• Pediatric Infection and Vaccine
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• v.18 no.2
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• pp.143-153
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• 2011

Purpose : It is known that carriage rates of Staphylococcus aureus (S. aureus) are highest in newborns and that the asymptomatic carriage of methicillin-resistant Staphylococcus aureus (MRSA) is associated with invasive MRSA infection with the colonizing strain. This study was carried out to investigate the carriage rates of MRSA in neonates with neonatal jaundice. Methods : We reviewed the medical records of 545 neonates admitted with neonatal jaundice to neonatal intensive care units between January 2006 and December 2010. Nasal and inguinal swab specimens had been taken from them and cultured for the isolation of S. aureus. Antimicrobial susceptibility tests had been done for such isolates to determine methicillinresistance. Results : Out of 545 neonates, 318 (58.3%) were colonized with S. aureus and 214 (39.3%) were colonized with MRSA. Results of the antibiogram analysis showed that 65.7% of MRSA isolates were likely to be community-associated (CA) MRSA. Conclusion : Based on the MRSA carriage rate of 39.3%, a surveillance program for MRSA colonization is considered necessary in neonates transferred from other clinics or hospitals. Out of MRSA isolates, 65.7% were likely to be CA-MRSA. This suggests that CA-MRSA strains were already present in obstetric clinic environments where the neonates were born. It is thought that MRSA surveillance programs in these environments are also necessary.

• Pediatric Infection and Vaccine
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• v.3 no.2
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• pp.133-138
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• 1996

Purpose : In the treatment of MRSA infection, rapid detection of MRSA is extremely important. The mecA gene codes the new drug resistant polypeptides called PBP2' which mediates the clinically relevant resistance to all beta-lactam antibiotics. The identical mecA gene has been found in coagulase-negative staphylococcus with the methicillin-resistant phenotype. On the other hand, the femA gene was absent from coagulase negative staphylococcus strains with the methicillin resistant phenotype. This study is aimed at early detection and definite diagnosis of MRSA. Methods : A total of 24 MRSA strains were studied. All strains were tested for antimicrobial susceptibility and purified DNA. We amplified both mecA and femA genes by PCR in 24 strains. Results : In MRSA all the 16 strains (100%) carried femA gene and 11 strains (68.7%) carried mecA gene. In contrast, in methicillin sensitive staphylococcus all the 8 strains (100%) carried femA and only 3 strains (37.5%) were detected mecA. Conclusions : As results, there are difference in the phenotype and genotype of methicillin resistance by PCR of mecA and femA. Such disparities between methicillin resistance and the presence of mecA gene suggest the presence of control gene of the mecA.

• Journal of Life Science
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• v.11 no.1
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• pp.24-34
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• 2001

Methicillin Resistant Staphylococcus aureus (MRSA) was obtained from the clinical specimens at Pusan national university Hospital, Pusan, Korea. The sensitivities against various antibiotics were examined by using disc diffusion test and associated genes such as mecA, mecR1, mecI and femA were detected by polymerase chain reaction. Among Seventy-nine strains of MRSA, 38 strains(48.1%)were sensitive to streptomycin and 32 strains(40.5%) to cefoperazone, while one strain(1.3%) were resistant to vancomycin. In considering the result of this study, 7 strains showed resistance to 9 kinds of different antibiotics, 12 strains were to 8 kinds, 24 strains were to 7,25 strains were to 6, 9 strains were to 5, and 2 strains were to 4 antibiotics. Among 79 strains of MRSA, 67 strains were coagulase positive and 12 were coagulase negative. In the detection of MRSA associated genes by PCR method, mecA, mecR1, mecI, and femA genes were detected in 30 strains(44.8%), 28 strains(41.8%), 23 strains(34.3%) and 15 strains(22.4%), respectively. MecA type that is without femA were found in 21 strains(31.3%), femA type that is without regulator genes were shown in 4 strains(6.0%), while mecA-mecR1-mecI type with regulator genes were shown more to be 17 strains(25.4%). There was little statistical significance between multidrug resistance and MRSA associated genes. Considering these result, it is necessary to include moecular biological studies of related genes to the study drug resistance.

