• Journal of Veterinary Science
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• v.23 no.3
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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.

• Microbiology and Biotechnology Letters
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• v.46 no.2
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• pp.135-144
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• 2018

The rapid increase in number and diversity of Extended Spectrum ${\beta}$-Lactamases (ESBLs) producing Enterobacteriaceae in natural aquatic environment is a major health concern worldwide. This study investigates abundance and distribution of ESBL producing multidrug resistant Enterobacteriaceae and molecular characterization of ESBL genes among isolates from highly polluted stretch of river Yamuna, India. Water samples were collected from ten different sites distributed across Delhi stretch of river Yamuna, during 2014-15. A total of 506 non duplicate Enterobacteriaceae isolates were obtained. Phenotypic detection of ESBL production and antibiotic sensitivity for 15 different antibiotics were performed according to CLSI guidelines (Clinical and Laboratory Standard Institute, 2015). A subset of ESBL positive Enterobacteriaceae isolates were identified by 16S rRNA gene and screened for ESBL genes, such as $bla_{CTX-M}$, $bla_{TEM}$ and $bla_{OXA}$. Out of 506 non-duplicate bacterial isolates obtained, 175 (34.58%) were positive for ESBL production. Susceptibility pattern for fifteen antibiotics used in this study revealed higher resistance to cefazolin, rifampicin and ampicillin. A high proportion (76.57%) of ESBL positive isolates showed multidrug resistance phenotype, with MAR index of 0.39 at Buddha Vihar and Old Delhi Railway bridge sampling site. Identification and PCR based characterization of ESBL genes revealed the prevalence of $bla_{CTX-M}$ and $bla_{TEM}$ genes to be 88.33% and 61.66%, respectively. Co-occurrence of $bla_{CTX-M}$ and $bla_{TEM}$ genes was detected in 58.33% of the resistant bacteria. The $bla_{OXA}$ gene was not detected in any isolates. This study highlights deteriorating condition of urban aquatic environment due to rising level of ESBL producing Enterobacteriaceae with multidrug resistance phenotype.

• Korean Journal of Clinical Laboratory Science
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• v.48 no.3
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• pp.210-216
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• 2016

Recently, there has been a considerable increase in the prevalence of CTX-M type extended-spectrum ${\beta}$-lactamase (ESBL)-producing E. coli isolates worldwide, including Korea. To investigate the ESBL genes in the E. coli strains isolated from a university hospital in the Chungcheong area, a study was conducted using PCR amplification and nucleotide sequence analysis of the amplified products to detect the plasmid mediated quinolone resistance (PMQR) genes in ESBL producing E. coli isolates. The number of CTX-M-14 producing isolates was 25 (16.0%) isolates, and of them, 9 (5.8%) isolates also produced CTX-M-15. All CTX-M type ESBL producing E. coli isolates showed resistance to cefotaxime. Twelve (48%) CTX-M type ESBL producing E. coli isolates contained the PMQR genes, 8 contained qnrS1, and 8 contained aac(6')-Ib-cr. Four isolates harbored both qnrS1 and aac(6')-Ib-cr genes. In our study, we confirmed that the plasmid mediated antimicrobial resistant determinants-the ESBL and PMQR genes-were distributed in the E. coli isolates. To prevent further spreading of the resistant genes among the E. coli isolates, consistent effort is required to investigate and monitor the resistant genes.

• Korean Journal of Veterinary Research
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• v.48 no.3
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• pp.259-265
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• 2008

This study was conducted to investigate incidence of extended-spectrum ${\beta}$-lactamase (ESBL) producing strains and characteristics of ESBL gene in pathogenic Escherichia coli isolated from poultry during the period from April 2003 to December 2005 in Korea. Among 203 isolates, 4 isolates (3 from broilers and 1 from layer) were confirmed as ESBL producing strains by double disk synergy test, polymerase chain reaction and sequencing for ${\beta}$-lactamase genes. $bla_{CTX-M-15}$ and $bla_{CMY-2}$ were detected in these 4 isolates and were transferred to recipient by conjugation, respectively. Also, these ESBL producing strains were associated with multiple drug resistance. In conclusion, these results exhibit incidence of CTX-M and CMY-2 ${\beta}$-lactamase in pathogenic E coli from poultry in Korea, and clinically important meaning in human. And they also suggest the needs for rapid and broad surveillance to monitor ESBL genes and R plasmid transferring resistant gene in poultry.

• Journal of the Korean Applied Science and Technology
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• v.39 no.6
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• pp.916-923
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• 2022

Water samples were collected from three spots(Namcheon, Changwoncheon and Cheongwoonji) in Changwon and genomic DNA was isolated from them. Quantitative PCR was performed with the isolated DNA as template and primers targeting five different class A extended-spectrum beta-lactamase(ESBL) genes(bla_OXA-1, bla_SHV, bla_TEM, bla_CTX-M-1, bla_CTX-M-9). The number of total ESBL genes from each sample showed large variations between each sample. Thirty nanograms of DNA from Namcheon contained 1.93×10⁶ copies of ESBL genes whereas the same amount of DNA from Changwoncheon contained 1.47×10⁵ copies of ESBL genes. However, the same amount of DNA from Cheongwoonji pond contained only 9.5×10³ copies of ESBL genes. The ratio of each ESBL genes showed little difference between Namcheon river and Changwoncheon river, but DNA from Cheongwoonji pond showed a large difference from the rest. bla_OXA-1 gene was present at 65.3%, and bla_CTX-M-1 gene 33.6% for Namcheon comprising together almost 99%. bla_OXA-1 gene was present at 64.1%, and bla_CTX-M-1 gene 19.1% for Changwoncheon comprising together over 83%. bla_CTX-M-1 gene was present at 87.5% and bla_CTX-M-9 genes 9.8% for Cheongwoonji, a pond which is a closed and isolated environment.

