• 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.

• The Journal of the Korean Society for Microbiology
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• v.34 no.6
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• pp.543-554
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• 1999

The purpose of this study was to evaluate the existence of amoxicillin, clarithromycin, and metronidazole resistance Helicobacter pylori and to determine the in-vitro MIC of two and three kinds of antibiotic concominant administration in the isolates. The antimicrobial agents tested against 169 H. pylori included metronidazole, amoxicillin, ciprofloxacin, clarithromycin, omeprazole, josamycin, erythromycin, and tetracycline. MIC of each antimicrobial agents was determined by broth microdilution method. The 169 strains of H. pylori were isolated from biopsy specimens of patients with gastric cancer. $MIC_{50}$ of clarithromycin, amoxicillin, metronidazole, omeprazole, erythromycin, josamycin, tetracycline, and ciprofloxacin was 2.0, 1.0, 4.0, 8.0, 0.5, 0.5, and $0.5\;{\mu}g/ml$, respectively. $MIC_{90}$ of clarithromycin, amoxicillin, metronidazole, omeprazole, erythromycin, josamycin, tetracycline, and ciprofloxacin was 64.0, 64.0, 32.0, 16.0, 8.0, 2.0, and $1.0\;{\mu}g/ml$, respectively. H. pylori isolates were detected in the following resistaince rates: 34.3% to clarithromycin, 31.9% to metronidazole, 20.7% to amoxicillin, 12.4% to erythromycin, and 10.1% to josamycin. The prevalence of the antibiotic resistant strains of H. pylori were detected 18.1% for two kind of antibiotics and 9.6% for three kind of antibiotics, and 3.9% for four kind of antibiotics. The $MIC_{90}$ of clarithromycin-, metronidazole-, and amoxicillin-resistant H. pylori was decreased under the $1\;{\mu}g/ml$ by the two or three kind of antibiotic concomitant administration in-vitro. These results suggest that two or three antibiotics concomitant administration could be more effective for the treatment of clarithromycin-, amoxicillin-, metronidazole-, and josamycin-resistant H. pylori strains.

• Journal of Veterinary Clinics
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• v.21 no.2
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• pp.133-139
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• 2004

Bacterial pathogens were isolated from 36 dogs with respiratory signs, that were submitted to Veterinary Clinics in Jeju, including Veterinary Medical Teaching Hospital in Cheju National University. Of 36 isolates, 16 (44.4%) bacterial pathogens were Gram-positive and 20 (55.6%) were Gram-negative. Gram-positive bacteria identified with API Staph were 12 S. intermedius (33.3%), 2 S. aureus (5.6%), 1 S. haemolyticum (2.8%), and 1 S. xylosus (2.8%). Gram-negative organisms identified with API 20E or API NE included 8 Bordetella bronchiseptica (22.2%), 6 Escherichia coli (16.7%), 4 Pasteurella spp. (11.1%), 1 Enterobacter intermedius (2.8%), and 1 Oligella ureolytica (2.8%). Both Staphylococcus spp. isolates and Gram-negative pathogens were resistant to one or more antibiotics, including ampicillin (AM), amoxicillin/clavulanic acid (AMC), chloramphenicol (C), cefazolin (CZ), erythromycin (E), gentamicin (GM), kanamycin (K), lincomycin (L), oxacillin (OX), trimethoprim/sulfamethoxazole (SXT), and tetracycline (TE). All Staphylococcus spp. were susceptible to AMC, OX and VA, while many isolates were highly resistant to L (87.5%), E (68.8%), P (62.5%), and AM (56.3%). Antibiotic-resistant patterns of staphylococcal isolates were shown ranges from single to 9-resistant patterns. Resistant rates to antibiotics of Gram-negative bacteria were usually higher than those of Staphylococcus spp. in this study. Most Gram-negative bacteria were highly resistant to L (90.0%), AM (85.0%), E (85.0%), P (85.0%), OX (80.0%), and CZ (75.0%). B. bronchiseptica isolates showed 5 to 8 antibiotics-resistant patterns and Pasteurella spp., 2 to 8-resistant patterns. In particular, all 6 E. coli isolates were resistant to more than 9 different kinds of antibiotics, including one strain resistant to all antibiotics tested.

