• Korean Journal of Veterinary Service
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• v.21 no.4
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• pp.451-465
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• 1998

The present study was carried out to investigate the prevalence of brucellosis in Kyungbuk area for the 3 years from 1966 to 1998. Collective milk samples were routinely screened to detect positive farms by using the milk ring test(MRT), and serum agglutination test was performed to detect sero-positive individuals in the MRT positive farms. Attempt were made to isolate the causative organismas from slaughtered sero-positive reactors and some biochemical and polymerase chain reation characters of the isolates were also made to identify the organisms. Seroprevalence to brucellosis in peoples who are close contact with infected dairy herds was also investigated. Brucellosis of dairy cattle was rare before 1997, but has been broken more frequently since early 1998. By the MRT for dairy herds, positive rate was gradually increased every year : 0.6% in 1996, 1.5% in 1997, 3.9% in 1998. Among 262 MRT-positive herds, only 21 herds(8.0%) showed positive brucellosis in serological test. The isolation rates of Brucella sp from tested materials were 51.2% in supramammary glands, 39.5% in milks, and 50.0% in pulmonary Iymphnode, respectively. Isolated strain and biotype were Brucella(B) arbortus biotype 1 in 26 heads, and were B suis biotype 1 in 2 heads. Isolated strain and vaccine strain were very similar in their colony morphology and staining. In drug susceptibility, isolated stains(B abortus) and vaccine strain(B abortus RB-51) were sensitive to ampicillin, gentamycin, kanamycin, neomycin, penicillin, streptomycin, and to tetracycline, but resistant to erythromycin. In the PCR, field strains reacted to BA and IS711 primers, and vaccine strain reacted to BA, IS711, and RB5l primers. In the plate agglutination test of 96 sera of human contacted with animals, serum antibody titer detected 1 : 100 in one person, 1 : 200 in one, and below 1 : 25 in the others.

• YAKHAK HOEJI
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• v.41 no.1
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• pp.132-138
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• 1997

The antimicrobial activity of Manuka oil, a steam distillate from Leptospermum scoparium, was investigated, and it's MIC against ten kinds of microorganisms was determin ed. MICs against bacteria and fungi were measured by means of both two-fold dliution method and agar plate two-fold dilution method, respectively. MICs of Manuka oil against Staphylococcus aureus KCTC 1916 and Micrococcus luteus KCTC 1915, gram-positive microrganisms, were identical as 3.05 ${\mu}$g/ml, while it's antibacterial activity against gram-negative microrganisms such as Pseudomonas aeruginosa KCTC 2513, Escherichia coli KCFC 1682, Klebsiella pneunioniae KCTC 2001 or Proteus vulgaris KCTC 2433 was negligible(MIC: ${\geq}$ 1000 ${\mu}$g/ml), suggesting a high susceptibility of gram-positive bacteria to Manuka oil. In addition, MIC against Aspergillus niger KCTC 6077 was 24 ${\mu}$g/ml. and that against the other fungi, Tricophyton mentagrophytes KCTC 1374 and Candida albicans KCTC 1940 was ${\geq}$ 1000 ${\mu}$g/ml. When Manuka oil ointment was used in combination with other drugs. i.e.. gentamycin sulfate, chlotrimazol and hydrocortisone acetate, and diphenhydramine HCl and hydrocortisone acetate. it's antibacterial activity against Staphylococcus aureus KCTC 1916 was higher than Manuka oil ointment or other drugs alone. In conclusion, Manuka oil possesses a selective antibacterial activity against Staphylococcus aureus KCTC 1916, and can be used as a potent antibacterial agent against it.

