OXA-23-producing Acinetobacter baumannii: a new hotspot of diversity in Rio de Janeiro?

OBJECTIVES: this study focused on the population structure of OXA-23-producing Acinetobacter baumannii clinical isolates from Rio de Janeiro, Brazil.

METHODS: the analysis included several genomic typing methods, including PFGE, two multilocus sequence typing (MLST) schemes, sequence group (SG) determination and bla(OXA-51-like) sequencing. The genomic context of the bla(OXA-23) gene was also evaluated using I-CeuI hybridizations and PCR assays.

RESULTS: congruent clustering was obtained revealing four lineages. In accordance, four new sequence types (STs) (ST131, ST132, ST133 and ST134) were obtained with the MLST-OD scheme (associated with the Oxford Database) and four (ST79, ST15 and two new allelic profiles) with the MLST-IP scheme (developed by the Institute Pasteur). Four SGs (SG1, SG4 and two new profiles) were identified, allowing the association of 70% of the isolates with European clone II. bla(OXA-51-like) sequencing revealed the presence of bla(OXA-66), bla(OXA-69), bla(OXA-95) and bla(OXA-132).

CONCLUSIONS: identification of new STs together with new SG profiles are findings suggestive of a local diversity hotspot that is worth exploring.