Evaluation of Infrequent-Restriction-Site PCR for Epidemiological Typing of Candida tropicalis / 대한임상미생물학회지

BACKGROUND: We evaluated the usefulness of a newly developed molecular typing method of infrequent restriction site polymerase chain reaction (IRS-PCR) as an epidemiological DNA fingerprinting tool for Candida tropicalis. METHODS: Thirty-two strains of C. tropicalis comprising eight sporadic strains and 24 clonal strains belonging to six clones, of which clonal type were previously confirmed by pulsed-field gel electrophoresis (PFGE), were tested by IRS-PCR to evaluate the usefulness of this technique. Twenty strains of Candida species, including C. glabrata, C. krusei, C. albicans, and C. parapsilosis, were also tested to assess the ability of IRS-PCR to discriminate among species of Candida. RESULTS: Using the IRS-PCR assay, sporadic strains of C. tropicalis could not be differentiated from clonal strains. Most strains belonging to the same clones were classified as different IRS-PCR types or clusters, and some different sporadic strains were classified as the same IRS-PCR types. When pattern variation was examined for different strains of C. tropicalis using IRS-PCR, pairwise similarity measured by the Dice coefficient was 75.4~100%. In contrast, pairwise similarity among isolates of five different species of Candida was 25~69.2%. Therefore, five different species of Candida were easily differentiated. CONCLUSION: The IRS-PCR typing assay appears to be an inadequate tool for the epidemiological typing of C. tropicalis, because the typing result of IRSPCR is not comparable to that of PFGE. To our knowledge, this is the first evaluation study for IRSPCR as an epidemiological typing tool for C. tropicalis.

Comparison of Clinical Characteristics of Patients with Rotavirus Gastroenteritis Relative to the Infecting Rotavirus G-P Genotype / 대한진단검사의학회지

BACKGROUND: Group A rotavirus is a major cause of severe diarrhea in children throughout the world. For the proper management of rotavirus infections, it will be helpful to know their clinical characteristics according to the G and P genotypes of the infecting virus. METHODS: The diarrheal stool specimens from patients hospitalized in Chosun University Hospital during 2002-2003 were tested for rotavirus by Dipstick 'Eiken' Rota kit. Rotavirus antigen-positive stool specimens were analyzed for group A rotavirus by RT-PCR, and the group A-positive PCR products were genotyped for P and G types by PCR. RESULTS: Among the 119 specimens analyzed for genotypes, the predominant strain was genotype G4P[6] (51.3%), followed by G2P[4] (19.3%), G1P[8] (7.6%), G3P[8] (5.0%), and G9P[8] (4.2%). To examine the characteristics of each rotavirus genotype, a clinico-epidemiological study was performed for 100 patients whose medical records were available. The frequencies of diarrhea, vomiting, dehydration, and fever; the rates of nosocomial infection and transfer from other hospitals; and the mean severity scores were significantly different among the patients infected with different types of rotavirus. Especially, patients with G4P[6] type were more likely than those infected with other genotypes to show the following distinct features: Most patients showed milder symptoms and were neonates transferred from other obstetric hospitals and 68.4% of the cases were nosocomial infection. G4P[6] strains were isolated almost all along the year. The mean severity scores of patients infected by G4P[6], G2P[4], G1P[8], G3P[8], and G9P[8] strains were 6.8, 9.5, 8.0, 9.0, and 10.8, respectively. CONCLUSIONS: Many features of rotavirus infections including the epidemic period, rate of nosocomial infection, age and severity of symptoms were different according to the genotypes of the infecting virus.

Evaluation of the detectability of Vitek II System for Inducible Clindamycin Resistance in Staphylococci / 대한진단검사의학회지

BACKGROUND: While broth based antimicrobial susceptibility test methods work well for the detection of the majority of antimicrobial resistance mechanisms, antimicrobial resistance mechanism in some microorganisms may not be detected by these methods. The purpose of this study was to compare Vitek II system with a standard method for the ability to detect inducible clindamycin resistance in Staphylococcus aureus. METHODS: Of 200 clinical isolates of S. aureus tested, 183 were methicillin resistant (MRSA) and 17 were methicillin susceptible (MSSA). A disk approximation test (Clinical Laboratory Standards Institute; CLSI, Wayne, PA, USA) was performed as the standard method by placing standard erythromycin and clindamycin disks in adjacent positions. Vitek II ID-GPI (bioMerieux, Durham, NC, USA) was used for identification and Vitek AST-P536 (bioMerieux, Durham, NC, USA) for antimicrobial susceptibility tests. RESULTS: Clindamycin resistance rates of S. aureus tested by disk diffusion and Vitek II system were 89% and 56%, respectively. All but one inducible clindamycin resistant MRSA isolates were susceptible to clindamycin by Vitek II system. Five inducible clindmycin resistant MSSA isolates were all susceptible to clindamycin by Vitek II system. Vitek II system did not detect the inducible clindamycin resistance in S. aureus. CONCLUSIONS: Our results showed that Vitek II system was unacceptable for the detection of inducible clindamycin resistance in S. aureus. We suggests that the disk approximation test should be used to detect the inducible clindamycin resistance in S. aureus.