• Microbiology and Biotechnology Letters
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• v.41 no.3
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• pp.335-340
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• 2013

The antimicrobial effect of the methanol extract of Inula britannica flowers against methicillin resistant Staphylococcus aureus (MRSA) was investigated. It was confirmed that the methanol extract is mainly composed of quercetin, which has antimicrobial properties. The antimicrobial effect of the methanol extract against 3 MRSA strains was determined by the disc diffusion method. The minimal inhibitory concentrations were ranged from 0.625 mg/ml to 1.25 mg/ml, and the minimum bactericidal concentrations were 2.5 mg/ml. Time kill kinetics revealed bactericidal activities, and the morphological alterations in S. aureus ATCC 33591 treated with the extract were observed using a scanning electron microscope. The methanol extract affected the expression of the resistant genes, mecA, mecI, and mecRI in mRNA. Therefore, the methanol extract of I. britannica flowers clearly demonstrated an antimicrobial effect against MRSA and these results suggest a potential for application as a natural antimicrobial agent.

• Korean Journal of Microbiology
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• v.48 no.3
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• pp.212-215
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• 2012

The antimicrobial activity of ursolic acid (UA) and oleanolic acid (OA), both triterpenoid compounds, against methicillin-resistant Staphylococcus aureus (MRSA) is controversial. We examined the antimicrobial effects of UA and OA against 19 strains of MRSA isolated from Koreans by determining minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC). The data showed that the methicillin-sensitive strain S. aureus KCTC $1621^T$ was more resistant to UA and OA than that of the MRSA strains. The MBC values of UA and OA against MRSA had broad ranges; 4 to 32 ${\mu}g/ml$ and 16 to >256 ${\mu}g/ml$, respectively. It was difficult to understand the different antimicrobial activities of UA and OA among the MRSA strains, because UA and OA antimicrobial mechanisms are unknown. These results indicate that the antimicrobial effects of UA and OA against MRSA are dependent on resistance to UA and OA in each strain.

• Pediatric Infection and Vaccine
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• v.20 no.2
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• pp.63-70
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• 2013

Purpose : This study aimed to explore how prevalent the community-related methicillin-resistant Staphylococcus aureus (CA-MRSA) was in children with muscular-skeletal infections. Methods : We retrospectively reviewed the medical records of patients of 18 years or under who were diagnosed with suppurative arthritis or osteomyelitis and S. aureus from September 2000 through August 2012 at the CHA Bundang Medical center. Results : Thirty-one cases of suppurative arthritis or osteomyelitis were identified. The patients were between 17 days old and 18 years old with an average age of 7. Eleven cases (33.5%) of suppurative arthritis and 16 cases (51.6%) of osteomyelitis were observed. Five cases were accompanied by the two diseases. Methicillin sensitive S. aureus (MSSA) was isolated in 25 cases (80.6%) and methicillin resistant S. aureus (MRSA) was isolated in 6 cases (19.4%). Multidrug resistant strains were not observed. MRSA was not found from 2000 through 2005. All patients were treated with antibiotics and the duration of antibiotics treatment was $26.4{\pm}12.7$ days. Vancomycin was used as the initial antibiotic treatment in 4 cases (12.9%) and vancomycin was used as the definitive antibiotics in the 10 cases (32.3%). Conclusions : The result of this study showed that methicillin resistance rate of S. aureus from muscular-skeletal infections was concentrated in the latter half of the 12 year period.

• Pediatric Infection and Vaccine
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• v.16 no.2
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• pp.205-209
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• 2009

Staphylococcal toxic shock syndrome (TSS) is a severe systemic illness caused by toxins produced by Staphylococcus aureus. We report a case of staphylococcal TSS in a 16 month-old boy who presented with high fever, vomiting, skin rash, and shock after a burn injury. He was managed with intravenous vancomycin, fresh frozen plasma, and intravenous immunoglobulin. Methicillin-resistant S. aureus (MRSA) was isolated from the burn wound site and anterior nostril of the patient. In addition, the MRSA isolate was genetically characterized.

• Korean Journal of Veterinary Research
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• v.39 no.2
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• pp.376-382
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• 1999

A methicillin-resistant Staphylococcus aureus (MRSA) isolate was recovered from a 9-month-old female Shih-Tzu dog with canine distemper virus infection. We performed in vitro antimicrobial susceptibility test to determine the most effective antimicrobial drug against the isolate and thus, to emphasize its potential clinical importance in animal practices. Isolate was confirmed MRSA by oxacillin agar screening test. The isolate was fully resistant to all $\beta$-lactam antibiotics and was susceptible to glycopeptides. Of the other antibiotics, mupirocin, TMP/SMZ (trimethoprim-sulfamethoxazole), and chloramphenicol showed inhibitory effect at the concentration of 4x MIC. The MICs ranged 0.25->$128{\mu}g/ml$, and MBCs ranged 0.5->$128{\mu}g/ml$. The combined TMP/SMZ with cefamandole or novobiocin showed synergistic effect, whereas the combination of novobiocin plus cefamandole or teicoplanin resulted in antagonistic effects. Although MRSA in animals so far has been reported in the geographically limited countries, at least theoretically, it could be occurred in the future more frequently through either human or animal origin. The use of this combination may be of value in this situation. As with all antimicrobial agents, inappropriate or unnecessarily prolonged therapy may contribute to the emergence of resistance strains and loss of efficacy.

