Carbapenem resistance in Acinetobacter baumannii: mechanisms and epidemiology
1Service de Bactériologie-Virologie, Hôpital de Bicêtre, South-Paris Medical School, University Paris XI, Le Kremlin-Bicêtre, France. laurent.poirel@bct.ap-hop-paris.fr
Abstract:
The increasing trend of carbapenem resistance in Acinetobacter baumannii worldwide is a concern since it limits drastically the range of therapeutic alternatives. Metallo-beta-lactamases (VIM, IMP, SIM) have been reported worldwide, especially in Asia and western Europe, and confer resistance to all beta-lactams except aztreonam. The most widespread beta-lactamases with carbapenemase activity in A. baumannii are carbapenem-hydrolysing class D beta-lactamases (CHDLs) that are mostly specific for this species. These enzymes belong to three unrelated groups of clavulanic acid-resistant beta-lactamases, represented by OXA-23, OXA-24 and OXA-58, that can be either plasmid- or chromosomally-encoded. A. baumannii also possesses an intrinsic carbapenem-hydrolysing oxacillinase, the expression of which may vary, that may play a role in carbapenem resistance. In addition to beta-lactamases, carbapenem resistance in A. baumannii may also result from porin or penicillin-binding protein modifications. Several porins, including the 33-kDa CarO protein, that constitute a pore channel for influx of carbapenems, might be involved in carbapenem resistance.
Related Concept Videos
Mechanism of Antibiotic Resistance in MRSA
Development of Antibiotic Resistance
Clinical Significance of Antibiotic Resistance
Gene Regulation in Microbial Communities: Quorum Sensing
Inhibitors of Gram-positive Cell Wall Synthesis
Atypical Pneumonia

