Antibiotic Susceptibility of Enterococcal Isolates causing Bacteremia / 감염

BACKGROUND: Enterococci have emerged as an important nosocomial pathogen. Enterococcal infections are a therapeutic challange because of antibiotics resistance, especially high-level aminoglycoside resistance and vancomycin resistance. METHODS: We reviewed the medical records of enterococcal bacteremia patients admitted to Seoul National University Hospital between April 1996 and May 1998. The susceptibility of enterococci to ampicillin, vancomycin, teicoplanin, gentamicin, streptomycin, ciprofloxacin, imipenem, rifampin, and tetracyclin were determined by micro-dilution method. RESULTS: Forty-two episodes of enterococcal bacteremia were identified. Of the 42 bacteremia, 74% (31/42) were caused by E. faecalis, and 26% (11/42) by E. faecium. The most common underlying diseases were hepatobiliary diseases (24%) and cardiovascular diseases (24%). Cholangitis (21%), pneumonia (14%), catheter-related infection (10%), peritonitis (7%), urinary tract infection (7%) were the frequent primary infections for the enterococcal bacteremia. Of the 31 isolates of E. faecalis, 29 (94%) were susceptible to ampicillin, whereas only 36% (4/11) of E. faecium were susceptible to ampicillin. Of the isolates of E. faecalis, 61% (19/31) were highly resistant to gentamicin, 39% (12/31) highly resistant to streptomycin, and 32% (10/31) highly resistant to both gentamicin and streptomycin. Of the isolates of E. faecium, 45% (5/11), 55% (6/11), and 27% (3/11) were highly-resistant to gentamicin, streptomycin, and both gentamicin and streptomycin, respectively. Only one isolate of E. faecium showed resistance to vancomycin. CONCLUSION: Approximately one third of enterococcal blood isolates showed high-level resistance to gentamicin and streptomycin.

Molecular Epidemiology and Surveillence of Vancomycin-resistant Enterococci at Seoul National University Hospital / 감염

BACKGROUND: The purpose of this study is to investigate the epidemiology and microbiological susceptibility patterns of vancomycin-resistant enterococci (VRE) in Seoul National University Hospital. METHODS: The VRE isolates between May 1998 and October 1999 were studied. We reviewed the medical records of VRE-isolated patients for clinical and epidemiologic data. The susceptibility of VRE to ampicillin, vancomycin, teicoplanin, gentamicin, streptomycin, ciprofloxacin, imipenem, rifampin, tetracyclin were determined by micro-dilution method. PCR for genotyping and PFGE for molecular epidemiology were performed. RESULTS: Twenty-nine VRE isolates were identified from 14 patients, 12 patients from clinical specimens and two from only rectal surveillence cultures. All strains were E. faecium and expressed vanA genotype. The vancomycin MIC and teicoplanin MIC were >128microgram/mL for all isolates. All isolates also resistant to most other antibiotics tested (ampicillin 84.2%, gentamicin 73.7%, streptomycin 73.7%, ciprofloxacin 84.2%, tetracycline 63.2%, rifampin 84.2%, imipenem 94.7%). PFGE analysis revealed 17 distinct PFGE strain types from 14 patients and there were no predominent types. Two patterns, each of them represented by two isolates, were identical. One of which was not associated epidemiologically but the other was associated with direct spread from colonized patient at the intensive care unit. CONCLUSION: The majority of VRE cases occurring at Seoul National University Hospital were not caused by epidemiologic strains but sporadic isolations although there was one case of patient to patient spread.