Detection of CMY-type beta-lactamases in Escherichia coli isolates from paediatric patients in a tertiary care hospital
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RESEARCH
Detection of CMY‑type beta‑lactamases in Escherichia coli isolates from paediatric patients in a tertiary care hospital in Mexico Jocelin Merida‑Vieyra1, Agustín De Colsa‑Ranero1,2, Yair Calderón‑Castañeda3 and Alejandra Aquino‑Andrade1*
Abstract Background: The aim of this study was to detect CMY-type beta-lactamases in E. coli isolates obtained from paediat‑ ric patients. Methods: In total, 404 infection-causing E. coli isolates resistant to third and fourth generation cephalosporins (3GC, 4GC) were collected from paediatric patients over a 2 years period. The identification and susceptibility profiles were determined with an automated microbiology system. Typing of blaCMY and other beta-lactamase genes (blaTEM, blaSHV, blaCTX-M, blaVIM, blaIMP, blaKPC, blaNDM, blaOXA and blaGES) was realized by PCR and sequencing. Phenotypic detection of AmpC-type enzymes was performed using boronic acid (20 mg/mL) and cloxacillin (20 mg/mL) as inhibitors, and the production of extended-spectrum beta-lactamases was determined with the double-disk diffusion test with cefotaxime (CTX) and ceftazidime (CAZ) discs alone and in combination with clavulanic acid. The CarbaNP test and modified carbapenem inhibition method (mCIM) were used for isolates with decreased susceptibility to carbapen‑ ems. The clonal origin of the isolates was established by pulsed-field gel electrophoresis (PFGE), phylotyping method and multilocus sequence typing. Results: CMY-type beta-lactamases were detected in 18 isolates (4.5%). The allelic variants found were CMY-2 (n = 14) and CMY-42 (n = 4). Of the E. coli strains with CMY, the AmpC phenotypic production test was positive in 11 isolates with cloxacillin and in 15 with boronic acid. ESBL production was detected in 13 isolates. Coexistence with other beta-lactamases was observed such as CTX-M-15 ESBL and original spectrum beta-lactamases TEM-1 and TEM-190. In one isolate, the CarbaNP test was negative, the mCIM was positive, and OXA-48 carbapenemase was detected. Phylogroup A was the most frequent (n = 9) followed by B2, E and F (n = 2, respectively), and through PFGE, no clonal relationship was observed. Eleven different sequence types (ST) were found, with ST10 high-risk clone being the most frequent (n = 4). Seventy-two percent of the isolates were from health care-associated infections; the mortality rate was 11.1%. Conclusions: This is the first report in Mexico of E. coli producing CMY isolated from paediatric patients, demonstrat‑ ing a frequency of 4.5%. In addition, this is the first finding of E. coli ST10 with CMY-2 and OXA-48. Keywords: CMY beta-lactamases, AmpC, E. coli, Paediatrics, Mexico
*Correspondence: [email protected] 1 Molecular Microbiology Laboratory, Instituto Nacional de Pediatria, Insurgentes Sur 3700C, Insurgentes Cuicuilco, Coyoacan, 04530 Mexico City, Mexico Full list of author information is available at the end of the article
Background Of the family Enterobacteriaceae, Escherichia coli is one of the main causative agents of infections,
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