Effective transfer of a 47 kb NDM-1-positive plasmid among Acinetobacter species.

Tzu-Wen Huang; Tsai-Ling Lauderdale; Tsai-Lien Liao; Ming-Chia Hsu; Feng-Yee Chang; Shan-Chwen Chang; Wei Xin Khong; Oon Tek Ng; Ying-Tsong Chen; Shu-Chen Kuo; Te-Li Chen; Jung-Jung Mun; Shih-Feng Tsai; Huang, Tzu-Wen; Lauderdale, Tsai-Ling; Liao, Tsai-Lien; Hsu, Ming-Chia; Chang, Feng-Yee; Chang, Shan-Chwen; Khong, Wei Xin

Objectives: To investigate the link between two NDM-1-positive Acinetobacter isolates from the same hospital, the plasmid profiles of the isolates were examined. These two isolates were found from a surveillance programme within 3 months from two patients without obvious physical contact or hospitalization time overlap.Methods: Antimicrobial susceptibility tests, genome sequencing of both isolates and plasmid transfer experiments were performed. A comparative study of similar plasmids was performed using BLAST analysis.Results: The antimicrobial susceptibility of the isolates (Acinetobacter soli M131 and Acinetobacter pittii MS32) and their Escherichia coli transconjugants revealed a conjugative plasmid that carried the carbapenem resistance determinant. Eleven plasmids were observed in M131 and three in MS32. Each isolate shared an identical plasmid that carried the blaNDM-1 gene. This 47 271 bp plasmid harbours a conserved blaNDM-1-containing region that is flanked by ISAba125 and ISAba11 elements, and also contains a Ti-type conjugative operon. The plasmid is nearly identical in sequence to those of Acinetobacter isolates from China. In contrast to the mobilization of the blaNDM-1 sequence in Enterobacteriaceae, which is mainly by transposition, this plasmid moves as a whole among Acinetobacter species. Consistently, this plasmid was found to transfer effectively by in vitro conjugation to several Acinetobacter species.Conclusions: The clinical and laboratory findings suggest that Acinetobacter species may serve as a reservoir of this blaNDM-1 plasmid. Our study demonstrates the potential of applying genome sequencing to the surveillance of antimicrobial-resistant bacteria.

ACINETOBACTER infections; ANTIBIOTICS; CROSS infection; DNA; DRUG resistance in microorganisms; GENES; GENETICS; GENOMES; HYDROLASES; MICROBIAL sensitivity tests; GRAM-negative aerobic bacteria; PHARMACODYNAMICS

Journal of Antimicrobial Chemotherapy (JAC), 2015, Vol 70, Issue 10, p2734

0305-7453

Academic Journal

10.1093/jac/dkv191