ObjectivesTo confirm genotype diversities of clinical isolates of Bordetella pertussis and to evaluate the risk of pertussis outbreak in Korea.MethodsSeven housekeeping genes and 10 antigenic determinant genes from clinical B. pertussis isolates were analyzed by Multilocus sequence typing (MLST).ResultsMore variant pattern was observed in antigenic determinant genes. Especially, PtxS1 gene was the most variant gene; five genotypes were observed from eight global genotypes. In the bacterial type, the number of observed sequence types in the isolates was seven and the most frequent form was type 1 (79.6%). This major sequence type also showed a time-dependent transition pattern. Older isolates (1968 and 1975) showed type 1 and 6 in housekeeping genes and antigenic determinant genes, respectively. However, these were changed to type 2 and 1 in isolates 1999–2008. This transition was mainly attributed to genotype change of PtxS1 and Fim3 gene; the tendency of genotype change was to avoid vaccine-derived genotype. In addition, there was second transition in 2009. In this period, only the sequence type of antigenic determinant genes was changed to type 2. Based Upon Related Sequence Types (BURST) analysis confirmed that there were two clonal complexes (ACCI and ACCII) in the Korean isolates. Moreover, the recently increased sequence type was revealed as AST2 derived from AST 3 in ACCI.ConclusionsGenotype changes in Korean distributing strains are still progressing and there was a specific driving force in antigenic determinant genes. Therefore continuous surveillance of genotype change of the distributing strains should be performed to confirm interrelationship of genotype change with vaccine immunity.
ObjectivesMycobacterium intracellulare is the major causative agent of nontuberculous mycobacteria-related pulmonary infections. The strain typing of M. intracellulare is important for the treatment and control of its infections. We compared the discrimination capacity and effective value of four different molecular typing methods.MethodsAntibiotic susceptibility testing, hsp65 and rpoB sequencing, pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), mycobacteria interspersed repetitive-unit-variable-number tandem-repeat analysis (MIRU-VNTR), and VNTR assay targeting 44 M. intracellulare isolates obtained from patients with pulmonary infections were performed.ResultsAll the antibiotic susceptibility patterns had no association with the molecular and sequence types tested in this study; however, the molecular and sequence types were related with each other. PFGE gave best results for discriminatory capacity, followed by VNTR, MLST, and MIRU-VNTR.ConclusionThe high discriminatory power of PFGE, VNTR, and MLST is enough for differentiating between reinfection and relapse, as well as for other molecular epidemiological usages. The MLST could be regarded as a representative classification method, because it showed the clearest relation with the sequence types.
Nuruk plays a significant role in the flavor and quality of Takju and Yakju, which are produced through saccharification and alcohol fermentation by various microorganisms. In this study, we identified microbial strains isolated from a plate count and PCR-denaturing gradient gel electrophoresis (DGGE) analysis targeting the 16S and 28S rRNA genes, in order to characterize bacterial and fungal diversity in Sansung Nuruk. The numbers of bacteria and fungi in Nuruk were 1.5x10 9 CFU/g and 2.2x10 8 CFU/g, respectively. The 16S rRNA gene sequence indicated that the predominant bacteria in the isolates and PCR-DGGE profile of Nuruk were Kocuria spp., Pantoea spp., Lactobacillus spp., Pediococcus spp., Weissella spp., Staphylococcus spp., endophytic bacterium, uncultured Gamma-proteobacteria, uncultured Cyanobacteria, and Actinobacteria. Dominant bacteria from the PCR-DGGE profile were Pediococcous pentosaceus and uncultured Cyanobacteria. The 28S rRNA gene sequence indicated the predominant fungi in the isolates and PCR-DGGE profile to be Trichomonascus spp. Pichia spp., Torulaspora spp., Wickerhamomyces spp., Sacharomycopsis spp., Lichtheimia spp., Mucor spp., Rhizopus spp. Aspergillus spp., and Cladosporium spp. Dominant fungi from the PCR-DGGE profile were Pichia kudriavzevii and Aspergillus oryzae. The PCR-DGGE technique was used for the first time in this study to assess a microbial community in Nuruk and proved to be an effective protocol for profiling microbial diversity.
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