Background: Enterococcus faecium has emerged as an important nosocomial pathogen worldwide, and this trend has been associated with the dissemination of a genetic lineage designated clonal complex 17 (CC17). In the present study, characterization of the glycopeptide resistance mechanism, genetic relatedness, and pathogenicity in isolates of vancomycin-resistant E. faecium in the Chungcheong area were investigated. Methods: A total of 37 consecutive, non-duplicate, vancomycin-resistant E. faecium were isolated at three university hospitals in the Chungcheong area. The mechanism of glycopeptide resistance and pathogenicity factors were studied using PCR, and the genetic relatedness was determined via multilocus sequence type and esp repeat profile analysis. Additionally, the quinolone resistance-determining regions of parC and gyrA were sequenced to identify mutations involved in ciprofloxacin resistance. Results: Two genotypes of VRE were confirmed: VanAphenotype vanA genotype VRE (25 isolates) and VanB-phenotype vanA genotype VRE (12 isolates). MLST analysis revealed five sequence types. A significant result was that ST414 and CNS4 (4-1-1-1-1-1-1) were considered as belonging to CC17. The esp and hyl genes were found in 100% and 86.4% of the isolates, respectively. A total of 37 isolates showed genetic mutations in parC and gyrA. Conclusion: All isolated strains in the present study belonged to one of the CC17 genotypes including ST414 and CNS4 (4-1-1-1-1-1-1), which were not previously detected in Korea. The combination of MLST and the esp gene repeat profiles can be useful for genetic characterization of VREF isolates with regard to the evolutionary process and epidemiology of the clones. (Korean J Clin Microbiol 2011;14:60-66)

Acinetobacter baumannii is a gram-negative organism reported worldwide as a cause of health-care associated infections. Due to its increasing drug resistance, several studies on coproduction of armA and carbapenemase in South Korea and other parts of the world were reported, which can pose significant therapeutic threat. The aim of this study was to investigate genetic characteristics of multidrug-resistant A. baumannii coproducing armA and carbapenemase and its epidemiological relatedness. Forty-five multidrug resistant (MDR) A. baumannii clinical isolates were collected. Antimicrobial susceptibility was determined by agar dilution, Etest and VITEK 2 system. The presence of 16S rRNA methylase and carbapenemase were analyzed by polymerase chain reaction (PCR) and sequencing. Repetitive element palindromic (REP)-PCR was also performed for epidemiologic investigation. All of A. baumannii isolates harbored bla OXA-51 -like gene and 10 isolates showed an upstream ISAba1. 36 isolates (80%) showed amplification of OXA-23, all of which except one had an upstream ISAba1. 16S rRNA methylase armA was found in 44 isolates with high level resistance to aminoglycosides. The rate of coproduction was found in 36 isolates (80%). All isolates showed dominant two patterns in REP-PCR profile. The prevalence of MDR A. baumannii coproducing OXA-23 and armA was high, which the rate of bla OXA-23 coproduction was also high.