ABSTRACT
BACKGROUNDS: The emergence of resistant strains to glycopeptide in enterococci(GRE) is increasingly serious problem in the worldwide. Automated methods and disk diffusion test have difficulties in detecting vancomycin resistance of some strains of vancomycin-resistant enterococci(VRE), especially having vanC genotypes. And a few studies have been done assessing the ability of antimicrobial susceptibility testing methods to detect teicoplanin resistance in enterococci. METHODS: We evaluated the abilities of two commercial kits including Vitek GPS-IZ(BioMerieux, Vitek, Inc., USA) and E-test(AB Biodisk, USA), and disk diffusion test to detect glycopeptide resistance using 34 strains of vanA and 15 strains of vanC1/C2 VRE. We compared the results with those of standard agar dilution test. RESULTS: In detecting vancomycin resistance, no very major or major errors were seen, and minor error rates were observed with disk diffusion(25%), Vitek GPS-IZ(20%) and E-test(8%). Overall sensitivities of all three methods in detecting vancomycin resistance of vanA VRE were 97-100%, but sensitivities in detecting vancomycin resistance of vanC VRE were 20% in disk diffusion, 87% in E-test and 87% in Vitek GPS-IZ. In detecting teicoplanin resistance, very major error rate was high in Vitek GPS-IZ(47%), but no very major or major errors were seen in disk diffusion and E-test; minor error rates of 2% and 6% were seen in Vitek GPS-IZ and E-test, respectively. CONCLUSION: All three methods detect vancomycin resistance of vanA VRE, but they continue to demonstrate problems in detecting low-level vancomycin resistance and the Vitek GPS-IZ is difficult to detect teicoplanin resistance in enterococci.
Subject(s)
Agar , Diffusion , Genotype , Teicoplanin , Vancomycin ResistanceABSTRACT
BACKGROUND: It has been well known that normal leukocyte counts in blood can vary depending on age, gender, other environmental factors and ethnic differe nces. However, the normal white blood cell counts in Koreans has not been settled yet. Over past several years, a large number of patients were referred to the Hematology Clinic of Asan Medical Center (AMC) for evaluation of "leukopenia", and most of them were found to have no medical problems other than leukocyte counts less than 4,000/mm3. We performed this study on persons who visited Health Screening Center to analysis of leukopenic patients and also to establish the normal value of white blood cell counts in Korean. METHOD: We studied 31,307 persons (19,540 men, 11,767 women, aged 15-90), who visited to Health Screening Center of AMC during the period from January through December 1995. We have carried out retrospec tive analysis of complete medical record of 2,406 patients (838 men, 1,568 women, aged 20-81) who were found to have leukocyte counts less than 4,000/ mm3. And we tried to establish the normal values of leukocyte counts and differential counts of 24,079 adults (15,807 men, 8,272 women, aged 19-90), who were assessed to be healthy at Health Screening Center of AMC. RESULTS: 1) Leukopenia (WBC<4,000/mm3) were found in 2,406 subjects (7.7%) among 31,307 persons screened. 2) Among them, 77 subjects (3%) had medical illness; 39 of them had chronic B or C viral hepatitis, 24 of them had iron deficiency anemia, and other diseases were de tected in remaining 14 patients. But other hematologic dis eases or significant infectious diseases were not detected. Follow-up study of them has indicated no increased incidence of infection or other hematologic diseases. 3) The total white blood cell counts of 24,097 healthy Korean adults were 3,640-9,870/mm3 (5,900/ mm3) in men, and 3,270-8,400/mm3 (5,264/mm3) in women. Neutrophil counts ranged 1,288-6,866/mm3 (3,098/mm3) in men, and 1,180-5,985/mm3 (2,816/mm3) in women. Leukocyte counts were significantly lower in female, but no significant variation was found among age groups. CONCLUSION: Normal range of leukocyte counts and neutrophil counts of healthy Korean adults were lower than those of white populations. Thus, a new normal values of leukocyte and neutrophil counts should be established in Koreans. And many persons with leuko cyte counts less than 4,000/mm3 who are otherwise he althy could be normal.