Vancomycin Resistance of Staphylococcus aureus in Korean Primary Hospitals

According to a United States study, 13 cases of vancomycin-resistant Staphylococcus aureus (VRSA) have been reported to date. In 2001, a survey conducted in Korea revealed that 0.5% of methicillin-resistant S. aureus (MRSA) isolates have a vancomycin minimum inhibitory concentration (MIC) of 4 microg/ml, and are thus referred to as vancomycin intermediate S. aureus (VISA). However there are no reports of VISA found in primary hospitals. We evaluated the MIC of vancomycin in MRSA samples obtained from primary hospitals to determine whether VISA was present in primary hospitals. The population analysis was performed to determine whether hetero-VISA was present in primary hospitals. As a result, twenty of the 103 isolates were S. aureus which were all MRSA and the vancomycin MIC was similar to that seen in tertiary hospitals. Population analysis confirmed that three strains were hetero-VISA, by showing that one strain grew in 8 microg/ml vancomycin and that two strains grew in 4 microg/ml vancomycin. In conclusion, hetero-VISA was detected in Korean primary hospitals, which may develop into VISA, however a larger sample size will be needed to confirm these results.

Urinary Isolates and Antimicrobial Resistance in the Urine Collected from Patients Admitted into Primary-Care Hospital in Shiheung District / 대한임상미생물학회지

Urinary isolates and antimicrobial resistance of a primary hospital representing community were analyzed. The beta-lactam and aminoglycoside resistances of E. coli and P. aeruginosa were lower than that seen in a tertiary hospital. Imipenem-resistant P.aeruginosa or VRE was not isolated; however the prevalence of ESBL was thought to be similar to that observed in a tertiary hospital.

In Vitro Activity of Antimicrobial Combination against Multidrug-Resistant Pseudomonas aeruginosa, Korea / 대한임상미생물학회지

BACKGROUND: Pseudomonas aeruginosafrequently causes nosocomial infection. Recently, there have been reports of infection with multidrug-resistant P. aeruginosa. The purpose of this study was to evaluate the in vitro effect of antimicrobial combination against multidrug-resistant P. aeruginosa. METHODS: Twenty isolates of imipenem and/or cefepime resistant P. aeruginosa were collected from the microbiology laboratory of Ewha Womans Unversity Mokdong Hospital. Checkerboard titration method was used to assess the activity of ceftazidime or cefepime in combination with amikacin, gentamicin or aztreonam, and colistin in combination with ceftazidime or rifampin. RESULTS: All isolates were resistant to more than 12 antimicrobial agents including imipenem and/or cefepime by broth microdilution method; however, no isolates were resistant to colistin. Most of the isolates showed high level resistance to ceftazidime, cefepime and meropenem, with MIC90 of 128, 512 and 64 microgram/mL, respectively. The MIC90 of colistin was 2 microgram/mL, which is within the su ceptiblerange. Synergistic effect was not detected by the checkerboard titration method with any antimicrobial combinations. However, a partial synergy was observed in 40% of the isolates with the combination of ceftazidime and amikacin, 65% with ceftazidime and gentamicin, 45% with cefepime and amikacin, and 75% with cefepime and gentamicin. Other antimicrobial combinations showed indifference against most strains, and antagonism was not observed. CONCLUSION: Multidrug-resistant P. aeruginosa isolates were all susceptible to colistin. The combined regimens of ceftazidime with amikacin or gentamicin and cefepime with amikacin or gentamicin revealed a partially synergistic effect in 40-75% of the isolates.