pediatrics. ;138(1) Lasry MS, Goldman M, Paret M, Bahat H (2024) Urinary tract infections in young infants with a normal urine dipstick. Acta Paediatr 113(9):2134–2139 Northern California Pediatric Hospital Medicine Consortium (2024) Consensus Guidelines for Management of Pediatric Urinary Tract Infection (UTI) Shaikh N, Osio VA, Wessel CB, Jeong JH (2020) Prevalence of Asymptomatic Bacteriuria in Children: A Meta-Analysis. J Pediatr 217:110–117e4 Kim SH, Lyu SY, Kim HY, Park SE, Kim SY (2016) Can absence of pyuria exclude urinary tract infection in febrile infants? About 2011 AAP guidelines on UTI. Pediatr Int 58(6):472–475 Crain EF, Gershel JC (1990) Urinary tract infections in febrile infants younger than 8 weeks of age. Pediatrics 86(3):363–367 Cite Share Download PDF Status: Published Journal Publication published 23 Feb, 2026 Read the published version in Pediatric Nephrology → Version 1 posted Editorial decision: Major Revisions Needed 02 Jan, 2026 Reviewers agreed at journal 08 Oct, 2025 Reviewers invited by journal 06 Oct, 2025 Editor assigned by journal 06 Oct, 2025 First submitted to journal 02 Oct, 2025 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. 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particularly in during the first months of life (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e). UTI in this age group represents a potentially serious infection that may progress to sepsis or meningitis. Parents are generally advised to seek medical care if their infant presents with fever of unknown origin, even though most febrile infants do not have a serious bacterial infection (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). Consequently, febrile infants constitute a substantial proportion of patients at pediatric emergency departments (PEDs), and screening for UTI is a central component of the diagnostic evaluation (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eUrine dipstick analysis is a reliable screening method for the exclusion of UTI in older children and adults (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e). Its reliability in infants, however, has been debated (\u003cspan additionalcitationids=\"CR5 CR6 CR7 CR8\" citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e). According to the 2011 American Academy of Pediatrics (AAP) guidelines, the diagnosis of a clinically relevant UTI requires the presence of symptoms, pyuria, and a positive urine culture of a single bacterial strain with \u0026gt;\u0026thinsp;50,000 colony-forming units (cfu) per milliliter (ml) (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e). Several research groups and local guidelines have questioned these recommendations and advocate urine culture in all febrile infants regardless of urine dipstick results (\u003cspan additionalcitationids=\"CR9 CR10\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eBecause fever of unknown origin is common in infants\u0026thinsp;\u0026lt;\u0026thinsp;3 months presenting to PEDs, universal urine culture testing would substantially increase workload and healthcare costs, as well as subject infants to unnecessary and painful procedures. The primary aim of the present study was to determine the prevalence of clinically relevant UTI in febrile infants under 3 months of age with negative dipstick tests. A secondary aim was to assess whether missed febrile UTIs could have been identified by clinical or laboratory characteristics other than routine urine cultures.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eStudy population\u003c/h2\u003e\u003cp\u003eThe PED at Queen Silvia Children\u0026rsquo;s Hospital is the only PED in the Gothenburg metropolitan area, serving nine municipalities. With approximately 60,000 annual visits, it is the largest PED in the Nordic countries. All infants younger than 3 months presenting with fever between October 1, 2022, and November 11, 2023, were eligible if they had a negative dipstick test. Exclusion criteria were previous UTI or increased susceptibility to UTI (e.g., urinary tract reflux or other anomalies).\u003c/p\u003e\u003cp\u003eAt our PED, clean-catch urine is the first-line method for UTI screening. If the clinical history or symptoms suggest UTI, or if the initial sample indicates UTI, suprapubic aspiration is performed for culture. For participants in this study, who had neither a history nor a dipstick suggestive of UTI, most cultures were based on clean-catch samples.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eStudy design\u003c/h3\u003e\n\u003cp\u003eThis was a prospective, single-center observational study. Medical chart review included data on age, sex, temperature, symptoms, systemic inflammatory markers (C-reactive protein [CRP], interleukin-6), length of hospital stay, antibiotic treatment (agent and duration), urine culture results, and follow-up within 3 months.