O2221: Antimicrobial Susceptibility Trends in E. coli Causing Pediatric Urinary Tract Infections in the United States

Background: Escherichia coli (E.coli) is the leading uropathogen among children with urinary tract infections (UTIs). Antibiotic resistance poses a significant challenge to treatment. This study evaluates antimicrobial susceptibility patterns of uropathogenic E.coli (UPEC) in pediatric UTIs over a 10-year-period, examining variations across age, gender, and U.S regions. Additionally, we investigated the prevalence of extended-spectrum beta-lactamase (ESBL)-producing, carbapenem-non-susceptible, multi-drug-resistant (MDR), and extensively drug-resistant (XDR) phenotypes across demographic categories to elicit susceptibility trends and their implications for treatment.

Methods: This retrospective multicenter study analyzed antibiotic susceptibility data from UPEC isolates from pediatric patients across 89 U.S. medical centers with a UTI diagnosis between 2014 and 2023 through the SENTRY Antimicrobial Surveillance Program. Isolates were processed at Element Iowa City (JMI Laboratories). Bacterial identification was confirmed using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry, molecular sequencing, or biochemical tests. Susceptibility testing covered 24 antimicrobials. Minimum inhibitory concentrations (MICs) were determined via the broth microdilution method. Susceptibility rates were calculated as the proportion of isolates meeting defined thresholds. MIC50 and MIC90 values represented the concentration inhibiting 50% and 90% of isolates, respectively. Data were analyzed by age, gender, U.S. region, and resistance profile. Susceptibility comparisons were conducted using the chi-square test.

Results: The study included 3,511 UPEC isolates (aged 0-18 years, mean: 7.28 years). UPEC susceptibility remained high (>95%) for ceftazidime–avibactam, ceftolozane–tazobactam, colistin, imipenem, meropenem, nitrofurantoin, piperacillin–tazobactam, and tigecycline, with ceftazidime–avibactam and meropenem exhibiting 100% susceptibility. Ampicillin–sulbactam, tetracycline, and trimethoprim–sulfamethoxazole displayed the lowest susceptibility rates ( < 80.0%). Age-related differences were notable, with infants and young (0-24 months) and preschool (3-5 years) children exhibiting lower susceptibility to ampicillin–sulbactam, cefepime, ceftaroline, and ceftriaxone (P < 0.05). Significantly more UPEC isolates were recovered from females (n = 3011; 86.05%) than males (n = 488; 13.95%). Females showed higher susceptibility for most antibiotics. Regional variability was evident, as the Middle Atlantic region (New Jersey, New York, and Pennsylvania) consistently presented with the lowest susceptibility rates. MDR and ESBL phenotypes were detected in 21.4% (n = 752) and 9.7% (n = 339) isolates, respectively. ESBL prevalence rose from 7.1% in 2014 to 10.8% in 2023 (P = 0.06). MDR and ESBL were most prevalent in infants and young (0-24 months) (MDR: n = 225, 29.9%; ESBL: n = 113, 33.3%) and school-aged (6-12 years) children (MDR: n = 214, 28.5%; ESBL: n = 93, 27.4%). The Pacific region had the highest MDR (n = 194; 25.8%) and ESBL (n = 116; 34.2%) prevalence.

Conclusion: This study highlights substantial demographic variations in UPEC susceptibility and rising ESBL prevalence. Lower susceptibility rates ( < 80%) for certain antibiotics may warrant revised recommendations regarding agents that are used as first-line empiric treatment. Ongoing monitoring and adaptive treatment strategies are essential to address evolving resistance patterns.