• Journal of Microbiology and Biotechnology
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• v.32 no.2
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• pp.220-227
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• 2022

The spread of antibiotic-resistant strains of Staphylococcus aureus, a gram-positive opportunistic pathogen, has increased due to the frequent use of antibiotics. Inhibition of the quorum-sensing systems of biofilm-producing strains using plant extracts represents an efficient approach for controlling infections. Torilis japonica is a medicinal herb showing various bioactivities; however, no studies have reported the anti-biofilm effects of T. japonica extracts against drug-resistant S. aureus. In this study, we evaluated the inhibitory effects of T. japonica ethanol extract (TJE) on biofilm production in methicillin-sensitive S. aureus (MSSA) KCTC 1927, methicillin-resistant S. aureus (MRSA) KCCM 40510, and MRSA KCCM 40511. Biofilm assays showed that TJE could inhibit biofilm formation in all strains. Furthermore, the hemolysis of sheep blood was found to be reduced when the strains were treated with TJE. The mRNA expression of agrA, sarA, icaA, hla, and RNAIII was evaluated using reverse transcription-polymerase chain reaction to determine the effect of TJE on the regulation of genes encoding quorum sensing-related virulence factors in MSSA and MRSA. The expression of hla reduced in a concentration-dependent manner upon treatment with TJE. Moreover, the expression levels of other genes were significantly reduced compared to those in the control group. In conclusion, TJE can suppress biofilm formation and virulence factor-related gene expression in MSSA and MRSA strains. The extract may therefore be used to develop treatments for infections caused by antibiotic-resistant S. aureus.

• Archives of Plastic Surgery
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• v.33 no.5
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• pp.632-636
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• 2006

Purpose: Methicillin-Resistant-Staphylococcus aureus(MRSA) has been increasingly recognized as a cause of nosocomial infection. MRSA is hardly-controllable organism among the pathogen of nosocomial infection, because it is resistant to most antibiotics except vancomycin, and local treatment with most antiseptics are not effective to eradicate MRSA from the infection. The effectiveness of Vacuum-Assisted-Closure(VAC) was reported widely. we tried to modify original VAC. We tried VAC dressing on MRSA infected wound to evaluate whether or not the VAC is effective to eradicate MRSA which existed in the open wound. Methods: From September 2003 to December 2003, 24 patients admitted to the plastic and reconstructive surgery and orthopedic surgery, were studied. All patients were found to be positive in previous wound. Using clinical randomized study, 24 patients were divided into two groups: VAC dressing group and the $Betadine^{(R)}$ dressing group(control). During treatment, wound culture was done twice a week for evaluation of MRSA infection elimination. Results: The mean period that MRSA become not detected in all case was 17.1 days in VAC dressing group, and 25.8 days in control group, respectively. The p value was 0.013. The result reveals that the VAC dressing group is more effective to MRSA infection control. As a result, the VAC dressing was more effective in MRSA infected wound than conventional dressing. Conclusion: Through this study, we found objective result of VAC dressing. We hope that VAC dressing is more widely applied to fresh and infected wound.

• Microbiology and Biotechnology Letters
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• v.51 no.1
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• pp.132-133
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• 2023

Clonal complex (CC) 398 community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has emerged worldwide in a variety of livestock animals and humans. We report complete genome sequences of Panton-Valentine leucocidin (PVL) and immune evasion cluster (IEC) gene-positive CC398 MRSA strains isolated from patients in Korea.

• Journal of Microbiology
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• v.44 no.3
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• pp.336-343
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• 2006

We compared the antimicrobial resistance and clonal relationships among the community-acquired (CA) and hospital-acquired (HA) methicillin-resistant Staphylococcus aureus (MRSA) strains that were isolated from blood cultures in a university hospital over a 4-year period. A total of 131 MRSA isolates, including 28 CA-MRSA and 103 HA-MRSA strains, were identified; antimicrobial susceptibility testing indicated that the CA-MRSA isolates were more susceptible to erythromycin (21 % vs 6% ; P=0.02), clindamycin (46% vs 12%; P<0.01), ciprofloxacin (43% vs 11%; P<0.01), and gentamicin (43% vs 6%; P<0.01) than were the HA-MRSA isolates. Pulsed-field gel electrophoresis (PFGE) typing and antimicrobial resistance profiles separated the 20 CA-MRSA isolates into 14 and 10 different patterns, respectively, and the 53 HA-MRSA isolates were separated into 24 and 7 different patterns, respectively. Twenty-one (40%) of the 53 HA-MRSA isolates belonged to two predominant PFGE types, and most of them showed multi-drug resistant patterns. Four (20%) of the 20 CA-MRSA and 10 (19%) of the 53 HA-MRSA isolates fell into two common PFGE patterns, and each of them showed the same multi-drug resistant pattern. This study suggests that, although the CA-MRSA blood isolates showed diverse PFGE and antimicrobial resistance patterns, some of these isolates may have originated from the HA-MRSA strains.

• Korean Journal of Veterinary Research
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• v.45 no.1
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• pp.113-119
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• 2005

Resistance to antibiotics is a problem all over the world, and this problem also is so extended in veterinary fields. Therefore, this study aimed to find out the antibacterial substances from natural medicinal herbs against bovine mastitis pathogens, especially methicillin-resistant Staphylococcus aureus (MRSA). Among seventy two medicinal herbs, Terminaliae chebula extract showed antimicrobial effect against MRSA isolated from mastitis milk in cow and patient in human. However, Terminaliae chebula extract didn't show antibacterial effects on various strains including other contagious and environmental pathogens related with mastitis of dairy cows.