• Journal of Microbiology
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• 제45권6호
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• pp.590-592
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• 2007

We report the isolation of Salmonella enterica serotype Typhimurium phage type DT104 (CCARM 8104) from swine in Korea. The CCARM 8104 isolate was resistant to nalidixic acid and showed reduced susceptibility to quinolones. The CCARM 8104 isolate had a missense mutation, Asp87Asn, in the quinolone resistance-determining region in gyrA and produced PSE-1. The CCARM 8104 isolate carried two different class 1 integrons, and the PSE-1 ${\beta}$-lactamase gene was inserted into a 1,200 bp class 1 integron. The presence of DT104 with pse-1 in an integron located in a plasmid and reduced susceptibility to quinolone in swine pose a significant threat of possible horizontal spread between swine and humans.

• 대한임상검사과학회지
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• 제49권4호
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• pp.427-434
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• 2017

Acinetobacter calcoaceticus-baumannii (Acb) complex에 속한 종들은 빈번하게 병원감염 및 기회감염을 일으킨다. 또한 다제내성인 경우가 많아 이 균들의 감염증 치료를 위한 항균제 선택이 매우 제한적이다. 본 연구에서는 ciprofloxacin 내성 Acinetobacter species 53균주를 대상으로 fluoroquinolone 내성기전을 조사했다. 항균제 감수성 양상을 조사하기 위해 디스크확산법이 시행되었다. Fluoroquinolone 내성과 관련된 유전자 및 돌연변이 검출을 위해 PCR과 염기서열분석이 이루어졌다. 본 연구에서 수집된 53균주의 ciprofloxacin 내성 Acinetobacter 중 47균주가 gyrA 유전자의 83번째 serine 아미노산 잔기와 parC 유전자의 80번째 serine 아미노산 잔기가 leucine 잔기로 치환된 sense mutations 가지고 있는 것으로 나타났다. gyrA와 parC 유전자에 sense mutations을 가지고 있는 47균주 중 44균주가 A. baumannii 였고 3균주는 A. pittii였다. 본 연구에서 조사대상이 되었던 Acb complex 균주들 중 plasmid-mediated quinolone resistance (PMQR) determinants를 가지고 있는 균주는 한나도 없었다. 46 균주의 ciprofloxacin 내성 A. baumannii 는 A, B, 또는 F형의 banding pattern을 보였는데 이는 충청지역에 위치한 일개의 병원에 ciprofloxacin 내성 A. baumannii가 수평확산 되어 있음을 의미한다. Fluoroquinolone 내성 Acb complex 균주의 집락화 및 확산을 막기 위해서 다제내성 균주들을 대상으로 항균제 내성인자들을 지속적으로 조사하고 모니터링할 필요가 있을 것으로 사료된다.

• Asian Pacific Journal of Cancer Prevention
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• 제14권11호
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• pp.6321-6326
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• 2013

Introduction: Lung cancer is extremely harmful to human health and has one of the highest worldwide incidences of all malignant tumors. Approximately 80% of lung cancers are classified as non-small cell lung cancers (NSCLCs). Cisplatin-based multidrug chemotherapy regimen is standard for such lesions, but drug resistance is an increasing problem. F-box/WD repeat-containing protein 7 (FBW7) is a member of the F-box protein family that regulates cell cycle progression, and cell growth and differentiation. FBW7 also functions as a tumor suppressor. Methods: We used cell viability assays, Western blotting, and immunofluorescence combined with siRNA interference or plasmid transfection to investigate the underlying mechanism of cisplatin resistance in NSCLC cells. Results: We found that FBW7 upregulation significantly increased cisplatin chemosensitivity and that cells expressing low levels of FBW7, such as NCI-H1299 cells, have a mesenchymal phenotype. Furthermore, siRNA-mediated silencing or plasmid-mediated upregulation of FBW7 resulted in altered epithelial-mesenchymal transition (EMT) patterns in NSCLC cells. These data support a role for FBW7 in regulating the EMT in NSCLC cells. Conclusion: FBW7 is a potential drug target for combating drug resistance and regulating the EMT in NSCLC cells.

