• 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.

• Korean Journal of Clinical Laboratory Science
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• v.45 no.2
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• pp.43-47
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• 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.

• Journal of Microbiology and Biotechnology
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• v.34 no.5
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• pp.1101-1108
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• 2024

Earlier studies have validated the isolation of extended-spectrum beta-lactamase-producing Salmonella (ESBL-Sal) strains from food. While poultry is recognized as a reservoir for Salmonella contamination, pertinent data regarding ESBL-Sal remains limited. Consequently, the Ministry of Food and Drug Safety has isolated Salmonella spp. from retail meat and evaluated their antibiotic susceptibility and genetic characteristics via whole-genome sequencing. To further elucidate these aspects, this study investigates the prevalence, antibiotic resistance profiles, genomic characteristics, and homology of ESBL-Sal spp. obtained from livestock-derived products in South Korean retail outlets. A total of 653 Salmonella spp. were isolated from 1,876 meat samples, including 509 beef, 503 pork, 555 chicken, and 309 duck samples. The prevalence rates of Salmonella were 0.0%, 1.4%, 17.5%, and 28.2% in the beef, pork, chicken, and duck samples, respectively. ESBL-Sal was exclusively identified in poultry meat, with a prevalence of 1.4% in the chicken samples (8/555) and 0.3% in the duck samples (1/309). All ESBL-Sal strains carried the bla_CTX-M-1 gene and exhibited resistance to ampicillin, ceftiofur, ceftazidime, nalidixic acid, and tetracycline. Eight ESBL-Sal isolates were identified as S. Enteritidis with sequence type (ST) 11. The major plasmid replicons of the Enteritidis-ST11 strains were IncFIB(S) and IncFII(S), carrying antimicrobial resistance genes (β-lactam, tetracycline, and aminoglycoside) and 166 virulence factor genes. The results of this study provide valuable insights for the surveillance and monitoring of ESBL-Sal in South Korean food chain.

• Korean Journal of Microbiology
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• v.46 no.1
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• pp.38-45
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• 2010

The study performed to identify the type of ESBL against strains which are producing extendedspectrum ${\beta}$-lactamases and isolated from sewage in Suyeong sewage disposal plant, Busan Environmental Corporation. By the standard activated sludge method, Suyeong sewage disposal plant purify living and lavatory sewage gathering from the northeast Busan and the facility purify total 550,000 tons of living sewage disposal a day. 14 strains were isolated by double disk synergy test and the third generation cepha-antibiotics test. Indole, methyl-red, Voges-Proskauer, Simmon's citrate, decarboxylasedihydrolase and sugar-fermentation tests identified as Klebsiella pneumoniae (n=4) and Escherichia coli (n=10). Plasmid-mediated transmission test against isolated 14 strains proved 11 strains transmitted resistance to recipient E. coli J53 (sodium $azide^R$, $ceftazidime^S$). 9 strains of conjugant were expressed ESBL genes transferred from parental strain but 2 conjugants did not expressed. The type of ESBL from each strain was determined by isoelectric focusing points, DNA and amino acids sequencing. The results indicated that the types of ESBL transmitted to recipient E. coli J53 were TEM-1, the parental TEM type and SHV-12 type.

• Korean Journal of Clinical Laboratory Science
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• v.38 no.1
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• pp.26-33
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• 2006

