First Description of blaCTX-M-14- and blaCTX-M-15-Producing Escherichia coli Isolates in Brazil

We evaluated the antimicrobial resistance patterns and molecular characteristics of 11 extraintestinal Escherichia coli strains and 1 intestinal E. coli from human infections collected in Brazil. Two E. coli strains were non-susceptible to extended spectrum cephalosporins (cefotaxime, ceftazidime, and cefepime); one isolated from diarrhea carried bla(CTX-M-14) and bla(TEM-1), whereas the other, isolated from tracheal secretion, carried bla(CTX-M-15) and bla(OXA-1). Five E. coli strains showed resistance to quinolones. Integrase associated with class 1 integron (intl1) was detected in 8 of the 12 E. coli strains belonging to various serotypes and this gene was carried by plasmids showing similar size. Pulsed-field gel electrophoresis showed that E. coli strains were genetically diverse, and phylogenetic grouping showed that the E. coli strains belonged to groups A, B2, and D (33.3%), respectively. This is the first report of E. coli isolates carrying bla(CTX-M-14) and bla(CTX-M-15) in Brazil. The presence of mobile elements containing antimicrobial resistance genes is worrisome since it could promote the dissemination of resistance and lead to the acquisition of resistance to other antimicrobials agents such as the carbapenems.