• Journal of Veterinary Clinics
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• v.25 no.5
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• pp.346-354
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• 2008

The combined effects of EDTA-Tris and eighteen antimicrobial agents have been evaluated in eight clinically isolated methicillin-resistant bacteria (Staphylococcus aureus, Escherichia coli, Streptococcus uberis and Streptococcus agalactiae) from bovine mastitis. The antimicrobial activity was evaluated by measuring the minimal bactericidal concentration (MBC) for the antibiotics alone or in combination with EDTA-Tris in Mueller-Hilton broth and milk. Combined use of EDTA-Tris and antibiotics potentiated or antagonized activity of antibiotics against mastitic pathogens. Milk increased the antibiotic potency of erythromycin and spiramycin on S. aureus. Culture in milk changed patterns of EDTA-Tris combinational effects compared with that in standard Mueller-Hilton broth. Combined with EDTA-Tris in milk, synergic effects were observed in colistin, dihydrostreptomycin, kanamycin, erythromycin, gentamycin, oxytetracycline, streptomycin to E. coli, Str. uberis, and Str. agalactiae. However, significant antagonistic effects of milk on antibiotic susceptibility in combination with EDTA-Tris were noted in neomycin, streptomycin, penicillin, roxithromycin, and amoxicillin. This study indicates that combination therapy of EDTA-Tris with antibiotics in bovine mastitis should be used with caution because of the possible antagonistic effects of antibiotic combination with EDTA-Tris on mastitic pathogens. In addition, antibiotic susceptibility test in combination with EDTA-Tris in milk culture condition can be benefit in search of effective treatment regimen for some antibiotic-resistant bacteria of mastitis.

• Korean Journal of Veterinary Service
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• v.33 no.1
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• pp.59-66
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• 2010

This study was carried out to investigate the characters of Listeria monocytogenes isolated from food, animal feces, dry cattle food, and the environment in Seoul and Kyonggi province during the period from 1998 to 2003. Serotyping of 70 L. monocytogenes isolates was performed according to the manufacturer's instruction. Minimum inhibitory concentrations (MICs) were determined by the microdilution method according to the guidelines of the Clinical and Laboratory Standards Institute. All the isolates were tested against 20 antimicrobial agents. The serotypes of the 70 L. monocytogenes isolates were 1/2c (62.8%), 1/2a (20%) and 1/2b (17.2%). Of the 70 L. monocytogenes isolates, 67.1%, 57.1%, 11.4%, 5.7%, 2.8%, 1.4% and 1.4% were resistant to tetracycline (Te), minocycline (Mi), norfloxacin (Nor), ciprofloxacin (Cip), neomycin (N), chloramphenicol (C) and cephalothin (Cf), respectively. However, all isolates were 100% sensitive to antibiotics such as amikacin, ampicillin, erythromycin, gentamycin, imipenem, kanamycin, ofloxcin, streptomycin, penicillin, trimethoprim, trimethoprim/sulfamethoxazole, tobramycin, and vancomycin. Multiple resistance patterns of the isolates were observed in TeMiNor Cip (1.4%), TeMiNor (7.1%), TeMiCip (2.9%), TeMiN (1.4%) and TeMi (44.3%). The results of this study indicate that many L. monocytogenes isolates are resistant to antimicrobial agents including Te and Mi. The possibility that the isolates could increasingly acquire multiple antimicrobial resistant properties cannot be precluded.

• Korean Journal of Veterinary Research
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• v.40 no.2
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• pp.325-332
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• 2000

The growth characteristics and the cellular protein patterns of the Lactobacillus plantarum isolated and identified from oat silage were examined in order to confirm whether it will be used practically as probiotics or not. L plantarum was identified by morphological and biochemical tests including of final conforming by API 50CHL kit. The cultivation in MRS broth of the strain under the condition of different temperature, proved that they grew into $2.0{\times}10^{9}$ in $25^{\circ}C$, into $1.4{\times}10^{9}$ in $35^{\circ}C$ but they decreased into $4.5{\times}10^{5}$ growth in $45^{\circ}C$. The comparison of the growth by measurement of O.D600nm value after 24 hour cultivation between L plantarum and commercial probiotics, showed that the strain had a higher growth than commercial as 1.841 : 1.623. The measurement of it under bile acid's existence, indicated that this isolation was not influenced by bile acid and the tolerance was $3.2{\times}10^{9}$, $3.9{\times}10^{9}$ and $3.2{\times}10^{9}$, respectively, when each of 0%, 1%, and 2% oxigall existed. The examination of their antibiotics susceptibility by disk diffusion test, proved that L plantarum showed resistance against danofloxacin(5mcg), gentamycin(10mcg), kanamycin(30mcg), neomycin(30mcg) and streptomycin(10mcg). Based upon the test of the bacteriocin formation of this L plantarum, it was found out that the inhibition zone was not formed. In growth of L plantarum and E coli in nutrient broth, all E coli died out within 6 hours after cultures.

