• Journal of Life Science
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• v.20 no.5
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• pp.649-654
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• 2010

A total of 68 samples were collected including vaginal mucosa (n=66) from Jangsu stud farm, an equine aborted fetus (n=1), and uterine contents (n=1) from Jeju island. Seventeen Streptococcus equi subsp. zooepidemicus (S. zooepidemicus) strains isolated from horses in Korea were identified as S. zooepidemicus by biochemical tests and sodA.seeI specific multiplex PCR. All isolated strains were divided into 4 clusters: group 1 (No. 2, 3, 5, 6, 7, 11, 12, 13, 14, 15), group 2 (No. 4, 9), group 3 (No. 10, 16, 17), and group 4 (No. 1, 8) by RAPD typing. In group 3, No. 10 isolate that was isolated from vaginal mucosa was indistinguishable from No. 16 and 17 isolates, which were isolated from the equine uterine contents and the equine aborted fetus, respectively. The results of this study suggest that a limited epidemiological relationship exists between the strains from Jangsu (No. 10) and Jeju (No. 16 and No. 17). All isolates showed a high susceptibility to ampicillin, cefoxitin, ceftiofur, cephalothin, florofenicol, gentamicin, nalidixic acid, oxacillin, penicillin, tiamulin, tylosin and vancomycin in antimicrobial susceptibility tests. These results may provide the basic information needed to establish strategies for the treatment and prevention of reproductive diseases in mares in Korea.

• Korean Journal of Veterinary Research
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• v.37 no.2
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• pp.389-403
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• 1997

Survey on MIC of antimicrobial drugs and its treatment efficacy in mice were conducted for the strains of Escherichia coli and Salmonella spp isolated from feces of young domestic animals with diarrhea in 1996. A total of 338 strains of E coli and 61 strains of Salmonella spp were examined for the susceptibility to 20 antibiotics and 7 synthetic antimicrobial drugs. The results indicated that the majority of strains were susceptible to amikacin(93.5%), cefoperazone/sulbactam(93.5%), cefotaxim(93.3%), cefomandole(92.8%), cefoperazone(91.6%) and ciprofloxacin(85.1%), in order. Although gentamicin, ciprofloxacin and norfloxacin showed the relatively low MIC distributions, erythromycin, doxycycline, sulfamethoxazole and oxytetracycline revealed the high MIC distributions to most of isolates. The $MIC_{90}$ of antimicrobials for E coli were > $62.5{\mu}g/ml$ in gentamicin, $2.0{\mu}g/ml$ in ciprofloxacin, $1.0{\mu}g/ml$ in norfloxacin, > $500{\mu}g/ml$ in erythromycin, $125{\mu}g/ml$ in doxycycline, > $1000{\mu}g/ml$ in sulfamethoxazole and > $250{\mu}/ml$ in oxytetracycline. In general, the MIC of E coli isolates was higher than that of Salmonella spp isolates. Although variation in synergism or additivity of antibiotic combinations were demonstrated, ampicillin-gentamicin was the most efficacious combination both against E coli and Salmonella spp with the fluctuation of 7.7-77.5%. In the experiment of treatment efficacy in mice, the highest survival ratio(83.3%) after challenge with pathogenic E coli and Salmonella typhimurium was detected in the group treated with gentamicin.

• Journal of Food Hygiene and Safety
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• v.21 no.1
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• pp.23-30
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• 2006

