• Journal of Microbiology and Biotechnology
• /
• 제24권6호
• /
• pp.765-770
• /
• 2014

This study aimed to characterize CTX-M producers of urinary E. coli and K. pneumoniae isolates and to determine the prevalence of plasmid-mediated antimicrobial resistance genes among them. Minimum inhibitory concentrations (MICs) were determined, and PCR and sequencing were performed. Among the 42 (82.3%) E. coli and 24 (77.4%) K. pneumoniae isolates containing $bla_{CTX-M}$, $bla_{CTX-M-14}$ and $bla_{CTX-M-15}$ were detected in 23 and 19 E. coli isolates, respectively, and in 7 and 17 K. pneumoniae isolates, respectively. CTX-M producers of urinary E. coli and K. pneumoniae were resistant to multiple antibiotics and contained other antimicrobial resistance genes. CTX-M-15 producers contained more antimicrobial resistance genes than did CTX-M-14 producers.

• Journal of Microbiology and Biotechnology
• /
• 제27권9호
• /
• pp.1716-1723
• /
• 2017

The rapid dissemination of extended-spectrum ${\beta}$-lactamase (ESBL)-producing Escherichia coli has significantly contributed to public health hazard globally. A total of 281 E. coli strains recovered from pigs and chickens between 2009 and 2015 in South Korea were analyzed for ESBL production. ESBL phenotypes were recognized in 14 E. coli isolates; ten and three ESBL-producing isolates carried only $bla_{CTX-M}$ and $bla_{CMY}$ genes, respectively, and one isolate harbored both genes. The predominant CTX-M and CMY types were CTX-M-15 (n = 8) and CMY-2 (n = 3). We also detected ESBL-producing isolates harboring $bla_{CTX-M-65}$, $bla_{CTX-M-14}$, $bla_{CMY-6}$, $bla_{DHA-1}$, and $bla_{TEM-1}$ genes. All ESBL-producing isolates showed resistance to the extent of the fourth generation cephalosporins, along with multidrug resistance. CTX-M-15-producing isolates showed higher MIC values than CTX-M-14- and CTX-M-65-producing isolates. The $bla_{CTX-M}$ and $bla_{CMY}$ genes have the potential to be transferable. The spreading of $bla_{CMY}$ and $bla_{CTX-M}$ genes was arbitrated mainly via Frep and IncI1 plasmids. Our isolates showed clonal diversity in PFGE analysis. This is the first report of E. coli isolates carrying $bla_{CMY-6}$ in chicken from South Korea. The emergence of CMY-6 ESBLs in a population of poultry suggests that extensive screening with long-term surveillance is necessary to prevent the dissemination of ESBL from chicken to human.

• 디지털융복합연구
• /
• 제14권10호
• /
• pp.349-354
• /
• 2016

다양한 extended-spectrum ${\beta}$-lactamase (ESBL)를 생성하는 폐렴막대균의 출현 및 확산은 세균에 의한 감염증 치료에 어려움을 가중시키고 있다. 본 연구에서는 충청지역에서 분리된 폐렴막대균을 대상으로 ESBL 유전자를 검출하고 항균제 감수성 양상을 조사하였다. 또한 같은 클론에서 유래하였는지를 확인하기 위해 repetitive element sequence-based (REP)-PCR을 수행하였다. 충청지역에서 분리된 폐렴막대균 102균주 중 21균주가 CTX-M-14 및/또는 CTX-M-15를 생성하는 것으로 나타났으며 이 균주들은 3세대 cephalosporin 계열 항균제에 대해 70% 이상의 높은 내성율을 보였다. 본 연구에서 분리된 CTX-M형 ESBL생성 폐렴막대균은 다양한 클론으로부터 유래되었으며 그 중 일부는 지역사회에 확산되어 있음이 확인되었다. 이러한 폐렴막대균의 감염 및 확산을 방지하기 위해서는 감염관리의 강화가 필요하다. 아울러 좀 더 효과적인 내성세균의 관리를 위해서는 내성유전자의 생물학적 조사와 통계학적 분석을 통해 통합적으로 구축된 데이터베이스를 모니터링 할 필요가 있을 것으로 사료된다.

• Journal of Microbiology and Biotechnology
• /
• 제26권9호
• /
• pp.1643-1649
• /
• 2016

The aims of this study were to characterize the molecular epidemiological profiles of CTX-M-producing uropathogenic Escherichia coli isolates from a tertiary hospital in Daejeon, Korea, and to investigate the genetic diversity and compare the prevalence of sequence types (STs) in different areas. Extended spectrum β-lactamase-producing E. coli strains isolated from urine were analyzed for CTX-M, integrons, and insertion sequence common regions (ISCRs) by PCR and sequencing. Multilocus sequence typing (MLST), pulsed-field gel electrophoresis (PFGE), phylogenetic analysis, and rep-PCR were also used for molecular typing of the isolates. Of 80 CTX-M producers, 31 and 46 expressed CTX-M-15 and CTX-M-14, respectively. MLST analysis indicated that the most prevalent ST was ST131 (n = 34, 42.5%), followed by ST38 (n = 22, 27.5%), ST405 (n = 8, 10.0%), and ST69 (n = 6, 7.5%). Most CTX-M producers harbored class 1 integrons. ST131 strains belonged to phylogenetic group B2 and showed identical rep-PCR patterns, whereas ST69, ST38, and ST405 strains belonged to phylogenetic group D; the ST38 and ST405 strains displayed the same rep-PCR pattern, respectively. ST131 and ST38 isolates showed 21 and 19 distinct types, respectively, by PFGE. In Daejeon, D-ST38 CTX-M-14 producers were relatively more prevalent than in other countries and Korean cities. Our results indicate that CTX-M-producing E. coli isolates belonged mostly to ST131 or ST38 and were more related to hospital-onset than to community-onset infections and that the bla_CTX-M gene may vary according to the ST.

