• Journal of Microbiology and Biotechnology
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• 제24권7호
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• pp.1008-1013
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• 2014

The use of antimicrobial agents for additives or therapeutics is strongly associated with a prevalence of antimicrobial resistance in commensal Enterobacteriaceae. We aimed to characterize integrons in Enterobacteriaceae isolates obtained from chicken cecums in Korea. Moreover, the correlation between integron gene cassettes and antimicrobial resistance was also investigated. A total of 90 isolates the belonged to Enterobacteriaceae were recovered from chickens grown at Gyeongsang and Chungcheong provinces in Korea. Antimicrobial susceptibility tests were performed by the disk diffusion method. PCR and DNA sequencing were also performed to characterize the gene cassette arrays of the integrons. Of the 90 Enterobacteriaceae isolates tested, 39 (43.3%) and 10 (11.1%) isolates carried class 1 and 2 integrons, respectively. Whereas the class 2 integron did not contain gene cassettes, the class 1 integrons carried seven different gene cassette arrays. The class 1 integrons harbored genes encoding resistant determinants to aminoglycosides (aadA1, aadA2, and aadA5), trimethoprim (dfrA1, dfrA12, dfrA17, and dfrA32), lincosamides (linF), and erythromycin (ereA). Moreover, the presence of a class 1 integron was significantly related to a high resistance rate of antimicrobial agents, such as spectinomycin and trimethoprim. We confirmed that diverse class 1 integrons were widely distributed in Enterobacteriaceae isolates from chickens and directly contributed to the resistance to diverse antimicrobial agents in Korea.

• 대한임상검사과학회지
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• 제43권2호
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• pp.68-74
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• 2011

Pseudomonas aeruginosa is an aerobic, Gram-negative, glucose-nonfermenting bacterium, which has emerged as a serious opportunistic pathogen. Recently, outbreaks of carbapenem resistant P. aeruginosa give rise to significant therapeutic challenges for treating nosocomial infections. The genes of metallo-${\beta}$-lactamase (MBL), a powerful carbapenemase, are carried as a part of the mobile gene cassettes inserted into integrons playing an important role in rapid dissemination of antibiotic resistance genes among bacterial isolates. In this study, we investigated the prevalence of integron in imipenem resistant P. aeruginosa isolates. A total of 61 consecutive, non-duplicate, and imipenem resistant P. aeruginosa strains were isolated from a university hospital in the Chungcheong province of Korea. We employed repetitive extragenic palindromic sequence-based PCR (rep-PCR) method for the selection of clonally different P. aerusinosa strains. PCR and DNA sequencing were conducted for the detection of integrons. Twenty-one clonally different P. aeruginosa strains were isolated. Only one (P28) of the strains harbored $bla_{VIM-2}$ that was found as gene cassettes in class 1 integrons. Four of 21 carbapenem resistant P. aeruginosa strains harbored class 1 integron containing aminoglycoside resistance determinant. All of the integrons detected in the study contained more than one resistance gene cassette, which can mediate resistance to multiple antibiotics. To prevent further spreading of the multi-drug resistant P. aeruginosa, conseguent monitoring and clinical polices are required.

• 식물병연구
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• 제16권2호
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• pp.125-128
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• 2010

자두 주산지인 경북 김천을 비롯하여 의성, 경산, 군위지역에 발생하는 자두과실의 검은점무늬병 병원균을 조기 검출하기 위하여 integrons를 이용한 primer를 제작하고 DNA 추출향상을 위해 전배양법을 그리고 검출감도 향상을 위해 nested PCR을 시도하였다. 제작된 integrons primer로 병반 시료를 PCR한 결과 예상되는 크기인 760 bp로 증폭이 되어 검은점무늬병의 원인 병원균은 Xanthomonas arboricola pv. pruni로 확인되었고 진단용 primer로 사용 될 수 있음을 확인할 수 있었다. DNA 추출 방법별로 PCR 진단효율은 조사한 결과 직접 추출하는 방법보다는 10% LB배지로 전배양한 다음 DNA를 추출하는 방법이 더 효과적이었고 nested PCR을 이용할 경우에는 과원내 강우중의 X. arboricola pv. pruni의 검출도 가능하였다. 이번에 개발된 Integrons primer를 이용, 전배양법과 nested PCR을 실시할 경우 1일 이내에 병징이 나타나지 않은 유묘에서의 X. arboricola pv. pruni 감염여부나 식물검역에서의 X. arboricola pv. pruni 감염식물 진단 등에도 활용이 가능할 것으로 생각된다.

• 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.

