Distribution of Strain Type and Antimicrobial Susceptibility of Escherichia coli Isolates Causing Meningitis in a Large Urban Setting in Brazil

Abstract

The clinical management of meningitis caused by Escherichia coli is greatly complicated when the organism becomes resistant to broad-spectrum antibiotics. We sought to characterize the antimicrobial susceptibilities, sequence types (ST), and presence of known drug resistance genes of E. coli isolates that caused meningitis between 1996 and 2011 in Salvador, Brazil. We then compared these findings to those for E. coli isolates from community-acquired urinary tract infections (UTI) that occurred during the same time period and in the same city. We found that 19% of E. coli isolates from cases of meningitis and less than 1% of isolates from UTI were resistant to third-generation cephalosporins. The sequence types of E. coli isolates from cases of meningitis included ST131, ST69, ST405, and ST62, which were also found among isolates from UTI. Additionally, among the E. coli isolates that were resistant to third-generation cephalosporins, we found genes that encode the extended-spectrum beta-lactamases CTX-M-2, CTX-M-14, and CTX-M-15. These observations demonstrate that compared to E. coli strains isolated from cases of community-acquired UTI, those isolated from cases of meningitis are more resistant to third-generation cephalosporins, even though the same sequence types are shared between the two forms of extraintestinal infections.