Bakour S1,2, Olaitan AO1, Ammari H3, Touati A2, Saoudi S2, Saoudi K2, Rolain JM1.
Microb Drug Resist. 2015 Jun;21(3):279-85. doi: 10.1089/mdr.2014.0214. Epub 2015 Jan 14.


AIM: The aim of this study was to investigate the prevalence and the mechanisms of carbapenem and colistin resistance in Acinetobacter baumannii clinical isolates in an Algerian hospital.

RESULTS: Twelve isolates were collected between October 2013 and March 2014. All isolates were resistant to almost all antibiotics tested with a high-level resistance to imipenem (minimum inhibitory concentrations [MICs] >32 mg/L) with one strain showing resistance to colistin (MIC=16 mg/L). The results of the modified Hodge test and the modified Carba NP test were positive for all isolates. Besides, the activity of β-lactamases was inhibited by EDTA in only two isolates. All the 12 isolates contained the naturally occurring blaOXA-51-like gene. Ten of them harbored the OXA β-lactamases: blaOXA-23 (six isolates) and blaOXA-24 (four isolates) genes, while two isolates were positive for blaNDM-1 gene. The colistin-resistant isolate producing OXA-24 enzyme harbored a single mutation in the pmrB gene. Multilocus sequence typing demonstrated that the 12 isolates belonged to 2 clones: 10 to ST2 and 2 to ST85.

CONCLUSIONS: Here, we describe the mechanisms of carbapenem resistance and we report the first colistin and carbapenemase-producing A. baumannii clinical isolate from a patient in Algeria