Recently, the rapid increase in extended-spectrum ${\beta}$-lactamase (ESBL) producing clinical isolates has become a serious problem. In this study, the epidemiologic features and molecular characteristics of ESBL among clinical isolates of Escherichia coli and Klebsiella pneumoniae, antibiotic susceptibility testing, genotype of the ESBL and patterns of chromosomal DNA from PFGE (pulsed field gel electrophoresis) were observed. A total of 53 ESBL-producing clinical isolates (30 of E. coli and 23 of Klebsiella pneumoniae) were collected from two university hospitals in the period of June to July in 2002 and 2003 respectively. The antibiotic resistance frequency of those 53 strains was tested by the disk agar diffusion method with the result that all the strains were resistant to cephalothin. To other antibiotics, the resistance rates of E. coli (30 isolates) were in order of ceftazidime (90.0%), cefotaxime and aztreonam (respectively 83.3%). Also, the resistance rates of K. pneumoniae (23 isolates) were in order of aztreonam (78.3%), ceftazidime (73.9%) and cefotaxime (65.3%). Also the sensitivity of ceftazidime-clavulanic acid were 100% in E. coli and 95.7% in K. pneumoniae. And the sensitivity of cefotaxime-clavulanic acid was 96.7% in E. coli and 91.3% in K. pneumoniae. The types of the ESBL genes were determined by using polymerase chain reaction (PCR). Among the 30 isolates of ESBL-producing E. coli, 6 (20.0%) have SHV only, 5 (16.7%) have TEM only and, 18 (60.0%) have both of TEM and SHV. Among the 23 isolates of ESBL-producing K. pneumoniae, 7 (30.4%) have SHV only, 2 (8.7%) have TEM only, and 14 (60.9%) have both of TEM and SHV. These results show that 52 strains, with only one exception, were confirmed as either TEM or SHV. The patterns of Xba I-digested chromosomal DNA of ESBL-producing E. coli and K. pneumoniae isolates were analyzed by PFGE. PFGE patterns of E. coli and K. pneumoniae were multiclonal, but many strains were grouped into a few types. Therefore, it seems that there were clonal outbreaks or possible horizontal spread. In conclusion, the TEM and SHV ${\beta}$-lactamase are most widely spread in E. coli and K. pneumoniae in Korea. As these types are usually carried by plasmids, the spread of these ${\beta}$-lactamase genes could compromise the future usefulness of third generation cephalosporins for the treatment of infections caused by E. coli and K. pneumoniae.

• Korean Journal of Clinical Laboratory Science
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• v.41 no.4
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• pp.153-157
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• 2009

The production of extended-spectrum ${\beta}$-lactamases ($ESBL_S$) of the TEM or SHV type by bacterial pathogens is a major threat to the use of the clinically important expanded-spectrum cephalosporins. The characterization of the SHV ESBLs producing Klebsiella pneumoniae strains present in clinical isolates is time-consuming processes. We describe here in the development of a novel system, which consists of a real time PCR. We found 11 K. pneumoniae strains to be presumptive strains ESBLs producers by clinical and laboratory standards institute (CLSI) guidelines. The double disk synergy test showed 8 ESBL positive and conventional PCR showed 10 SHV ESBL positive, which were K. pneumoniae strains isolates. By real time PCR analysis, SHV gene in 11 of 11 strains were identified. When sequencing analysis was compared with real time PCR, both analysis were presented 99% similarity. In this study, we used a rapid, sensitive, and specific real-time PCR (RT-PCR) method for detection of the assay SHV ESBL producing K. pneumoniae strains in clinical isolates.

• Korean Journal of Clinical Laboratory Science
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• v.37 no.3
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• pp.149-154
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• 2005

Fifty-one extended-spectrum-${\beta}$-lactamase(ESBL) producing Klebsiella pneumoniae strains were isolated from national university hospitals. All K. pneumoniae strains showed resistance to broad-spectrum antibiotic and most of them presented resistance to amikacin, gentamicin and ciprofloxacin. The results of amplified polymorphic DNA (RAPD) pattern for randomly isolated fifty-one strains were as follows; both twenty-one strains from Chungnam National University hospital and ten strains from Chungbuk National University hospital showed RAPD type Ia and Ib. However, twenty strains isolated from Gyeongsang National University hospital belonged to RAPD type IIa and IIb. All isolates were divided into four molecular types and showed high level of genetic diversity. These results suggested that RAPD analysis provided a rapid and simple method for analysing genotypes of ESBL.

