Pediatric Carbapenem-resistant Enterobacteriaceae in Los Angeles, California, a High-prevalence Region in the United States

Background: Infections caused by carbapenem-resistant Enterobacteriaceae (CRE) are on the rise worldwide but are not well described in pediatric populations. This study characterizes the clinical, phenotypic and genotypic characteristics of CRE infections at a free-standing US children's hospital. Methods: CRE were defined as any clinical Enterobacteriaceae isolate non-susceptible to either imipenem or meropenem and resistant to ceftriaxone, cefotaxime and ceftazidime determined by routine antimicrobial susceptibility testing. The modified Hodge test was performed to screen for the production of carbapenemase. Clinical data were reviewed, and molecular characterization of phylogenetic and resistance-associated traits was performed. Results: CRE isolates were recovered from sterile and non-sterile sites in 10 patients, 6 weeks to 24 years of age, between 2011 and 2013. Comorbidities included hematologic, genetic and urologic abnormalities. Two patients had traveled abroad (India, Lebanon) before CRE recovery. Carbapenemase determinants were detected in 5 cases, including KPC-3 in 2 Klebsiella pneumoniae (ST258 and ST18) and 1 Escherichia coli (ST131), and NDM-1 in 1 K. pneumoniae (ST37) and 1 E. coli (ST101) isolate. Additional resistance determinants were detected, including CTX-M-15, SHV11, TEM-1, CMY-2, CMY-4 and CMY-42. Four patients died, including 2 of 3 patients with CRE bacteremia. There was no evidence of epidemiologic or molecular relatedness between any 2 cases. Conclusions: This report documents the appearance of highly resistant Gram-negative pathogens in a vulnerable patient population at a pediatric tertiary referral center in a major US metropolitan area. Detailed understanding of the distribution and spread of CRE is essential for the timely detection and containment of these perilous pathogens.