• Journal of Veterinary Clinics
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• v.20 no.3
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• pp.302-307
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• 2003

Although, in human medicine, strains of methicillin-resistant staphylococi have become the most important causative agents of nosocomial infections, studies on the small animals are very. limited. The aim of this study was to determine mecA gene and susceptibility to antibiotics of staphylococci strains isolated from clinically ill or healthy dogs and cats, during the period August 2002-July 2003. A total of 136 staphylococci (87 coagulase-positive and 49 coagulase-negative) were investigated for antibiotic resistance, using disk diffusion and minimum inhibitory concentration (MIC) test. The mecA gene was detected using the polymerase chain reaction. The isolates belonged to the species S. aureus (53 isolates), S. intermedius (34 isolates), S. epidermidis (26 isolates) and other coagulase-negative staphylococci (CNS, 23 isolates). Of the 136 isolates, 43 (31.6%) were mecA-positive and the frequency of the ,presence of mecA gene varied among the different species. All S. aureus strains were mecA-negative and were found to be susceptible, with an oxacillin MIC $\leq$1 $\mu\textrm{g}$/ml. Five (13.6%) isolates of 36 that exhibited oxacillin resistance on the MIC testing were found to be mecA-negative, suggesting not all mecA-positive strains may be an oxacillin resistant. However, the mecA presence of the strains was correlated with high oxacillin resistance: 71.4% (10 isolates of 14; P < 0.001) for mecA-positive S. intermedius and 72.4% (21 isolates of 29; P < 0.001) for mecA-positive CNS isolates. About 69% (94 isolates of 136) showed resistance to at least one drug, and 22.8% (31 isolates) were resistant to four or more different drug classes. Resistance (36 isolates, 71.7%) to penicillin G was a common finidng. This study suggest that the mecA-positive staphylococci are prevalent in small animals, and selection of antibiotics to treat infections caused by mecA-positive staphylococci may be very limited because of multi-drug resistance.

• Archives of Pharmacal Research
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• v.19 no.1
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• pp.52-59
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• 1996

The in vitro activity of LB20304 was evaluated against clinical isolates and compared with those of Q-35, ciprofloxacin, sparfloxacin, lomefloxacin and ofloxacin. LB20304 demonstrated 16-to 64-fold more potent activity than ciprofloxacin against gram-positive bacteria. LB20304 inhibited 90% of the isolates of methicillin-susceptible Staphylococcus aureus(MSSA) at a concentration of $0.016\mug/ml\; (MIC_{90}). MIC_{90}$ values of LB20304 against methicillin-resistant Staphylococcus aureus (MRSA), methicillin-susceptible Staphylococcus epidermidis (MSSE), methicillin-resistant S. epidermidis (MRSE) and Streptococcus pneumoniae were $2\mug/ml,\; 0.016\mug/ml,\; 0.5\mug/ml \;and\; 0.031\mug/ml,$ respectively. LB20304 was also very active against gram-negative bacteria. Against Escherichia coli, Klebsiella pneumoniae, Serratia marcescens, Pseudomonas aeruginosa and Acinetobacter calcoaceticus, $MIC_{90}s of\; LB20304 were\; 0.031\mug/ml,\; 0.25\mug/ml,\; 2\mug/ml,\; 8\mug/ml\; and\; 0.5\mug/ml$, respectively. Its activity was comparable to that of ciprofloxacin but much better than those of Q-35, sparfloxacin, ofloxacin and lomefloxacin. LB20304 also exhibited the most potent acitvity among quinolones tested against laboratory standard strains, ofloxacin-resistant strains, .betha.-lactamase-producing strains and anaerobic strains. The inhibitory effect$ (IC_{50)$ of LB20304 on DNA gyrase from Micrococcus luteus, determined by the supercoiling assay, was 8-fold more potent than that of ciprofloxacin. LB20304 did not induce topoisomerase-associated DNA cleavage even at a concentration of 10 mg/ml, although ciprofloxacin induced DNA cleavage at a concentration of 1 mg/ml.

