Genomic Analysis of the Multidrug-Resistant Acinetobacter baumannii Strain MDR-ZJ06 Widely Spread in China

Abstract

We previously reported that the multidrug-resistant (MDR) Acinetobacter baumannii strain MDR-ZJ06, belonging to European clone II, was widely spread in China. In this study, we report the whole-genome sequence of this clinically important strain. A 38.6-kb AbaR-type genomic resistance island (AbaR22) was identified in MDR-ZJ06. AbaR22 has a structure similar to those of the resistance islands found in A. baumannii strains AYE and AB0057, but it contained only a few antibiotic resistance genes. The region of resistant gene accumulation as previously described was not found in AbaR22. In the chromosome of the strain MDR-ZJ06, we identified the gene bla oxa-23 in a composite transposon (Tn2009). Tn2009 shared the backbone with other A. baumannii transponsons that harbor bla oxa-23 , but it was bracketed by two ISAba1 elements which were transcribed in the same orientation. MDR-ZJ06 also expressed the armA gene on its plasmid pZJ06, and this gene has the same genetic environment as the armA gene of the Enterobacteriaceae. These results suggest variability of resistance acquisition even in closely related A. baumannii strains.

Dissemination of bla OXA-23 in Acinetobacter spp. in China: Main Roles of Conjugative Plasmid pAZJ221 and Transposon Tn 2009

“…The complete genome sequencing of Acinetobacter spp. showed that, even for isolates sharing the same genetic background that were collected from the same country and the same time period, the locations of bla OXA-23 can be different (10,15). This phenomenon suggests that frequent horizontal transmission of this carbapenemase-encoding gene is possible, which is distinct from the simple clonal spread we previously anticipated (14).…”

“…Four main transposons, Tn2006, Tn2007, Tn2008, and Tn2009, were found to be associated with the transfer of bla in A. baumannii (5,(9)(10)(11). Besides sharing a common region (OXA-23-⌬ATPase), all the transposons have ISAba1 upstream from bla OXA-23 except Tn2007, which is correlated with ISAba4 (5, 9-11).…”

“…in China (16,17). In 2011, we reported the first genome sequence of a multidrugresistant (MDR) A. baumannii strain in China, MDR-ZJ06, which belonged to clonal complex 92 (CC92) (10). In this strain, bla OXA-23 is carried on the composite transposon Tn2009 and is located on the chromosome.…”

“…The bla OXA-23 gene has mostly been identified on plasmids, although a chromosomal location has also been reported (5,10,14). The complete genome sequencing of Acinetobacter spp.…”

Dissemination of a Carbapenem-Resistant Acinetobacter baumannii Strain Belonging to International Clone II/Sequence Type 2 and Harboring a Novel AbaR4-Like Resistance Island in Latvia

“…The second model, AbaR4-like, consists of Tn6022 as a backbone transposon and has mainly been identified among isolates from international clone II (11)(12)(13)(14). Complex structures of AbaR4-like islands, such as Tn6167 and AbaR22, have recently been described (15,16). Importantly, the AbaR4-like islands have repeatedly been found to be interrupted by Tn2006 carrying the bla OXA-23-like gene (12)(13)(14)(15).…”