Plasmid-Mediated Rifampin Resistance Encoded by an arr-2 -Like Gene Cassette in Klebsiella pneumoniae Producing an ACC-1 Class C β-Lactamase

For Pseudomonas spp., two plasmid-mediated mechanisms of resistance to rifampin have been reported: one involves an efflux pump (1), and the other involves an ADP-ribosylating transferase (3) encoded by a gene (arr-2) that is integrated as a gene cassette in a class 1 integron (10). Recently, plasmid-mediated rifampin resistance (Arr-2) was described for various Enterobacteriaceae from Southeast Asia producing the extended-spectrum β-lactamase VEB-1 (4, 6). The genes encoding these mechanisms of resistance are integron located as gene cassettes (4, 6).