• 미생물학회지
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• 제28권1호
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• pp.27-34
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• 1990

지속성 및 유발성 발한의 두 macrolide-lincosamide-streptogramin B 저항성 인자가 한 Staphylococcus aureus DHI 균주의 염색체 DNA 및 plasmid pDE1(7.4kb)로부터 각각 분리되었다. pDE1상의 유발성 Em 저항성 인자의 염기서열은 이미 보고 된 바 있는 pE194상의 ermC와 동일하였으며 지속성 Em 저항성 인자의 경우는 그 제한효소 인식부위의 mapping 결과로 보아 ermCdb전자에서 유발성 기구에 관여하는 leader peptide 부위가 결여된 인자인 것으로 밝혀졌다.

• Journal of Microbiology and Biotechnology
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• 제15권6호
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• pp.1214-1220
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• 2005

Decreased porin-mediated outer membrane penetration of hydrophilic antibiotics is a common mechanism of antibiotic resistance in Gram-negative bacteria. This study was undertaken to determine whether a null mutation in Pseudomonas putida would suppress porin synthesis, and therefore reduce the susceptibility of the organism to streptomycin, norfloxacin, and tetracycline. Inverse PCR amplification and double-stranded DNA sequencing were used to identify chromosomal genes carrying TnphoA'-1 inserts. Genome database available was used to identify putative homologue genes, one of which encodes protein with homology to domains of the MutS of P. putida, suggesting a crucial role in the multidrug resistance. Increased resistance to streptomycin, norfloxacin, and tetracycline might be due to accumulation of compensatory mutations. Either no growth or slow growth was observed in P. putida KH1027 when grown in minimal medium containing gluconate, glucose, or citrate; however, it is not clear whether the growth patterns contributed to the multidrug resistance.

• 한국수산과학회지
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• 제51권4호
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• pp.397-403
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• 2018

We determined the resistance rates of pathogenic bacteria isolated from cultured olive flounder Paralichthys olivaceus to erythromycin (Em), antibiotic typically used in aquaculture and analyzed the genotypes of resistant bacteria using polymerase chain reaction (PCR). We isolated and utilized 160 isolates of Streptococcus parauberis, 1 of S. iniae, 66 of Edwardsiella tarda, 56 of Vibrio sp. and 23 of unidentified bacteria from presumed infected olive flounder from Jeju Island from March 2016 to October 2017. Of the 306 isolated strains, Em-resistant strains included 33 of S. parauberis, 39 of E. tarda and 2 of Vibrio sp. We conducted PCR to assess the resistance determination of Em-resistant strains. Five different types of Em-resistance genes were detected in the 74 Em-resistant strains: erm (A), erm (B), erm (C), mef (A) and mef (E); erm (A) and erm (B) were detected in 1 (3%) and 24 (72.7%) S. parauberis isolates, respectively. In E. tarda, erm (B) was detected in five isolates (12.8 %) and no Em-resistance genes were detected in the two Vibrio sp. isolates.

• 미생물학회지
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• 제53권2호
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• pp.134-136
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• 2017

이유자돈용 생균제 개발을 위해, 본 연구자들은 유산균의 일종인 Lactobacillus salivairus KLW001 균주를 대한민국 양돈가에서 사육 중인 이유자돈으로부터 분리하였다. 이 균주는 K88 antigen-positive Escherichia coli, Salmonella enterica serovar Typhimurium에 대한 항균 활성이 타 균주보다 우수하여, 우리는 이 균주의 유전체를 분석하였다. 유전체 초안 속의 166개 Contig (${\geq}500bp$)들에서, G+C content (%)가 33.0%였고, 2,326,706 bp 크기의 염기서열을 확보할 수 있었다. 유전체 초안으로부터 항생제 저항 유전자 4개, Phage 관련 유전자 36개, Bile 대사 유전자 3개, CRISPR Spacer 27개를 확인하였다.

• 한국미생물·생명공학회지
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• 제51권2호
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• pp.214-216
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• 2023

메로페넴에 내성을 갖는 Pseudomonas peli CJ30 균주가 대한민국의 한강에서 분리되었다. CJ30 균주의 유전체는 크기가 4,919,106 bp이고 G + C 함량이 60.0%인 아홉 개의 contig로 조립되었다. CJ30 균주의 유전체 서열은 5,411개의 단백질 코딩 유전자, 18개의 rRNA 유전자 및 70개의 tRNA 유전자를 포함하였다. 균주 CJ30에는 bla_SFC-3 및 ampC β-락타마아제 유전자가 포함되어 있습니다.

