• 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 Veterinary Service
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• v.46 no.1
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• pp.35-45
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• 2023

Pathogenic Escherichia coli is the cause of a wide range of diseases in pigs, including diarrhea, edema disease, and septicemia. Diarrhea caused E. coli may result in significant economic losses, making pathogenic E. coli an important pathogen for the swine industry. This study investigated the prevalence of virulence factor genes, antimicrobial resistance phenotypes, and resistance genes in E. coli isolated from feces of piglets in Korea between 2017 and 2020. As a result, 119 pathogenic E. coli isolates were obtained from 601 fecal samples. The F4 adhesin gene and the STb enterotoxin gene were commonly present in E. coli isolated from diarrhea samples. The dominant virulotypes of isolates from diarrhea samples were STb, Stx2e, and F4:LT:STb. More than 80% of the screened isolates were resistant to ampicillin, sulfisoxazole, chloramphenicol, or tetracycline. To confirm the resistance mechanisms for β-lactam or quinolone, we investigated the genotypic factors of resistance. Each of the ceftiofur-resistant E. coli produced an extended-spectrum β-lactamase encoded by bla_CTX-M-14, bla_CTX-M-27, and bla_CTX-M-55. And all ciprofloxacin-resistant E. coli harbored mutations in quinoloneresistance-determining-regions. In addition, some of the ciprofloxacin-resistant E. coli contained the plasmid-mediated-quinolone-resistance genes such as qepA, qnrB1, or qnrD. This study has confirmed that the F4 fimbria and the STb enterotoxin are the most predominant in pathogenic E. coli isolated from piglets with diarrhea in Korea and there is a great need for responsible and prudent use of antimicrobials to treat colibacillosis.

• Biomedical Science Letters
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• v.13 no.4
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• pp.293-304
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• 2007

The emergence of extended spectrum $\beta$-lactamase (ESBL) producing bacteria is worldwide concern. Until recently, the most frequently identified strains in the Republic of Korea were E. coli and Klebsiella spp. The incidence of resistance to extended spectrum $\beta$-lactam antibiotics is increasing in Wonju city, Korea. Total 57 strains of ESBL producing E. coli and Klebsiella species were isolated from Wonju Christian Hospital during a 9 month-period from April to December, 2003. To determine the prevalence and genotypes of the ESBL producing clinical isolates, antibiotic susceptibility and ESBL activity test by VITEK system and double disk synergy (DDS) test, and PCR based genotyping were performed. Fourteen (82%) isolates of 17 ESBL producing E. coli were found to have $bla_{TEM}$ gene and 5 (29%) isolates were found to have $bla_{CTX-M}$ gene by polymerase chain reaction (PCR). Thirty (75%) isolates of 40 ESBL producing Klebsiella species with $bla_{TEM}$ gene, 38 (95%) isolates with $bla_{SHV}$ gene, and 7 (20%) isolates with $bla_{CTX-M}$ type gene were also identified. Enterobacterial repetitive intergenic consensus (ERIC) PCR and similarity index by dendrogram for genetical similarity to band pattern of each clinical isolates were examined. ESBL producing E. coli were grouped into 6 clusters up to 84% of similarity index and Klebsiella species were grouped into 12 clusters up to 76% of similarity index. In conclusion, ESBL producing clinical isolates were characterized with the results from antimicrobial resistance pattern and genetical similarity using ERiC PCR.

• 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.

• Biomedical Science Letters
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• v.19 no.3
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• pp.275-279
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• 2013

Etiological agents of extended spectrum ${\beta}$-lactamase (ESBL) producing uropathogenic Escherichia coli (UPEC) have become a major problem in urinary tract infections. The purpose of this study was to compare the molecular characteristics of ESBL producing UPEC strains isolated from 1989 and 2010. A total of 301 strains of UPEC clinical isolates was collected from Korean healthcare facility in 1989 (126 strains) and in 2010 (175 strains). UPEC clinical isolates were analyzed by multiplex polymerase chain reaction method (ESBL related bla genes and phylogenetic groups) and amplified fragment length polymorphism (AFLP). Among 301 isolates, ESBL producing UPEC were 8 strains (6.3%) in 1989 isolates and 35 strains (20%) in 2010 isolates. The rate of bla genes in ESBL producing UPEC from 1989 isolates and 2010 isolates were $bla_{TEM}$ (75% and 85.7%), $bla_{CTX-M}$ (0% and 91.4%), $bla_{OXA}$ (25% and 20%), $bla_{PER}$ (0% and 2.9%). The distribution of phylogenetic groups in 1989 isolates and 2010 isolates were A (37.5% and 11.4%), B2 (12.5% and 51.4%), and D (50% and 37.1%). The most prevalent ESBL related bla gene and phylogenetic group were $bla_{CTX-M}$ (91.4%) and B2 (51.4%) in 2010 isolates, while $bla_{CTX-M}$ was not detected in 1989 isolates. Among 43 ESBL producing UPEC were grouped into 12 clusters up to 76% of genetic similarities by AFLP analysis. During past twenty one years, the rate of the ESBL producing UPEC strains in 2010 isolates was increased than that of in 1989 isolates. Also, the most prevalent ESBL related bla gene has been changed from $bla_{TEM}$ to $bla_{CTX-M}$.

• 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.

