Introduction / objectives
Aim of this study was to assess the role of active extrusion in mediating decreased susceptibility to biocides in the persistance and spread of multi-drugs resistant of A. baumannii strains isolated in intensive care units of a tertiary-care teaching hospital.
67 clinical and 24 environmental strains isolated from 2007 to 2010 were genotyped by PFGE, MLST and REP-PCR. Multiplex PCRs were performed for identification of the ompA, csuE and blaOXA-51like sequence type groups. The antimicrobial susceptibility was determined and the presence of carbapenemase-encoding genes was analysed by characterization of the blaOXA genes. Chlorine susceptibility was analysed according to BS EN 1040:1997
The cross-analysis of genotyping methods allowed to group strains into 4 clones, only the clone A belonging to the Group 1 corrisponding to European II clonal complex and the clone B belonging to Group 2 clonal complex European I. Since 2008, a new variant of clone A has emerged as the predominant clinical and environmental strain, resulting positive for the presence of the carbapenemase OXA-58 plasmid-mediated and showing reduced chlorine susceptibility in vitro
Multi-antibiotic resistance may not be the only strategy applied by A. baumannii to spread and persist in healthcare setting, but also the increased resistance to biocides
Disclosure of interest