Antimicrobial susceptibility and multiple drug resistance patterns have been carried out on total of 364 isolates of Salmonella enterica serovar Enteritidis isolated from foodborne patients in Seoul from 2001 to 2005. Overall, the highest percentage of resistance was found to the following antimicrobial agents: streptomycin (46.7%), ampicillin (37.3%), ticarcillin (36.7%), tetracycline (36.0%), nalidixic acid (20.7%), chloramphenicol (13.3%), amoxicillin/clavulanic acid (6.7%) and Ampicillin/sulbactam (4.0%). Seventy five percentage of isolates were found to be resistant to one or more of the antimicrobes tested. The resistant rates to nalidixic acid and chloramphenicol in S. Enteritidis tested were annually increased but the resistant rate to tetracycline was decreased and the resistant rates to streptomycin, ampcilin and ticarcillin were remained steadily. The most frequent patterns of multiresistant isolates were only nalidixic acid resistant (18.0%) and streptomycin-tetracycline (18.0%), streptomycin-ampicillin-ticarcillin (10%), and ampicillin-ticarcillin (5.5%). Overall the resistant rates of 1 drug was 19.3%,2 drugs 24.7%, 3 drugs 6.7% and 4 or more drugs 24.0%. The resistant rates of 1 drug and 2 drugs in 2005 were increased dramatically.

• Korean Journal of Veterinary Service
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• v.34 no.4
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• pp.361-368
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• 2011

The growth rate of piglets will be decreased and the mortality of piglets will be increased in the postpartum sow with mastitis. The aim of this study was to isolate microorganisms from milk samples found in postpartum sows with suckling piglets and to further investigate antimicrobial susceptibility against isolated bacteria. Milk samples were collected from 567 udders of 42 lactating sows and the isolated bacteria was then identified. Isolated bacteria were tested with 12 antimicrobial agents. Bacteria were isolated from 260 milk samples (64.5%). Staphylococcus spp. were the most common microorganisms (74.5%) isolated from sow milk, followed by Streptococcus hyicus (53.9%), Staphylococcus epidermis (11.8%), Staphylococcus aureus (9.8%), and Staphylococcus haemolyticus (53.9%). In the Staphylococcus spp., Streptococcus pneumoniae (5.1%) was isolated as was Streptococcus sanguinis (3.8%) and Streptococcus ovis (2.9%). Results indicated that bacteria isolated from healthy sow milk were mostly susceptible to cephalothin (88.0%), amikacin (85.3%) and cefoxitin (82.4%), but were resistant to streptomycin (10.0%), kanamycin (33.1%) and tetracycline (19.6%).

• Korean Journal of Clinical Laboratory Science
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• v.38 no.3
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• pp.166-172
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• 2006

Metallo-${\beta}$-lactamase (MBL) can hydrolyze all ${\beta}$-lactams except monobactams and frequently coexists with various antibiotic resistance genes such as aminoglycoside resistance, sulfonamide resistance gene, etc. Therefore, the effective antibiotics against infections by these bacteria are markedly limited or can't even be found. We tried to search in-vitro antimicrobial combinations with synergistic effects for a VIM-2 type MBL producing Pseudomonas aeruginosa, isolated from clinical specimen. On the selection of antibiotic combinations with synergistic effects, we performed a one disk synergy test, modified Pestel's method, in agar without aztreonam (AZT). The bacteriostatic synergistic effects of this tests were scored as $S_1$ (by susceptibility pattern in agar without antibiotics), $S_2$ (by the change of susceptibility in agar with or without antibiotics) and $S_3$ ($S_1$ + $S_2$) and was classified into weak (1 point), moderate (2 points) and strong (3 points) by $S_3$ score. Subsequently, we carried out the time-killing curve for the antibiotic combinations with the strong synergistic bacteriostatic effect. One VIM-2 type MBL producing P. aeruginosa confirmed by the PCR showed all resistance against all ${\beta}$-lactams except AZT, aminoglycoside and ciprofloxacin. In the one disk synergy test, this isolate showed a strong bacteriostatic synergistic effect for the antibiotic combination of AZT and piperacillin-tazobactam (PIP-TZP) or AZT and amikacin (AN). On the time-killing curve after six hours of incubation, the colony forming units (CFUs/mL) of this bacteria in the medium broth with both combination antibiotics were decreased to 1/18.7, 1/17.1 of the least CFUs of each single antibiotics. The triple antibiotic combination therapy including AZT, PIP-TZP and AN was shown to be significantly synergistic after 8 hrs of exposure. In a VIM-2 MBL producing P. aeruginosa with susceptibility for AZT, the triple antibiotic combination therapy including AZT, PIP-TZP and AN may be considered as an alternative antibiotics modality against the infection by some MBL type. But the antimicrobial combination therapy for many more MBL producing isolates is essential to know as soon as possible for the selection of effective treatment against the infection by this bacteria.

