Genotypic characterization of carbapenem-nonsusceptible Acinetobacter spp. isolated in Latin America.

The principal aim of this study was to evaluate the genomic diversity among the imipenem-nonsusceptible Acinetobacter spp. (INSA) collected from the Latin American medical centers within the SENTRY Antimicrobial Surveillance Program. The INSA isolates were collected from patients with bloodstream infections, who were hospitalized in seven Latin American countries between 1997 and 1999. For epidemiologic comparison, 20 carbapenem-susceptible Acinetobacter spp. (CSA) isolates were collected in the same period of time from the respective medical centers. A total of 23 Acinetobacter spp. isolates exhibiting imipenem MIC values of >/=8 microg/ml were typed by ribotyping, an automated molecular method. The isolates showing an identical ribogroup were also typed by pulsed-field gel electrophoresis (PFGE). The antimicrobial susceptibility to various antimicrobial agents was evaluated using a reference broth microdilution technique. Among the INSA isolates, 13 distinct ribogroups were observed, whereas 16 ribogroups were detected among the CSA. Nearly 57% of the INSA belonged to only four ribogroups. Identical ribogroups and PFGE patterns were observed among INSA and CSA isolates collected from medical centers located in different countries (Brazil and Argentina). Our results showed: (1) a higher genomic variability among the CSA; (2) presence of epidemic clones among INSA isolates encountered in Latin American medical centers; and (3) spread of INSA and CSA epidemic clones between Latin American countries.