• Journal of Microbiology
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• v.43 no.2
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• pp.172-178
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• 2005

To determine the prevalence and genotypes of $\beta$-lactamases among clones of a metagenomic library from the cold-seep sediments of Edison seamount (10,000 years old), we performed pulse-field gel electrophoresis, antibiotic susceptibility testing, pI determination, and DNA sequencing analysis. Among the 8,823 clones of the library, thirty clones produced $\beta$-lactamases and had high levels of genetic diversity. Consistent with minimum inhibitory concentration patterns, we found that five ($167\%$) of thirty clones produced an extended-spectrum $\beta$-lactamase. 837- and 259-bp fragments specific to bla$_{TEM}$ genes were amplified, as determined by banding patterns of PCR amplification with designed primers. TEM­1 was the most prevalent $\beta$-lactamase and conferred resistance to ampicillin, piperacillin, and cephalothin. TEM-116 had a spectrum that was extended to ceftazidime, cefotaxime, and aztreonam. The resistance levels conferred by the pre-antibiotic era alleles of TEM-type $\beta$-lactamases were essentially the same as the resistance levels conferred by the TEM-type alleles which had been isolated from clinically resistant strains of bacteria of the antibiotic era. Our first report on TEM-type $\beta$-lactamases of the pre-antibiotic era indicates that TEM-type $\beta$-lactamases paint a picture in which most of the diversity of the enzymes may not be the result of recent evolution, but that of ancient evolution.

• Journal of Microbiology and Biotechnology
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• v.28 no.9
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• pp.1563-1572
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• 2018

Gold nanoparticles (AuNP) and their conjugates have been gaining a great deal of recognition in the medical field. Meanwhile, extended-spectrum ${\beta}$-lactamases (ESBL)-producing bacteria are also demonstrating a challenging problem for health care. The aim of this study was the biosynthesis of AuNP using Rosa damascenes petal extract and conjugation of ceftriaxone antibiotic (Cef-AuNP) in inhibiting ESBL-producing bacteria and study of in vitro anticancer activity. Characterization of the synthesized AuNP and Cef-AuNP was studied. ESBL-producing strains, Acinetobacter baumannii ACI1 and Pseudomonas aeruginosa PSE4 were used for testing the efficacy of Cef-AuNP. The cells of MCF-7 breast cancer were treated with previous AuNP and Cef-AuNP at different time intervals. Cytotoxicity effects of apoptosis and its molecular mechanism were evaluated. Ultraviolet-visible spectroscopy and Fourier transform infrared spectroscopy established the formation of AuNP and Cef-AuNP. Transmission electron microscope demonstrated that the formed nanoparticles were of different shapes with sizes of 15~35 nm and conjugation was established by a slight increase in size. Minimum inhibitory concentration (MIC) values of Cef-AuNP against tested strains were obtained as 3.6 and $4{\mu}g/ml$, respectively. Cef-AuNP demonstrated a decrease in the MIC of ceftriaxone down to more than 27 folds on the studied strains. The biosynthesized AuNP displayed apoptotic and time-dependent cytotoxic effects in the cells of MCF-7 at a concentration of $0.1{\mu}g/ml$ medium. The Cef-AuNP have low significant effects on MCF-7 cells. These results enhance the conjugating utility in old unresponsive ceftriaxone with AuNP to restore its efficiency against otherwise resistant bacterial pathogens. Additionally, AuNP may be used as an alternative chemotherapeutic treatment of MCF-7 cancer cells.

• Tuberculosis and Respiratory Diseases
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• v.78 no.4
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• pp.371-374
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• 2015

Pulmonary pneumatoceles are air-filled thin-walled spaces within the lung and are rare in adult cases of pneumonia. We report the case of a 74-year-old male who was admitted with a cough and sputum production. He had been treated with oral dexamethasone since a brain tumorectomy 6 months prior. Contrast-enhanced computed tomography (CT) of the chest revealed a large pneumatocele in the right middle lobe and peripheral pneumonic consolidation. Bronchoalveolar lavage was performed; cultures identified extended-spectrum ${\beta}$-lactamase (ESBL) producing Proteus mirabilis. A 4-week course of intravenous ertapenem was administered, and the pneumatocele with pneumonia resolved on follow-up chest CT. To the best of our knowledge, this is the first reported case of pulmonary pneumatocele caused by ESBL-producing P. mirabilis associated with pneumonia.