• Korean Journal of Veterinary Research
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• v.30 no.1
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• pp.51-57
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• 1990

In order to know the prevalence of S. hyicus subsp hyicus in pigs, attempts were made to isolate the organism from 549 healthy adult pigs, 277 healthy suckling piglets and 17 piglets with exudative epidermitis from April 1988 to January 1989 in Chinju, Korea. Also determined was antibiotic susceptibility of the isolates. Isolation rates of S. hyicus subsp. hyicus from adult pigs and suekling piglets were 27.0% and 53.1%, respectively. The organism was isolated predominantly from abdomen (10.9%) of adult pigs and external ear (31.6%) of suckling piglets. Isolation rates of the organism from piglets of different age group were in order of prevalence of 1(82.1%), 3(74.0%), 2(54.7%), 4(52.9%), 5(15.2%) and 6(5.7%) post-natal weeks. All of 489 isolates were sensitive to gentamicin, kanamycin and cephalexin but 23.7~79.6% of the strains were resistant to erythromycin, penicillin G and tetracycline. The 49.2% of these resistant strains exhibited multiple drug resistance. The drug resistant patterns most frequently encountered were PG TC EM(10.7%) in triple pattern, PG TC(23.0%) in double pattern and TC(44.4%) in single pattern.

• Journal of Microbiology and Biotechnology
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• v.29 no.9
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• pp.1460-1469
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• 2019

The extensive distribution of multidrug-resistant (MDR) methicillin-resistant Staphylococcus aureus (MRSA) poses a threat to healthcare worldwide. This study aimed to investigate the MDR and molecular patterns of MRSA isolates in children admitted to the two biggest tertiary care pediatric hospitals in northern and southern Vietnam. A total of 168 MRSA strains were collected to determine antibiotic susceptibility by minimum inhibitory concentration tests. Antibiotic-resistant genes, pulsed-field gel electrophoresis, staphylococcal cassette chromosome mec (SCCmec) typing, and multilocus sequence typing were used for the molecular characterization of MRSA. Among the total strains, the MDR rate (51.8%) was significantly higher in the northern hospital than in the southern hospital (73% vs. 39%, p < 0.0001). The MDR-MRSA with the highest rates were "ciprofloxacin-erythromycin-gentamicintetracyclines" (35.6%), followed by "erythromycin-tetracycline-chloramphenicol" (24.1%), and "ciprofloxacin-erythromycin-gentamicin" (19.5%), showing an accumulative total of 79.3%. The most susceptible antibiotics were rifampicin (100%) and vancomycin (100%), followed by doxycycline (94.0%), meropenem (78.0%), and cefotaxime (75.0%). The SCCmecII strains showed greater resistance to gentamicin, ciprofloxacin, tetracycline, meropenem and cephalosporins compared with the other strains. The SCCmecII strains exhibited the highest rate in the tested genes (aacA/aphD: 55.2%, ermA/B/C: 89.7%, and tetK/M: 82.8%). ST5-SCCmecII was the predominant clone in the northern hospital, whereas SCCmecIVa was more pronounced in the southern hospital. In conclusion, our results raised concerns about the predominant MDR-MRSA strains in the pediatric hospitals in Vietnam. The north-south difference in the antibiotic resistance patterns and genetic structure of MRSA suggests different MRSA origins and various uses of antimicrobial agents between the two regions.

• 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.

• Journal of Food Hygiene and Safety
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• v.35 no.6
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• pp.602-606
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• 2020

This study was designed to investigate the dynamic behaviors of phages against Salmonella enterica subsp. enterica serovar Typhimurium ATCC 19585 (STWT), S. Typhimurium KCCM 40253 (STKCCM), ciprofloxacin-induced S. Typhimurium ATCC 19585 strains (STCIP), and S. Typhimurium CCARM 8009 (STCCARM). Phages, including PBST-10, PBST-13, PBST-32, PBST-35, P-22, and P-22 B1 had narrow host ranges. The adsorption rates of all phages ranged from 47 to 85%, 58 to 95%, and 61 to 93%, respectively, against STWT, STKCCM, and STCIP, while the lowest adsorption rates ranged from 14 to 36% against STCCARM. The phage burst sizes were from 43 to 350, 37 to 530, 66 to 500, and 24 to 500 plaque-forming units (PFUs) per infected STWT, STKCCM, STCIP, and STCCARM, respectively. The STCIP strain was effectively inhibited by all phages at the early of incubation period. These results provide useful information for better understanding the phage behaviors against antibiotic-resistant and antibiotic-sensitive pathogens.

