• Korean Journal of Microbiology
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• v.46 no.4
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• pp.341-345
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• 2010

The prevalence and antimicrobial susceptibilities of Staphylococcal isolates from bovine milk samples were assessed. From January 2009 to October 2009, a total 287 bovine milk samples were randomly collected from 15 stock raising farms located in northern area of Kyunggi province and cultured for the presence of Staphylococci spp. A total 79 staphylococcal isolates were recovered from the milk samples. The predominant isolates were S. aureus (43.03%) and S. chromogenes (24.05%). Antimicrobial resistance patterns of 79 Staphylococcal isolates against ampicillin, chloramphenicol, ciprofloxacin, erythromycin, gentamicin, oxacillin, teicoplanin, tetracyclin, and vancomycin were tested. Staphylococcal isolates revealed the highest resistance to ampicillin (56.96%) and oxacillin (39.23%). Of 31 oxacillin resistance strains, 8 strains carry mecA gene which is responsible for methicillin resistance.

• YAKHAK HOEJI
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• v.52 no.6
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• pp.434-440
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• 2008

The purpose of this research was to investigate the microbiological quality and antimicrobial susceptibilities of the ready-to-eat side dishes, which are were collected from the grocery stores, big markets, and department stores in Seoul throughout November, 2007. Of total 124 samples, presence of staphylococci and enteric bacilli was observed in 38 samples (31%) and 53 samples (43%), respectively. And 30 samples (24%) were shown to be of unsatisfactory quality for total bacterial count (>$10^5$). Antimicrobial susceptibilities of the staphylococci isolated from the side dishes were tested for six different antimicrobial agents, which are in widespread clinical use in Korea, as well as four new antimicrobials, daptomycin, linezolid, quinupristin/dalfopristin and tigecycline. As a result, the staphylococcal isolates were found to be resistant to oxacillin (${MIC}_{90}$, >128 ${\mu}g$/ml), teicoplanin (${MIC}_{90}$, >128 ${\mu}g$/ml), mupirocin (${MIC}_{90}$, >128 ${\mu}g$/ml), linezolid (${MIC}_{90}$, 128 ${\mu}g$/ ml) and quinupristin/dalfopristin (${MIC}_{90}$, 32 ${\mu}g$/ml). Especially, some of the staphylococcal isolates exhibited high level and multi-drug resistance. Moreover, these bacteria were also resistant to new antimicrobials, except tigecycline.

• Journal of Microbiology
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• v.38 no.4
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• pp.265-269
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• 2000

Iron increased the susceptibilities of clinical isolates Pseudomonas aeruginosa to quinolones. In the presence of iron, increased susceptibilities to ofloxacin were observed in twenty-six out of thirty isolates and with no change in four isolates. In the case of norfloxacin, iran increased susceptibilities of twelve isolates but did not render any change in eighteen isolates. In the case of ciprofloxacin, iron decreased the MICs (Minimal Inhibitory Concentration) of twenty isolates, increased the MIC of one isolate, and did net change the MICs of nine isolates. To find out how iron increased susceptibility to ofloxacin, bacterial cells were grown in Muller Hinton (MH) media and succinate minimal media (SMM) to induce iran acquisition systems and the intracellular ofloxacin concentrations were assayed in the presence of iron. The addition of iron to the media decreased the MICs of cells whether they were grown in MH or SMM. Siderophores, carbonyl cyanide m-chlorophenylhydrazone (an inhibiter of proton motive force), and ouabain (an inhibitor of ATPase) did not decrease the effect of iron. Results suggested that the increase in the intracellular ofloxacin concentration by iron is accomplished not by decreasing the efflux but by increasing the of ofloxacin permeability.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.5
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• pp.659-664
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• 2010

The present study was to investigate the effect of the transition from conventional to organic dairy farming on the antimicrobial resistant pattern of pathogens in milk. A farm with tie-stall management, with an average herd size of 20 milking cows, was selected based on the owner' willingness to accept, for at least 6 months, the highly restricted protocol developed in this study. Comparisons of bacterial isolates and antimicrobial susceptibilities before changing to an organic farm system (BEFORE) and for 6 months after (AFTER) operating the experimental organic farm system were performed by Fisher's Exact Chi-square tests. Significant levels were defined at p<0.05. During the AFTER period, average frequency of antibiotic treatment was decreased from more than 3 cases/month to less than 1 case/month during which the antibiotic use was authorized only by the veterinarian. In total, 92 and 70 quarter milk samples from 24 and 18 cows during BEFORE and AFTER, respectively, were included in the study. Overall, isolates ranged from a non-resistant level for cephazolin to a very high resistant level to streptomycin (64.71% to 95.45%). Percentages of antimicrobial resistant isolates during BEFORE were significantly higher than during AFTER for ampicillin (43.48% and 5.88%, respectively) and streptomycin (95.45% and 64.71%, respectively). In conclusion, percentages of antimicrobial resistant isolates were decreased after 6 months of operating as an organic farm system.

