• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.5
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• pp.564-572
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• 2016

In this study, we isolated and characterized Escherichia coli from mussels and inland pollution sources in or in proximity to the Changseon area on the southern coast of Korea in 2014. A total of 147 strains of E. coli were isolated from 54 mussels and 32 pollution-source samples. The susceptibility of the isolates to 24 antimicrobial agents was analyzed. The resistance of E. coli isolates to rifampin was highest at 100%, followed by cephalothin (98.6%), tetracycline (91.8%), amikacin (81.0%), ampicillin (79.6%), cefazolin (79.6%), streptomycin (73.5%), piperacillin (70.7%), gentamicin (37.4%), cefoxitin (35.4%), cefamandole (34.7%), tobramycin (29.9%), amoxicillin/clavulanic acid (24.5%), nalidixic acid (21.8%), trimethoprim (19.0%), chloramphenicol (17.7%), cefotaxime (12.9%), trimethoprim (10.9%), ceftazidime (10.2%), aztreonam (7.5%), imipenem (2.7%), cefepime (2.0%), and cefotetan (0.0%). In addition, the antimicrobial resistance of E. coli isolates from inland pollution sources was slightly greater than or similar to that of isolates from mussels.

• 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 Applied Biological Chemistry
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• v.58 no.3
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• pp.227-232
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• 2015

A microarray study has been employed to understand changes of gene expression in E. coli KD43162 resistant to ampicillin, ampicillin-sulbactam, piperacillin, piperacillin-tazobactam, cefazolin, cefepime, aztreonam, imipenem, meropenem, gentamicin, tobramycin, ciprofloxacin, levofloxacin, moxifloxacin, fosfomycin, and trimethoprim-sulfamethoxazole except for amikacin using disk diffusion assay. Using Sodium dodecyl sulphate-polyacrylamide gel electrophoresis and MALDI-TOF MS analyses, 36 kDa of outer membrane proteins (OMPs) was found to be deleted in the multidrug resistant E. coli KD 43162. Microarray analysis was used to determine up- and down-regulated genes in relation to multidrug resistant E. coli KD43162. Among the up-regulated genes, these genes were corresponded to express the proteins as penicillin-binding proteins (PBPs), tartronate semialdehyde reductase, ethanolamine utilization protein, shikimate kinase I, allantoinase, predicted SAM-dependent methyltransferase, L-glutamine: D-fructose-6-phosphate aminotransferase (GFAT), phospho-glucosamine mutase, predicted N-acetylmannosamine kinase, and predicted N-acetylmannosamine-6-P epimerase. Up-regulation of PBPs, one of primary target sites of antibiotics, might be responsible for the multidrug resistance in E. coli with increasing amount of target sites. Up-regulation of GFAT enzyme may be related to the up-regulation of PBPs because GFAT produces N-acetylglucosamine, a precursor of peptidoglycans. One of GFAT inhibitors, azaserine, showed a potent inhibition on the growth of E. coli KD43162. In conclusion, up-regulation of PBPs and GFATs with the loss of 36 kDa OMP refers the multidrug resistance in E. coli KD 43162.

• Korean Journal of Clinical Laboratory Science
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• v.38 no.1
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• pp.22-25
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• 2006

Ochrobactrum anthropi, previously known as Achromobacter species biotypes 1 and 2 (CDC groups Vd-1, Vd-2), belong to the groups of non-Enterobacteriaceae- nonfermentative Gram negative bacilli. Achromobacter is not presently a recognized genus. Achromobacter xylosoxidans has been transferred to genus Alcaligenes as A. xylosoxidans subsp. xylosoxidans, and "Achromobacter" sp. group Vd has been named Ochrobactrum anthropi. O. anthropi was isolated from a blood culture. Organisms were identified as O. anthropi by use of the biochemical test and the VITEK 2(bioMerieux, USA). The Organism was susceptible only to colistin, imipenem, meropenem, and tetracycline, but were resistant to amikacin, aztreonam, cefepime, ceftazidime, cefpirome, ciprofloxacin, gentamicin, isepamcin, netilmicin, pefloxacin, piperacillin, piperacillin/tazobactam, ticarcillin, ticarcillin/clavulanic acid, tobramycin, and trimethoprim/sulfamethoxazole. We report the clinical and microbiologic characteristics of O. anthropi infection in the patient. This is the first case of O. anthropi infection after using a plant as medicine at Chosun University Hospital.

