High prevalence of carbapenem-resistant Acinetobacter baumannii carrying the blaOXA-143 gene in Brazilian hospitals.

A recent article by Higgins et al. reported the identification of a novel carbapenem-hydrolyzing class D -lactamase (CHDL), defined as OXA-143, in a carbapenem-resistant Acinetobacter baumannii strain isolated in Brazil in 2004 (5). This enzyme, which has 88% identity with OXA-40, is the first representative of a novel subgroup of CHDLs whose prevalence remains to be determined (5). In an attempt to carry out this task, we have conducted a surveillance study of carbapenem-resistant A. baumannii isolates in order to determine the antimicrobial susceptibility patterns and prevalence of blaOXAtype carbapenemase genes in medical centers in both the southeastern and southern regions of Brazil. We report here a high prevalence of carbapenem-resistant A. baumannii carrying the blaOXA-143 and blaOXA-23 genes, along with the first isolation of strains carrying the blaOXA-72 (OXA-72 is a singleamino-acid variant of OXA-40) and blaOXA-58 genes in Brazilian hospitals. From 2004 to 2008, 36 carbapenem-resistant A. baumannii isolates recovered from different patients hospitalized in eight medical centers were screened for the presence of genes encoding metallo-lactamases (M Ls) and OXA-type -lactamases (6, 15). Flanking sequences of blaOXA-type genes were characterized by PCR using primers targeting ISAba-1 or -3 (12). PCR products were confirmed by sequencing, and the