\u003c/p\u003e\n\u003ch3\u003eDefinitions\u003c/h3\u003e\n\u003cp\u003eFever was defined as \u0026ge;\u0026thinsp;38.0\u0026deg;C measured at any site (rectal, ear, axillary, or forehead), either at home or in the PED. A dipstick was defined as negative if all of the following were absent: leukocytes, nitrite, erythrocytes, protein, glucose, and ketones. Strict criteria for clinically relevant FUTI were applied. Cultures were deemed clinically irrelevant if any of the following were present: growth of 1000 cfu/ml, mixed bacterial growth, negative inflammatory markers combined with spontaneous resolution of fever without antibiotics, or identical bacterial growth with the same resistance pattern in an asymptomatic period within 3 months.\u003c/p\u003e\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\u003ch2\u003eStatistical analysis\u003c/h2\u003e\u003cp\u003eCategorical variables were presented as counts and percentages. Continuous variables were presented as medians with interquartile ranges (IQR). Categorical comparisons were performed using Chi-square or Fisher\u0026rsquo;s exact test, and continuous variables using the Mann\u0026ndash;Whitney U test. A two-tailed p\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered statistically significant. Analyses were performed with SPSS Statistics version 29 (IBM Corp., Armonk, NY, USA, 2025). The study was approved by the Swedish Ethical Review Authority, which waived the requirement for informed written consent.\u003c/p\u003e\u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\n\u003ch2\u003eStudy population\u003c/h2\u003e\n\u003cp\u003eA total of 111 infants were included over the study period. Twenty-three (21%) were younger than 1 month, while 44 (40%) each were 1 or 2 months of age. Forty-two infants (38%) were female (Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n\u003ctable id=\"Tab1\" border=\"1\"\u003e\u003ccaption\u003e\n\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n\u003cdiv class=\"CaptionContent\"\u003e\n\u003cp\u003eCharacteristics of included participants (N\u0026thinsp;=\u0026thinsp;111).\u003c/p\u003e\n\u003c/div\u003e\n\u003c/caption\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eNegative urinary cultures\u003c/p\u003e\n\u003cp\u003e(N\u0026thinsp;=\u0026thinsp;67)\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003ePositive urinary cultures\u003c/p\u003e\n\u003cp\u003e(N\u0026thinsp;=\u0026thinsp;44)\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eP value\u003c/p\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eAge, n (%)\u003c/p\u003e\n\u003cp\u003e-0 months\u003c/p\u003e\n\u003cp\u003e-1 month\u003c/p\u003e\n\u003cp\u003e-2 months\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e16 (24%)\u003c/p\u003e\n\u003cp\u003e23 (34%)\u003c/p\u003e\n\u003cp\u003e28 (42%)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e7 (16%)\u003c/p\u003e\n\u003cp\u003e21 (48%)\u003c/p\u003e\n\u003cp\u003e16 (36%)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e0.3*\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eSex, n (%)\u003c/p\u003e\n\u003cp\u003e-Girls\u003c/p\u003e\n\u003cp\u003e-Boys\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e26 (39%)\u003c/p\u003e\n\u003cp\u003e41 (61%)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e16 (36%)\u003c/p\u003e\n\u003cp\u003e28 (64%)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e0.8**\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eSymptoms (other than fever), n (%)\u003c/p\u003e\n\u003cp\u003e-Upper respiratory symptoms\u003c/p\u003e\n\u003cp\u003e-Vomiting\u003c/p\u003e\n\u003cp\u003e-Diarrhea\u003c/p\u003e\n\u003cp\u003e-Vomiting and diarrhea\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e40 (60%)\u003c/p\u003e\n\u003cp\u003e2 (3%)\u003c/p\u003e\n\u003cp\u003e0\u003c/p\u003e\n\u003cp\u003e0\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e23 (52%)\u003c/p\u003e\n\u003cp\u003e1 (2%)\u003c/p\u003e\n\u003cp\u003e1 (2%)\u003c/p\u003e\n\u003cp\u003e1 (2%)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e0.5*\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eConfirmed infection, n (%)\u003c/p\u003e\n\u003cp\u003e-Otitis media\u003c/p\u003e\n\u003cp\u003e-Respiratory viral infection\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e19 (28%)\u003c/p\u003e\n\u003cp\u003e8 (12%)\u003c/p\u003e\n\u003cp\u003e11 (16%)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e14 (32%)\u003c/p\u003e\n\u003cp\u003e6 (14%)\u003c/p\u003e\n\u003cp\u003e8 (18%)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.4*\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eInflammatory response, median (IQR)\u003c/p\u003e\n\u003cp\u003e-C-reactive protein\u0026dagger;\u003c/p\u003e\n\u003cp\u003e-Interleukine-6\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e0 (0\u0026ndash;5)\u003c/p\u003e\n\u003cp\u003e18 (10\u0026ndash;36)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e0 (0\u0026ndash;6)\u003c/p\u003e\n\u003cp\u003e14 (5\u0026ndash;40)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e0.3***\u003c/p\u003e\n\u003cp\u003e0.4***\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eInpatient