• Korean Journal of Veterinary Service
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• v.37 no.1
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• pp.19-27
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• 2014

This study was conducted to investigate the antimicrobial resistance, presence of ${\beta}$-lactamase genes and integrons in 83 ESBL-producing Escherichia coli isolated from Nakdong river and Geumho river in Daegu. Among the ${\beta}$-lactam antimicrobials, all isolates were resistant to ampicillin, cephalothin, cefamandole and cefotaxime, followed by piperacillin (98.8%), ampicillin/sulbactam (86.7%), aztreonam (60.2%) and cefepime (59.0%), whereas resistance to piperacillin/tazobacram, ticarcillin/clavulanic acid and cefoxitin was less than 30%. Many of the ESBL-producing Escherichia coli were also resistant to non-${\beta}$-lactams antimicrobials such as nalidixic acid (83.1%), sulfonamides (72.3%), ciprofloxacin (62.7%) and gentamicin (38.6%). All isolates showed resistance to seven or more antimicrobial agents. The most frequently detected gene was $bla_{TEM+CTX-M}$ (49.4%), followed by $bla_{CTX-M}$ (27.7%), $bla_{TEM}$ (6.0%) and $bla_{OXA}$ (1.2%). But $bla_{SHV}$ was not found. Class 1 integrons were found in 61.4% (51 isolates) of isolates, however, class 2 and 3 integrons were not detected. The results showed water from Nakdong river and Geumho river is contaminated with ESBL-producing E. coli isolates. These results suggest the need for further investigation of antibiotic resistant bacteria to prevent public health impacts in the water environment.

• The Journal of the Korean Society for Microbiology
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• v.22 no.3
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• pp.251-258
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• 1987

A total of 58 strains of Enterobacter species isolated from clinical specimens at Kyungpook National University Hospital in Taegu and Yonsei University Hospital in Seoul were tested for the molecular characterization to investigate the nosocomial infection through the study of R plasmids which might spread among Gram negative organisms regardless of their originated strains. All strains resistant to ampicillin, cefoxitin and cephalothin but susceptible to moxalactam were subjected to the further test for the determination of in detail MIC value against 23 drugs of common use including beta-lactam antibiotics and R plasmid profile analysis. The reistance frequency of strains against carbenicillin (53.4%) was similar to those against chloramphenicol, tobramycin, and sulfisomidine. Though the MIC values of resistance criteria against ceftazidime, aztreonam, imipenem, and norfloxacine in NCCLS manual were not available but MIC ranges of strains tested were very low. There were differences in patterns and frequencies of resistance between the strains isolated in Seoul and Taegu isolates. Seoul isolates showed a tendency of higher multiplicity of resistance than those of Taegu isolates. The resistances against cefoxitin, cephalothin, cefoperazone, cefotaxime, nalidixic acid, and rifampin were not conferred to the conjugally transferable R plasmid. The approximate molecular size of conjugally transferable R plasmids ranged 30 to 151 megadalton, and one or 2 to 3 R plasmids were identified in each transconjugants.

• Archives of Pharmacal Research
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• v.24 no.6
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• pp.590-596
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• 2001

A new extended-spectrum ${\beta}-lactamase$ with an isoelectric point (pl) of 6.2 was detected in Klebsiella pneumoniae Fl 61 that was isolated from a patient with infection. This strain was highly resistant to the third or fourth generation cephalosporins such as cceftazidime ceftriaxone, cefoperzaone, and cefpirome. Analysis of this strain by the double disk diffusion test showed synergies between amoxicillin-clavulanate (AMX-CA) and cefotaxime, and AMX-CA and aztreonam, which suggested that this strain produced a extended-spectrum ${\beta}-lactamase$ (ESBL). Cenetic analysis revealed that the resistance was due to the presence of a 9.4-kb plasmic, designated as pkpl 61, encoding for new ${\beta}-lactamase$ gene (bla). Sequence analysis showed that a new bla gene of pkpl 61 differed from $bla_{TEM-1}$ by three mutations leading to the following amino acid substitutions: $Val_{84}{\rightarrow}lie,{\;}Ala_{184}{\rightarrow}Val,{\;}and{\;}Gly_{238}{\rightarrow}Ser$. These mutations have not been reported previously in the TIM type ${\beta}-lactamases$ produced by clinical strains. The novel ${\beta}-lactamase$ was overexpressed in E. coli and purified by ion exchange chromatography on Q-Sepharose and CM-Sepharose, and then further purified by gel filtration on Sehadex G-200. The catalytic activity of th8 purified ${\beta}-lactamase$ was confirmed by the nitrocefin disk.