• Fisheries and Aquatic Sciences
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• 제16권4호
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• pp.221-227
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• 2013

In total, 131 Escherichia coli isolates from surface seawater of the Gomso Bay, of Korea, were analyzed for their susceptibility to 22 different antimicrobials and for genes associated with antimicrobial resistance and virulence. According to the disk diffusion susceptibility test, the resistance to tetracycline was most prevalent (33.6%), followed by that to ampicillin (22.1%), ticarcillin (22.1%), and trimethoprim (16.8%). More than 46.6% of the isolates were resistant to at least one antimicrobial, and 22.9% were resistant to three or more classes of antimicrobials; these were consequently defined as multidrug resistant. We further found that 29 ampicillin-resistant isolates possessed genes encoding TEM-type (93.1%) and SHV-type (6.9%) ${\beta}$-lactamases. Among the 44 tetracycline-resistant isolates, tetA and tetC were found in 35 (79.5%) and 19 (43.2%), respectively, whereas tetB was detected in only three isolates (6.8%). With regard to virulence genes, merely 0.8% (n = 1) and 2.3% (n = 3) of the isolates were positive for the enteroaggregative E. coli-associated plasmid (pCVD432) gene and the enteropathogenic E. coli-specific attaching and effacing (eae) gene, respectively. Overall, these results not only provide novel insight into the necessity for seawater sanitation in Gomso Bay, but they help reduce the risk of contamination of antimicrobial-resistant bacteria.

• 한국미생물·생명공학회지
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• 제51권3호
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• pp.314-316
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• 2023

Colistin is one of the last-resort antibiotics used to treat multidrug-resistant Gram-negative bacterial infection in both human and animals. Here, we report the complete genome sequence of colistin-resistant Salmonella enterica serotype Enteritidis strain CRSE-01 isolated from poultry carcass in South Korea. The assembled genome consists of a 4,783,907-bp circular chromosome containing numerous antimicrobial resistance genes and a 59,372-bp plasmid.

• Journal of Microbiology and Biotechnology
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• 제22권1호
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• pp.25-33
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• 2012

The association of verotoxic E. coli and Acinetobacter spp. with various antibiotic-resistant, diarrhogenic, and nosocomial infections has been a cause for concern worldwide. E. coli and A. haemolyticus isolated on a number of selective media were screened for virulence factors, antibiotic resistance, and transformation of resistance genes. Out of 69 E. coli isolates obtained, 25 (35.23%), 14 (20.30%), and 28 (40.58%) were positive for Vtx1&2, Vtx1, and Vtx2, respectively, 49 (71.015%) for extendedspectrum beta-lactamases (ESBLs), 34 (49.28%) for serum resistance, 57 (82.61%) for cell surface hydrophobicity, 48 (69.57%) for gelatinase production, and 37 (53.62%) for hemolysin production. For the 14 A. haemolyticus isolates, only 2 (14.29%) in each case from all the samples investigated were positive for Vtx1, Vtx2 and Vtx1&2 respectively, 8 (57.14%) for ESBLs, 7 (50.00%) for serum resistance, 11 (78.57%) for cell surface hydrophobicity, 4 (28.57%) for gelatinase production, and 8 (57.14%) for hemolysin production. Although transformation occurred among the E. coli and Acinetobacter isolates (transformation frequency: $13.3{\times}10^{-7}-53.4^{-7}$), there was poor curing of the plasmid genes, a confirmation of the presence of stable antibiotic-resistant genes (DNA concentration between 42.7 and 123.8 ${\mu}g$) and intragenetic transfer of multidrug-resistant genes among the isolates. The isolates were potentially virulent and contained potentially transferable antibiotic resistance genes. Detection of virulence factors, antibiotic resistance genes, and transformation among these isolates is a very significant outcome that will influence approaches to proactive preventive and control measures and future investigations. However, continued surveillance for drug resistance among these bacteria and further investigation of the mechanism of action of their virulence factors are a necessity.