• 대한임상검사과학회지
• /
• 제48권3호
• /
• pp.210-216
• /
• 2016

최근 들어 CTX-M형 extended-spectrum ${\beta}$-lactamase(ESBL) 생성 대장균이 국내는 물론 전세계적으로 빠르게 증가하고 있다. 본 연구에서는 충청지역에 위치한 일개의 대학병원에서 분리된 대장균을 대상으로 ESBL 유전자를 중합효소연쇄반응 및 염기서열 분석방법을 통해 확인하였으며, 같은 방법으로 ESBL 생성 대장균으로부터 plasmid mediated quinolone resistance (PMQR) 유전자의 빈도를 조사하였다. 16.0%에 해당하는 25균주가 CTX-M-14를 생성하였으며 이중 9균주는 CTX-M-15도 동시에 생성하는 것으로 나타났다. 항균제 감수성 시험결과 CTX-M형 ESBL을 생성하는 대장균은 모두 cefotaxime에 내성을 보였다. 한편 CTX-M형 ESBL을 생성하는 대장균의 48% (12균주)가 PMQR 유전자를 포함하고 있음이 확인되었는데 8균주가 qnrS1유전자를 그리고 8균주가 aac(6')-Ib-cr 유전자를 포함하고 있었다. 그 중 4균주는 두 개의 유전자를 모두 가지고 있는 것으로 나타났다. 본 연구에서는 플라스미드를 통해 확산될 수 있는 ESBL 및 PMQR 유전자가 대장균 사이에 확산되어 있음을 확인하였다. 항균제 내성유전자들의 확산을 막기 위해서는 지속적인 내성유전자의 모니터링과 감시가 필요할 것으로 사료된다.

• Journal of Microbiology and Biotechnology
• /
• 제26권2호
• /
• pp.270-276
• /
• 2016

Extended-spectrum β-lactamases (ESBLs), particularly those of the CTX-M types, are the predominant resistance determinants of Escherichia coli that are rapidly spreading worldwide. To determine CTX-M types, E. coli isolates were collected from retail chickens (n = 390) and environmental samples from chicken farms (n = 32) and slaughterhouses (n = 67) in Korea. Fifteen strains harboring bla_CTX-M genes were isolated from 358 E. coli isolates. The most common CTX-M type was eight of CTX-M-15, followed by six of CTX-M-1 and one of CTX-M-14. The bla_CTX-M genes were identified in the isolates from retail chickens (n = 9), followed by feces, water pipes, floors, and walls. Conjugations confirmed the transferability of the plasmids carrying bla_CTX-M genes to the recipient E. coli J53 strain. Furthermore, eight addiction systems carried by the replicons in CTX-M types were confirmed. The dominant system was identified as ccdAB, vagCD, and pndAC in donor strains and transconjugants. The clonal relationship between the two strains carrying bla_CTX-M genes indicates that E. coli may transmit from the farm to retail chickens, suggesting a possible public health risk. Our findings demonstrate that the detection of CTX-M types in E. coli isolates is important for tracking ESBL production in animals, and suggest linkage of multiple addiction systems in plasmids bearing bla_CTX-M genes.

• Journal of Microbiology and Biotechnology
• /
• 제24권3호
• /
• pp.421-426
• /
• 2014

To characterize the extended-spectrum beta-lactamases (ESBLs) in diarrheagenic Escherichia coli from Korea in 2008-2011, we screened seven enterotoxigenic E. coli (ETEC) and one enteroaggregative E. coli (EAEC) that produce ESBLs from a nationwide survey. All eight isolates produced CTX-M-type ESBLs, including CTX-M-12 (n = 4), CTX-M-14 (n = 2), and CTX-M-15 (n = 2). PCR-based replicon typing indicated that the $bla_{CTX-M-12}$ genes of four ETEC isolates were carried on a conjugative IncF plasmid, whereas the $bla_{CTX-M-14}$ of one EAEC was located on an IncK plasmid. This is the first report of the occurrence of $bla_{CTX-M}$ genes in clinical isolates of EAEC in Korea. The ESBL-producing isolates were shown to be different based on pulsed-field gel electrophoresis and multilocus sequence typing, whereas the four isolates with CTX-M-12 were clonally related. These observations raise an alarm for the spread of plasmid-mediated resistance to ESBL among diarrheagenic E. coli.