• The Journal of the Korean Society for Microbiology
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• v.13 no.1
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• pp.63-73
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• 1978

28 strains of Enterococci isolated at doctorless areas in Korea from Oct. 1976 through Mar. 1977 and 30 strains of Enterococci isolated at Seoul National University Hospital from Sep. 1976 through Dec. 1976 were examined for susceptibilities to 14 antimicrobial agents by agar dilution method. The susceptibilities of two groups to each antimicrobial agent were compared and incidence of resistant strains in each antimicrobial agent, incidence of multiply resistant strains and correlations in the antimicrobial susceptibility of 58 strains of Enterococci among 14 antimicrobial agents were analyzed. 1. With Tetracycline, Oxytetracline, Doxycycline, Minocycline and Erythromycin, the mean MIC's of Enterococci isolated at Seoul National University Hospital were 1.9-2.5 times higher than those of Enterococci isolated at doctorless areas, though there were no statistical significance. 2. Frequency of resistant strains in Enterococci isolated at Seoul National University Hospital was the highest with Cephalexin(100%), Gentamicin(100%), and Streptomycin(100%), followed by Kanamycin(93.3%), Carbenicillin(90%), Tetracycline(26.7%), Oxytetracycline(26.7%), Doxycycline(26.7%), Minocycline(20%), Erythromycin(10%), Troleandomycin(10%), Penicillin(6.7%), Cotrimoxazole(6.7%) and Ampicillin(0%). 3. Frequency of resistant strains in Enterococci isolated at doctorless areas was the highest with Kanamycin(100%) and Streptomycin(100%), followed by Cephalexin(96.4%), Gentamicin(96.4%), Carbenicillin(92.9%), Tetracycline(10.7%), Oxytetracycline(10.7%), Doxycycline(10.7%), Minocycline(10.7%), Cotrimoxazole(10.7%), Penicillin(3.6%), Ampicillin(0%), Erythromycin(0%), and Troeandomycin(0%). 4. In study with Penicillin, Ampicillin, Tetracycline, Cotrimoxazole, Erythromycin and Troleandomycin, there were no multiply resistant strains in Enterococci isolated at doctorless areas, while 4 strains of Enterococci isolated at Seoul National University Hospital showed multiple resistance. 5. There were high correlation in susceptibility of 58 strains of Enterococci among Tetracycline, Oxytetracycline, Doxycycline and Minocycline(correlation coefficients 0.86-0.97). Correlation coefficients of susceptibility among penicillin analogues(Penicillin, Ampicillin, Carbenicillin and Cephalexin) ranged between 0.75-0.89. Correlation coefficients of susceptibility among aminoglycosides(Kanamycin, Gentamicin and Streptomycin) ranged between 0.09-0.51.

• Journal of Veterinary Clinics
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• v.21 no.1
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• pp.7-14
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• 2004

Bacteria that are resistant to several different groups of antibiotics have increased during the past few years. The importance of surveillance of antimicrobial resistance is now widely recognized. Unfortunately, this development has not been documented continuously in veterinary medicine in Korea. Therefore, the clinical prevalence and trend of antimicrobial susceptibility of aerobic isolates were investigated in this study. Total 121 isolates of aerobic bacteria were isolated from clinical specimens of dogs and cats at Veterinary Medical Teaching Hospital of Seoul National University from May 2001 to October 2002. Among them, the most common isolated species was Staphylococcus spp. (48 isolates), followed by E.coli (26 isolates), Enterococcus spp. (21 isolates), Klebsiella pneumoniae (9 isolates), Streptococcus spp. (6 isolates), Enterobacter cloacae (3 isolates), Pseudomonas aeruginosa (3 isolates), Corynebacterium xerosis (2 isolates), Chryseomonas spp. (2 isolates), and Providencia stuartii (1 isolate). The susceptibility of isolates to antibiotics was determined by the disk diffusion method. Gram-positive bacterial isolates were showed high susceptibilities to amikacin, amoxacillin/clavulanate, ceftazidime, and oxacillin, while Gram-negative bacterial isolates were showed high susceptibilities to amikacin and ceftazidime. Staphylococcus spp. were showed high susceptibilities to amikacin, amoxicillin/clavulanate, ceftazidime, cephalothin, and oxacillin. Streptococcus spp. and E.coli were showed high susceptibilities to amikacin and ceftazidime. Of the 48 staphylococci, seven Methicillin Resistant staphylococci were observed (14.6%), distributed among S. auricularis (1), S. hemolyticus (2), S. sciuri (1), S. saprophyticus (1), S. warneri (2) isolates. One strain of E.coli and one strain of Corynebacterium xerosis were resistant to all antibiotics tested. And, resistance trends between the you 2000 (from July 1999 to September 2000) and 2002 (from May 2001 to October 2002) were compared. Resistance to antibiotics was increased in both Gram-positive and Gram-negative bacterial isolates (p＜ 0.05). The resistance rates of Staphylococcus spp., E.coli and Klebsiella pneumoniae to all antibiotics tested were also increased (p＜0.05). This study investigated increasing resistance between the year 2000 and 2002 in Veterinary Medical Teaching Hospital of Seoul National University. Surveillance resistance is helpful to alert to veterinarian and select of appropriate therapy. Antimicrobial susceptibility surveillance of isolates should urgently be continued in veterinary medicine.

