• 대한미생물학회지
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• 제21권1호
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• pp.17-31
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• 1986

Forty clinical isolates of Serratia marcescens were tested for their susceptibility to 19 antimicrobial drugs and studied on the molecular characteristics of R plasmids. Cefotaxime (Ct) was the most effective drug and only 2 (5%) strains were resistant to this drug. Thirteen to 18% of strains were resistant to cefoperazone (Cz), amikacin (Ak). and trimethoprim (Tp), and 28 to 40% were resistant to piperacillin (Pi), nalidixic acid (Na), gentamicin (Gm), and cefoxitin (Cx). A majority of strains were resistant to carbenicillin (Cb), tobramycin (Tp), kanamycin (Km), and cefamandole (Cd), and all to cephalothin. One half of the isolates were resistant to 10 or more drugs. $MIC_{90}$ of Pi to Gm-resistant strains (Gm') were 8 times higher than that to Gm-susceptible strains (Gm'), but $MIC_{90}$ of Ak, Cx, Ct, and Cz were almost the same between both Gm' and Gm' strains. Nine (23.7%) strains among 38 of multiply drug-resistant S. marcescens transferred conjugally their partial patterns of resistance to E. coli or Klebsiella strains, and two S. marcescens strains producing bacteriocin transferred their resistance to Klebsiella only, but not to E. coli. The plasmid profiles of S. marcescens were studied by the methods of SDS lysis and agarose gel electrophoresis. Twenty-four (60%) strains carried one to four plasmids of 1.4. to 144 Mdal, and conjugative R plasmids of 49 to 127 Mdal were noted in transconjugants. MIC levels of drugs in transconjugants were variable by the R plasmids and recipient strains.

• 대한수의학회지
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• 제30권3호
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• pp.287-295
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• 1990

The purpose of this study was the examination for presence of pilus antigen, O serogroups, colicin production, antibiotic susceptibility and plasmid profiles among E coli isolated from diarrheal piglets and fattening pigs in Taegu province. Of 145 E coli isolated, 98 strains (67.4%) possesed pilus antigens which belonged to either K88 (47.6%), K99 (11.7%) or 987P (8.3%) types. Fifty-nine strains (40.7%) were classified into tenO serogroups and their types were O8 (22.0%), O20(16.9%), O141(15.3%), O9(10.2%), O45(10.2%), O139(8.5%), O064(6.8%), O149(5.0%), O157(3.4%), and O115(1.7%). Thirty-three strains (22.8%) were colicinogenic and 6 strains (4.1%) were hemolytic. One hundred and thirty-nine strains (95.9%) of 145 E coli isolates were resistant to ampicillin, chloramphenicol, gentamicin, kanamycin, streptomycin, tetracycline, rifampicin and nalidixic acid, alone or in combination thereof. Ninety strains (64.7%) of 139 drug resistant strains carried R factor (R) which were transferable to the recipient by conjugation. In gel electrophoresis for the isolation of plasmid DNA, the number of plasmid DNA band varied from 2 to 11 in 16 E coli with pilus antigen. It's molecular weight ranged from 1.0 to 60.0 megadalton.

• 대한미생물학회지
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• 제21권4호
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• pp.461-471
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• 1986

