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

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

• 대한의생명과학회지
• /
• 제25권4호
• /
• pp.321-330
• /
• 2019

Carbapenem is recently considered as the last resort of the therapeutics for gram negative bacterial infection. Increasing of organisms producing metallo-β-lactamase (MBL), we have difficulty in choosing the antimicrobial agents. Among 345 clinical isolates of Pseudomonas spp., 61 isolates (17.7%) were positive for the modified imipenem or meropenem-Hodge test and 55 isolates (15.9%) were positive for the imipenem-EDTA + SMA double disk synergy test (DDS). PCR and sequencing of bla_VIM-2-allele and bla_IMP-1-allele showed that 17 isolates of Pseudomonas aeruginosa, 9 isolates of Pseudomonas taiwnensis and 2 Pseudomonas plecoglossicida had bla_VIM-2, and 22 isolates of P. aeruginosa and one Pseudomonas otitidis had bla_IMP-6. These MBL genes were all in class 1 integron. The size of class 1 integron with bla_VIM-2 ranged from 3.5 kb to 5.5 kb in clinical isolates of Pseudomonas spp. including P. aeruginosa. bla_VIM-2 was most often located first in the class 1 integron, sometimes in the second or third position, and these integrons often had aacA4 or aadA1. Strict infection control measures are needed to more effectively prevent further spread of these MBL-producing Pseudomonas spp. In addition, MBL-producing Pseudomonas spp. is expected to continue to spread in various countries and regions.

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

• 대한임상검사과학회지
• /
• 제47권2호
• /
• pp.71-77
• /
• 2015

최근 항균제의 광범위한 사용으로 인한 항균제 내성세균의 출현과 확산이 축산환경에서 빈번하게 일어나고 있고 이렇게 출현한 다제 내성세균은 사람에게 직접 전파될 수 있어 큰 문제가 되고 있다. 본 연구는 2013년 7월부터 2014년 7월까지 충청지역의 임상검체(n=44) 및 양계농장의 닭(n=34)에서 분리된 78주의 대장균을 대상으로 이루어졌다. PCR과 염기서열 분석을 통하여 MLST 분석과 class 1 integron의 유전형을 분석하였다. 항균제 감수성 검사는 디스크 확산법으로 시행하였다. 사람 유래 대장균의 경우 ST131 (n=20)과 ST38 (n=15)이 가장 많았고 닭 유래 대장균은 ST752 (n=7)이 가장 많았으며 ST117, ST189, ST69는 각각 4주였다. 사람에서 유래한 대장균은 총 44주 중 25주가 class 1 integron을 가지고 있었다. 반면 닭에서 유래한 대장균은 총 34주 중 11주가 class 1 integron을 가지고 있었다. 충청지역에 분포되어있는 사람 유래 대장균과 닭 유래 대장균의 유전형 및 항균제 내성 패턴에 차이를 보였다.

• 한국동물위생학회지
• /
• 제37권4호
• /
• pp.225-231
• /
• 2014

In this study, 185 cefotaxime-resistant Escherichia coli were isolated from different stages of a wastewater treatment plant (WWTP) in Daegu in Korea. Among them, 99.5% (184 isolates) originated from raw sewage and 0.5% (1 isolates) from the final effluent. Cefotaxime-resistant E. coli were high resistant to ampicillin, piperacillin, cefazolin, cephalothin, cefachlor and cefamandole (99.5~100%). About 93% of the cefotaxime-resistant E. coli were extended-spectrum ${\beta}$-lactamases (ESBL)-producing E. coli. The $bla_{TEM+CTX}$ gene was the most predominant of the ESBL genes (72.5%), followed by $bla_{CTX-M}$ (16.2%), $bla_{TEM}$ (8.7%), $bla_{TEM+CTX+SHV}$ (1.1%), $bla_{TEM+SHV}$, $bla_{TEM+OXA}$, and $bla_{TEM+CTX+SHV}$ (respectvely 0.5%). Class 1 and 2 integron were found in 49.7% and class 3 integron was not found. All of integron positive isolates were multiresistant (i.e. resistant to four or more antibiotics). Our findings showed WWTP is contaminated with antibiotic resistant bacteria with resistance genes.

• Journal of Microbiology and Biotechnology
• /
• 제26권11호
• /
• pp.1983-1992
• /
• 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 Veterinary Science
• /
• 제23권1호
• /
• pp.9.1-9.11
• /
• 2022

