title: Characterization of carbapenem-resistant Acinetobacter calcoaceticus-baumannii complex isolates from nosocomial bloodstream infections in southern Iran.
abstract: Acinetobacter baumannii is an important opportunistic bacterial pathogen responsible for serious infections in hospitalized patients. From a total of 78 consecutive non-repetitive Acinetobacter spp. isolates from patients with blood infections, 61 were carbapenem resistant, which were positive for blaOXA-51-like (96.7%), blaOXA-23-like (77 %), blaOXA-58-like (8.1%) and blaOXA-40-like genes (32.8%) by multiplex PCR. The isolates were identified as A. baumannii (n = 59) and Acinetobacter nosocomialis (n = 2). Also, we found a case of Acinetobacter junii, causing bacteraemia, that possessed the IMP gene. High levels of resistance were observed to fluoroquinolones, aminoglycosides, tigecycline and to the beta-lactam antibiotics, including piperacillin/tazobactam and ampicillin/sulbactam. ISAba1 was present in 96.7% of all Acinetobacter calcoaceticus-baumannii complex (Acb) isolates. Also, 33 (54.1%) and 23 (37.7%) isolates harboured ISAba1 upstream of blaOXA-23-like and blaOXA-51-like genes, respectively, though this was not observed in A. nosocomialis isolates. No relationship was observed between the presence of ISAba1 upstream of oxacillinase genes and the level of carbapenem resistance in all Acb isolates. Only two genes encoding metallo-beta-lactamase (VIM, SPM) were detected in all Acb isolates. This suggests that carbapenem resistance in blood-isolate Acb is mostly due to the presence of acquired carbapenemases. This is the first report from Iran on the identification of A. nosocomialis isolates that possess multiple oxacillinase genes and lack upstream ISAba1.
authors.affiliation: Department of Pathobiology, School of Veterinary Medicine, Shiraz University, Shiraz, Iran.
authors.forename: Bahman
authors.initials: B
authors.lastname: Pourabbas
authors.affiliation: Department of Pathobiology, School of Veterinary Medicine, Shiraz University, Shiraz, Iran.
authors.forename: Roya
authors.initials: R
authors.lastname: Firouzi
authors.affiliation: Professor Alborzi Clinical Microbiology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Gholamreza
authors.initials: G
authors.lastname: Pouladfar
mesh_terms: D040981:Acinetobacter baumannii / Q000145:classification / Q000187:drug effects* / Q000235:genetics; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D016470:Bacteremia / Q000453:epidemiology / Q000382:microbiology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D015780:Carbapenems / Q000494:pharmacology*; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology*; D004269:DNA, Bacterial / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D007492:Iran / Q000453:epidemiology; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D015780:Carbapenems; D004269:DNA, Bacterial; D001618:beta-Lactamases; C063912:carbapenemase