• Korean Journal of Veterinary Service
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• v.32 no.1
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• pp.49-59
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• 2009

At the present study, it was aimed to explore the states of antimicrobial resistant Salmonella spp. isolates from 3,850 pigs (2,732 ileocecocolic lymphnodes and 1,118 cecal contents) and 1,764 cattle (965 cecal lymphnodes and 799 cecal contents) slaughtered in Busan province from December 2000 to November 2001. Among 5,614 samples, 457 of Salmonella spp. were isolated from pig lymphnodes (13.5%), pig cecal contents (4.4%), cattle lymphnodes (3.5%) and cattle cecal contents (0.5%). Salmonella spp. were showed different isolation ratio, that was 10.8% in summer, 9.0% in autumn, 8.4% in spring and 5.0% in winter. As a result of serotyping, B group (65.4%) were identified as the most common in pigs and cattle, in order of $C_1$ (14.0%), $D_1$ (5.5%), $C_2$ (4.2%), $E_1$ (4.2%) and L (3.5%). 34 serotypes were found, among them, Salmonella Typhimurium (S. Typhimurium) (21.0%) was the most common serotype from pigs and cattle. The major serotypes were in order of S. Derby (15.3%), S. Schwarzengrund (14.7%), S. Typhimurium var Copenhagen (9.2%), S. Mbandaka (5.7%), S. Enteritidis (5.5%) and S. Ruiru (3.5%). The most common serotype was S. Typhimurium in pigs, and S. Ruiru in cattle. S. Ruiru was firstly isolated from pigs and cattle in Korea. In antimicrobial susceptibility test, all the isolates were demonstrated susceptibility to norfloxacin and ofloxacin. But the isolates were showed resistance other antibiotics in order of doxycycline (68.3%), tetracycline (67.8%), penicillin (54.5%) and streptomycin (52.5%). S. Typhimurium were exhibited resistance to ampicillin (34.8%), chloramphenicol (36.2%), streptomycin (94.9%), sulfamethoxazole/trimethoprim (34.8%) and tetracycline (97.8%). There were 53 strains (38.4%) which had multi drug resistant (MDR) isolates, resistant to more than 6 antimicrobial agents. The most common resistance patterns of MDR isolates were ampicillin, chloramphenicol, carbenicillin, doxycycline, nalidixic acid, penicillin, streptomycin, sulfamethoxazole/trimethoprim and tetracycline (ACCbDNaPSSuT).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.41 no.6
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• pp.435-439
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• 2008

The antimicrobial resistance of 160 strains of Enterococcus faecalis and 173 strains of E. faecium to 12 antimicrobial agents was investigated. The test strains were isolated from 126 wild seawater and farmed fish, including olive flounder (Paralichthys olivaceus), black rock fish (Sebastes schlegeli), red sea bream (Pagrus major), and sea bass (Lateolabrax japonicus), in 2005 and 2006. Overall, 91.9% of the E. faecalis isolates and 88.4% of the E. faecium isolates showed antimicrobial resistance to at least one antimicrobial agent. The pattern of antimicrobial resistance of the isolates differed little according to the species of fish. The percentage of E. faecalis and E. faecium with specific antimicrobial resistance differed according to the sample source. For the isolates from farmed fish samples, 66.7% of E. faecalis were tetracycline resistant and 54.5% of E. faecium were erythromycin resistant. By contrast, in the wild fish seawater samples, 92.0% of E. faecalis were rifampin resistant and 88.5% of E. faecium were tetracycline resistant.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.1
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• pp.13-19
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• 2016