• 대한임상검사과학회지
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• 제47권2호
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• pp.65-70
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• 2015

최근까지도 세균 감염증 치료 또는 성장촉진을 목적으로 가축에게 광범위하게 항균제를 사용해 왔으며, 이는 사람에게 보편적으로 사용되는 항균제들에 대한 내성세균의 출현 및 확산을 유도했다. 이렇게 출현한 다제 내성세균은 사람에게 음식을 통해 전달되고 내성유전자를 확산시킬 수 있어 더 큰 문제가 되고 있다. 본 연구에서는 충청지역에서 사육된 닭으로부터 분리된 Proteus mirabilis 균주를 대상으로 integron의 빈도 및 integron의 존재에 따른 항균제 내성 비율의 변화를 조사하였다. 총 26 균주의 Proteus mirabilis가 분리되었으며 이 균주를 대상으로 항균제 감수성 검사와 PCR 및 DNA 염기서열분석을 통한 integron의 유전자 카세트 분석이 이루어졌다. 또한 extragenic palindromic sequence-based PCR (REP-PCR) 방법을 이용하여 P. mirabilis 균주들의 clonality를 확인하였다. P. mirabilis 26균주 중 14 균주(53.8%)가 class 1 integrons을 가지고 있음이 확인되었다. Class 1 integron 내에는 aminoglycoside (aacC, aadA), trimethoprim (dfrA), lincosamide (linF), 및 erythromycin (ereA) 등의 내성을 유도하는 유전자 카세트가 위치해 있었다. 이들 class 1 integron을 포함하는 균주는 integron을 포함하지 않는 균주보다 aminoglycoside 및 trimethoprim 계열 항균제에 대해 높은 내성율을 보였다. 본 연구에서 class 1 integron은 P. mirabilis 균주들 사이에 광범위하게 확산되어 있으며 다양한 항균제에 내성을 나타내는데 중요한 역할을 하고 있음이 확인되었다. 따라서 축사환경에 다제 내성세균의 출현 및 증가에 중요한 역할을 하는 integron의 확산에 대한 지속적인 감시가 필요할 것으로 사료된다.

• 대한임상검사과학회지
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• 제48권4호
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• pp.327-334
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• 2016

최근 사람과 가축에 항균제의 과도한 사용으로 감염병을 일으키는 병원성 세균들의 항균제 내성이 증가하고 있다. 본 연구에서는 PCR과 염기서열분석법을 이용하여 충청지역 일개의 대학병원에 의뢰된 임상검체와 같은 지역에서 사육된 닭으로부터 분리된 P. mirabilis 균주를 대상으로 16S ribosomal RNA methyltransferase(RMTase) 유전자와 integron을 조사하였다. 또한 Repetitive extragenic palindromic sequence-based PCR (REP-PCR)을 이용하여 P. mirabilis 균주들의 역학적 연관성 조사하였다. 총 38균주의 P. mirabilis 중에서 임상검체로부터 분리된 7균주 (18.4%)만이 RMTases 유전자를 가지고 있었는데 이들은 모두 amikacin, tobramycin, 및 gentamicin에 내성을 나타냈다. 또한 대상균주 중 23균주(60.5%)가 class 1 integron을 가지고 있는 것으로 나타났으며 class 2 및 class 3 integron은 검출되지 않았다. 본 연구에서 확인된 integrons에는 aminoglycoside 내성유전자(aadA2, aadA5, aadA7, 및 aacCA5), ${\beta}$-lactmam 내성유전자($bla_{PSE}$), erythromycin 내성유전자(ereA), lincosamides 내성유전자(linF), 및 trimethoprim 내성유전자(dfrA12, dfrA17 및 dfrA32)등이 유전자 카세트로 포함되어 있었다. 본 연구결과 RMTase 유전자는 임상검체로부터 분리된 P. mirabilis 균주에만 확산되어 있었던 반면 class 1 integrons는 임상검체와 닭으로부터 분리된 P. mirabilis 균주에 광범위하게 확산되어 있음을 확인할 수 있었다. 게다가 닭으로부터 분리된 균주 중에는 동일한 REP-PCR 밴드패턴을 보인 균주들이 있었는데 이는 닭들 사이에서 P. mirabilis 균주가 수평확산 되었음을 의미한다. P. mirabilis 균주에서 항균제 내성유전자의 확산을 막기 위해서는 내성유전자 지속적인 모니터링과 감시가 필요할 것으로 사료된다.

• 한국동물위생학회지
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• 제37권1호
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• pp.19-27
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• 2014

