Extended-spectrum ß-lactamase-producing and third-generation cephalosporin-resistant Enterobacteriaceae in children: Trends in the United States, 1999-2011

Background. Enterobacteriaceae infections resistant to extended-spectrum ß-lactams are an emerging problem in children.We used a large database of clinical isolates to describe the national epidemiology of extended-spectrum ß-lactamase (ESBL)-producing and third-generation cephalosporin-resistant (G3CR) Enterobacteriaceae. Methods. Antimicrobial susceptibilities of Klebsiella pneumoniae, Escherichia coli, and Proteus mirabilis reported to ~300 laboratories participating in The Surveillance Network (TSN) between January 1999 and December 2011 were used to phenotypically identify G3CR and ESBL isolates cultured from patients <18 years. Bi-annual trends in the prevalence of each phenotype were stratified by species, patient location, culture site, age, and region. Children of age 0-1 years were excluded from analysis as data were only available from 2010 onwards. Results. Out of 368,398 pediatric isolates, 1.97% (7255) were identified as G3CR, and 0.47% (1734) as ESBL producers. The prevalence of both phenotypes increased, respectively, from 1.39% and 0.28% in 1999-2001 to 3% and 0.92%in 2010-2011. Trends were significant across all demographic and age groups, including outpatients, with the highest proportion of isolates in the 1-5-year-old age group. The majority of G3CR and ESBL isolates were E. coli (67.8% and 65.2%, respectively). Among ESBLs, resistance to ≥3 antibiotic classes was 74%. The lower regional prevalence of ESBL-producing bacteria in the upper Midwest relative to the rest of the country is consistent with recent local data. Conclusions. Rates of G3CR and ESBL infections in children are increasing in both inpatient and ambulatory settings nationally. The identification of host factors and exposures leading to infection in children is essential.