1973년부터 1985년 사이에 대구지방에서 분리된 Shigella는 약 1,200주였는데, 대부분이 Shigella flexneri였고, S. sonnei는 약 20%였으며, S. dysenteriae와 S. boydii는 극히 적었다. 분리균의 95%이상이 chloramphenicol(Cm), tetracycline(Tc), streptomycin(Sm), sulfisomidine(Su), ampicillin(Ap), trimethoprim(Tf) 등의 전부 또는 일부 약제에 내성이었으며, kanamycin, nalidixic acid(Na)와 rifampin(Rf)에 내성인 균주는 소수 있었으나, cephaloridine, gentamicin, amikacin 등에 내성인 균주는 없었다. 1973년에 분리된 균은 약 절반이 약제내성이었으나, 1977년 이후 분리된 균은 95% 이상이 약제내성이었다. 1977년 까지는 Cm, Tc, Sm 및 Su의 4제 내성균이 가장 많았으나 1978년 부터는 Cm, Tc, Sm, Su, Ap 및 Tp의 6제 내성균이 가장 많았다. 약 75%의 균이 그 약제내성을 접합에 의하여 Escherichia coli에 전달하였으므로 이 약제내성은 R plasmid에 의한 것으로 생각되었다. 대다수의 균에 있어서 약제내성 전부를 E. coli에 전달하였으나, Na와 Rf의 내성은 전달되지 않았다. 일부 균주의 약제내성은 E. coli에 전달될 때 분리되는 일이 있었으나, 그 수는 극히 적었다. Shigella의 R Plasmid는 대부분이 비적합성군(incompatibility group) F II에 분류되었으나, 극소수는 B군에 속하였고 군별이 안되는 것도 있었다.

• 대한수의학회지
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• 제48권3호
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• pp.275-285
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• 2008

Antimicrobial drugs are widely used in poultry industry as growth promoters or to control infectious diseases. However, this practice is reported to have caused high resistance to antimicrobial drugs in normal chicken flora and pathogens. Antimicrobial resistance to Escherichia coli (E. coli) from chicken has been mainly reported in normal flora, but rare in pathogenic organism in Korea, recently. Therefore, this study was conducted to investigate prevalence of antimicrobials resistance, transfer of R plasmid, and association between antimicrobial drug resistance and O serotype of 203 pathogenic E. coli from poultry in Korea during the period from April 2003 to December 2005. These isolates showed a high resistance to tetracycline (Tc, 93.6%), nalidixic acid (Na, 92.6%), streptomycin (Sm, 81.8%), ampicillin (Ap, 77.3%), ciprofloxacin (Ci, 70.9%), sulfisoxazole (Su, 66.5%), and trimethoprim (Tp, 58.1%). Two hundred-one (99.0%) of the isolates were resistant to one or more drugs. They showed 57 different resistant patterns, and the most prevalent resistant pattern among them was Tc, Sin, Su, Ap, Tp, Ci, Na. Sixty-eight (33.8%) of the isolates transferred all or a part of their antimicrobial resistant pattern to the recipient strain by R plasmid. The most common antimicrobial resistant pattern was Tc, Sm, Su, Ap, Tp, Ci, Na in serotype O78, O88 and O15, respectively. These results exhibit high individual and multiple resistance to antimicrobials of pathogenic E. coli from poultry in Korea. They also suggest the needs for surveillance to monitor antimicrobial resistance in pathogenic bacteria that can be potentially transmitted to humans from food animals and to regulate the abuse of antimicrobials on food-producing animals in Korea.

• Journal of Microbiology and Biotechnology
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• 제30권7호
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• pp.974-981
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• 2020

Sequence type 410 (ST410) of Escherichia coli is an extraintestinal pathogen associated with multi drug resistance. In this study, we aimed to investigate the horizontal propagation pathway of a high-risk clone of E. coli ST410 that produces Klebsiella pneumoniae carbapenemase (KPC). blaKPC-encoding E. coli and K. pneumoniae isolates were evaluated, and complete sequencing and comparative analysis of blaKPC-encoding plasmids from E. coli and K. pneumoniae, antimicrobial susceptibility tests, polymerase chain reaction, multilocus sequence typing, and conjugal transfer of plasmids were performed. Whole-genome sequencing was performed for plasmids mediating KPC-2 production in E. coli and K. pneumoniae clinical isolates. Strains E. coli CPEc171209 and K. pneumoniae CPKp171210 were identified as ST410 and ST307, respectively. CPEc171209 harbored five plasmids belonging to serotype O8:H21, which is in the antimicrobial-resistant clade C4/H24. The CPKp171210 isolate harbored three plasmids. Both strains harbored various additional antimicrobial resistance genes. The IncX3 plasmid pECBHS_9_5 harbored blaKPC-2 within a truncated Tn4401a transposon, which also contains blaSHV-182 with duplicated conjugative elements. This plasmid displayed 100% identity with the IncX3 plasmid pKPBHS_10_3 from the K. pneumoniae CPKp171210 ST307 strain. The genes responsible for the conjugal transfer of the IncX3 plasmid included tra/trb clusters and pil genes coding the type IV pilus. ST410 can be transmitted between patients, posing an elevated risk in clinical settings. The emergence of a KPC-producing E. coli strain (ST410) is concerning because the blaKPC-2-bearing plasmids may carry treatment resistance across species barriers. Transgenic translocation occurs among carbapenem-resistant bacteria, which may spread rapidly via horizontal migration.

