Characterization of Plasmids in Extensively Drug-Resistant Acinetobacter Strains Isolated in India and Pakistan

Abstract

The bla NDM-1 gene is associated with extensive drug resistance in Gram-negative bacteria. This probably spread to Enterobacteriaceae from Acinetobacter spp., and we characterized plasmids associated with bla NDM-1 in Acinetobacter spp. to gain insight into their role in this dissemination. Four clinical NDM-1-producing Acinetobacter species strains from India and Pakistan were investigated. A plasmid harboring bla NDM-1 , pNDM-40-1, was characterized by whole-genome sequencing of Acinetobacter bereziniae CHI-40-1 and comparison with related plasmids. The presence of similar plasmids in strains from Pakistan was sought by PCR and sequencing of amplicons. Conjugation frequency was tested and stability of pNDM-40-1 investigated by real-time PCR of isolates passaged with and without antimicrobial selection pressure. A. bereziniae and Acinetobacter haemolyticus strains contained plasmids similar to the pNDM-BJ01-like plasmids identified in Acinetobacter spp. in China. The backbone of pNDM-40-1 was almost identical to that of pNDM-BJ01-like plasmids, but the transposon harboring bla NDM-1 , Tn125, contained two short deletions. Escherichia coli and Acinetobacter pittii transconjugants were readily obtained. Transconjugants retained pNDM-40-1 after a 14-day passage experiment, although stability was greater with meropenem selection. Fragments of pNDM-BJ01-like plasmid backbones are found near bla NDM-1 in some genetic contexts from Enterobacteriaceae, suggesting that crossgenus transfer has occurred. pNDM-BJ01-like plasmids have been described in isolates originating from a wide geographical region in southern Asia. In vitro data on plasmid transfer and stability suggest that these plasmids could have contributed to the spread of bla NDM-1 into Enterobacteriaceae.

Genomic Analysis of Hospital Plumbing Reveals Diverse Reservoir of Bacterial Plasmids Conferring Carbapenem Resistance

“…Chromosomally, no link could be demonstrated among these isolates, as they belonged to different strains or species. However, the bla NDM-1 gene is carried on a plasmid that has been described previously in other Acinetobacter spp., including Acinetobacter lwoffii, Acinetobacter baumannii, Acinetobacter bereziniae, and Acinetobacter schindleri (37)(38)(39)(40)(41). One of the first descriptions of this plasmid backbone was in pNDM-BJ01 (JQ001791.1) (38), and variants missing a 6-kb region encoding GroE proteins have also been described (e.g., pNDM-JN02) (42).…”

The Acquisition of Resistance to Carbapenem and Macrolide-mediated Quorum Sensing Inhibition byPseudomonas aeruginosavia a Novel Integrative and Conjugative Element ICETn43716385

“…The macrolide resistance gene msr(E) and its variants were mainly identified from Grampositive bacteria and several Gram-negative bacterial species such as Enterobacteriaceae spp., Pasteurella multocida and A. baumannii, but has been rarely described in P. aeruginosa (29,(40)(41)(42). Hence, the transmission of msr(E) by ICETn43716385 into the clinical isolates characterized in this study has led us to investigate its possible functional roles in P. aeruginosa.…”

Detection of an NDM-1-producing Acinetobacter bereziniae strain in Brazil

“…The bla NDM-1 -carrying plasmid observed was ca. 41 kb, similar to the bla NDM-1 -carrying plasmids in Acinetobacter strains isolated from Asia (30-55 kb) [4,5], but smaller than the bla NDM-1 -carrying plasmid described in A. baumannii isolated from Brazil [2]. Acinetobacter baumannii was the most common NDM-1-producing Acinetobacter spp., and the bla NDM-1 gene was mostly chromosomally located [8].…”

“…Acinetobacter baumannii was the most common NDM-1-producing Acinetobacter spp., and the bla NDM-1 gene was mostly chromosomally located [8]. However, NDM-producing Acinetobacter isolates have been recently reported with bla NDM gene-bearing plasmids [2,4,5,8].…”