care\u003c/p\u003e\n\u003cp\u003e-Admitted, n (%)\u003c/p\u003e\n\u003cp\u003e-Days, median (IQR)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e29 (43%)\u003c/p\u003e\n\u003cp\u003e1 (0.75\u0026ndash;1.5)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e17 (39%)\u003c/p\u003e\n\u003cp\u003e1 (\u003cspan class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e1\u003c/span\u003e)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e0.5*\u003c/p\u003e\n\u003cp\u003e0.96***\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eBacterial strain (isolated cultures), n (%)\u003c/p\u003e\n\u003cp\u003e-E.coli\u003c/p\u003e\n\u003cp\u003e-Enterobacteria\u003c/p\u003e\n\u003cp\u003e-Enterococcus\u003c/p\u003e\n\u003cp\u003e-S.aureus\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eNA\u003c/p\u003e\n\u003cp\u003eNA\u003c/p\u003e\n\u003cp\u003eNA\u003c/p\u003e\n\u003cp\u003eNA\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e14 (32%)\u003c/p\u003e\n\u003cp\u003e1 (2%)\u003c/p\u003e\n\u003cp\u003e4 (9%)\u003c/p\u003e\n\u003cp\u003e1 (2%)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003ctfoot\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"4\"\u003e\u003cstrong\u003e\u0026dagger;\u003c/strong\u003eValues 0\u0026ndash;4 were reported as \u0026lt;\u0026thinsp;5 in the lab system and recorded as 0 in the data collection.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"4\"\u003e*Pearson Chi-square (2-sided)\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"4\"\u003e**Fishers exact test (2-sided)\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"4\"\u003e***Mann-Whitney U test\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tfoot\u003e\n\u003c/table\u003e\n\u003c/div\u003e\n\u003c/div\u003e\n\u003ch3\u003ePresenting symptoms\u003c/h3\u003e\n\u003cp\u003eAll infants presented with fever at some point. Sixty-three (57%) also had signs of viral upper respiratory tract infection, 3 (3%) had vomiting, 1 (1%) had diarrhea, and 1 (1%) had both vomiting and diarrhea.\u003c/p\u003e\n\u003ch3\u003eUrine cultures\u003c/h3\u003e\n\u003cp\u003ePositive cultures were obtained from 44 infants (40%), of which 24 (22%) showed mixed growth (Fig.\u0026nbsp;1). Among the remaining 20 (18%) isolated cultures, 14 (13%) grew \u003cem\u003eEscherichia coli\u003c/em\u003e, 4 (4%) \u003cem\u003eEnterococcus\u003c/em\u003e, 1 (1%) Enterobacteriaceae, and 1 (1%) \u003cem\u003eStaphylococcus aureus\u003c/em\u003e. All isolates fulfilled criteria for being clinically irrelevant: 12 (11%) had low colony counts (1000 cfu/ml), 17 (15%) had fever that resolved without antibiotics before the urinary culture result, and 8 (7%) represented asymptomatic bacteriuria (Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e). No clinically relevant UTI was identified.\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n\u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n\u003cdiv class=\"colspec\" align=\"char\"\u003e\u0026nbsp;\u003c/div\u003e\n\u003cdiv class=\"colspec\" align=\"char\"\u003e\u0026nbsp;\u003c/div\u003e\n\u003cdiv class=\"colspec\" align=\"char\"\u003e\u0026nbsp;\u003c/div\u003e\n\u003cdiv class=\"colspec\" align=\"char\"\u003e\u0026nbsp;\u003c/div\u003e\n\u003ctable id=\"Tab2\" border=\"1\"\u003e\u003ccaption\u003e\n\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n\u003cdiv class=\"CaptionContent\"\u003e\n\u003cp\u003eIndividual results for the 20 infants with isolated bacterial growth in the urinary cultures.\u003c/p\u003e\n\u003c/div\u003e\n\u003c/caption\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eInfant\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eAntibiotic treatment\u003csup\u003e1\u003c/sup\u003e\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eAsymptomatic bacteriuria\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eSpontaneously resolved\u003csup\u003e3\u003c/sup\u003e\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eInsignificant growth\u003csup\u003e4\u003c/sup\u003e\u003c/p\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e2\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e3\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e4\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e5\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e6\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e7\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e8\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e9\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e10\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e11\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e12\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e13\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e14\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e15\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e16\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e17\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e18\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e19\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e20\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003ctfoot\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"5\"\u003e\u003csup\u003e1\u003c/sup\u003eAntibiotic treatment that covers urinary tract infection pathogens, not including treatment with Phenoxymethylpenicillin for otitis media.