A total of 423 shellfish (Oysters, Crassostrea gigas; short-necked clams, Ruditapes philippinarum and corb shells, Cyclina sinensis) were collected from the west coast of Korea, from which 277 Escherichia coli strains were isolated. The antimicrobial susceptibility patterns of isolated strains were analyzed for 22 antimicrobial agents used in Korea for clinical or veterinary therapy. The resistance of E. coli isolates to ampicillin (37.2%) was highest, followed by cephalothin (21.7%), cefazolin (19.9%), trimethoprim (15.2%). Antimicrobial resistance was present in 56.7% of E. coli isolates against at least one antimicrobial agent. Of 277 isolates, 44 (15.9%) were resistant to multiple antimicrobial agents.

• Animal Bioscience
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• v.35 no.1
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• pp.138-146
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• 2022

Objective: The objective of the current study was to investigate the influences of conventional (CO) and deep litter (DE) systems on antimicrobial resistance in fecal Escherichia coli (E. coli). Methods: A cross-sectional study was carried out to detect antimicrobial resistance to E. coli in swine fecal samples in CO and DE systems located in western and northeastern Thailand. Individual rectal swab samples were taken only from healthy pigs. A total of 215 individual and healthy pigs were randomly selected for isolation and antimicrobial susceptibility test of E. coli by the disc diffusion method. The test panel included amoxicillin (AMX), colistin, doxycycline (DOX), enrofloxacin, gentamicin (GEN), kanamycin, neomycin (NEO), and trimethoprim-sulfamethoxazole (SXT). Results: There were significant (p<0.05) lower resistance levels for GEN, NEO, and SXT in the DE farms compared to those in the CO farms. There was a lower number of antimicrobial resistance agents (p<0.001) in the DE farms compared to those in the CO farms. This result was consistent with those in western (p<0.01) and northeastern (p<0.01) Thailand. Overall, antibiograms of AMX-SXT and AMX-DOX-SXT were found in the CO (19.09% and 20.91%, respectively) and the DE (16.19% and 24.76%, respectively) farms. No antimicrobial resistance (5.71%) was found and AMX (13.33%) resistant pigs in the DE farms, whereas the pattern of AMX-GEN-SXT (6.36%) and AMX-DOX-GEN-SXT (11.82%) resistant pigs was found in the CO farms. Conclusion: The DE system for pig farming was superior to conventional pig farming by lowering the resistance level of fecal E. coli to GEN, NEO, and SXT, with decreasing the number of antimicrobial resistance agents and inducing a small proportion of pigs to be free from antimicrobial resistance.

• Journal of Microbiology and Biotechnology
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• v.33 no.4
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• pp.500-510
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• 2023

In this study, lactic acid bacteria were isolated from 21 top-selling probiotic products on Korean market and their antimicrobial resistance were analyzed. A total 152 strains were claimed to be contained in these products and 70 isolates belonging to three genera (Bifidobacterium, Lactobacillus, and Lactococcus) were obtained from these products. RAPD-PCR showed diversity among isolates of the same species except for two isolates of Lacticaibacillus rhamnosus from two different products. The agar dilution method and the broth dilution method produced different MICs for several antimicrobials. With the agar dilution method, five isolates (three isolates of Bifidobacterium animalis subsp. lactis, one isolate of B. breve, one isolate of B. longum) were susceptible to all nine antimicrobials and 15 isolates were multi-drug resistant. With the broth microdilution method, only two isolates (one isolate of B. breve and one isolate of B. longum) were susceptible while 16 isolates were multi-drug resistant. In this study, only two AMR genes were detected: 1) lnu(A) in one isolate of clindamycin-susceptible and lincomycin-resistant Limosilactobacillus reuteri; and 2) tet(W) in one tetracycline-susceptible isolate of B. longum B1-1 and two tetracycline-susceptible isolates and three tetracycline resistant isolates of B. animalis subsp. lactis. Transfer of these two genes via conjugation with a filter mating technique was not observed. These results suggest a need to monitor antimicrobial resistance in newly registered probiotics as well as probiotics with a long history of use.