• 한국동물위생학회지
• /
• 제43권2호
• /
• pp.79-88
• /
• 2020

The aim of this study was to investigate the prevalence of CTX-M β-lactamase and plasmid-mediated quinolone resistance (PMQR) genes, and the pattern of antibiotic resistance in cefotaxime-resistant gramnegative bacteria. A total 126 gram-negative bacteria were isolated from hospitalized dogs and cats between 2018 and 2019. The most predominant isolates were E. coli (n=41), followed by Pseudomonas aeruginosa (n=25), Proteus mirabilis (n=14), Klebsiella pneumoniae (n=9), Sphingomonas paucimobilis (n=7), and Enterobacter cloacae and Serratia marcescens (respectively, n=5). Cefotaxime-resistant isolates were identified in 26.2% (33 isolates) of 126 gram-negative bacteria. CTX-M type β-lactamase were found in 15 isolates (10 E. coli, 1 Ent, cloacae and 4 K. pneumoniae, respectively). Among the CTX-M producing gram-negative bacteria, CTX-M-1 and CTX-M-9 were detected in 10 (66.7%) and 5 (33.3%) isolates, respectively. While, CTX-M-2 and CTX-M-8 were not found. PMQR genes were detected in 12 (36.4%) isolates (4 E. coli, 2 Ent, cloacae and 6 K. pneumoniae, respectively), and the predominant PMQR gene was aac(6')-lb-cr (n=9), followed by qnrB (n=8) and qnrS (n=1) alone or in combination. qnrA and qepA were not found. Additionally, 9 (60%) of 12 PMQR positive isolates were co-existence with CTX-M-1 or CTX-M-9. CTX-M or PMQR producing isolates showed highly resistance to penicillins (100%), cephalosporins (100~66.7%), monobactams (72.2%), and non-β-lactam antibiotics (94.4~61.1%) such as quinolones, trimethoprim/sulfamethoxazole, tetracycline and gentamicin. These findings showed CTX-M-1, CTX-M-9, aac(6')-lb-cr and qnrB were highly prevalent in cefotaxime-resistant Enterobacteriaceae isolates from companion animals in our region. Moreover, PMQR genes were closely associated with CTX-M type β-lactamase.

• The Korean journal of internal medicine
• /
• 제33권6호
• /
• pp.1137-1142
• /
• 2018

Background/Aims: This study tested the hypothesis that prolonged low-dose cyclophosphamide (CTX) treatment after pulse therapy attenuate paraquat (PQ)-induced lung injury in rats. Methods: PQ (25 mg/kg) was administered intraperitoneally to induce PQ-intoxicated rat model. The rats were randomly divided into four groups: control group (1 mL/day saline solution for 14 days), PQ group (1 mL/day saline solution for 14 days after PQ exposure), pulse group (15 mg/kg/day CTX in 1 mL of saline solution for 2 days and subsequent 1 mL/day saline solution for 12 days), and prolonged low-dose group (15 mg/kg/day CTX in 1 mL of saline solution for 2 days and subsequent 1.5 mg/kg/day CTX in 1 mL of saline solution for 12 days). A 14-day follow-up was conducted to determine the survival rat, and lung hydroxyproline (HYP), wet-to-dry weight ratios (W/Dc) and histopathological changes were evaluated. Results: Results showed similar survival rate (55% vs. 50%, p > 0.05) between prolonged low-dose and pulse groups. Lung W/Dc ($4.94{\pm}0.38$ vs. $5.47{\pm}0.28$, p < 0.01), HYP ($3.34{\pm}0.29{\mu}g/mg$ vs. $3.65{\pm}0.19{\mu}g/mg$, p < 0.001), and fibrosis score ($2.69{\pm}0.84$ vs. $3.13{\pm}0.63$, p < 0.05) were lower in prolonged low-dose group than those in the pulse group. Conclusions: These findings suggested prolonged low-dose CTX treatment after pulse therapy could attenuate PQ-induced lung injury in rats.

• 대한임상검사과학회지
• /
• 제45권2호
• /
• pp.43-47
• /
• 2013

This study was designed to evaluate the prevalence of ESBL genes and monitor antimicrobial resistance pattern in Escherichia coli, isolated from a hospital and a community. We tested 200 E. coli strains isolated in the hospitals and community in Chungcheong area from January to March 2012. Antimicrobial susceptibilities were tested by using the disk diffusion method. A search for ESBL genes was conducted by PCR amplification, and the genotypes were determined by direct nucleotide sequence analysis of the amplified products. An Epidemiologic study was performed by repetitive extragenic palindromic sequence-based PCR (REP-PCR). The percentage of ESBL-producing isolates was 17% for hospital associated E. coli and 11% for community associated E. coli. The ESBL gene sequencing results showed that the most common ESBL in E. coli was CTX-M-14 (19/28), followed by CTX-M-15 (9/28). The REP-PCR study also showed the genetic diversity, but there was no difference between the hospital and community associated E. coli. In this study, the most common types of class A ESBLs identified were CTX-M in the hospital and the community in Chungcheong area. ESBL-producing E. coli isolates showed diverse clonality.