This study was conducted to investigate the antimicrobial resistance, presence of ${\beta}$-lactamase genes and integrons in 83 ESBL-producing Escherichia coli isolated from Nakdong river and Geumho river in Daegu. Among the ${\beta}$-lactam antimicrobials, all isolates were resistant to ampicillin, cephalothin, cefamandole and cefotaxime, followed by piperacillin (98.8%), ampicillin/sulbactam (86.7%), aztreonam (60.2%) and cefepime (59.0%), whereas resistance to piperacillin/tazobacram, ticarcillin/clavulanic acid and cefoxitin was less than 30%. Many of the ESBL-producing Escherichia coli were also resistant to non-${\beta}$-lactams antimicrobials such as nalidixic acid (83.1%), sulfonamides (72.3%), ciprofloxacin (62.7%) and gentamicin (38.6%). All isolates showed resistance to seven or more antimicrobial agents. The most frequently detected gene was $bla_{TEM+CTX-M}$ (49.4%), followed by $bla_{CTX-M}$ (27.7%), $bla_{TEM}$ (6.0%) and $bla_{OXA}$ (1.2%). But $bla_{SHV}$ was not found. Class 1 integrons were found in 61.4% (51 isolates) of isolates, however, class 2 and 3 integrons were not detected. The results showed water from Nakdong river and Geumho river is contaminated with ESBL-producing E. coli isolates. These results suggest the need for further investigation of antibiotic resistant bacteria to prevent public health impacts in the water environment.

• 한국수산과학회지
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• 제52권6호
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• pp.596-604
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• 2019

Vibrio parahaemolyticus causes food poisoning, mainly via marine fisheries products. We investigated the virulence factors and drug resistance of V. parahaemolyticus isolated from fisheries products purchased from the Yeosu Fisheries Market. The isolates were identified using a variety of biochemical tests and the detection of toxR and hns gene. The presence of the virulence factor-encoding genes tdh and trh in the isolates was also investigated by PCR. The resistance of the isolates to 13 antibacterial agents was tested using the disc-diffusion method and carriage of β-lactamase genes and class 1 integrons by ampicillin-resistant isolates was investigated by PCR. Four of seventeen isolates identified as V. parahaemolyticus by biochemical tests produced a species-specific PCR band. Those isolates showed >98% 16S rRNA gene sequence homology with V. parahaemolyticus and only one isolate harbored the tdh gene. All of the V. parahaemolyticus isolates were resistant to ampicillin and amoxicillin; moreover, VPA0477, a class A β-lactamase gene, and class 1 integrons were detected. Therefore, V. parahaemolyticus from fisheries products represents a low risk to human health. Also, V. parahaemolyticus is likely to develop multidrug resistance because it has class 1 integrons.

• Journal of Microbiology and Biotechnology
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• 제26권11호
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• pp.1983-1992
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• 2016

Pseudomonas strains isolated from the heavily contaminated Lubin copper mine and Zelazny Most post-flotation waste reservoir in Poland were screened for the presence of integrons. This analysis revealed that two strains carried homologous DNA regions composed of a gene encoding a DNA_BRE_C domain-containing tyrosine recombinase (with no significant sequence similarity to other integrases of integrons) plus a three-component array of putative integron gene cassettes. The predicted gene cassettes encode three putative polypeptides with homology to (i) transmembrane proteins, (ii) GCN5 family acetyltransferases, and (iii) hypothetical proteins of unknown function (homologous proteins are encoded by the gene cassettes of several class 1 integrons). Comparative sequence analyses identified three structural variants of these novel integron-like elements within the sequenced bacterial genomes. Analysis of their distribution revealed that they are found exclusively in strains of the genus Pseudomonas.

• Journal of Microbiology and Biotechnology
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• 제25권1호
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• pp.137-142
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• 2015

Trimethoprim-sulfamethoxazole (TMP-SMX) has been used for the treatment of urinary tract infections, but increasing resistance to TMP-SMX has been reported. In this study, we analyzed TMP-SMX resistance genes and their relatedness with integrons and insertion sequence common regions (ISCRs) in uropathogenic gram-negative bacilli. Consecutive nonduplicate TMP-SMX nonsusceptible clinical isolates of E. coli, K. pneumoniae, Acinetobacter spp., and P. aeruginosa were collected from urine. The minimal inhibitory concentration was determined by Etest. TMP-SMX resistance genes (sul and dfr), integrons, and ISCRs were analyzed by PCR and sequencing. A total of 45 E. coli (37.8%), 15 K. pneumoniae (18.5%), 12 Acinetobacter spp. (70.6%), and 9 Pseudomonas aeruginosa (30.0%) isolates were found to be resistant to TMP-SMX. Their MICs were all over 640. In E. coli and K. pneumoniae, sul1 and dfr genes were highly prevalent in relation with integron1. The sul3 gene was detected in E. coli. However, in P. aeruginosa and Acinetobacter spp., only sul1 was prevalent in relation with class 1 integron; however, dfr was not detected and sul2 was less prevalent than in Enterobacteriaceae. ISCR1 and/or ISCR2 were detected in E. coli, K. pneumoniae, and Acinetobacter spp. but the relatedness with TMP-SMX resistance genes was not prominent. ISCR14 was detected in six isolates of E. coli. In conclusion, resistance mechanisms for TMP-SMX were different between Enterobacteriaceae and glucose non-fermenting gram-negative bacilli. Class 1 integron was widely disseminated in uropathogenic gram-negative baciili, so the adoption of prudent use of antimicrobial agents and the establishment of a surveillance system are needed.