• International Journal of Oral Biology
• /
• 제39권1호
• /
• pp.9-13
• /
• 2014

Streptococci are among the normal human microflora that populate the oral cavity. However, oral streptococci are known as a major causative agent for dental caries and bacterial endocarditis. Tetracycline is a broad-spectrum antibiotic that is used for oral infections but two mechanisms of tetracycline resistance in streptococci have been reported. The tet(K) and tet(L) genes in these bacteria are related to the active efflux of tetracycline, whereas tet(M) and tet(O) confer ribosomal protection from this antibiotic. It has been reported that the tetracycline resistance of streptococci is related mainly to the activity of tet(M) and tet(O). In our present study, we examined the prevalence of tet(M) and tet(O) in oral streptococci isolated from Korean dental plaques using PCR. One hundred and forty eight of 635 isolates (23.3%) were tetracycline resistant; 68 of these strains (46%) harbored tet(M) and 3 strains (2%) were positive for tet(O). However, tet(M) and tet(O) did not co-exist in any of the resistant strains. Seventy seven of the 148 tetracycline resistant strains (52%) were negative for both the tet(M) and tet(O) genes.

• 한국수산과학회지
• /
• 제45권3호
• /
• pp.238-245
• /
• 2012

In this study, the molecular structures of tet(M) and tet(G) carried by tetracycline (Tc) resistant bacteria in intestinal microflora from the imported ornamental fish were characterized and compared with each other depend on the imported countries. Of the total isolates, approximately 8.9% of the Ent-lac+(lactose fermentative bacteria on coliform media) Tc resistant isolates in fish from three different countries, Singapore, Taiwan and Brazil, were appeared to contain tet(M). Three representative isolates of different countries, Aeromonas spp. JSM-1 (Singapore), JTM-1 (Taiwan) and JBM-1 (Brazil), were isolated and analyzed the molecular structures of tet(M) gene. Interestingly, partial sequence of tet(M) genes (1099 bp) in JBM-1 (Brazil) showed 99.5% homology with the tet(M) found in the Vibrio spp. RV16 isolate, obtained from marine fish in Korea and known to carry Tn1545 parent type of tet(M). In contrast, tet(M) gene in JSM-1 and JTM-1 showed mosaic structure of Tn1545 and Tn916, and 100% homology with each other. It may suggest the presence of various characteristics in terms of tet(M) gene structure. The determined sequence of the tet(G) from Aeromonas spp. JSG-1 and JBG-1 isolated from Singapore and Indonesia ornamental fish respectively showed similar nucleotide sequence homology but revealed a few nucleotide changes in comparison with the sequence of the prototype tet(G) gene (S52437 in GenBank).

• 미생물학회지
• /
• 제40권1호
• /
• pp.1-6
• /
• 2004

대구지역에서 수집한 50점의 김치 중에서 10점의 김치로부터 tetracycline내성 세균을 분리하였다. 이 균주들의 tetracycline에 대한 MIC는 25-100 mg/l 이상의 범위로 분포하였으며 다른 항생제에 대한 내성도 다양하였다. tet(M), tet(O)특이적 primer를 이용한 PCR에서 HJ9 한 균주에서만 tet(M)유전자가 검출되었으며, tet(M)은 플라스미드상에 존재하는 것으로 나타났다. HJ9 균주의 tet(M)부분 염기서열을 분석한 결과 기존에 보고된 Gram양성균의 tet(M)의 DNA 염기서열 및 아미노산 서열과 각각 90-99%, 94-100%의 높은 상동성을 보였다. 165 rRNA 염기서열을 분석한 결과 HJ9 균주는 Lactobacillus sakei로 동정되었다. 김치를 통하여서도 항생제 내성 유전자의 전파 확산이 가능할 것으로 생각된다.

