Diversity of metallo-β-lactamase-encoding genes found in distinct species of Acinetobacter isolated from the Brazilian Amazon Region

BACKGROUND: The multidrug resistance (MDR) phenotype is frequently observed in Acinetobacter baumannii, the most clinically relevant pathogenic species of its genus; recently, other species belonging to the A. calcoaceticus-A. baumannii complex have emerged as important MDR nosocomial pathogens. OBJECTIVES: The present study aimed to verify the occurrence of metallo-β-lactamase genes among distinct Acinetobacter species in a hospital located in the Brazilian Amazon Region. METHODS: Antimicrobial susceptibility profiles were determined by broth microdilution. The genetic relationships among these isolates were assessed by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Pyrosequencing reads of plasmids carrying the bla (NDM-1) gene were generated using the Ion Torrent™ platform sequencing. FINDINGS: A total of six isolates carried bla (NDM-1): A. baumannii (n = 2), A. nosocomialis (n = 3), and A. pittii (n = 1); three carried bla (IMP-1): A. baumannii, A. nosocomialis, and A. bereziniae. Resistance to colistin was observed for an NDM-1-producing A. nosocomialis isolate. Diverse PFGE patterns and sequence types were found among A. nosocomialis and A. baumannii isolates. The bla (NDM-1) sequence was inserted in a Tn125 transposon, while the bla (IMP-1) was found as a gene cassette of the class 1 integron In86. MAIN CONCLUSIONS: To the best of our knowledge, this is the first report describing the dissemination of bla (NDM-1) among distinct Acinetobacter species recovered from the same hospital in South America.