Molecular Genetic Characterization of Clinical Isolates of Streptococcus pyogenes / 대한진단검사의학회지

BACKGROUND: Group A streptococcus (Streptococcus pyogenes) is the most common cause of bacterial pharyngitis and an important cause of a variety of suppurative and nonsuppurative diseases. The molecular genetic analysis of group A streptococci in clinical isolates is rarely reported in Korea. In this study, molecular genetic analysis using serotyping and emm sequence analysis, testing the presence of the SpeA and SpeB gene, and the determination of an antimicrobial resistance pattern were investigated. METHODS: Sixty nine strains of S. pyogenes from clinical isolates in Korea during 1999-2002 were examined by T agglutination, serum opacity reaction, and emm sequence analysis. Also investigated were antimicrobial susceptibility and the frequency of SpeA and SpeB genes. RESULTS: The antibiotic resistance rates for S. pyogenes isolates were shown at 28.9% of erythromycin, 14.2% of ampicillin, 9.5% of chloramphenicol, and 6.3% of levofloxacin. However, all strains were susceptible to penicillin, vancomycin, and teicoplanin. By T agglutination typing, forty-one (59.4%) among sixty-nine isolates were identified as T28 (13%), T6 (13%), T1 (10%), T12 (8.7%), T4 (4%), T5/27/44 (4%), T3/B3264 (2.9%), T11/12 (1.4%), and TB3264 (1.4%). Thirty-five (50.7%) among sixty nine isolates were positive in serum opacity reaction. The SpeB gene showed positive in all strains but the SpeA gene in eleven (15.9%) strains. By emm gene sequence analysis, forty-seven (68.1%) CONCLUSIONS: Our data showed that antimicrobial resistance of clinical isolates to erythromycin were higher than those reported from the United States and Europe, and emm genotyping could be used for a reliable and efficient typing method.

Direct Detection of Mycobacterium Tuberculosis in Respiratory Specimens by Ligase Chain Reaction / 대한임상병리학회지

BACKGROUND: The most common clinical manifestation of tuberculosis is respiratory tract infections. Currently, respiratory tract tuberculosis is diagnosed by using X-ray, acid-fast smear, culture, or DNA probe technology. The nucleic acid amplification technologies include the polymerase chain reaction (PCR) and the ligase chain reaction (LCR). The potential utility of LCx (Abbott Lab.) kit for the detection and identification of Mycobacterium tuberculosis in respiratory specimens has been measured. METHODS: Four different methods such as acid-fast smear, culture, PCR, and LCR were evaluated using 58 specimens isolated from patients. The IS6110 sequences for Mycobacterium tuberculosis synthesized and provided by Applied Biosystems were used for PCR procedure. The LCR assay using LCx kit was performed according to the manufacturer's instruction (Abbott Lab., U.S.A.). RESULTS: Sensitivity, specificity, and positive and negative predicative values for acid-fast smear method were 72, 100, 100 and 89%, respectively and were 89, 100, 100 and 95%, respectively for culture method. Whereas those values for PCR method were 78, 100, 100, and 91% respectively, and those for LCR were 100, 95, 90 and 100%, respectively. CONCLUSIONS: The LCR assay performed on respiratory specimens for the detection of Mycobacterium tuberculosis has been evaluated as a highly effective method among 4 different identification systems.