• Korean Journal of Veterinary Research
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• v.39 no.3
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• pp.560-565
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• 1999

The present work was conducted to investigate the drug susceptibility of microorganisms isolated from canine external ear canals. Antifungal susceptibility test of M pachydermatis (17 strains) was perfomed by agar dilution method, using 11 antifungal drugs including amphotericin B(A), nystatin(N), pimaricin(P), griseofulvin(G), bifonazole(B), clotrimazole(C), miconazole(M), econazole(E), ketoconazole(K), tolnaftate(T), 5-fluorocytosine(F). All isolates were highly sensitive to K, M, T(geometric mean MIC ; GM $MIC{\leq}0.16{\mu}g/ml$) but they weren't sensitive to P, F and G(GM $MIC{\geq}92.37{\mu}g/ml{\sim}{\geq}128{\mu}g/ml$). Antibacterial susceptibility test against 119 isolates of bacteria was performed by agar dilution method, using 9 antibacterial drugs including erythromycin(ET), chloramphenicol(CP), gentamycin(G), vancomycin(V), ampicillin(AP), amoxacillin(AX), chlortetracycline(CT), ciprofloxacin(CF), enrofloxacin(EF). All isolates of Staphylococcus spp(101 strains) were highly sensitive to EF, CF, G(GM MIC $0.33{\sim}1.47{\mu}g/ml$). In other gram positive cocci(4 strains), they were highly sensitive to EF, CF, V(GM MIC $1{\sim}4.76{\mu}g/ml$) and CT(GM MIC 1 UFL unit/ml). In gram positive rods(13 strains), they were highly sensitive to EF, CF, G(GM $MIC{\leq}0.19{\sim}1{\mu}g/ml$). In Pseudomonas aeruginosa(1 strain), it was highly sensitive to AX, EF, ET, CF(GM MIC $0.06{\sim}1{\mu}g/ml$) and CT(GM MIC 1 UFL unit/ml). All isolates weren't sensitive to AP(GM MIC 16~>$32{\mu}g/ml$).

• Molecules and Cells
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• v.37 no.6
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• pp.480-486
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• 2014

Growth restriction by antibiotics is a common feature that pathogenic bacteria must overcome for survival. The struggle of bacteria to escape from growth restriction eventually results in development of antibiotic-resistance through the expression of a set of genes. Here we found that some physiologically important transcriptional regulators of Pseudomonas aeruginosa including QscR, a quorum sensing (QS) receptor, SoxR, a superoxide sensor-regulator, and AntR, a regulator of anthranilate-related secondary metabolism, are activated by various growth-restricted conditions. We generated the growth-restricted conditions by various methods, such as overexpression of PA2537 and treatment with antibiotics or disinfectants. The overexpression of PA2537, encoding an acyltransferase homologue, tightly restricted the growth of P. aeruginosa and significantly activated QscR during the growth restriction. Similarly, treatments with gentamycin, tetracycline, and ethanol also activated QscR near their minimal inhibitory concentrations (MICs). Some non-QS regulators, such as AntR and SoxR, were also activated near the MICs in the same conditions. However, LasR and PqsR, other QS receptors of P. aeruginosa, were not activated, suggesting that only a specific set of transcriptional regulators is activated by growth restriction. Since paraquat, a superoxide generator, significantly activated QscR and AntR, we suggest that the oxidative stress generated by growth restriction may be partly involved in this phenomenon.

