• 약학회지
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• 제43권6호
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• pp.789-792
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• 1999

The complete nucleotide sequence of pKH4, a small multidrug resistance (smr) plasmid isolated from multidrug resistant Staphylococcus aureus SA5, was determined. Sequence analysis has revealed that pKH4 has two open reading frames for Rep and Smr proteins. The comparison of the amino acid sequence of Smr protein of pKH4 with those of other Smr proteins of various Staphylococcus showed that Smr protein of pKH4 is a new member of the SMR family.

• Journal of Microbiology and Biotechnology
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• 제6권2호
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• pp.145-146
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• 1996

The 2.4-kb cryptic plasmid (pKH8) of multidrug-resistant Staphylococcus aureus SA2 was characterized by complete nucleotide sequencing and homology comparison. pKH8 was found to contain three open reading frames. Protein analysis of pKH8 showed that pKH8 was a multidrug resistance plasmid and mediated resistance to ethidium bromide and quaternary ammonium compounds.

• Journal of Microbiology and Biotechnology
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• 제6권3호
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• pp.219-220
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• 1996

The pKH2 isolated from the multidrug-resistant Staphylococcus aureus SA2 is a 40.98-kb plasmid and mediates resistance to ampicillin, clindamycin, erythromycin, kanamycin, and streptomycin. The 3.4-kb HindIII fragment conferring kanamycin resistance was cloned from the pKH2 into pBluescriptII $KS^+$ and partial sequence determination of that fragment was carried out. Sequence analysis revealed that the kanamycin resistance gene which encoded aminoglycoside 3'-phosphotransferase was linked to the streptothricin resistance gene. But a nonsense mutation was found in the streptothricin resistance gene and this mutation resulted in a truncated protein of streptothricin acetyltransferase. Homology comparison with nucleotide sequence databases revealed that the 3.4-kb HindIII fragment of pKH2 had been derived not from S. aureus but from Gram-negative Campylobacter coli.

• 약학회지
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• 제37권6호
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• pp.621-624
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• 1993

The clirical isolate Staphylococcus aureus SA2 had four kinds of plasmids and was resistant to ampicillin, chloroamphenicol, clindamycin. erythromycin, gentamicin, kanamycin, methicillin, streptomycin, tetracycline and tobramycin. Transformation experiment demonstrated that 4.14kb plasmid(pKH7) encoded resistance to chloramphenicol. The cleavage map of pKH7 was determined by restriction enzyme mapping techniques. The cleavage map is given for BstEll, Hindlll, Hpall, and Xbal. The above restriction endonucleases have a single site, but nucleases BamHl, Bgll, BglII, EcoRl, EcoRV, HaeIII, Hpal, Kpnl, Pstl, PvnII, Sall, Smal, and XhoI have no site on this plasmid.

• 약학회지
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• 제39권1호
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• pp.6-9
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• 1995

The clinical isolate Staphylococcus aureus SA2 had four kinds of plasmids and was resistant to ampicillin, chloramphenicol, clindamycin, erythromycin, gentamicin, kanamycin, methicillin, streptomycin, tetracycline and tobramycin. Transformation experiment demonstrated that 4.44 kb plasmid(pKH6) encoded resistance to tetracycline. The cleavage map of pKH6 was determined by restriction enzyme mapping techniques. The cleavage map is given for EcoRV, HindIII, HpaI, HpaII, KpnI and Xbal. Restriction endonucleases BamHl, BglI, BGIII, BstEII, EcoRI, HaellI, PstI, PvuII, SalI, Smal, and Xhol have no site on this plasmid. The restriction map revealed extensive structural homology between pKH6 and pT181.

• Journal of Microbiology and Biotechnology
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• 제30권8호
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• pp.1180-1183
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• 2020

The prevalence and characterization of plasmid-mediated quinolone resistance (PMQR) determinants in ciprofloxacin-resistant Escherichia coli isolated from a Korean commercial layer farm were studied. A total of 45 ciprofloxacin-resistant E. coli isolates were recovered and all isolates were multidrug-resistant. Eight isolates have the PMQR genes aac(6')-Ib-cr, qnrS1, and qnrB4, and seven isolates exhibited double amino acid exchange at both gyrA and parC, and have high fluoroquinolone minimum inhibitory concentrations. Five transconjugants demonstrated transferability of PMQR and β-lactamase genes and similar antimicrobial resistance. Because PMQR genes in isolates from commercial layer chickens could enter the food supply and directly affect humans, control of ciprofloxacin resistance is needed.

• Journal of Microbiology and Biotechnology
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• 제20권6호
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• pp.1042-1052
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• 2010