• Journal of Microbiology and Biotechnology
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• v.11 no.5
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• pp.788-797
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• 2001

The usefulness of three PCR methods were evaluated for the epidemiological typing of Staphylococcus aureus: an enterobacterial repetitive intergenic consensus sequence PCR (ERIC-PCR), repetitive extragenic palindromic element PCR (REP-PCR), and 16S-23S intergenic spacer PCR (ITS-PCR). The analysis was performed using a collection of S. aureus strains comprised of 6 reference and 79 isolates from patients with various diseases. Among the 85 S. aureus strains tested, 6 references and 6 isolates were found to be susceptible to methicillin, whereas the remaining 73 isolates were resistant to it. PCR methods are of special concern, as conventional phenotypic methods are unable to clearly distinguish among methicillin-resistant S. aureus (MRSA) strains. The ability of the techniques to detect different unrelated types was found to be as follows: ERIC-PCR, 19 types; REP-PCR, 36 types; and ITS-PCR, 14 types. On the basis of combining the ERIC, REP, and ITS fingerprints, the 85 S. aureus strains were grouped into 56 genetic types (designated G1 to G56). The diversities for the 85 S. aureus strains, calculated according to Simpson\`s index, were 0.88 for an ERIC-PCR, 0.93 for a REP-PCR, and 0.48 for an ITS-PCR, and the diversity increased up to 0.97 when an ERIC-PCR and REP-PCR were combined. The above discrimination indices imply that the genetic heterogeneity of S. aureus strains is high. Accordingly, this study demonstrates that DNA sequences from highly conserved repeats of a genome, particularly a combination of ERIC sequences and REP elements, are a convenient and accurate tool for the subspecies-specific discrimination and epidemiologic tracking of S. aureus.

• Korean Journal of Veterinary Research
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• v.51 no.4
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• pp.267-275
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• 2011

Methicillin-resistant Staphylococcus (S.) aureus (MRSA) is one of the most important nosocomial pathogens worldwide and the emergence of this strain has become a major clinical problem. In this study, we investigated the prevalence of MRSA and their genetic characteristics in 69 S. aureus isolated from humans and animals. In human isolates, higher antimicrobial resistance rates were observed against penicillin (80.6%), followed by erythromycin (11.9%) and tetracycline (9.0%). All of them were susceptible to clindamycin, enrofloxacin, novobiocin, pirlimycin, trimethoprim/sulfamethoxazole and vancomycin. The resistance patterns in animal isolates were similar to those of human isolates. Two (2.9%) MRSA strains were isolated from human (n = 1) and animal (n = 1), and these isolates were confirmed as carrying the mecA gene. One isolate originating from human was resistant to 7 drugs and the other isolate derived from animal was resistant to 11 drugs. Staphylococcal cassette chromosome mec (SCCmec) variant IIIB was identified in animal isolate but SCCmec type of an isolate from human was not exactly determined. Two MRSA isolates showed unrelated PFGE pattern between them. Our results indicated although the frequency of MRSA isolates from humans and animals was low, a continuous surveillance and monitoring should be called for to prevent the contamination and spread of MRSA in the community. To our knowledge, this is the first time that SCCmec type variant IIIB was detected from animals in Korea.

• Journal of Physiology & Pathology in Korean Medicine
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• v.23 no.3
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• pp.704-709
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• 2009

The emergence of methicillin-resistant of Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) has led to an urgent need for the discovery and development of new antibacterial agents. As part of an ongoing investigation into the antibacterial properties of the natural products, (2S)-7,4'-dihydroxy-5-methoxy-8-(${\gamma}$, ${\gamma}$-dimethylally)-f1avanone (2S-DMDF), isolated from the roots of Sophora flavescens, was found to be antibacterial active MRSA and VRE. Sophora flavescens has been used as antibacterial, antiviral, antiprotozoal, anti-inflammatory. Therefore, this study investigated the antibacterial activity of 2S-DMDF against all the bacterial strains tested. In this result, at the end point of an optically clear well, the minimum inhibitory concentrations (MICs) ranged from 0.97 to 15.6 mg/ml for 2S-DMDF, from 125 to 256 mg/ml for ampicillin, and from 64 to 512 mg/ml for gentamicin with MRSA, also, 7.8 to 15.6 mg/ml for 2S-DMDF, from 125 to 256 mg/ml for ampicillin, and from 512 to 1024< mg/ml for vacomicin with VRE. These findings indicated that the application of the tested 2S-DMDF alone might prove useful in the control and treatment of MRSA and VRE infections.