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"5\"\u003e\u003csup\u003e2\u003c/sup\u003eRenewed urinary culture in asymptomatic period within 3 months showed the same bacterial species and resistance pattern\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"5\"\u003e\u003csup\u003e3\u003c/sup\u003eNegative serum inflammatory reactants (CRP and IL-6) and resolved fever at the result of the urinary culture without antibiotic treatment.\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"5\"\u003e\u003csup\u003e4\u003c/sup\u003eInsignificant growth was defined as 1000 cfu/ml.\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tfoot\u003e\n\u003c/table\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\n\u003ch2\u003eAntibiotic treatment\u003c/h2\u003e\n\u003cp\u003eEighty-four infants (76%) did not receive antibiotics. Of the 27 (24%) who were treated, 19 (17%) received phenoxymethylpenicillin for otitis, which does not cover typical urinary pathogens. The remaining 8 (7%) received agents active against urinary pathogens, most commonly trimethoprim\u0026ndash;sulfamethoxazole; one infant with pneumonia was treated with cefotaxime.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\n\u003ch2\u003eInpatient care\u003c/h2\u003e\n\u003cp\u003eThirty-six infants (32%) were admitted. Two were observed overnight in the PED without admission, and admission data were unavailable for two referred infants. Admission was more frequent among infants\u0026thinsp;\u0026lt;\u0026thinsp;1 month (17/23, 74%) compared with those aged 1 month (23/44, 52%) and 2 months (6/42, 14%; p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Median length of stay was 1 day (IQR 1\u0026ndash;1).\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\n\u003ch2\u003eInfectious diagnoses\u003c/h2\u003e\n\u003cp\u003eThirty-three infants (30%) were diagnosed with infections other than UTI. Acute otitis media was diagnosed in 14 (13%) based on clinical examination. Nineteen (17%) had viral respiratory infections confirmed by PCR, including 8 (7%) with COVID-19, 4 (4%) with RSV, and 7 (6%) with other viruses. One case of pneumonia with rhinovirus was considered a possible secondary bacterial infection.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eIn this prospective cohort of 111 febrile infants\u0026thinsp;\u0026lt;\u0026thinsp;3 months of age with negative urine dipsticks, positive urine cultures were common, but none were classified as clinically relevant UTI. These findings contribute to the ongoing debate balancing the need to detect serious infections against the imperative to avoid unnecessary, invasive, and potentially harmful investigations.\u003c/p\u003e\u003cp\u003eOur results align with the 2011 AAP guidelines, which define clinically relevant UTI as the combination of symptoms, pyuria, and a single positive culture\u0026thinsp;\u0026gt;\u0026thinsp;50,000 cfu/ml (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e). The guidelines further state that in children 2 months to 2 years, a negative urine dipstick is a reasonable screen, allowing observation without urine culture or antimicrobial therapy. However, several studies have challenged this approach (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e), citing reduced reliability of pyuria and nitrite in newborn infants due to frequent voiding, low dietary nitrate intake, and higher prevalence of pathogens that do not convert nitrate to nitrite (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eA retrospective study by Lasry et al. of positive urine cultures from admitted infants\u0026thinsp;\u003cem\u003e\u0026le;\u003c/em\u003e\u0026thinsp;2 months of age during 11 years of study, identified 2 cases of urosepsis and 32 cases of clinically relevant UTI among 308 children with positive cultures but negative dipsticks, concluding that cultures should be obtained in all febrile infants\u0026thinsp;\u0026lt;\u0026thinsp;2 months (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e). The controversy thus centers not on whether dipsticks are imperfect but whether the rare missed UTIs would be detected clinically regardless, or remain untreated with potential long-term consequences.