• Journal of Pharmaceutical Investigation
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• v.30 no.3
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• pp.151-158
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• 2000

Gel and cream containing 5% and 10% ketonic fraction (KF) of Leptospermum scoparium, respectively were formulated. Antimicrobial activity, stability, anti-inflammatory effect, rheological properties, drug release and acute toxicity for these topical efficacy were evaluated. Gel and cream containing neomycin or gentamycin in combination with KF has potent antimicrobial activity. Gel and cream were physically stable and did not show any creaming for 6 months storage. Gel showed plastic flow with yield value and cream showed pseudoplastic flow with hysteresis loop. The gel and cream containing KF showed higher viscosity than control or commercial one. The viscosity increased as the concentration of KF increased. Both 10% gel and cream showed a significant decrease in swelling when applied to the carrageenan- injected paw, suggesting local antiinflammatory activity. Particularly, 10% gel preparation showed similar antiinflammatory activity when compared with commercially available drugs. Percent of drug released and diffusion coefficient were in the order of 5% gel, 10% gel, 5% cream, and 10% cream, respectively. There were no significant changes of body weight in rats percutaneously administered with 10% cream and gel when compared with control. There were no induced acute toxicity when 10% cream or gel was applied to rats. Leptospermum scoparium could be practicaly used in topical preparations.

• YAKHAK HOEJI
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• v.43 no.6
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• pp.716-728
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• 1999

Whole oil and ketonic fraction (KF) of Leptospermum scoparium have been tested for their antimicrobial activity and combination effect with several antibiotics against various bacterial strains and fungi by using microbiological assay methods. Antibacterial activities of KF against a number of test strains were 2-3 fold stronger than those of whole oil. MICs of the KF were $65~125{\;}{\mu\textrm{g}}/ml$ against seven gram positive bacterial strains, $65~250{\;}{\mu\textrm{g}}/ml$ against 19 methicillin resistance Staphylococcus aureus strains, and $65~50{\;}{\mu\textrm{g}}/ml$ against 14 quinolone resistance strains. However, KF showed little or no activity against gram negative bacteria. MICs of the KF were $16~250{\;}{\mu\textrm{g}}/ml$ against more than 50% of the anaerobic bacterial strains tested. KF showed the higher antibacterial activity than bacitracin against 10 strains of Bacteroids thetaiotaomicron, or three strains of Bacteroides ovatus, and the more active than ciprofloxacin against one strain of Bacteroides thetaiotaomicron and three strains of Bacteroids ovatus. The MICs of KF was 63 and $250{\;}{\mu\textrm{g}}/ml$ against Aspergillus niger and Candida albicans, respectively. Antibacterial activities of KF in combination with 19 antibiotics against 14 strains and with four antifungal agents against one fungal strain were determined by paper strip diffusion method. While most of combination showed additivity, KF showed synergism with bacitracin, exfadroxil, cephradin, and meropenem for 29~57% of the strains tested. However, ofloxacin, enoxacin, sparfloxacin showed antagonism with KF for 43~71% of the strains. KF alone and in combination with bacitracin, gentamycin, neomycin, itraconazole, fluconazole, terfinafine and ketoconazole against five bacterial strains or one fungus strain synergistic effect was demonstrated against 33% of strains examined with FIC index value below 0.5 by checkerboard study. Synergistic effect of KF with gentamicin against Staphylococcus epidermidis 329 (QRS) was found by time-kill study.

• Korean Journal of Microbiology
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• v.9 no.2
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• pp.86-93
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• 1971

Escherichiae-like organisms were isolated from rectal specimens of 56 children who were either in preschool age or in elementary school. The isolated strains were subjected to tests to screen enteropathogens producing heat-labile enterotoxin and susceptibility test to various antibiotics by disc diffusion method on agar plates. Production of heat-labile enterotoxin by the strains was assyed in the sensitive and reproducible cultured adrenal tumor cell system. The assay was sterodogenesis of the cell in the presence of heat-labile enterotoxin. Among 56 strains, gave positive reaction in the test of toxin production. This meant that about 10% of the children population objected to the study harbored the toxigenic strain of enteropathogenes. Some of these toxigenic strains were resistant to the antibiotics employed in the test. This study suggested that considerable population in Korea may harbor entertoxigenic E. coli as a part of intestinal normal flora. The toxigenic strains which are resistant to antibiotics may bring issue of public health in the future.