• Osong Public Health and Research Perspectives
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• v.9 no.6
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• pp.325-333
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• 2018

Objectives: The purpose of this study was to determine the presence of IMP and OXA genes in clinical strains of Pseudomonas aeruginosa (P. aeruginosa) that are carriers of the ampC gene. Methods: In this study, 105 clinical isolates of P. aeruginosa were collected. Antibiotic resistance patterns were determined using the disk diffusion method. The strains carrying AmpC enzymes were characterized by a combination disk method. Multiplex-PCR was used to identify resistance and virulence genes, chi-square test was used to determine the relationship between variables. Results: Among 105 isolates of P. aeruginosa, the highest antibiotic resistance was to cefotaxime and aztreonam, and the least resistance was to colictin and ceftazidime. There were 49 isolates (46.66%) that showed an AmpC phenotype. In addition, the frequencies of the resistance genes were; OXA48 gene 85.2%, OXA199, 139 3.8%, OXA23 3.8%, OXA2 66.6%, OXA10 3.8%, OXA51 85.2% and OXA58 3.8%. The IMP27 gene was detected in 9 isolates (8.57%) and the IMP3.34 was detected in 11 isolates (10.47%). Other genes detected included; lasR (17.1%), lasB (18%) and lasA (26.6%). There was a significant relationship between virulence factors and the OX and IMP genes ($p{\leq}0.05$). Conclusion: The relationship between antibiotic resistance and virulence factors observed in this study could play an important role in outbreaks associated with P. aeruginosa infections.

• Korean Journal of Environmental Agriculture
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• v.42 no.4
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• pp.269-278
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• 2023

Antibiotics either kill or inhibit the growth of bacteria. However, antibiotic-resistant bacteria are difficult to treat with antibiotics. Infections caused by such bacteria often lead to severe diseases. Antibiotic resistance genes (ARG) can be horizontally transmitted across different bacterial species, necessitating a comprehensive understanding of how ARGs spread across various environments. In this study, we analyzed the plasmid sequences of 33 extended-spectrum beta-lactamases (ESBL) producing Escherichia coli isolated from pigs, farms, and their owners. We conducted an antibiotic susceptibility test (AST) with aztreonam and seven other antibiotics, as well as whole genome sequencing (WGS) of the strains using MinION. Our results demonstrated that the plasmids that did not harbor ARGs were mostly non-conjugative, whereas the plasmids that harbored ARGs were conjugative. The arrangement of these ARGs exhibited a pattern of organization featuring a series of ARG cassettes, some of which were identical across the isolates collected from different sources. Therefore, this study suggests that the sets of ARG cassettes on plasmids were mostly shared between pigs and their owners. Hence, enhanced surveillance of ARG should be implemented in farm environments to proactively mitigate the risk of antibiotic-resistant bacterial infections.

• Clinical and Experimental Pediatrics
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• v.48 no.7
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• pp.760-765
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• 2005

Purpose : We studied the changes in antibiotic sensitivity to the causative organisms of urinary tract infection(UTI), in order to provide useful information on the choice of adequate drugs in the treatment of UTI. Methods : We retrospectively analyzed the major causative organisms and their antibiotic sensitivities in 69 patients diagnosed with UTI in the Department of Pediatrics, Samsung Cheil Hospital from 2002 to 2003. Results : The frequency of UTI was the highest in infants younger than 1 year of age(88.4 percent). The male to female ratio was 3.05 : 1. Escherichia coli was the most frequent organism(78.3 percent), followed by Klebsiella(11.6 percent), Pseudomonas(2.9 percent), Proteus(2.9 percent), Enterobacter, Morganelle, and Enterococcus(1.4 percent) in descending order. Antibiotic sensitivity of gram negative organisms was above 90 percent against imipenem, amikacin, 80 percent against aztreonam, cefepime, ceftriaxone, 50-70 percent against gentamicin, trimethoprime-sulfamethoxazole (TMP/SMX), and 23 percent against ampicillin(23.4 percent). Conclusion : Antibiotict sensitivity of gram negative organisms was high to amikacin and third generation cephalosporins but low to ampicillin, gentamicin and TMP/SMX. The use of ampicillin or TMP/SMX, as the first choice of the empiric and prophylactic treatment for UTI, should be reconsidered and investigated further.