• 대한수의학회지
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• 제23권1호
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• pp.123-128
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• 1983

This study was conducted to evaluate the modified drug sensitivity test for the shortening of detection time and clinical application. The results obtained were summarized as follows. 1. Inhibitory zone in 6 strains of Staphylococcus and Escherichia coli tested to sensitivity teat were reached at 100% between 2 and 6 hours. 2. The sensitivity test of Staphylococcus A, B and E. coli No. 2, No. 3 to antibacterial ointment drugs were strong positive(+++), but Staphylococcus A. A. and E. coli No. 1 were mild resistant(+). 3. The sensitivity test of Staphylococcus A. B and E. coli No. 2, No. 3 to antibacterial injection drugs in 6 hours after treatment were strong positive(+++), and Staphylococcus A. A. and E. coli No. 1 were moderate positive(++). 4. This modified method was detected 86% degree of sensitive between 7 to 12 hours after treatment. 5. We think this modified method was more practical compare to other methods.

• Clinical and Experimental Pediatrics
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• 제49권7호
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• pp.777-783
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• 2006

목 적 : 최근 소아 요로감염의 가장 흔한 원인균인 E. coli에 대한 항생제 내성 문제가 점차 대두되고 있다. 본 연구에서는 소아 원외 요로감염 환아에서 분리된 E. coli에 대한 cefixime을 포함하여 흔히 사용되고 있는 경구용 항생제의 시험관 내 감수성 연구를 시행하여 적합한 치료 항생제 선택의 기초 자료를 얻고자 하였다. 방 법 : 2004년 10월부터 2005년 9월까지 연구 참여 병원 소아과 외래에서 요로감염으로 진단된 206명 환아의 요 배양검사에서 동정된 211개 균주 중 188개 E. coli를 대상으로 경구용 항생제(ampicillin, amoxillin, ampicillin-sulbactam, cefaclor, TMP-SMX, cefixime)에 대한 시험관 내 감수성 검사를 실시하였다. 결 과 : 분리된 E. coli 균주에 대한 항생제별 감수성 결과에서 내성률은 각각 ampicillin 81.4%, amoxicillin 85.6%, ampicillin-Sulbactam 77.2%, cefaclor 93.6%, TMP-SMX 50.5%, cefixime 13.3%이었다. ESBL 생성 E. coli는 7.0%이었다. 결 론 : Aminopenicillins계, cefaclor, sulfa약제들은 E. coli에 대한 내성률이 매우 높아 소아 요로감염의 일차 선택 항생제로 유용하지 못한 것으로 추정할 수 있었다. 그러나 cefixime과 같은 3세대 cephalosporin은 일차 치료 실패할 경우 이차 선택항생제로 유용할 수 있으며, 일차 선택 항생제로도 사용될 수 있을 것으로 추정되었다. E. coli의 항생제 내성 양상에 대한 광범위한 연구와 지속적 감시를 통하여 소아 원외 요로감염 치료에서 1차적으로 선택될 수 있는 경구용 항생제에 대한 지침 자료가 요구된다.

