Overexpression of the Naturally Occurring bla OXA-51 Gene in Acinetobacter baumannii Mediated by Novel Insertion Sequence IS Aba9

作者：Samy Figueiredo, Laurent Poirel, Anna Papa, V. Koulourida, Patrice Nordmann · 发表于：Antimicrobial Agents and Chemotherapy · 年份：2009 · DOI：10.1128/aac.00292-09 · 被引用次数：71 · 研究领域：Antibiotic Resistance in Bacteria、Infections and bacterial resistance、Pharmaceutical and Antibiotic Environmental Impacts

Resistance to carbapenems in Acinetobacter baumannii is increasingly reported and is mostly associated with expression of carbapenemases (3, 6). Those carbapenemases are most frequently carbapenem-hydrolyzing class D β-lactamases, which have been identified worldwide, including in Greece (4, 10). Four major subgroups of carbapenem-hydrolyzing class D β-lactamases have been identified in A. baumannii: the naturally occurring OXA-51/69-type β-lactamase and the acquired OXA-23, OXA-24/40 and OXA-58-type β-lactamases. Despite a weak catalytic activity, the naturally occurring OXA-51/69-type β-lactamases might contribute to carbapenem resistance by insertion of ISAba1 in the promoter region of the blaOXA-51/69-like genes (1, 8, 11). Twenty nonrepetitive carbapenem-resistant A. baumannii clinical isolates were isolated from August 2001 to November 2006 at the Papageorgiou General Hospital, Thessaloniki, Greece (Table (Table1).1). All 20 isolates were resistant to imipenem, among which 8 were additionally resistant to meropenem (MICs ranging from 8 to 64 μg/ml) (Table (Table1).1). No metallo-β-lactamase (MBL) production was detected by using Etest MBL strips (AB Biodisk, Solna, Sweden). Pulsed-field gel electrophoresis (PFGE) analysis was done as previously described (Bio-Rad, Ivry-sur-Seine, France) (5, 9) and showed that the 20 A. baumannii isolates exhibited 5 distinct PFGE profiles defining clones I to V (Table (Table1).1). PCR experiments performed using primers specific for...