• Fisheries and Aquatic Sciences
• /
• 제9권2호
• /
• pp.97-100
• /
• 2006

To determine whether the tetracycline resistance genes tet (34), tet (M), and tet (S) can be transferred among bacteria, we used a filter mating experiment allowing intimate cell-cell contact between donor and recipient. The tet(34) gene, conveyed on a chromosome of Vibrio species (No. 6 and SW-42) was not transferred to Escherichia coli JM109, suggesting that it is not transferred among bacterial species. The tet (M) gene was transferred from three Vibrio strains (4-E, SW-18, and SW-38) to E. coli at frequencies of $8.5{\times}10^{-5}\;to\;2.1{\times}10^{-6}$. The tet(S) gene was transferred from Lactococcus garvieae KHS98032 to E. coli at a frequency of $1.8{\times}10^{-6}$. Transconjugated recipients showed increased minimum inhibitory concentrations against oxytetracycline. Although the donors possess the Tn916-Tn1545 transposons, they were not detected in transformed recipients, suggesting that the transfer of tet(M) and tet(S) is mediated by elements or mechanisms. Two ribosomal protect protein genes were also transmissible from marine bacteria to E. coli, suggesting gene hopping among marine, terrestrial, and human environments.

• 한국식품위생안전성학회지
• /
• 제27권1호
• /
• pp.63-67
• /
• 2012

동물성 식품 유래 장구균의 항생제 내성은 내성균주 또는 내성 유전자가 먹이사슬을 통해 인체로 전달될 수 있다는 가능성 때문에 공중보건학적으로 중요하게 대두되고 있다. 본 연구는 원유 시료에서 분리된 장구균의 tetracycline에 대한 내성을 표현형 및 유전형 수준에서 분석하였다. 원유 시료에서 총 245주의 장구균을 분리하였으며 그 중 $E.$ $faecalis$ 가 199주로 전체의 81.2%를 차지 하였으며 그 외에 $E.$ $faecium$ 이 25주(10.2%), $E.$ $avium$ 이 7주(2.9%), $E.$ $durans$ 이 6주(2.5%), $E.$ $gallinarum$ 이 4주(1.6%), $E.$ $raffinosus$ 이 4주(1.6%)의 비율로 분리되었다. 분리 균주중 76.3%에 해당하는 187주가 tetracycline에 내성을 나타내었으며 내성균주의 83.4%에 해당하는 156주가 $tet$(M)을 26.7%에 해당하는 50주가 $tet$(S)를 16.1%에 해당하는 30주가 $tet$(L)을 3.2%에 해당하는 6주가 $tet$(M) + $tet$(L) + $tet$(S)의 3개의 유전자를 동시에 소유하고 있는 것으로 분석되었다.

• 수산해양교육연구
• /
• 제29권3호
• /
• pp.834-846
• /
• 2017

Aquaculture practices to ensure greater production, such as high density breeding and excessive feeding, are become stressors that raise the prevalence of diseases. Accordingly, increasingly large volumes of antibiotics are used more frequently each year. Long term use antibiotics can generate resistant bacteria, which interrupt treatments and cause a potential transfer to human bodies. Thus, antibiotic resistance is of importance in public health. Tetracycline (Tc) is one of the typical medicines used in the aquaculture drugs, which has a wide range of application including gram-positive and gram-negative bacteria. In the examination of 153 strains isolated from olive flounder (Paralichthys olivaceus) farms located in Jeju in 2016, it turned out that a total of 84 strains were resistant to Tc or oxytetracycline (OTC). The extent to which the strains are resistant to Tc and OTC was confirmed through MIC test, mostly within the range of 25 to $100{\mu}g/m{\ell}$. Twelve different types of tet genes were detected using single and multiplex PCR in the 84 Tc-resistant strains. The PCR was used to find tet(K), tet(M), tet(O), and tet(S), which are known to exist primarily in gram positive strains. According to the results, - tet(S) is the most dominant gene in 49 strains of Streptococcus parauberis, accounting for 63.2%. And there were two strains that have two different types of resistant genes. The multiplex PCR was used to detect tet(A), tet(B), tet(C), tet(D), tet(E), and tet(G), which are commonly found in gram-negative strains. Each of tet(B), tet(D), and tet(B)&(M) was found in a strain presumed to be Vibrio sp., and only tet(D) was found in 10 Edwardsiella tarda strains.

