Acinetobacter calcoaceticus – Acinetobacter baumannii complex species in clinical specimens in Singapore

This study was performed to determine the prevalence, distribution of specimen sources, and antimicrobial susceptibility of the Acinetobacter calcoaceticus–Acinetobacter baumannii (Acb) species complex in Singapore. One hundred and ninety-three non-replicate Acb species complex clinical isolates were collected from six hospitals over a 1-month period in 2006. Of these, 152 (78·7%) were identified as A. baumannii , 18 (9·3%) as ‘ Acinetobacter pittii ’ [genomic species (gen. sp.) 3], and 23 (11·9%) as ‘ Acinetobacter nosocomialis ’ (gen. sp. 13TU). Carbapenem resistance was highest in A. baumannii (72·4%), followed by A. pittii (38·9%), and A. nosocomialis (34·8%). Most carbapenem-resistant A. baumannii and A. nosocomialis possessed the bla OXA-23-like gene whereas carbapenem-resistant A. pittii possessed the bla OXA-58-like gene. Two imipenem-resistant strains ( A. baumannii and A. pittii ) had the bla IMP-like gene. Representatives of carbapenem-resistant A. baumannii were related to European clones I and II.