• Journal of Microbiology and Biotechnology
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• 제34권5호
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• pp.1101-1108
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• 2024

Earlier studies have validated the isolation of extended-spectrum beta-lactamase-producing Salmonella (ESBL-Sal) strains from food. While poultry is recognized as a reservoir for Salmonella contamination, pertinent data regarding ESBL-Sal remains limited. Consequently, the Ministry of Food and Drug Safety has isolated Salmonella spp. from retail meat and evaluated their antibiotic susceptibility and genetic characteristics via whole-genome sequencing. To further elucidate these aspects, this study investigates the prevalence, antibiotic resistance profiles, genomic characteristics, and homology of ESBL-Sal spp. obtained from livestock-derived products in South Korean retail outlets. A total of 653 Salmonella spp. were isolated from 1,876 meat samples, including 509 beef, 503 pork, 555 chicken, and 309 duck samples. The prevalence rates of Salmonella were 0.0%, 1.4%, 17.5%, and 28.2% in the beef, pork, chicken, and duck samples, respectively. ESBL-Sal was exclusively identified in poultry meat, with a prevalence of 1.4% in the chicken samples (8/555) and 0.3% in the duck samples (1/309). All ESBL-Sal strains carried the bla_CTX-M-1 gene and exhibited resistance to ampicillin, ceftiofur, ceftazidime, nalidixic acid, and tetracycline. Eight ESBL-Sal isolates were identified as S. Enteritidis with sequence type (ST) 11. The major plasmid replicons of the Enteritidis-ST11 strains were IncFIB(S) and IncFII(S), carrying antimicrobial resistance genes (β-lactam, tetracycline, and aminoglycoside) and 166 virulence factor genes. The results of this study provide valuable insights for the surveillance and monitoring of ESBL-Sal in South Korean food chain.

• 한국환경보건학회지
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• 제42권4호
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• pp.255-265
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• 2016

Objectives: Mobile phones have become one of the most essential accessories in daily life. However, they may act as reservoir of infectious pathogens if they are used without hygienic practices in their handling. Therefore, this study aimed to isolate food-borne pathogens from mobile phones and investigate the characteristics of toxin genes and antibiotic susceptibility patterns. Methods: A total of 146 mobile phones were collected from 83 middle- and 63 high-school students in Busan. The surfaces of the mobile phones were aseptically swabbed. Results: Among the food-borne pathogens, Staphylococcus aureus, Bacillus cereus and Escherichia coli were detected in 26 (17.8%), 20 (13.7%) and four (2.7%) samples, respectively. There were no statistically significant differences according to school level, gender or phone type. None of four E. coli strains had pathogenic toxic genes. All of the B. cereus strains carried at least three different toxin genes among the nine enterotoxin and emetic toxin genes. Three out of 20 B. cereus strains (15%) possessed emetic toxin genes, which are rarely detected in food-poisoning cases in Korea. Among the 26 strains of S. aureus, the detection rate of staphylococcal enterotoxin genes, toxic shock syndrome toxin (tsst) and factors essential for methicillin resistance (femA) were 84.6%, 7.7% and 100%, respectively. In the antibiotic susceptibility test, there was no methicillin-resistant S. aureus (MRSA) or vancomycin-resistant S. aureus (VRSA). Conclusion: The results show that students' mobile phones in Busan were contaminated by food-borne pathogens which carried various toxic genes. Therefore, regular phone disinfection and hand hygiene is important in order to reduce cross-contamination.

• 미생물학회지
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• 제54권1호
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• pp.53-59
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• 2018

이 실험은 제주도내 양식장으로부터 유입수와 방출수의 다제내성(MDR)을 가진 Vibrio 균의 plasmid profiling을 위해 진행하였다. Plasmid profiling을 위해 사용한 다제내성을 가진 균주는 디스크 확산법을 통해 확인하였고, 유입수와 방출수으로부터 각각 150개의 Vibrio 균주를 분리하였다. 모든 다제내성 균주를 대상으로 plasmid profiling을 실시하였으며, 유입수와 비교하여 방출수에서 많은Vibrio 균이 열거되었다(유입수 39%, 방출수 61%). 방출수에서는 neomycin, sulfamethoxazole, amoxicillin 및 oxytetracycline의 내성을 가진 균주가 유의적으로 많은 것으로 확인되었고, 대조적으로 Vibrio 균주는 florfenicol, chloramphenicol, ciprofloxacin 및 nalidixic acid에 더 민감한 것으로 확인이 되었다. 99종의 다제내성 균주(유입수 39종과 방출수 60종) 중에서 총 58종(유입수 38종과 방출수 20종)이 1.7 kb에서 10 kb 이상의 플라스미드를 가지고 있는 것을 확인하였으며 플라스미드 크기마다 19가지의 다른 다제내성 패턴을 보였다. 6종의 유입수와 4종의 방출수에서 다제내성 균주는 특이적인 plasmid profile이 확인되었다. 방출수 샘플은 보다 많은 플라스미드를 가진 다제내성 Vibrio 균주와 다양한 plasmid profile들과 다제내성 패턴을 가지고 있었고 이는 양식장의 저장탱크가 항생제내성 유전자의 저장소 역할을 할 수 있다는 점을 시사한다. 양식장의 방출수에서 plasmid를 가진 다제내성 Vibrio 균주의 존재는 항생제 내성 유전자의 전파에 기여할 수 있으며 이로 인해 인간의 건강을 위협할 수 있다.