• 수산해양교육연구
• /
• 제28권1호
• /
• pp.59-68
• /
• 2016

For comparison of tetracycline-resistant ($Tc^R$) genes, we obtained 21 and 14 $Tc^R$ Staphylococcus spp. from marine environment and human patient, respectively. Although all isolates from human were identified as Staphylococcus aureus, higher proportion of $Tc^R$ isolates (12 out of 14) from human were utilizing tet(M) gene compared to that of $Tc^R$ isolates (6 out of 21) from marine environment. Additionally, collaborated utilization of tet(M) and erm(A) in $Tc^R-Em^R$ S. aureus in human patient, but not in $Tc^R$ Staphylococcus spp. isolates from marine environment was also characterized. Based on the nucleotide sequence of transposon related to $Tc^R$ gene, we confirmed the origin of tet(M) gene in $Tc^R$ Staphylococci isolated from marine environments and human are derived from Tn916/1545-like and Tn5801 transposon, respectively. It is the first report showing the presence of Tn5801 in all $Tc^R$ S. aureus carrying tet(M) in human patient. Alignment of the fully sequenced tet(M) from marine environmental isolates was also agreed with the determined transposons by showing the genomic mosaic structure composed with three genomic parts from Tn916/1545 and unknown transposons. Genetic characteristics of these tet(M) in environmental isolates were similar to each other but different from those in isolates from human showing only tet(M) from Tn916/5801 type. It may imply the presence of less dramatic communication of antibiotic resistant genes between Staphylococci isolated from marine environment and human.

• BMB Reports
• /
• 제47권11호
• /
• pp.609-618
• /
• 2014

DNA methylation at cytosines (5mC) is a major epigenetic modification involved in the regulation of multiple biological processes in mammals. How methylation is reversed was until recently poorly understood. The family of dioxygenases commonly known as Ten-eleven translocation (Tet) proteins are responsible for the oxidation of 5mC into three new forms, 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC). Current models link Tet-mediated 5mC oxidation with active DNA demethylation. The higher oxidation products (5fC and 5caC) are recognized and excised by the DNA glycosylase TDG via the base excision repair pathway. Like DNA methyltransferases, Tet enzymes are important for embryonic development. We will examine the mechanism and biological significance of Tet-mediated 5mC oxidation in the context of pronuclear DNA demethylation in mouse early embryos. In contrast to its role in active demethylation in the germ cells and early embryo, a number of lines of evidence suggest that the intragenic 5hmC present in brain may act as a stable mark instead. This short review explores mechanistic aspects of TET oxidation activity, the impact Tet enzymes have on epigenome organization and their contribution to the regulation of early embryonic and neuronal development.

• 약학회지
• /
• 제52권4호
• /
• pp.279-282
• /
• 2008

Plasmids were isolated from 15 tetracycline (Tc) resistant S. aureus. Two small tetracycline resistance plasmids, pKH16 and pKH17, have been isolated from Staphylococcus aureus JY10 and Staphylococcus aureus JY22, respectively and the complete nucleotide sequences of those plasmids have been determined. pKH16 consisted of 4,442 bp and showed high identity to pKH6 (99% matching percentage) isolated in 1989 from S. aureus SA2. pKH17 consisted of 4,441 bp and showed less identity to pKH6 (95% matching percentage) than pKH16. PCR analysis showed that tetK and tetM did not exist in ten large plasmids isolated from ten Tc resistant S. aureus. Twelve Tc resistant S. aureus showed reistance both to Tc and Mn and we might analogize that twelve Tc resistant S. aureus had tetM in their chromosome.

• Journal of Microbiology and Biotechnology
• /
• 제18권2호
• /
• pp.199-206
• /
• 2008

Four hundred and thirteen oxytetracycline-resistant bacteria were recovered from six freshwater giant prawn farms with a history of oxytetracycline use. Most oxytetracycline-resistant isolates were Gram-negative bacteria. Six groups of oxytetracycline-resistant bacteria were classified using cluster analysis based on a comparison of levels of oxytetracycline resistance. Complex fingerprint patterns were obtained for 71 isolates studied. In general, the band patterns of isolates from different ponds were very similar, and the data indicated that the isolates were closely related. The exploration for cross-resistance found that most of the 71 oxytetracycline-resistant isolates were also resistant to tetracycline and chlortetracycline, but had a relatively low resistance to doxycycline. Many isolates showed higher chlortetracycline resistance than oxytetracycline resistance. Additionally, the oxytetracycline-resistant isolates were examined for the presence of tetracycline resistance (tet) genes. Fifty percent of the isolates carried one of the 14 known tet genes examined. The most common determinants were TetA and TetD. However, TetB, TetC, TetE, TetK, TetL, and TetM were also found with various frequencies.