Abstract
BackgroundInfections by A. calcoaceticus-A. baumannii (ACB) complex isolates represent a serious threat for wounded and burn patients. Three international multidrug-resistant (MDR) clones (EU clone I-III) are responsible for a large proportion of nosocomial infections with A. baumannii but other emerging strains with high epidemic potential also occur.Methodology/Principal FindingsWe automatized a Multiple locus variable number of tandem repeats (VNTR) analysis (MLVA) protocol and used it to investigate the genetic diversity of 136 ACB isolates from four military hospitals and one childrens hospital. Acinetobacter sp other than baumannii isolates represented 22.6% (31/137) with a majority being A. pittii. The genotyping protocol designed for A.baumannii was also efficient to cluster A. pittii isolates. Fifty-five percent of A. baumannii isolates belonged to the two international clones I and II, and we identified new clones which members were found in the different hospitals. Analysis of two CRISPR-cas systems helped define two clonal complexes and provided phylogenetic information to help trace back their emergence.Conclusions/SignificanceThe increasing occurrence of A. baumannii infections in the hospital calls for measures to rapidly characterize the isolates and identify emerging clones. The automatized MLVA protocol can be the instrument for such surveys. In addition, the investigation of CRISPR/cas systems may give important keys to understand the evolution of some highly successful clonal complexes.
Highlights
The genus Acinetobacter currently counts 27 validly named species and several unnamed provisional species and genomic species [1,2]
Automatization of the MLVA Assay We previously described the identification of 10 variable number of tandem repeats (VNTR) in the genome of three A. baumannii strains available at that time, and the selection of 8 of those for an efficient MLVA-8 genotyping scheme
The VNTRs were amplified in two multiplex PCRs (Table 1) and the products were analysed on a capillary electrophoresis device
Summary
The genus Acinetobacter currently counts 27 validly named species (http://www.bacterio.cict.fr/a/acinetobacter.html) and several unnamed provisional species and genomic species [1,2]. 13 TU) [3] are mostly associated with clinical issues [4] These species and the closely related species A. calcoaceticus, an environmental species, are difficult to distinguish phenotypically, which has led to the proposal to lump them together into the A. calcoaceticus-A. baumannii (ACB) complex [3,5]. Three clonal lineages (European (EU) clones I–III) of multidrug resistant (MDR) and extensively-drug resistant (XDR) A. baumannii strains have been found to be associated with outbreaks in hospitals at different locations [10,11]. Antimicrobial resistance and epidemic spread of strains of A. pittii and A. nosocomialis is still limited compared to A. baumannii [12,13]. Three international multidrug-resistant (MDR) clones (EU clone I-III) are responsible for a large proportion of nosocomial infections with A. baumannii but other emerging strains with high epidemic potential occur
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