• Clinical and Experimental Pediatrics
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• v.48 no.10
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• pp.1107-1115
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• 2005

Purpose : An outbreak of ESBL-producing Shigella sonnei enteritis was unprecedented not only in Korea but throughout the world in the past. We intended to devise a management guideline for ESBL-producing shigellosis based on analysis of clinical manifestations and response to therapy. Methods : We analyzed 103 patients who were admitted to the hospital with acute GI symptoms and were shown positive result for S. sonnei on stool culture. We performed sensitivity test to the antibiotics and DNA sequencing of ESBL gene in the isolated S. sonnei colonies. In addition, we retrospectively analyzed their clinical characteristics, laboratory results, and clinical and microbiological responses to the antibiotics. Results : Among the clinical manifestations, fever was the most frequent(96.1%), followed by diarrhea(93.2%), abdominal pain(76.7%), headache(71.8%), vomiting(65.0%), and nausea(41.7%). The fever was sustained for average of 2.0 days and diarrhea for 3.9 days. Watery diarrhea was the most common(69%) followed by mucoid(26%), and bloody stool(5%). On peripheral blood smear, leukocytosis was noted in 53.4% of patients, and 78.6% of patients tested positive for serum CRP response. On stool direct smear, 11.7% of patients showed more than 50 WBCs/HPF, and 9.7% of patients between 5 to 20 WBCs/HPF. Stool occult blood was positive in 71% of patients. Production of CTX-M-14 type ESBL was reported for all S. sonnei strains isolated from this outbreak. Microbiological eradication rates to various antibiotics were as follows : 100%(9/9) to ciprofloxacin, 100% 5/5) to azithromycin, 6.9%(5/72) to cefdinir, 0%(0/8) to ceftriaxone, 12.5%(1/8) to ceftizoxime, 0%(0/ 8) to TMP/SMX, 42.9%(3/7) to ampicillin/sulbactam, 20%(1/5) to amoxicillin/clavulanic acid, and 68.8 %(11/16) to imipenem/cilastatin. Conclusion : It is presumed that azithromycin can be an attractive option for the treatment of ESBL-producing S. sonnei enteritis in pediatric population, given its cost-effectiveness and safety. Although ciprofloxacin is another cost-effective agent, its use in pediatric population may be a bit too premature.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.4
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• pp.2295-2302
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• 2014

The study aims primarily to evaluate the resistance of antibiotics and the prevalence of these enzymes among Escherichia coli the most frequent isolate of Enterobacteriaceae producing Extended-Spectrum ${\beta}$-Lactamase(ESBLs), to differentiate the types of enzymes in these isolates. Total 74(26.2%) Strains of producing ESBLs among the 282 E. coli isolates were isolated from hospitals of Chungcheong area (Daejeon, Chungnam, and Chungbuk) during a 6 month-period from February to July, 2013. 282 E. coli isolates including ESBL shown resistance rates of aztreonam 30.8%, Cefotaxim 30.9%, and Ceftazidime 32.2%, 74 isolates producing ESBLs in E. coli were resistant rates to Aztreonam 58.1%, Cefotaxim 100%, and Ceftazidime 63.5% of ${\beta}$-lactam antibiotics. CTX-M-2 (48 isolates) was the most prevalent type of ESBLs identified. Followed the order of frequency by PER-1 (28 isolates), VEB-1 (26 isolates) and CTX-M-8 (20 isolates), of the 74 isolates, 2 isolates only showed GES-1 in Chungnam province. Accurate identification type of ESBLs would aid in hospital infection control. This would give aid to the physician to prescribe more appropriate antibiotics.

• Journal of the Korea Convergence Society
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• v.6 no.5
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• pp.77-84
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• 2015

This study was conducted to investigate the characteristics of antibiotic resistant E. coli. its antibiotic susceptibility and pathogenicity were analyzed via molecular convergence technique, for the relationship of antibiotic susceptibility and pathogenicity. The 60 isolated strains consisted of ESBL(+)(8) and ESBL(-)(52) strains. The ESBL(+)(8) strains consisted of 2 strains without a pathogenic gene, stb(3), flich7(1), and flich7-eae(2). The ESBL(-)(52) strains consisted of 26 strains without a pathogenic gene, stx1(3), stb(10), flich7(2), eae(2), stx1-flich7(2), stx1-stb(4), flich7-stb(2), and flich7-stb-eae(1). In conclusion, antibiotic resistance is increasingly, Focused on molecular convergence, showed the correlation of pathogenicity with antibiotic resistance was poor. However, It will be able to find the exact pathogenic factor in the future through convergence technique including the analysis of virulence genes.