Distribution of Intrinsic Plasmid Replicase Genes and Their Association with Carbapenem-Hydrolyzing Class D β-Lactamase Genes in European Clinical Isolates of Acinetobacter baumannii

Abstract

ABSTRACTNinety-six genetically diverse multidrug-resistant clinical isolates ofAcinetobacter baumanniifrom 25 hospitals in 17 European countries were screened by PCR for specific carbapenemase-hydrolyzing class D β-lactamase (CHDL) genes and by PCR-based replicon typing for the presence of 19 different plasmid replicase (rep) gene homology groups (GRs). Results were confirmed by DNA sequencing where necessary. All 96 isolates contained at least 1 (with a maximum of 4) of the 19 groups ofrepgenes. Groups detected were GR6 (repAci6; 93 isolates), GR2 (includingrepAci1 [67 isolates] andrepAci2 [3 isolates]), GR16 (repApAB49; 12 isolates), GR12 (p2ABSDF0001; 10 isolates), GR3 (repAci3; 4 isolates), GR4 (repAci4; 3 isolates), GR10 (repAciX; 1 isolate), and GR14 (repp4AYE; 1 isolate). Variations inrepgene content were observed even among epidemiologically related isolates. Genes encoding OXA-58-like CHDLs (22 isolates) were associated with carriage of therepAci1,repAci3,repAci4, andrepAciX genes, genes encoding OXA-40-like CHDLs (6 isolates) were associated withrepAci2 and p2ABSDF0001, and genes encoding OXA-23-like CHDLs (8 isolates) were associated withrepAci1. Most intrinsicAcinetobacterplasmids are non-self-transferable, but the almost ubiquitousrepAci6 gene was strongly associated with a potentialtralocus that could serve as a general system for plasmid mobilization and consequent horizontal transmission of plasmids and their associated antibiotic resistance genes among strains ofA. baumannii.