Molecular Epidemiology and Antimicrobial Resistance Determinants of Multidrug-Resistant Acinetobacter baumannii in Five Proximal Hospitals in Taiwan

We investigated the molecular epidemiology, antibiotic susceptibility, and antimicrobial resistance gene determinants of 23 multidrug-resistant (MDR) Acinetobacter baumannii samples that were collected from 5 proximal hospitals in Taiwan during April and May 2009. Major antibiotic resistance varied from 82.6 to 100%. Five pulsotypes were observed to spread clonally among the 5 hospitals. PCR screening revealed high distributions of intII (91%), bla(OXA-23) (57%), bla(ampC) (100%), adeB (100%), adeJ (100%), and abeM (100%) genes, which were prevalent in the MDR A. baumannii isolates. Resistance gene expression was examined by reverse transcription-PCR, and showed that increased ampC expression was associated with ceftazidime resistance, but expression of adeB, adeJ, or abeM did not guarantee antimicrobial resistance phenotypes. In addition, imipenem resistance in some A. baumannii strains may be mainly modulated by genes other than bla(OXA-51-like). This is the first direct evidence indicating local spread of MDR A. baumannii in Taiwan. The resistance gene determinants are widely distributed in clonal and nonclonal-related isolates.