\u003c/p\u003e\u003cp\u003eWe anticipated identifying a small number of clinically relevant UTIs in our cohort. However, no cases were detected, preventing secondary analyses of predictors of missed UTIs. This may partly reflect our strict definition of clinical relevance, which was narrower than that used in several prior studies (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e). For example, definitions based solely on symptoms and colony count (\u0026gt;\u0026thinsp;10,000 or \u0026gt;\u0026thinsp;50,000 cfu/ml) (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e), or combined with inflammatory markers would have classified several of our cases as UTI (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eClinical practice in Gothenburg favors liberal watchful waiting in well-appearing febrile infants with negative tests. This approach allowed observation of the natural course of illness in many infants without antibiotics, strengthening the validity of distinguishing clinically relevant infections from benign bacteriuria.\u003c/p\u003e\u003cp\u003eThe key question remains how many urine cultures should be obtained to detect the few false negatives and whether these missed cases, if clinically relevant, would otherwise be identified. A multicenter study of 13,000 children by Glissmeyer et al. supports dipstick as an adequate stand-alone screen in febrile infants (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e), consistent with our findings.\u003c/p\u003e\u003cp\u003e\u003cb\u003eLimitations\u003c/b\u003e include the restriction to infants with negative dipsticks, precluding sensitivity and specificity analysis. Data on circumcision status were unavailable, though unlikely to influence results in a Swedish setting. The use of clean-catch specimens likely increased contamination rates, though this did not affect the primary conclusion. Strengths include the prospective population-based design, limited antibiotic exposure enabling natural disease course assessment, and detailed participant data.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis prospective study demonstrates that clinically relevant UTIs are rare in febrile infants\u0026thinsp;\u0026lt;\u0026thinsp;3 months of age with negative urine dipsticks. Routine urine cultures should not be obtained in all febrile infants at first presentation but reserved for those with clinical or laboratory indications of UTI or serious bacterial infection, thereby avoiding unnecessary testing, painful procedures, and inconclusive results.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAcknowledgements\u003c/h2\u003e\u003cp\u003eThe authors would like to thank the managing physicians of the pediatric emergency department for their assistance in identifying patients for inclusion in the study. We also extend our special gratitude to Associate Professor Per Brandstr\u0026ouml;m for his valuable support and guidance.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eBrandstrom P, Hansson S (2022) Urinary Tract Infection in Children. Pediatr Clin North Am 69(6):1099\u0026ndash;1114\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eByington CL, Enriquez FR, Hoff C, Tuohy R, Taggart EW, Hillyard DR et al (2004) Serious bacterial infections in febrile infants 1 to 90 days old with and without viral infections. Pediatrics 113(6):1662\u0026ndash;1666\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSubcommittee on Urinary Tract Infection SCoQI, Management, Roberts KB (2011) Urinary tract infection: clinical practice guideline for the diagnosis and management of the initial UTI in febrile infants and children 2 to 24 months. Pediatrics 128(3):595\u0026ndash;610\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHerreros ML, Tagarro A, Garcia-Pose A, Sanchez A, Canete A, Gili P (2018) Performing a urine dipstick test with a clean-catch urine sample is an accurate screening method for urinary tract infections in young infants. Acta Paediatr 107(1):145\u0026ndash;150\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGlissmeyer EW, Korgenski EK, Wilkes J, Schunk JE, Sheng X, Blaschke AJ et al (2014) Dipstick screening for urinary tract infection in febrile infants. Pediatrics 133(5):e1121\u0026ndash;e1127\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDiviney J, Jaswon MS (2021) Urine collection methods and dipstick testing in non-toilet-trained children. Pediatr Nephrol 36(7):1697\u0026ndash;1708\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCoulthard MG (2019) Using urine nitrite sticks to test for urinary tract infection in children aged\u0026thinsp;\u0026lt;\u0026thinsp;2 years: a meta-analysis. Pediatr Nephrol 34(7):1283\u0026ndash;1288\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMori R, Yonemoto N, Fitzgerald A, Tullus K, Verrier-Jones K, Lakhanpaul M (2010) Diagnostic performance of urine dipstick testing in children with suspected UTI: a systematic review of relationship with age and comparison with microscopy. Acta Paediatr 99(4):581\u0026ndash;584\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eShaikh N, Shope TR, Hoberman A, Vigliotti A, Kurs-Lasky M, Martin JM (2016) Association Between Uropathogen and Pyuria. Pediatrics. ;138(1)\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLasry MS, Goldman M, Paret M, Bahat H (2024) Urinary tract infections in young infants with a normal urine dipstick. Acta Paediatr 113(9):2134\u0026ndash;2139\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eNorthern California Pediatric Hospital