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Background/purpose: The prevalence of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli is increasing worldwide. This study investigated the clinical features and bacteriology of pediatric patients with ESBL-producing E. coli bacteremia and compared their characteristics with those of adult patients., Methods: Clinical and laboratory data from all of the 41 patients aged ≤18 years diagnosed with E. coli bacteremia were collected over 5 years. Patients aged >18 years diagnosed with E. coli bacteremia, matched 1:1 for calendar time, were enrolled as the adult group. All E. coli isolates were tested for their blaCTX-M group and sequence type 131 (ST131). A novel seven-single nucleotide polymorphism-based clonotyping test was applied to detect the septatypes of each isolate., Results: In the adult group, patients with ESBL-producing E. coli bacteremia had more previous hospitalizations and antimicrobial agent use than did those with non-ESBL-producing E. coli bacteremia, but these differences were not found in pediatric group. In the pediatric group, the proportion of isolates producing CTX-M group 9 was higher than that in the adult group (85.7% vs. 42.9%; p < 0.05). Among both groups, there were more E. coli ST131 in ESBL isolates in than there were non-ESBL isolates. The distribution of septatypes was more homogenous in ESBL-producing E. coli among the pediatric patients than among the adult patients., Conclusion: ST131 was the major clone causing E. coli bacteremia in both pediatric and adult populations. The pediatric population demonstrated a higher number of isolates producing CTX-M group 9 with more homogenous septatypes compared with the adult population., (Copyright © 2017. Published by Elsevier B.V.)

Extended-spectrum β-lactamase (ESBL)-producing Escherichia coli sequence type ST131 has emerged as the leading cause of community-acquired urinary tract infections and bacteremia worldwide. Whether environmental water is a potential reservoir of these strains remains unclear. River water samples were collected from 40 stations in southern Taiwan from February to August 2014. PCR assay and multilocus sequence typing (MLST) analysis were conducted to determine the CTX-M group and sequence type, respectively. In addition, we identified the seasonal frequency of ESBL-producing E. coli strains and their geographical relationship with runoffs from livestock and poultry farms between February and August 2014. ESBL-producing E. coli accounted for 30% of the 621 E. coli strains isolated from river water in southern Taiwan. ESBL-producing E. coli ST131 was not detected among the isolates. The most commonly detected strain was E. coli CTX-M group 9. Among the 92 isolates selected for MLST analysis, the most common ESBL-producing clonal complexes were ST10 and ST58. The proportion of ESBL-producing E. coli was significantly higher in areas with a lower river pollution index (P = 0.025) and regions with a large number of chickens being raised (P = 0.013). ESBL-producing E. coli strains were commonly isolated from river waters in southern Taiwan. The most commonly isolated ESBL-producing clonal complexes were ST10 and ST58, which were geographically related to chicken farms. ESBL-producing E. coli ST131, the major clone causing community-acquired infections in Taiwan and worldwide, was not detected in river waters., (Copyright © 2016, American Society for Microbiology. All Rights Reserved.)

Background: Escherichia coli sero-group O25b-sequence type 131 (O25b-ST131), a multidrug-resistant clonal group, is a significant pathogen in adults and children. This study investigated the genotyping and role of extended spectrum β-lactamase (ESBL)-producing E. coli O25b-ST131 and non-O25b-ST131 in urinary tract infections in infants., Methods: Clinical and laboratory data from 111 infants less than 1 year of age, who were hospitalized for urinary tract infections caused by ESBL-producing E. coli between 2009 and 2012 were collected. Polymerase chain reactions and multi-locus sequence typing were used to identify E. coli O25-ST131 clones. The gene blaCTX-M groups 1, 2 and 9, a specific polymerase chain reaction of CTX-M 14 and 15, were also determined in ESBL-producing E. coli isolates., Results: O25b-ST131 accounted for 65% of the 111 isolates, although 92 isolates belonged to the blaCTX-M group 9, of which most were CTX-M-14. Those with O25b-ST131 clones had similar risk factors, clinical features and outcomes as those with non-O25b-ST131. The E. coli O25b-ST131 isolates were more resistant to ciprofloxacin and gentamicin, but more susceptible to cefoxitin, minocycline and trimethoprim/sulfamethoxazole than the non-O25b-ST131 isolates. Most of the infants (78%) were previously healthy with no apparent risk factors., Conclusions: E. coli O25b-ST131 is a major community-acquired uropathogen in the infant population. Regardless of O25b-ST131 or non-O25b-ST131 clones, CTX-M-14 accounts for majority of the ESBL genotype. The O25b-ST131 clone is not associated with more severe clinical disease, but it may make the diagnosis and selection of antimicrobials for treatment more challenging.