• The Journal of the Korean dental association
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• v.52 no.7
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• pp.425-431
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• 2014

Objectives : The purpose of our study was to evaluate penicillin as a still drug of choice for severe endodontic infection, by analyzing the antimicrobial susceptibilities from endodontic infections with swelling to figure out appropriate antibiotics as empirical treatment. Materials and methods : This study involved 18 patients who attended for emergency treatment because of facial or periapical swelling associated with root canal infections. Identification and antimicrobial susceptibility test of each pathogen were performed by Vitek2 Systems (bioM$\acute{e}$rieux, Marcy l'Etoile, France). Results : The most frequent bacteria was Streptococcus spp.(77%), and the resistance against penicillin was 35% in overall patients, followed by clindamycin and erythromycin (17%), which was much higher than previous studies. Conclusions : In our study, the higher resistance made penicillin alone not to be chosen as the first antibiotic drug for severe endodontic infections. Combinations with other drug, penicillin with wider spectrum of activity, or changing to other antibiotics was considered while remembering the increased risk of resistant microorganism.

• Korean Journal of Veterinary Service
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• v.14 no.2
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• pp.121-126
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• 1991

The present study was conducted to investigate biochemical properties and antimicrobial drug susceptibilities of 36 strains of Pasteurella haemolytica(P haemolytica) isolated from pneumonic calves in Kyongbuk province during the period from January 1990 to December 1990. P haemolytica was isolated from 36 of 111(32.4%) pneumonic calves of 1 to 6 months of age. The majority of biochemical and cultural properties of P haemolytica isolated from calves were identical to those of the reference strains employed. All isolated were susceptible to baytril, gentamicin, and kanamycin, some of them were resistant to tetracycline, amikacin, streptomycin, and ampicillin.

• CELLMED
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• v.2 no.4
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• pp.37.1-37.4
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• 2012

In the present study, the volatile oil, chloroform extract and methanol extract of the woods of the plants Cedrus deodara and Pinus roxburghii were screened for their antibacterial and antifungal activities against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis, Streptococcus pyogenes, Candida albicans, Aspergillus niger, and Aspergillus clavatus using the Agar diffusion method. The susceptibilities of the microorganisms to the extracts were compared with each other and with a selected standard antibiotic. It was observed that the volatile oil and chloroform extracts showed the significant antibacterial activities while the least antibacterial activity was recorded with the methanolic extracts. The higher Minimum Inhibitory Concentration value of the extracts and oils against fungus suggested that the plants may possess less antifungal activity. Phytochemical analysis and thin-layer chromatography profiling revealed the presence of flavonoids and terpenoids in the oil and chloroform extracts, which could explain the antimicrobial activity. The findings suggest that the Cedrus deodara and Pinus roxburghii have antimicrobial properties and they can be used in the treatment of infectious diseases. However, further work is required in order to isolate the active constituents of the plants responsible for the antibacterial activity.

• Journal of Applied Biological Chemistry
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• v.61 no.3
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• pp.233-238
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• 2018

Chitinases are glycosyl hydrolases which cleave the ${\beta}$-1,4 linkage of chitin into oligo or monomers of N-acetylglucosamine. These bacterial enzymes have been used for a wide range of applications in the food and pharmaceutical industries. In this study, we isolated two potential chitinolytic strains, BAO-01 and BAO-02, from salt-fermented shrimp, which were shown to belong to the genus Salinivibrio through genetic characterization using 16S rRNA. These isolates were gram-positive, rod-shaped, and non-spore forming. BAO-01 showed greater growth and chitinase activity than BAO-02 after the incubation at $37^{\circ}C$ for 4 days. Both strains grew on a wide range of carbon and nitrogen sources, pH values, temperatures, and salt levels. However, they showed minor biochemical differences. In addition, their antimicrobial activities against foodborne pathogens and antibiotic susceptibilities were evaluated. These Salinivibrio spp. did not show bioamine production, hemolytic activity, and mucin degradation. Therefore, the in vitro screening results suggested that these bacteria could be widely used as new candidates for chitin hydrolyzation and seafood fermentation.