Plasmids carrying DHA-1 ?-lactamases

AbstractThe aim of this review is to provide an update on the plasmids mediating DHA-1 cephalosporinase in Klebsiella pneumoniae.These plasmids have been mainly found in this bacteriumbut not only. The first was isolated from Salmonella sp. in France in theearly 1990s. They are currently reported worldwide. BlaDHA-1 beta-lactamase gene is usually co-expressed with many otherantibiotic resistance genes such as extended-spectrum?-lactamases (blaCTX-M-, blaSHV-types), oxacillinases (blaOXA-1, blaOXA-30),penicillinases (blaTEM-type), carbapenemases (blaOXA48, blaKPC-2), aminoglycosides (aacA, aadA, armA), fluoroquinolones(qnrB4, aac6?-1b-cr), and sulfonamide (sul1) resistance genes. Plasmids carrying DHA-1 cephalosporinase have different sizes(22 to 313 kb), belong to diverse groups of incompatibility (R, L/M, FII(k), FIB, A/C2, HI2, HIB), and are self-transferable ornot. The multidrug resistance region consists of a mosaic structure composed of resistance genes, insertion sequences, compositetransposon, and integrons.Keywords Plasmids .AmpC .DHA-1 . Cephalosporinase . Antibiotic resistance . Klebsiella pneumonia