• Journal of Microbiology and Biotechnology
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• 제32권12호
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• pp.1537-1546
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• 2022

Staphylococcus aureus is a cause of high mortality in humans and therefore it is necessary to prevent its transmission and reduce infections. Our goals in this research were to investigate the frequency of methicillin-resistant S. aureus (MRSA) in Taif, Saudi Arabia, and assess the relationship between the phenotypic antimicrobial sensitivity patterns and the genes responsible for resistance. In addition, we examined the antimicrobial efficiency and application of silver nanoparticles (AgNPs) against MRSA isolates. Seventy-two nasal swabs were taken from patients; MRSA was cultivated on Mannitol Salt Agar supplemented with methicillin, and 16S rRNA sequencing was conducted in addition to morphological and biochemical identification. Specific resistance genes such as ermAC, aacA-aphD, tetKM, vatABC and mecA were PCR-amplified and resistance plasmids were also investigated. The MRSA incidence was ~49 % among the 72 S. aureus isolates and all MRSA strains were resistant to oxacillin, penicillin, and cefoxitin. However, vancomycin, linezolid, teicoplanin, mupirocin, and rifampicin were effective against 100% of MRSA strains. About 61% of MRSA strains exhibited multidrug resistance and were resistant to 3-12 antimicrobial medications (MDR). Methicillin resistance gene mecA was presented in all MDR-MRSA strains. Most MDR-MRSA contained a plasmid of > 10 kb. To overcome bacterial resistance, AgNPs were applied and displayed high antimicrobial activity and synergistic effect with penicillin. Our findings may help establish programs to control bacterial spread in communities as AgNPs appeared to exert a synergistic effect with penicillin to control bacterial resistance.

• Journal of Veterinary Science
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• 제23권3호
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• pp.37.1-37.8
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• 2022

Background: Avian pathogenic Escherichia coli (APEC) causes colibacillosis, resulting in significant economic losses in the poultry industry. Objectives: In this study, the molecular characteristics of two extended-spectrum beta-lactamase (ESBL)-producing APEC isolates were compared with previously reported ESBL-producing E. coli isolates. Methods: The molecular characteristics of E. coli isolates and the genetic environments of the ESBL genes were investigated using whole genome sequencing. Results: The two ESBL-producing APEC were classified into the phylogenetic groups C and B1 and ST410 and ST162, respectively. Moreover, the ESBL genes of the two isolates were harbored in different Inc plasmids. The EC1809182 strain, harboring the bla_CTX-M-55 gene on the plasmid, exhibited extensive homology to IncFIB (98.4%) and IncFIC(FII) (95.8%). The EC1809191 strain, harboring the bla_CTX-M-1 gene, was homologous to IncI1-I (Gamma) (99.3%). All chromosomes carried the multidrug transporter, mdf(A) gene. Mobile genetic elements, adjacent to CTX-M genes, facilitated the dissemination of genes in the two isolates, analogous to other ESBL-producing E. coli isolates. Conclusions: This study clarifies the transmission dynamics of CTX-M genes and supports strengthened surveillance to prevent the transmission of the antimicrobial-resistant genes to humans via the food chain.

• 디지털융복합연구
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• 제13권12호
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• pp.313-318
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• 2015

본 연구에서는 세균의 항균제 내성기전을 연구하기 위해 일개의 대학병원에서 분리된 Enterobacter cloacae를 대상으로 extended spectrum ${\beta}$-lactamase (ESBL) 및 16S rRNA methyltransferase 유전자를 검출하고 항균제 감수성 양상을 조사하였다. 대상균주 중 총 8 균주가 CTX-M-15형 ESBL을 생성하는 것으로 확인되었으며 이 균주들 중 3 균주는 16S rRNA methyltransferase의 한 종류인 armA 유전자도 동시에 가지고 있는 것으로 나타났다. CTX-M-15형 ESBL 유전자와 armA 유전자를 동시에 가지고 있는 E. cloacae는 3세대 cephalosporin 계열 및 aminoglycoside 계열의 항균제 뿐 만 아니라 fluoroquinolone 계열의 항균제에도 내성을 보였다. 더구나 이러한 항균제 내성 유전자들은 플라스미드를 통해 다른 세균으로 전달 될 수 있어 다제내성 세균의 출현 및 확산을 촉진 할 수 있다. 따라서 E. cloacae를 대상으로 지속적인 항균제 내성 유전자를 모니터링 하는 것은 항균제 내성 확산방지를 위해 중요할 것으로 사료된다.