• Nutrition Research and Practice
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• v.9 no.5
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• pp.459-465
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• 2015

BACKGROUND/OBJECFTIVES: The effect of St. John's Wort extract (SJW) on MG-63 cell proliferation and trabecular bone loss induced by ovariectomy was examined. MATERIALS/METHODS: Proliferation, expression of estrogen receptor (ER) ${\alpha}$ and ER ${\beta}$, and gene expressions of osteoprotegerin (OPG), osteocalcin (OC) and alkaline phosphatase (ALP) were examined in MG-63 cells treated with or without SJW. Ovariectomized rats were treated with SJW at the dose of 100 or 200 mg/kg/day, ${\beta}$-estradiol-3-benzoate (E2), or vehicle only (OVX-C), and sham operated rats were treated with vehicle only (Sham-C). Serum ALP and C-telopeptide (CTX), and femoral trabecular bone loss were examined. RESULTS: SJW increased MG-63 cell proliferation and expression of ER ${\alpha}$ and ER ${\beta}$, and positive effect was shown on gene expressions of ALP, OC and OPG. SJW also showed estrogen like effect on bone associated with slowing down in trabecular bone loss. Histopathology by H&E showed rats treated with SJW displayed denser structure in metaphyseal region of distal femur compared with rats in OVX-C. SJW was shown to reduce serum CTX in OVX rats. CONCLUSION: The present study provides new insight in preventing estrogen deficiency induced bone loss of SJW and possibility for its application in bone health supplement.

• Korean Journal of Veterinary Service
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• v.42 no.1
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• pp.17-24
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• 2019

The aim of this study was to investigate the prevalence and characterization of plasmid-mediated quinolone resistance (PMQR) gene in 79 Enterobacteriaceae isolated from dogs and cats. Of 79 isolates, PMQR genes were found in 10 (12.7%) isolates, including aac(6')-lb-cr, qnrB, qnrS and qnrA detected alone or in combination in 8 (10.1%), 4 (5.1%), 2 (2.5%) and 1 (1.3%) isolates, respectively. Interestingly, two qnrS genes were detected in nalidixic acid and ciprofloxacin susceptible isolates. Extended-spectrum ${\beta}$-lactamase (ESBL) was detected in 90% (9 isolates) of PMQR positives isolates. Among ESBL genes, CTX-M, TEM and SHV were detected in 9, 8 and 3 isolates, respectively. Almost all PMQR genes were detected in co-existence with ESBL genes. All PMQR positives isolates were multidrug resistance (i.e. resistant to five or more antibiotics). qepA, OXA and CMY-2 genes were not found. The six transconjugants were obtained by conjugation experiment. The aac(6')-lb-cr, qnrB and qnrS were co-transferred with CTX-M, TEM and/or SHV, whereas qnrA was not observed among transconugants. This is the first report of the presence of aac(6')-lb-cr and qnrA gene among Enterobacteriaceae isolates from dogs in Korea. The prudent use of antimicrobials and continuous monitoring for companion animals are required.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.117-124
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• 2019

Vibrio cholerae is a very important pathogenic bacterium that has to be monitored in seafood and ships' ballast water. Various methods have been developed to identify this bacterium, yet these methods are time-consuming and have limitations for their sensitivity to detect contamination. The purpose of the present study was to develop a robust and reliable method for identifying V. cholerae. Peptide nucleic acid (PNA) probes were developed to use for PNA-based asymmetrical real-time PCR techniques. The toxigenic Cholera enterotoxin subunit B (ctxB) gene was selected as a target for detecting V. cholerae and the gene was synthesized as a positive template for conventional and real-time PCR. Real-time PCR primers and PNA probes were designed and standard curves were produced for the quantitative analysis. The selected PNA probes reacted specifically to V. cholerae without any ambiguity, even among closely related species, and the detection limit was 0.1 cfu/100 mL. Taken together, the PNA probes and asymmetrical qPCR methods developed in this present study could contribute to the rapid, accurate monitoring of V. cholerae in marine environments, and as well as in seafood and ships' ballast waters.

• Journal of Veterinary Clinics
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• v.32 no.2
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• pp.191-195
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• 2015

A 7-year-old castrated male Korean Shorthair cat was referred with lethargy and anorexia. Laboratory examination revealed moderate degenerative changes of peripheral neutrophils on blood smear examination and decreased levels of free and total thyroxine ($T_4$) as well as bacterial growth on blood culture. Molecular analyses of the 16S ribosomal RNA gene and heat shock protein 60 gene confirmed the bacterium as Enterobacter cloacae. A minimal inhibitory concentration test showed multidrug resistance of the bacterium against 16 antibiotics. Polymerase chain reaction (PCR) and subsequent sequencing specifically for $bla_{TEM}$, $bla_{SHV}$, $bla_{CTX-M}$, and plasmid-mediated ampC genes revealed positive results to $bla_{TEM-1}$, $bla_{CTX-M-15}$, and plasmid-mediated $bla_{ACT-1}$ genes, indicating that the isolated bacterium contains plasmids containing genes encoding extended-spectrum beta-lactamase and plasmid-mediated ampC beta-lactamase. After 1 month of treatment with antibiotics and levothyroxine, the cat's condition improved; both the thyroid function test and the blood culture showed no abnormalities. This is the first report of community-acquired multidrug-resistant E. cloacae-induced euthyroid sick syndrome in a cat. By the prompt diagnostic procedures and properly selected antibiotic therapy, the cat was recovered from the multidrug-resistant bacterium-induced septicaemia.