Forty-seven Salmonella Typhimurium (33 zoonotic, 14 clinical) strains were tested for antimicrobial resistance using the standard disk diffusion method. The presence of relevant resistance genes and class 1 integrons were investigated by using PCR. Pulsed-field gel electrophoresis (PFGE) and plasmid profiling were carried out to determine the genomic diversity of Salmonella Typhimurium. Approximately 57.4% of the S. Typhimurium strains were multidrug resistant (MDR) and showed high resistance rates to tetracycline (70.2%), sulfonamides (57.4%), streptomycin (53.1%), ampicillin (29.7%), nalidixic acid (27.6%), kanamycin (23.4%), chloramphenicol (21.2%), and trimethoprim (19.1%). Resistance towards cephalosporins was noted for cephalothin (27.6%), cephradine (21.2%), amoxicillin clavulanic acid (17.0%), and cephalexin (17.0%). Resistance genes, $bla_{TEM}$, strA, aadA, sul1, sul2, tetA, tetB, and tetC, were detected among the drug-resistant strains. Thirtythree strains (70.2%) carried class 1 integrons, which were grouped in 9 different profiles. DNA sequencing identified sat, aadA, pse-1, and dfrA genes in variable regions on class 1 integrons. Thirty-five strains (74.4%) were subtyped to 22 different plasmid profiles, each with 1-6 plasmids (2.0 to 95 kb). PFGE subtyped the 47 strains into 39 profiles. In conclusion, high rates of multidrug resistance were found among the Malaysian Salmonella Typhimurium strains. The emergence of multidrug-resistant Salmonella Typhimurium to cephalosporin antibiotics was also observed. The strains were very diverse and no persistent clone was observed. The emergence of MDR Salmonella Typhimurium is a worldwide problem, and this report provides information for the better understanding of the prevalence and epidemiology of MDR S. Typhimurium in Malaysia.

• Journal of Microbiology and Biotechnology
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• 제26권2호
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• pp.394-401
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• 2016

Recently, the clustered regularly interspaced short palindromic repeats (CRISPR)-associated protein 9 (CRISPR/Cas9) system, a genome editing technology, was shown to be versatile in treating several antibiotic-resistant bacteria. In the present study, we applied the CRISPR/Cas9 technology to kill extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli. ESBL bacteria are mostly multidrug resistant (MDR), and have plasmid-mediated antibiotic resistance genes that can be easily transferred to other members of the bacterial community by horizontal gene transfer. To restore sensitivity to antibiotics in these bacteria, we searched for a CRISPR/Cas9 target sequence that was conserved among >1,000 ESBL mutants. There was only one target sequence for each TEM- and SHV-type ESBL, with each of these sequences found in ~200 ESBL strains of each type. Furthermore, we showed that these target sequences can be exploited to re-sensitize MDR cells in which resistance is mediated by genes that are not the target of the CRISPR/Cas9 system, but by genes that are present on the same plasmid as target genes. We believe our Re-Sensitization to Antibiotics from Resistance (ReSAFR) technology, which enhances the practical value of the CRISPR/Cas9 system, will be an effective method of treatment against plasmid-carrying MDR bacteria.

• 한국임상수의학회지
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• 제32권2호
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• pp.191-195
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• 2015

7년령, 중성화 수컷 고양이가 무기력과 식욕부진으로 내원하였다. 실험실 검사는 말초혈액 호중구에서 중등도의 퇴행성 변화, free 및 total thyroxine의 농도 감소 및 혈액배양에서 세균증식이 관찰되었다. 16S ribosomal RNA 및 heat shock protein 60 유전자 검사 결과 세균은 Enterobacter cloacae로 확인되었다. 항생제 최소억제농도 평가결과 16개 항생제에 대한 다약제 내성이 관찰되었다. 중합효소연쇄반응 및 시퀀싱 결과 $bla_{TEM-1}$, $bla_{CTX-M-15}$ 및 플라스미드 유래 $bla_{ACT-1}$ 유전자에 대한 양성 반응이 관찰되었으며, 결과적으로 확인된 세균이 광범위 beta-lactamase 및 ampC beta-lactamase를 합성하는 플라스미드를 보유한 것을 확인하였다. 환자는 1개월 간 항생제와 levothyroxine 치료를 받은 후 증상이 호전되었고, 치료 후 갑상선 기능검사와 혈액배양 결과 이상소견은 소실되었다. 이 증례는 고양이의 지역사회획득 다약제내성 E. cloacae에 의한 정상 갑상샘 질환 증후군의 첫 예이다. 신속한 진단과정과 적절한 항생제 선택에 의해 이환된 고양이는 패혈증으로부터 회복되었다.

• Journal of Microbiology and Biotechnology
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• 제23권3호
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• pp.430-435
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• 2013

Multidrug resistance, especially multidrug efflux mechanisms that extrude structurally unrelated cytotoxic compounds from the cell by multidrug transporters, is a serious problem and one of the main reasons for the failure of therapeutic treatment of infections by pathogenic microorganisms as well as of cancer cells. Streptococcus mutans is considered one of the primary causative agents of dental caries and periodontal disease, which comprise the most common oral diseases. A fragment of chromosomal DNA from S. mutans KCTC3065 was cloned using Escherichia coli KAM32 as host cells lacking major multidrug efflux pumps. Although E. coli KAM32 cells were very sensitive to many antimicrobial agents, the transformed cells harboring a recombinant plasmid became resistant to several structurally unrelated antimicrobial agents such as tetracycline, kanamycin, rhodamin 6G, ampicillin, acriflavine, ethidium bromide, and tetraphenylphosphonium chloride. This suggested that the cloned DNA fragment carries a gene encoding a multidrug efflux pump. Among 49 of the multidrug-resistant transformants, we report the functional gene cloning and characterization of the function of one multidrug efflux pump, namely MdeA from S. mutans, which was expressed in E. coli KAM32. Judging from the structural and biochemical properties, we concluded that MdeA is the first cloned and characterized multidrug efflux pump using the proton motive force as the energy for efflux drugs.