• Journal of Microbiology and Biotechnology
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• 제30권12호
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• pp.1862-1869
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• 2020

The spread of plasmid-mediated colistin resistance has posed a serious threat to public health owing to its effects on the emergence of pandrug-resistant bacteria. In this study, we investigated the prevalence and characteristics of mcr-1-positive Escherichia coli isolated from retail meat samples in Korea. In total, 1,205 E. coli strains were isolated from 3,234 retail meat samples in Korea. All E. coli strains were subjected to antimicrobial susceptibility testing and were examined for the presence of mcr-1 gene. All mcr-1-positive E. coli (n = 10, 0.8%) from retail meat were subjected to pulse-field gel electrophoresis (PFGE) and whole-genome sequencing (WGS). The transferability of mcr-1 gene was determined by conjugation assays. The mcr-1-positive strains exhibited diverse clonal types. Our mcr-1 genes were located in plasmids belonged to the IncI2 (n = 1) and IncX4 (n = 8) types, which were reported to be prevalent in Asia and worldwide, respectively. Most mcr-1 genes from mcr-1-positive strains (9/10) were transferable to the recipient strain and the transfer frequencies ranged from 2.4 × 10-3 to 9.8 × 10-6. Our data suggest that the specific types of plasmid may play an important role in spreading plasmid-mediated colistin resistance in Korea. Furthermore, our findings suggest that the retail meat may be an important tool for disseminating plasmid-mediated colistin resistance.

• 대한수의학회지
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• 제28권1호
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• pp.67-73
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• 1988

This study was conducted to isolate etiological agents from the 103 scouring piglets in Gyeongnam area and also carried out antimicrobial drug susceptibility test and epidemiogical served. The incidence of scouring piglet was most prevalent as 81.6% in the age of 2 to 4 weeks after birth, while the rate was less than 10% in the age of 5 to 6 weeks and under 1 week after birch. When compared the isolation frequency of the each etiological agent, enteropathogenic E. coli was most prevalent as 46.6%, thermophilic Campylobacter 26.2% and Salmonellae was 8.7% in order. In the OK serotyping for 117 isolates of enteropathogenic E. coli, type 0141 : K85 (20.5%), 0157:K88ac(14.5%), 0138:K81 and 0149:K91 (13.3%) were encountered most frequently. In the biotyping for 27 isolates of thermophilic Campylobacter, most strains of C. jejuni were belong to type I (50.0%) and II (25.0%), and most strains of C. coli were belong to biotype I (78.9%). In the serotyping for 9 strains of Salmonellae, 3 strains were grouped as D, 2 strains as C. and each 1 strain was group B and E. The other 2 strains were untypable. The 117 isolates of enteropathogenic E. coli were resistant more than 90% to erythromycin, penicillin, tetracycline and streptomycin, wherease about 90% of the isolates were sensitive to kanamycin and gentamicin. In the case of Salmonellae, all of the isolates were resistant to penicillin, but about 89% of the isolates were sensitive to gentamicin and colistin. All of C. jejuni and C. coli isolates were resistant to cephalothin, but more than 89% of C.jejuni and C. coli were sensitive to kanamycin and gentamicin.

• 한국수산과학회지
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• 제54권4호
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• pp.388-396
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• 2021

Antimicrobial resistance patterns of Escherichia coli were investigated. Strains were isolated from 310 shellfish, 36 crustaceans, and 12 fish collected off the West Coast of Korea from April 2019 to October 2020. Two hundred and ninety-five E. coli strains were isolated from shellfish, 100 from crustaceans, and 54 from fish. Strains isolated from shellfish showed the highest resistance to ampicillin (27.5%), whereas those from crustaceans were resistant to sulfisoxazole (30.0%) and those from fish were resistant to ampicillin (59.3%) and sulfisoxazole (59.3%). Ceftazidime resistance was observed in strains isolated from short neck and hard clams, whereas gentamicin resistance was observed in strains from fish. Multi-drug resistance was observed in 56 strains (48.7%) isolated from shellfish, 11 (28.2%) from crustaceans and 27 (73.0%) from fish. Depending on the source of isolation, the strains showed specific antimicrobial resistance tendency. Strains isolated from shellfish showed 12 different multi-drug resistance patterns, whereas those from crustaceans showed high resistance (59%) to a single antimicrobial agent and those from fish showed a broad trend of multi-drug resistance to more than eight antimicrobials.