Medicine Consortium (2024) Consensus Guidelines for Management of Pediatric Urinary Tract Infection (UTI)\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eShaikh N, Osio VA, Wessel CB, Jeong JH (2020) Prevalence of Asymptomatic Bacteriuria in Children: A Meta-Analysis. J Pediatr 217:110\u0026ndash;117e4\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKim SH, Lyu SY, Kim HY, Park SE, Kim SY (2016) Can absence of pyuria exclude urinary tract infection in febrile infants? About 2011 AAP guidelines on UTI. Pediatr Int 58(6):472\u0026ndash;475\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCrain EF, Gershel JC (1990) Urinary tract infections in febrile infants younger than 8 weeks of age. Pediatrics 86(3):363\u0026ndash;367\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":true,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"pediatric-nephrology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"pnep","sideBox":"Learn more about [Pediatric Nephrology](http://link.springer.com/journal/467)","snPcode":"467","submissionUrl":"https://www.editorialmanager.com/pnep/default2.aspx","title":"Pediatric Nephrology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-7768006/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7768006/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eIntroduction\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe clinical significance of positive urine cultures in febrile infants with negative dipsticks remains debated. The aim of this study was to investigate the extent to which negative urine dipsticks in febrile infants \u0026lt;3 months of age correlate with clinically relevant urinary tract infections (UTI).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis prospective observational study included all febrile infants (\u0026lt;3 months of age, temperature ≥38.0 °C) visiting the emergency department between October 2022, and November 2023, who had a negative urine dipstick. Infants with a prior UTI or known susceptibility to UTI were excluded. Positive cultures were considered clinically irrelevant in cases of mixed growth, growth of 1000 cfu/ml, asymptomatic bacteriuria with the same bacteria and resistance pattern within 3 months, or negative inflammatory markers together with spontaneously resolved fever without antibiotic treatment.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e111 infants were included. The median age was 1 month (IQR 1–2), and 42 (38%) were female. Positive urine cultures were found in 44 infants (40%), of which 24 (22%) showed mixed growth. Among the remaining 20 (18%) isolated positive cultures, 12 (11%) were of insignificant growth (1000 cfu/ml), 17 (15%) had fever that resolved spontaneously without antibiotic treatment, and 8 (7%) were asymptomatic bacteriuria. No infant had a clinically relevant UTI.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eClinically relevant UTIs are rare in febrile infants \u0026lt;3 months of age with negative urine dipsticks. Urine cultures should not be obtained in all febrile infants with fever, but be reserved for those with an indication of UTI or serious bacterial infection.\u003c/p\u003e","manuscriptTitle":"Clinical relevance of urine cultures in febrile infants under 3 months of age with negative urine dipsticks","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-17 10:55:08","doi":"10.21203/rs.3.rs-7768006/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Major Revisions Needed","date":"2026-01-02T06:34:43+00:00","index":"","fulltext":""},{"type":"reviewerAgreed","content":"","date":"2025-10-08T08:56:26+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-10-06T16:08:30+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-10-06T12:51:46+00:00","index":"","fulltext":""},{"type":"submitted","content":"Pediatric Nephrology","date":"2025-10-02T12:28:27+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"pediatric-nephrology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"pnep","sideBox":"Learn more about [Pediatric Nephrology](http://link.springer.com/journal/467)","snPcode":"467","submissionUrl":"https://www.editorialmanager.com/pnep/default2.aspx","title":"Pediatric Nephrology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"d51f00c4-ffd2-4054-973e-eb8390a35fd8","owner":[],"postedDate":"October 17th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2026-03-02T16:13:58+00:00","versionOfRecord":{"articleIdentity":"rs-7768006","link":"https://doi.org/10.1007/s00467-026-07213-w","journal":{"identity":"pediatric-nephrology","isVorOnly":false,"title":"Pediatric Nephrology"},"publishedOn":"2026-02-23 15:57:55","publishedOnDateReadable":"February 23rd, 2026"},"versionCreatedAt":"2025-10-17 10:55:08","video":"","vorDoi":"10.1007/s00467-026-07213-w","vorDoiUrl":"https://doi.org/10.1007/s00467-026-07213-w","workflowStages":[]},"version":"v1","identity":"rs-7768006","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7768006","identity":"rs-7768006","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}