Abstract
BackgroundAcinetobacter baumannii strains co-producing carbapenemase and 16S rRNA methylase are highly resistant to carbapenems and aminoglycosides.MethodsNinety-three isolates of multidrug-resistant A. baumannii were obtained from an intensive care unit in a hospital in Vietnam. Antimicrobial susceptibility tests and whole genome sequencing were performed. Multilocus sequence typing and the presence of drug resistant genes were determined and a maximum-likelihood phylogenetic tree was constructed by SNP alignment of whole genome sequencing data.ResultsThe majority of isolates belonged to clonal complex 2 (ST2, ST570 and ST571), and carried carbapenemase encoding genes blaOXA-23 and blaOXA-66. Two isolates encoded carbapenemase genes blaNDM-1 and blaOXA-58 and the 16S rRNA methylase encoding gene armA and did not belong to clonal complex 2 (ST16).ConclusionA. baumannii isolates producing 16S rRNA methylase ArmA and belonging to clonal complex 2 are widespread, and isolates co-producing NDM-1 and ArmA are emerging, in medical settings in Vietnam.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-015-1171-x) contains supplementary material, which is available to authorized users.
Highlights
Acinetobacter baumannii strains co-producing carbapenemase and 16S rRNA methylase are highly resistant to carbapenems and aminoglycosides
Bacterial samples and drug susceptibility tests From 2011 to 2013, 93 clinical isolates of A. baumannii were obtained from respiratory tract samples taken from patients hospitalized in an intensive care unit (ICU) in Cho Ray Hospital in Ho Chi Minh City, Vietnam
Drug susceptibility tests The majority of the A. baumannii isolates tested were highly resistant to carbapenems, aminoglycosides, and ciprofloxacin, but sensitive to colistin and tigecycline (Table 1)
Summary
Acinetobacter baumannii strains co-producing carbapenemase and 16S rRNA methylase are highly resistant to carbapenems and aminoglycosides. MBLs are categorized by their amino acid sequences into various types [2,3,4], including AIM [5], DIM [6], FIM [7], GIM [8], IMPs [9], KHM [10], NDMs [11], SMB [12], SIM [13], SPM [14], TMBs [15] and VIMs [16]. The most prevalent MBLs are IMP-, VIM-, and NDM-type enzymes [1, 2, 17]. Between 2009 and 2012, 950 isolates of NDM-1producing bacteria, including 36 A. baumannii isolates, were reported worldwide [18]. At least 13 NDM variants (www.lahey.org/studies) have been reported in several countries [4, 19,20,21,22,23,24,25,26,27,28,29,30]
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