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Molecular and Clinical Epidemiology of Extended-Spectrum Cephalosporin-Resistant Infections Caused by Enterobacteriaceae Species Other Than Escherichia coli and Klebsiella pneumoniae

Year: 2016

Type: article

Abstract: Background. We aimed to describe the clinical, microbiological, and molecular characteristics of extended-spectrum cephalosporin-resistant (ESC-R) infections in children caused by Enterobacteriaceae species other than E. coli and K. pneumoniae. Methods. ESC-R Enterobacteriaceae isolates were prospectively collected from normally sterile sites (stool for Salmonella or Shigella) of patients aged <21 years, along with clinical data, from 4 free-standing pediatric hospitals over 4 years. Prevalence was estimated using the total number of Enterobacteriaceae isolates by species recovered at each hospital during the study period. All isolates underwent confirmatory testing for ESC susceptibility using disk diffusion (2010 CLSI breakpoints), phenotypic testing for extended-spectrum beta-lactamase (ESBL) or AmpC resistance patterns, and genotypic testing for common resistance determinants. Results. Overall, 362 isolates met criteria for ESC-R; 91% were E. coli or K. pneumoniae and were excluded from this study. Of 31 remaining isolates, 12 (39%) were K. oxytoca, 7 (23%) were P. mirabilis, 11 (35%) were Salmonella spp. and 1 (3%) was Shigella. The prevalence of ESC-R among these species was 0.9%. The median age of patients was 3.8 years (range, 0.1–19.2) and 52% were male. The ESBL phenotype was present in 13 (42%) isolates, the AmpC phenotype was present in 13 (42%) isolates, and 5 (16%) isolates did not exhibit a characteristic ESC-R phenotype despite non-susceptibility to ESCs. An ESBL determinant was detected in 6 (46%) isolates with an ESBL phenotype (CTX-M: 4, SHV: 2). An AmpC determinant was detected in all isolates with an AmpC phenotype (CMY: 12, DHA: 1); of interest, 9 Salmonella isolates carried CMY-2. Two isolates with no phenotype identified had CMY-2 detected. Resistance to trimethoprim-sulfamethoxazole (TMP/SMX), gentamicin, and ciprofloxacin occurred in 32%, 23%, and 6% of these ESC-R isolates, respectively. Conclusion. Overall, 9% of ESC-R infections in children were caused by Enterobacteriaceae species other than E. coli and K. pneumoniae. ESBL or AmpC phenotypes and determinants were common among these isolates. TMP/SMX resistance occurred in 32% of isolates, while ciprofloxacin resistance was uncommon. Disclosures. All authors: No reported disclosures.

Source: Open Forum Infectious Diseases

DOI: 10.1093/ofid/ofw172.240