• Clinical and Experimental Pediatrics
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• 제46권1호
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• pp.24-32
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• 2003

목 적 : 황색포도구균(S. aureus)은 건강인의 비강이나 피부에 정상 세균총으로 존재하지만, 병원 내 감염과 항생제 내성이 문제가 되고 있다. 본 연구는 신생아의 비강에서 S. aureus을 분리하여 항생제 감수성의 양상과 내성 관련 유전자를 검출하여 내성의 정도와 내성 관련 유전자의 상관관계를 규명해 보고자 하였으며, 병원성 인자의 검출을 실시하고, arbitrarily-primed polymerase chain reaction(AP-PCR)법에 의한 유전자형별을 통하여 역학적 해석을 시도하였다. 방 법 : 2001년 2월에서 5월 사이에 부산대학교병원 신생아 중환자실 및 신생아실에 입원한 28명을 대상으로 이들의 비강에서 총 120회의 nasal swab을 실시하여 51주의 S. aureus를 분리하였다. 분리균에 대한 항생제 감수성 검사, coagulase 검사과형별, plasmid DNA의 양상, mec 관련 유전자의 분포, 장독소의 유전자 및 TSST-1 독소의 유전자 보유 상태, AP-PCR법으로 유전자 형별을 조사하였다. 결 과 : 1) Methicillin 내성이 23주, vancomycin 내성이 6주였고, 3가지 이상의 약제에 대한 내성이 절반 이상을 차지하였다. 2) 42주가 coagulase 양성이었고, 이중 mecA 및 femA 유전 자를 보유한 12주를 대상으로 한 형별 검사에서 8종(coagulase I-VIII형)으로 분류되었다. 3) mecA 유전자가 22주에서, mecR1 유전자가 18주, mecI 유전자가 1주, femA 유전자가 17주에서 발견되었으며, 이들을 4가지의 유전자형으로 분류하였을 때 mecA형이 14주, mecR1형 10주, mecA-mecR1형 7주, mecA-mecR1-mecI형이 1주였다. mecA 및 mecA 관련 유전자와 항생제 다제내성과는 상관관계가 없었다. 4) 16주가 mecA와 femA를 모두 보유하였으며, 이들의 plasmid 양상은 I형이 7주, II형이 6주 그리고 III형이 2주였다. Oxacillin 및 vancomycin에 내성을 보이는 II형과 III형에서는 35.5kb의 plasmid DNA를 보유하였다. 5) 장독소 A, B, D, 및 E의 유전자는 51주 전부에서 검출되지 않았으나 장독소 C의 유전자는 64.7%, TSST-1 유전자는 80.4%가 양성이었다. 6) Coagulase 양성이며 mecA 및 femA 유전자를 보유한 MRSA 12균주에 대한 유전자 형별 검사에서 I형에서 X형으로 분류할 수 있었으며, II형 2주, X형 2주가 동일 유전자형이었고, 나머지는 다른 유전자형이었다. 결 론 : 입원 중인 신생아의 비강 내 S. aureus의 상재률이 아주 높았으며, 이들의 항생제 내성률, 특히 vancomycin의 내성률이 높아 이들에 의한 원내 감염에 대한 특별한 관리가 필요하며, 이들의 병원성 인자 및 관련 유전자에 대한 분석은 원내 감염에 대한 적절한 대책과 효과적인 치료에 많은 도움을 줄 수 있으리라 사료된다.