• YAKHAK HOEJI
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• v.51 no.4
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• pp.253-258
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• 2007

Bombycis corpus, a batryticated silkworm and white-stiff silkworm, is an oriental drug consisting of the dried larva of silkworm, dead and stiffened due to the infection of Beauveria. An peptidyl antimicrobial molecule was purified from B. corpus by reverse phase-column chromatography and HPLC. Its molecular weight was determined to be 2295.45 by using matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry. Its antimicrobial activity was diminished by trypsin digestion. It exhibited a broad antimicrobial spectrum against not only Gram-negative, but also Gram- positive bacteria. Furthermore, it was found to have an antimicrobial activity against vancomycin-resistant enterococci (VRE), methicillin-resistant S. arureus (MRSA), and vancomycin-intermediate resistant S. arureus (VISA). It may be a useful molecule for a new antibiotic development, especially against antibiotic resistant microbe. This substance may play a role in the defense system of this animal against Beauveria bassiana. This is the first report of a peptidyl antimicrobial substance from B. corpus.

• Korean Journal of Pharmacognosy
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• v.34 no.2 s.133
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• pp.142-144
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• 2003

Acetone extracts of 301 strains of marine-derived fungus were tested for antimicrobial activity against three strains of bacteria. The bacteria consisted of three pathogens, Staphylococcus aureus, methicillin-resistant S. Aureus, and multidrug-resistant S. aureus. The acetone extracts of 10 strains (MFA117, MFA130, MFA134, MFA206, MFA217, MFA268, MFA277, MFA291, MFA292, MFA301) showed strong activity, inhibiting 100% of the bacterial growth. These antimicrobial active strains were cultlued in SWS medium on a 1 L scale and the resulting broth and mycelium were extracted to afford mycelium extract (000M) and broth extract (000B), respectively. Antimicrobial activity for all extracts has been tested as the results, the mycelium extract of one strain (217M) and the broth extracts of 9 strains (117B,130B, 134B, 206B, 268B, 277B, 291B, 292B, 301B) exhibited relatively high levels of activity at minimal inhibitory concentration (MIC) values of $500-125\;{\mu}g/mL$ range. Among them, the extracts, 277B, 291B, 292B and 301B showed the most significant antimicrobial activity with $IC_{50}$ values of $125\;{\mu}g/mL$.

• Korean Journal of Veterinary Research
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• v.48 no.1
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• pp.75-81
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• 2008

The rapid evolution of antibiotic resistance in Staphylococcus (S.) aureus is of considerable concern. Methicillin-resistant S. aureus (MRSA) strains are especially one of the greatest public concerns since the treatment of infections is more difficult when encountering resistance. In this study, we conducted a nationwide survey on the antimicrobial resistance of S. aureus isolated from raw meat samples collected from 16 countries, including Korea, and investigated the prevalence of MRSA as a possible source of human infection. Of 1,984 meat samples, S. aureus was isolated from 218 (11.0%) samples consisting of 23 (12.1%) from domestic meat and 195 (10.9%) from imported meat. The isolation rates of poultry meat, pork and beef were 12.8%, 7.0% and 10.0%, respectively. With regard to imported meat, the incidence varied from 4.8% to 16.6% from 13 countries, with the exception of Austria and Poland. In a resistance test to 20 antimicrobial agents, one hundred and eighty-four isolates (84.4%) were resistant to one or more antimicrobial agents tested. Especially, 17 (7.8%), 124 (56.9%) and 28 (12.8%) isolates showed a resistance to 3, 2 and 1 drugs, respectively. One isolate originating from domestic beef was resistant to 7 drugs. Another isolate originating from imported poultry meat showed resistance to oxacillin and methicillin by the disk diffusion test and minimal inhibition concentration methods, but showed negative for detection of the mecA gene.

• Korean Journal of Microbiology
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• v.51 no.4
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• pp.444-447
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• 2015

This study was carried out to determine the antibacterial activity of $SeO_2$ against pathogenic bacteria, methicillin-resistant Staphylococcus aureus (MRSA). Using the disc diffusion method, $SeO_2$ showed higher antibacterial activity against Gram-positive bacteria than Gram-negative bacteria used in this study. Coccus-form bacteria showed much susceptible to $SeO_2$, compared to bacillus-form bacteria. Compared to antibiotics-susceptible S. aureus, antibiotics used in this study showed lower antibacterial activity against MRSA. As $200-500{\mu}g/disc$ of $SeO_2$ was applied, diameters of clear zone for S. aureus and MRSA were 20-32.7 mm and 13.5-17.9 mm, respectively. For MRSA, minimal inhibitory concentration of $SeO_2$ was $40{\mu}g/ml$. When $SeO_2$ was added in culture broth, cell growth of MRSA was inhibited. These results will be applied to determine antibacterial mechanism of MRSA and other pathogenic microorganisms.

• 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.