First Report of an OXA-23 Carbapenemase-Producing Acinetobacter baumannii Clinical Isolate Related to Tn2006 in Spain

A carbapenem-resistant Acinetobacter baumannii clinical isolate belonging to European clone II and sequence type 2 was recov-ered from a patient in the Son Espases hospital in Mallorca, Spain. Genetic analysis showed the presence of the bla OXA-23 gene in association with the widely disseminated transposon Tn2006. This is the first reported identification of A. baumannii carrying bla OXA-23 in Spain

Rapid and accurate identification of genomic species from the Acinetobacter baumannii (Ab) group by MALDI-TOF MS

AbstractThe closely related members of the Acinetobacter baumannii (Ab) group (A. baumannii, A. pittii and A. nosocomialis) are difficult to identify with phenotypic tests in diagnostic laboratories. Genotypic identification methods require special skills and most do not provide rapid results. The aim of this study was to investigate the ability of MALDI-TOF MS to identify members of the Ab group. Sixty epidemiologically unrelated Acinetobacter spp. isolates were investigated by MALDI-TOF MS: 18 A. baumannii, 17 A. pittii, 18 A. nosocomialis and seven additional isolates representing other Acinetobacter spp. All strains were verified by ARDRA, rRNA intergenic spacer (ITS), recA sequencing and b/aOXA-51. MALDI-TOF MS correctly identified all the genomic strains but erroneously identified A. nosocomialis as A. baumannii because there was no reference strain within the Bruker database. Peak analysis of individual spectra from representative strains of each member of A. baumannii, A. pittii and A. nosocomialis suggested enough differences between their protein signatures to allow accurate identification using MALDI-TOF MS. Inclusion of specific signature profiles for A. nosocomialis within the Bruker database allowed the correct identification of this genomic species. MALDI-TOF MS spectra can be used as a fast, simple and reliable method to identify members of the Ab group. The rapid and accurate identification of clinically significant Acinetobacter strains will improve insight into their epidemiology and allow for targeted therapeutic and infection control measures against clinically important strains

An Ribonuclease T2 Family Protein Modulates Acinetobacter baumannii Abiotic Surface Colonization

Acinetobacter baumannii is an emerging bacterial pathogen of considerable medical concern. The organism's transmission and ability to cause disease has been associated with its propensity to colonize and form biofilms on abiotic surfaces in health care settings. To better understand the genetic determinants that affect biomaterial attachment, we performed a transposon mutagenesis analysis of abiotic surface-colonization using A. baumannii strain 98-37-09. Disruption of an RNase T2 family gene was found to limit the organism's ability to colonize polystyrene, polypropylene, glass, and stainless steel surfaces. DNA microarray analyses revealed that in comparison to wild type and complemented cells, the RNase T2 family mutant exhibited reduced expression of 29 genes, 15 of which are predicted to be associated with bacterial attachment and surface-associated motility. Motility assays confirmed that RNase T2 mutant displays a severe motility defect. Taken together, our results indicate that the RNase T2 family protein identified in this study is a positive regulator of A. baumannii's ability to colonize inanimate surfaces and motility. Moreover, the enzyme may be an effective target for the intervention of biomaterial colonization, and consequently limit the organism's transmission within the hospital setting