• 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.

• Childhood Kidney Diseases
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• v.25 no.1
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• pp.22-28
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• 2021

Purpose: The purpose of this study was to investigate the clinical outcomes of non-carbapenem treatment for urinary tract infections (UTIs) caused by extended-spectrum β-lactamase (ESBL)-producing Escherichia coli (E. coli) in young children. Methods: We retrospectively reviewed the medical records of children under 2 years of age who were diagnosed and treated for UTIs caused by ESBL-producing E. coli from September 2014 to March 2020. Results: Forty-three children under 2 years of age were treated with non-carbapenem antimicrobials for UTIs caused by ESBL-producing E. coli without bloodstream infections. The overall clinical and microbiological success rates for empirical antimicrobial treatment were 90.7% and 97.7%. Three of the patients (7.0%) experienced a relapse of UTI within a month. An in vitro susceptibility test showed that two patients were sensitive and one was resistant to the antimicrobial treatments. Furthermore, there were no significant differences in the time to defervescence, clinical success, microbiological success, and relapse rate between the susceptible (n=13) and non-susceptible groups (n=30). Conclusion: In this study, the overall relapse rate of patients treated with non-carbapenem antimicrobials was 7.0%. The patients showed high success rates in the clinical and microbiological responses to the non-carbapenems regardless of the results of the in vitro antimicrobial susceptibility test. These results provide evidence that non-carbapenems may be viable alternative treatments for UTIs caused by ESBL-producing E. coli.

• Korean Journal of Microbiology
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• v.46 no.3
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• pp.303-307
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• 2010

Acinetobacter baumannii 1625, a clinical isolate identified by Vitek and 16S rDNA sequence, showed an extended resistance to most ${\beta}$-lactams including imipenem, kanamycin, gentamicin, tobramycin, and cephalosporins of the third and fourth generations, and produced metallo-${\beta}$-lactamase (MBL) of IMP-1 type which is rare in Korea. The isolate contained a class 1 integron of about 2.5 kb in size and the integron included accA4 (aminoglycoside resistance gene), $bla_{IMP-1}$ (carbapenem resistance gene), and $bla_{OXA-2}$ (extended-spectrum ${\beta}$-lactam resistance gene) gene cassettes in order. The coexistence of IMP-1 type and OXA-2 type ${\beta}$-lactamase gene cassettes in an integron has not been reported in Korea. The transformed integron rendered the E. coli transformant resistant more than eight folds against imipenem, ampicilin, piperacillin, cefazolin, cefoperazone, and aztreonam comparing to the reference strain. This study clearly showed that the extended multi-drug resistance of A. baumannii 1625 was mainly due to the integron.

• 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.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.

• 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 $bla_{CTX-M}$.

• Korean Journal of Microbiology
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• v.42 no.4
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• pp.252-256
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• 2006

We monitored antibiotic resistance of Escherichia coli isolates from healthy volunteers of community and hospital patients from February to July in 2006. From disc diffusion test on 4915 E. coli isolates from healthy volunteers of the community, the resistance rates were as follows; tetracycline resistant, 46.6%; ampicillin resistant, 41.1%; ticarcillin resistant,37.9%. From disc diffusion test on 120 E. coli isolates from hospital patients, the resistance rates were as follows: ampicillin resistant, 66.9%; ticarcillin resistant, 63.8%; tetracycline resistant, 47.2%. Extended spectrum $\beta$-lactamase producing E. coli were isolated 0.6% and 4.1% from healthy volunteers and hospital patients.