Five Rare Non-Tuberculous Mycobacteria Species Isolated from Clinical Specimens / 결핵및호흡기질환

BACKGROUND: Recently, the rate of infections with non-tuberculous mycobacteria (NTM) has been increasing in Korea. Precise identification of NTM is critical to determination of the pathogen and to target treatment of NTM patients. METHODS: Sixty-eight unclassified mycobacteria isolates by rpoB PCR-RFLP assay (PRA) collected in 2008 were analyzed by National Center for Biotechnology Information (NCBI) Basic Local Alignment Search Tool (BLAST) search after sequencing of 16S rRNA, hsp65, rpoB genes. RESULTS: Nineteen strains of 68 isolates were specified as species after sequencing analysis of 3 gene types. We found 3 M. lentifulavum, 5 M. arupense, 4 M. triviale, 4 M. parascrofulaceum, and one M. obuense. One M. tuberculosis and another M. peregrinum were mutated at the Msp I recognition site needed for rpoB PRA. The remaining 49 isolates did not coincide with identical species at the 3 kinds genes. CONCLUSION: Sequencing analysis of 16S rRNA, hsp65, rpoB was useful for identification of NTM unclassified by rpoB PRA.

Interferon-gamma Release Assay among Tuberculin Skin Test Positive Students in Korean High Schools / 결핵및호흡기질환

BACKGROUND: There are several active tuberculosis (TB) cases in Korean high schools each school year. The risk of transmission in schools is extremely high due to the considerable time spent in closed classrooms. We evaluated the control of latent tuberculosis infection in Korean high schools. METHODS: When a student was identified with active TB, tuberculin skin testing was performed on their classmates and on students in their same school grade. When a student had a positive tuberculin skin tests (TST), they underwent follow-up testing with QuantiFERON-TB Gold In-Tube (QFT). The manufacturer recommended a cut-off of 0.35 IU/mL to determine QFT positivity was applied. RESULTS: A total of 131 pulmonary tuberculosis (TB) patients were included based on the criteria for screening TB contacts in the National Tuberculosis Control Program. Seventy-five (57.2%) students tested smear positive. TST were performed on 7,109 students who were classmates of, or in the same grade as, a TB patient. Of the contacts, 1,231 students (17.3%) were TST positive and they were screened with QFT. Six hundred-sixty-six (55.0%) of the tested students returned a positive QFT result and the rate of positivity was significantly associated with the increasing size of TST indurations (p<0.0001). CONCLUSION: The use of QFT resulted in approximately 45% of TST positive students not being given chemoprophylaxis.