• Journal of Life Science
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• v.23 no.5
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• pp.703-709
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• 2013

The aim of this study was to investigate the prevalence of Extended-spectrum ${\beta}$-lactamase (ESBL) gene and quinolone resistance determinant (qnr) and the pattern of antibiotic resistance in the ESBL-producing Escherichia coli clinical isolates. The 42 ESBL-producing strains from total 274 isolates were detected using a double disk synergy test. They were isolated from various specimens, such as urine (28 strains), sputum (6 strains), pus (3 strains), wound (2 strains), blood (2 strains), and tissue (1 strain). Using the PCR with the specific primers ESBL, ESBL and qnr gene types were determined. Thirty-five strains possessed one or two ESBL genes. CTX-M-1 type was the most abundant followed by CTX-M-9 type and TEM, but SHV, CTX-M-2, and CTX-M-8 gene types were not detected. qnr gene types were detected from ten isolates in the order of qnrB4, qnrB1, and qnrS. Coexistence of ESBL and qnr genes was found. ESBL-producing isolates showed high resistance against some antibiotics, such as cefotaxmie (80.0%), levofloxacin (82.9%), and ampicillin (100%). Neither a synergy effect from the coexistence of ESBL and qnr genes on antibiotic resistance nor a correlation between the production of qnr gene and quinolone resistance were found.

• Journal of Microbiology and Biotechnology
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• v.27 no.9
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• pp.1716-1723
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• 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.

• Journal of Digital Convergence
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• v.13 no.12
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• pp.313-318
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• 2015

We investigated the prevalence of extended spectrum ${\beta}$-lactamase (ESBL) genes and 16S rRNA methyltransferase genes to study antimicrobial resistance mechanisms of Enterobacter cloacae strains isolated from a university hospital in the Chungcheong province of Korea. Eight of the bacteria strains involved in this study contained CTX-M-15 type ESBL. Among 8 strains harboring the ESBL gene, 3 strains also harbored armA gene. The three isolates showed resistance to antimicrobial agents belonged to third cephalosporin, aminoglycoside, and fluoroquinolones. Furthermore, interspecies plasmid transfer of the antimicrobial resistant genes may induced horizontal spreading of the genes and emergence of multidrug resistant bacteria. Therefore, surveillance for existence of antimicrobial resistance determinants is important to prevent distribution of antimicrobial resistant strains.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.3
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• pp.1191-1196
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• 2013

Among Gram-negative pathogens in Korea, the incidence of resistance to third generation cephalosporins is becoming an ever-increasing problem. The production of extended-spectrum ${\beta}$-lactamase (ESBL) is the main mechanism of bacterial resistance to a third-generation cephalosporins and monobactams. Accurate identification of the ESBL genes are necessary for surveillance and epidemiological studies of the mode of transmission in the hospital. This study was conducted to detect the genes encoding ESBL of 46 K. penumoniae isolated from Daejeon, Chungnam and Chungbuk regional university hospitals from February to August in 2012. The phenotypes of the isolated specimens were examined according to the combination disc test (CDT) by the Clinical and Laboratory Standards Institute (CLSI). Forty two ESBL producing K. penumoniae isolates could be detected using ceftazidime (CAZ) discs with and without clavulanate (CLA). By CDT, 42 K. pneumoniae strains were confirmed to be ESBL strains. Genotyping was performed by multiplex PCR with type-specific primers. By PCR analysis, TEM gene in 46 strains, SHV gene in 37 strains and CTX-M genes in 14 strains were identified. Ten isolates did carry genes encoding ESBLs of all types TEM, SHV and CTX-M. The multiplex polymerase chain reaction (PCR) analysis was better to detect and differentiate ESBL producing K. penumoniae strains in clinical isolates.

• Biomedical Science Letters
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• v.11 no.3
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• pp.389-396
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• 2005

Resent studies have reported increased isolation of extended-spectrum $\beta-lactamase$ (ESBL) producing strains at several hospital in Korea. We studied to investigate the isolation rates of ESBL strains from clinical isolates of Klebsiella pneumoniae and to characterize differences in types using analyses of genotyping and antibiotic susceptibility test. Antibiotic susceptibility test with confirmation of ESBL by double disk synergy test was performed on the 54 ESBL strains of Klebsiella pneumoniae from a hospital in Busan. Transfer of resistant gene in ESBL strains resistant to 3rd generated antibiotics was confirmed by transconjugation test using E. coli $RG176^{nal(r)}$. blaTEM, blaSHV, blaCTX-M genes were detected by PCR. ESBL producing strains had 100% of resistant rate to ampicillin, azteronam, cefazolin, cefepime and ceftriaxone ($\beta-lactam$ antibiotics). Forty strains of bla TEM$(74\%)$, 41 strains of bla SHV $(76\%)$, 23 strains of bla CTX-M $(43\%)$ were found, respectively. The strains had one or more genes. They had high resistant rates to $\beta-lactam$ antibiotics including cephalosporin. The resistant rates of strains with multiple resistant genes were higher than those of strains with single resistant gene.