Background: Escherichia coli, which causes subclinical or clinical mastitis in cattle, is responsible for transmitting antimicrobial resistance via human consumption of raw milk or raw milk products. Objectives: The objective of this study was to investigate the molecular characteristics of 183 E. coli from bulk tank milk of five different dairy factories in Korea. Methods: The molecular characteristics of E. coli such as serogroup, virulence, antimicrobial resistance, and integron genes were detected using polymerase chain reaction and antimicrobial susceptibility were tested using the disk diffusion test. Results: In the distribution of phylogenetic groups, group D was the most prevalent (59.6%) and followed by group B1 (25.1%). The most predominant serogroup was O173 (15.3%), and a total of 46 different serotypes were detected. The virulence gene found most often was fimH (73.2%), and stx1, fimH, incC, fyuA, and iutA genes were significantly higher in isolates of phylogenetic group B1 compared to phylogenetic groups A, B2, and D (p < 0.05). Among 64 E. coli isolates that showed resistance to at least one antimicrobial, the highest resistance rate was observed for tetracyclines (37.5%). All 18 integron-positive E. coli carried the integron class I (int1) gene, and three different gene cassette arrangements, dfrA12+aadA2 (2 isolates), aac(6')-Ib3+aac(6')-Ib-cr+aadA4 (2 isolates), and dfrA17+aadA5 (1 isolate) were detected. Conclusions: These data suggest that the E. coli from bulk tank milk can be an indicator for dissemination of antimicrobial resistance and virulence factors via cross-contamination.

• 한국미생물·생명공학회지
• /
• 제51권4호
• /
• pp.517-525
• /
• 2023

다제내성 P. aeruginosa (MRPA)의 출현과 확산은 전 세계적으로 심각한 문제가 되었다. 특히 metallo-β-lactamases (MBLs)의 carbapenem 고도내성 관여 정도는 심각한 수준이며, 특히 P. aeruginosa는 장내세균 속 균종과는 달리 새로운 클론들이 지속적으로 나타나고 기존에 확산되었던 우세 클론을 대체하는 과정이 매우 빠르게 진행되고 있다. 이에 본 연구에서는 2017년 9월부터 2019년 9월까지 부산의 한 종합병원에서 다양한 의료용 시료로부터 분리된 18균주의 P. aeruginosa 균주에 대한 항균제 내성 유전자 분석과 DNA 염기서열 분석을 통한 Integron의 유전자 카세트 분석 및 접합에 의한 Plasmid 전달 분석을 수행하며 이에 대한 역학관계를 조사하고자 하였다. 18균주 모두 XDR 표현형을 보이는 균주였으며, Colistin(100%)을 제외한 대부분의 항생제에 내성을 나타냈으나, aztreonam(22.2%), ceftazidime(16.6%)에 일부 감수성을 보였다. 균주의 66.7%는 다양한 항균제 내성을 나타내는 Class1 integron을 가지고 있었으며, 접합에 의한 Plasmid전달도 성공적으로 이루어졌다(83.3%). 이는 이전의 장내세균에 대한 연구결과보다 25.8% 상향한 결과를 보여 공중보건에 대한 심각한 역학관점의 고찰을 필요로 한다. 특히, IMP-6 ST235 (66.7%)가 주를 이루며, VIM-2 ST357 (16.7), IMP-1 ST446 (16.7)이 확인되었다. 흥미롭게도, 국내에서는 아직까지 보고된 바가 없는 IMP-1 생성 ST446의 확인은 또 다른 MRPA 고위험 클론의 생성과 유행이라는 관점에서 주목할 만하다.

• 한국환경농학회지
• /
• 제41권4호
• /
• pp.335-343
• /
• 2022

BACKGROUND: Antibiotics used in animal husbandry for disease prevention and treatment have resulted in the rapid progression of antibiotic resistant bacteria which can be introduced into the environment through livestock feces/manure, disseminating antibiotic resistant genes (ARGs). In this study, fecal samples were collected from the livestock farms located in Jeju Island to investigate the relationship between microbial communities and ARGs. METHODS AND RESULTS: Illumina MiSeq sequencing was applied to characterize microbial communities within each fecal sample. Using quantitative PCR (qPCR), ten ARGs encoding tetracycline resistance (tetB, tetM), sulfonamide resistance (sul1, sul2), fluoroquinolone resistance (qnrD, qnrS), fluoroquinolone and aminoglycoside resistance (aac(6')-Ib), beta-lactam resistance (bla_TEM, bla_CTX-M), macrolide resistance (ermC), a class 1 integronsintegrase gene (intI1), and a class 2 integrons-integrase gene (intI2) were quantified. The results showed that Firmicutes and Bacteroidetes were dominant in human, cow, horse, and pig groups, while Firmicutes and Actinobacteria were dominant in chicken group. Among ARGs, tetM was detected with the highest number of copies, followed by sul1 and sul2. Most of the genera belonging to Firmicutes showed positive correlations with ARGs and integron genes. There were 97, 34, 31, 25, and 22 genera in chicken, cow, pig, human, and horse respectively which showed positive correlations with ARGs and integron genes. In network analysis, we identified diversity of microbial communities which correlated with ARGs and integron genes. CONCLUSION(S): In this study, antibiotic resistance patterns in human and livestock fecal samples were identified. The abundance of ARGs and integron genes detected in the samples were associated with the amount of antibiotics commonly used for human and livestocks. We found diverse microbial communities associated with antibiotics resistance genes in different hosts, suggesting that antibiotics resistance can disseminate across environments through various routes. Identifying the routes of ARG dissemination in the environment would be the first step to overcome the challenge of antibiotic resistance in the future.