Molecular epidemiology of carbapenem-resistant Acinetobacter spp. from XiangYa Hospital, in Hunan Province, China.

Carbapenem-resistant Acinetobacter baumannii has been known as an opportunistic pathogen that causes a variety of illness worldwide. In this study, we characterize the molecular epidemiology of 174 non-repetitive clinical isolates of A. baumannii collected from January to June 2009 from Xiangya Hospital, in Hunan Province, China, including an outbreak period of A. baumannii. These 174 isolates harbored A. baumannii intrinsic gene OXA-51. They were resistant to multiple antibiotics with resistance rates as 49.4% to imipenem, 48.3% to meropenem, 46.6% to ampicillin-sulbactam, 6.9% to cefoperazone-sulbactam, and 6.3% to minocycline. 74 out of 174 isolates were identified as carbapenemase-producing strains, among which bla(OXA-23) gene was found in 71 isolates. These 74 carbapenemase expression strains could be divided into four genotypes by enterobacterial repetitive intergenic consensus (ERIC)-PCR, with 19, 17, 33 and 5 clones in each group. We also found four imipenem resistant isolates carrying OXA-23 gene without showing carbapenemase phenotype. Our findings show that the bla(OXA-23) gene is the common carbapenemase gene among carbapenem-resistant Acinetobacter spp. isolates, suggesting that clonal spread of carbapenemase-producing isolates may be one important factor which results in the high carbapenem resistance rate in the local hospital in Hunan Province, China.