• Biomedical Science Letters
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• v.5 no.2
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• pp.135-145
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• 1999

A total of 45 Staphylococcus aureus strains from clinical samples were tested for the biochemical test and antibiotic susceptibility test. Forty-five S. aureus strains were subjected to the molecular epidemiological study by susceptiblity test, antibiogram, bacteriophage typing, polymerase chain reaction and mec-associated hypervariable region gene in order to detect of mecA gene which was one of the structural gene related to antibiotic resistant expression factors. Three of 15 mecA-negative S. aureus isolates were classified as oxacillin resistant despite borderline minimal inhibitory concentration values. Methicillin susceptiblities were completely consistent with PCR results for these strains. On the other hand, 4 of 30 mecA-positive isolates yielded results in the oxacillin and methicillin susceptibility tests which were discrepant from those of PCR analysis. Except for SA6, the methicillin resistant S. aureus strains tested were highly resistant to penicillin, oxacillin, gentamicin, and chloramphenicol. In the phage typing, 27 strains were typable. The Iytic group III was as many as 12 strains, and 7 of 12 were 75/83A/84 type. In the PCR of specific mecA gene probe with chromosomal DNA of 30 methicillin resistant S. aureus, the amplified DNA band of 533 bp was confirmed in 30 strains and not in methicillin sensitive S. aureus. The single amplified band of hypervariable region related to mec was investigated in all of 30 methicillin resistant S. aureus, but in methicillin sensitive S. aureus it was amplified. The size of PCR products was between 200 bp and 600 Up. Four units was directly repeated.

• The Journal of Korean Society of Virology
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• v.26 no.2
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• pp.251-258
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• 1996

The V3 loop, a hypervariable domain of envelope glycoprotein, has an essential role in viral infectivity and has a major epitope for type-specific neutralizing antibody. In order to investigate genetic diversity of V3 region of gp120 of human immunodeficiency virus type 1 (HIV-1) isolated from Korean patients, DNA sequences encoding the C2 to V3 region were amplified by nested polymerase chain reaction (PCR) from uncultured peripheral blood mononuclear cells obtained from 15 HIV-1 seropositive patients and nucleotide sequences were determined. All nucleotide sequences from fifteen patients were compared with 8 distinctive subtypes (A-H) and another subtype O. Phylogenetic analysis was carried out with PHYLIP ver 3.5 (Dnapars) program. Of the 15 isolates, 14 HIV-1 subjects were clustered with subtype B, while one was clustered with subtype C. Intra-subtype B distance at the nucleotide and deduced amino acid level were maximum 17.7% and 37.0%, respectively. Intra-patient distance at the nucleotide and deduced amino acid level were maximum 7.3% and 17.8%, respectively. Analysis of the nucleotide sequences revealed that Korean types have relatively well conserved sequences. These findings could be useful for assessing the source of infection and developing an AIDS vaccine.

• Journal of Periodontal and Implant Science
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• v.52 no.5
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• pp.394-410
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• 2022

Purpose: The purpose of this study was to compare the microbial composition of 3 types of oral samples through 16S metagenomic sequencing to determine how to resolve some sampling issues that occur during the collection of sub-gingival plaque samples. Methods: In total, 20 subjects were recruited. In both the healthy and periodontitis groups, samples of saliva and supra-gingival plaque were collected. Additionally, in the periodontitis group, sub-gingival plaque samples were collected from the deepest periodontal pocket. After DNA extraction from each sample, polymerase chain reaction amplification was performed on the V3-V4 hypervariable region on the 16S rRNA gene, followed by metagenomic sequencing and a bioinformatics analysis. Results: When comparing the healthy and periodontitis groups in terms of alpha-diversity, the saliva samples demonstrated much more substantial differences in bacterial diversity than the supra-gingival plaque samples. Moreover, in a comparison between the samples in the case group, the diversity score of the saliva samples was higher than that of the supra-gingival plaque samples, and it was similar to that of the sub-gingival plaque samples. In the beta-diversity analysis, the sub-gingival plaque samples exhibited a clustering pattern similar to that of the periodontitis group. Bacterial relative abundance analysis at the species level indicated lower relative frequencies of bacteria in the healthy group than in the periodontitis group. A statistically significant difference in frequency was observed in the saliva samples for specific pathogenic species (Porphyromonas gingivalis, Treponema denticola, and Prevotella intermedia). The saliva samples exhibited a similar relative richness of bacterial communities to that of sub-gingival plaque samples. Conclusions: In this 16S oral microbiome study, we confirmed that saliva samples had a microbial composition that was more similar to that of sub-gingival plaque samples than to that of supra-gingival plaque samples within the periodontitis group.