• Journal of Microbiology and Biotechnology
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• 제29권9호
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• pp.1460-1469
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• 2019

The extensive distribution of multidrug-resistant (MDR) methicillin-resistant Staphylococcus aureus (MRSA) poses a threat to healthcare worldwide. This study aimed to investigate the MDR and molecular patterns of MRSA isolates in children admitted to the two biggest tertiary care pediatric hospitals in northern and southern Vietnam. A total of 168 MRSA strains were collected to determine antibiotic susceptibility by minimum inhibitory concentration tests. Antibiotic-resistant genes, pulsed-field gel electrophoresis, staphylococcal cassette chromosome mec (SCCmec) typing, and multilocus sequence typing were used for the molecular characterization of MRSA. Among the total strains, the MDR rate (51.8%) was significantly higher in the northern hospital than in the southern hospital (73% vs. 39%, p < 0.0001). The MDR-MRSA with the highest rates were "ciprofloxacin-erythromycin-gentamicintetracyclines" (35.6%), followed by "erythromycin-tetracycline-chloramphenicol" (24.1%), and "ciprofloxacin-erythromycin-gentamicin" (19.5%), showing an accumulative total of 79.3%. The most susceptible antibiotics were rifampicin (100%) and vancomycin (100%), followed by doxycycline (94.0%), meropenem (78.0%), and cefotaxime (75.0%). The SCCmecII strains showed greater resistance to gentamicin, ciprofloxacin, tetracycline, meropenem and cephalosporins compared with the other strains. The SCCmecII strains exhibited the highest rate in the tested genes (aacA/aphD: 55.2%, ermA/B/C: 89.7%, and tetK/M: 82.8%). ST5-SCCmecII was the predominant clone in the northern hospital, whereas SCCmecIVa was more pronounced in the southern hospital. In conclusion, our results raised concerns about the predominant MDR-MRSA strains in the pediatric hospitals in Vietnam. The north-south difference in the antibiotic resistance patterns and genetic structure of MRSA suggests different MRSA origins and various uses of antimicrobial agents between the two regions.

• Journal of Microbiology and Biotechnology
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• 제33권3호
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• pp.329-338
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• 2023

Enterohemorrhagic Escherichia coli (EHEC) is a foodborne pathogen that produces attaching and effacing lesions on the large intestine and causes hemorrhagic colitis. It is primarily transmitted through the consumption of contaminated meat or fresh produce. Similar to other bacterial pathogens, antibiotic resistance is of concern for EHEC. Furthermore, since the production of Shiga toxin by this pathogen is enhanced after antibiotic treatment, alternative agents that control EHEC are necessary. This study aimed to discover alternative treatments that target virulence factors and reduce EHEC toxicity. The locus of enterocyte effacement (LEE) is essential for EHEC attachment to host cells and virulence, and most of the LEE genes are positively regulated by the transcriptional regulator, Ler. GrlA protein, a transcriptional activator of ler, is thus a potential target for virulence inhibitors of EHEC. To identify the GrlA inhibitors, an in vivo high-throughput screening (HTS) system consisting of a GrlA-expressing plasmid and a reporter plasmid was constructed. Since the reporter luminescence gene was fused to the ler promoter, the bioluminescence would decrease if inhibitors affected the GrlA. By screening 8,201 compounds from the Korea Chemical Bank, we identified a novel GrlA inhibitor named Grlactin [3-[(2,4-dichlorophenoxy)methyl]-4-(3-methylbut-2-en-1-yl)-4,5-dihydro-1,2,4-oxadiazol-5-one], which suppresses the expression of LEE genes. Grlactin significantly diminished the adhesion of EHEC strain EDL933 to human epithelial cells without inhibiting bacterial growth. These findings suggest that the developed screening system was effective at identifying GrlA inhibitors, and Grlactin has potential for use as a novel anti-adhesion agent for EHEC while reducing the incidence of resistance.