• Natural Product Sciences
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• v.28 no.3
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• pp.93-104
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• 2022

Methicillin-resistant Staphylococcus aureus (MRSA) is a serious threat to the global healthcare system. Ineffective and resistance to antibiotic treatments have increased morbidity and mortality rates worldwide. New and effective antibiotics are needed to combat against bacterial resistance. Endophytic fungi are crucial reservoirs of novel bioactive metabolites. In particular, the secondary metabolites show promising therapeutic potential, notably, antibacterial. This review discussed the emerging potential of endophytic fungi as anti-MRSA agents. The ecological sources of endophytic fungi were discussed with the synthesis of bioactive metabolites. The mode of antibacterial actions was elucidated to give a better understanding of the mechanisms involved. This review may serve as an important reference for future discovery and developments of anti-MRSA agents from endophytic fungi.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.5
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• pp.626-633
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• 2023

Vibrio spp. are aquatic bacteria that are ubiquitous in warm estuarine and marine environments. Especially, V. vulnificus and V. cholerae are currently known to cause potentially fatal infections in humans. This study investigated the distribution and antibiotic resistance of V. vulnificus and V. cholerae isolated from coastal areas of Gyeongsangnam-do in 2022. A total of 252 samples of water, shellfish and coastal sediment were collected from 7 locations along the coast, and 124 samples of fishery products were collected from markets. Among the 252 samples, forty-four V. vulnificus (11.7%) and fourteen V. cholerae non-O1/non-O139 (3.7%), none of which carried the ctx gene, were isolated. Out of the 124 samples, 6 (4.8%) tested positive for V. vulnificus and V. cholerae was not detected. The isolation rates of V. vulnificus and V. cholerae showed a significant correlation with environmental factors such as seawater temperature and salinity. In an antibiotic resistance test, V. vulnificus was susceptible to amikacin, gentamicin, imipenem trimethoprim/sulfamethoxazole, and ciprofloxacin, but resistant to cefoxitin (100.0%), followed by tetracycline (9.1%). Multidrug resistance was also observed. Continuous monitoring of Vibrio pathogens with water temperature and salinity is expected to help reduce the outbreaks, and rational use of antibiotic agents is needed to prevent the accession of antibiotic-resistant microorganisms in aquatic ecosystems.

• Journal of Physiology & Pathology in Korean Medicine
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• v.26 no.6
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• pp.886-893
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• 2012

Methicillin-Resistant Staphylococcus aureus (MRSA) is a cephalosporin and beta-lactam antibiotic-resistant strain. In most cases, MRSA is spread from infected patients and infection rates are growing increasingly. Furthermore, increased resistance to antibiotics is causing serious problems in the world. Staphylococcus aureus is responsible for both nosocomial and community-based infections that range from relatively minor skin and soft tissue infections to life-threatening systemic infections. Therefore, there is a need to develop alternative antimicrobial drugs for the treatment of infectious diseases. In this study, we investigated antimicrobial activity of oriental medicine prescription against MRSA. The minimum inhibitory concentration (MIC) of Sohamhyung-tang water extract against S. aureus strains ranged from 500 to 2,000 ${\mu}g/mL$, so we have it confirmed that a strong antibacterial effect. Also, the combinations of Sohamhyung-tang water extract and conventional antibiotics exhibited improved inhibition of MRSA with synergy effect. We suggest that Sohamhyung-tang water extract against MRSA have antibacterial activity, it has potential as alternatives to antibiotic agent. We suggest that the Sohamhyung-tang water extract lead the treatment of bacterial infection to solve the resistance and remaining side-effect problems that are the major weak points of traditional antibiotics.