• Journal of Korean Medicine Rehabilitation
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• v.28 no.2
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• pp.21-35
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• 2018

Objectives The objective of this study is to determine the antimicrobial effect of Daehwanggyeonu-san(Dahwangqianniu-san,DGE) and synergistic effects with antibiotics oxacillin, ampicillin, and gentamicin against Methicillin-Resistant Staphylococcus aureus(MRSA). Methods The antibacterial activity of DGE extract was evaluated againest MRSA strains by using the Disc diffusion method, broth microdilution method(minimal inhibitory concentration; MIC), checkerboard dilution test. The checkerboard dilution test was used to examined synergetic effect of oxacillin, ampicillin, gentamicin, ciprofloxacin with DGE extract. Results DGE showed antimicrobial activity against MRSA with an MIC value of $125{\sim}250{\mu}g/mL$. In the checkerboard test, the interation of DGE with all tested antibiotics produced almost synergy or partial synergy against MRSA. Conclusions This study shows that DGE reduced the MICs of several antibiotics tested, and a remarkable antibacterial effect of DGE, with membrane permeability enhancers and ATP synthase inhibitors. This study can be a valuable source for the development of a new drug with low MRSA resistance.

• 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.

• 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.

• 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.

• Korean Journal of Veterinary Service
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• v.47 no.1
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• pp.27-33
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• 2024

At the present study, it was aimed to explore the states of antimicrobial resistant Staphylococcus aureus isolates from 1,360 chickens, pigs and cattle carcass (400 chickens, 480 pigs and 480 cattle) in Daegu province from January 2022 to December 2022. Among 1,360 samples, 81 of S. aureus were isolated cattle (1.4%), pigs (7.7%) and chickens (9.2%). In antimicrobial susceptibility test, all of the isolates were demonstrated susceptibility to rifampin. But the isolates were showed resistance other antibiotics in order of tetracycline (62.9%), ciprofloxacin (62.9%), tobramycin (58.0%), gentamicin (51.8%), amikacin (40.7%), penicillin (39.5%), clindamycin (35.8%), enrofloxacin (33.3%), trimethoprim/sulfamethoxazole (30.8%), oxacillin (30.8%), minocycline (29.6%), erythromycin (25.9%), quinupristin/dalfopristin (20.9%), chloramphenicol (12.3%), cefoxitin (9.8%). Among the 81 S. aureus isolates, 25 (30.8%) methicillin-resistant staphylococcus aureus (MRSA) were observed. Seven (28.0%) of 25 MRSA harbored mecA gene. About 96% of MRSA were multidrug resistance to at least 3 more drugs. A continuous monitoring and surveillance program to prevent antimicrobial resistance in livestock products is demanded.

• Journal of Veterinary Science
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• v.21 no.1
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• pp.2.1-2.14
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• 2020

The emergence of livestock-associated (LA)-methicillin-resistant Staphylococcus aureus (MRSA) in livestock animal has become a significant zoonotic concern. In the present study, we investigated nationwide prevalence of LA-MRSA across pork production chain including pig farms, slaughterhouses, and retail markets. A total of 40 MRSA strains were isolated during the investigation and the overall prevalence of MRSA was 3.4% (n = 37), 0.6% (n = 2), and 0.4% (n = 1) in pig farms, slaughterhouses, and retail markets, respectively. Multilocus sequence typing analyses revealed that the 2 most significant clonal lineages in pork production chain in Korea were ST398 (n = 25) and ST541 (n = 6). All of the 40 MRSA isolates were further characterized to investigate key genotypic and phenotypic correlates associated with the emergence and spread of clonal complex 398 (CC398; ST398, and ST541) LA-MRSA. Although the prevalence of swine-associated MRSA was still relatively low and mostly restricted to pig farms, multidrug-resistant CC398 LA-MRSA isolates with new spa types (t18102 and t18103) were identified as a major clonal lineage. The CC398 LA-MRSA strains tended to exhibit increased levels of multiple drug resistance (MDR) phenotype compared with non-CC398 MRSA strains. Of note, in comparison with non-CC398 MRSA isolates, CC398 LA-MRSA isolates exhibited significantly enhanced tetracycline (TET) and zinc resistance. These findings suggested that co-selection pressure associated with MDR phenotype, especially TET resistance, and zinc resistance may have played a significant role in the emergence and persistence of CC398 LA-MRSA in pig farms in Korea.

• 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.