New Delhi metallo-beta-lactamase-producing Acinetobacter baumannii: a novel paradigm for spreading antibiotic resistance genes

摘要

The impact of carbapenemase production among clinically significant Gram-negative rods is becoming a major medical issue. To date, Acinetobacter baumannii has been considered as a final recipient of carbapenemase genes (imipenemase, Verona metallo--lactamase, Guiana extended-spectrum -lactamase and Klebsiella pneumonia carbapenemase types) from Enterobacteriaceae and Pseudomonas aeruginosa. However, recent findings regarding the spread of the bla(NDM) carbapenemase genes revealed that A. baumannii likely acts as a source of emerging antibiotic resistance genes. The analysis of genetic structure surrounding the bla(NDM-1) gene revealed that the genetic structure (Tn125) responsible for its dissemination most probably originates from Acinetobacter. Moreover, analysis of the bla(NDM-1) gene itself demonstrated that it might be constructed in Acinetobacter through a recombination event with another resistance gene found in A. baumannii (aphA6). This novel paradigm highlights a novel and unexpected role played by A. baumannii.