• Journal of Korean Biological Nursing Science
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• 제8권1호
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• pp.5-14
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• 2006

Staphyloccus aureus is one of the most important pathogens in clinical settings. It is also one of the leading causes of nosocomial infections and the dissemination of multiple drug-resistant strains, mainly methicillin resistant Staphyloccus aureus, and the recent emergence of a vancomycin resistant MRSA is the concern to hospital worldwide. MRSA strains have acquired multiple resistance to a wide range of antibiotics, including aminoglycosides and macrolides. $\beta$-Lactam resistance of methicillin-resistnat Staphyococcus aureus is determined by the function of penicillin binding protein 2'(PBP2') encoded by the methicillin resistance gene mec A. MRSA strains carry methicillin resistance gene mecA, encoded by a mobile genetic element designated staphylococoal cassette chromosome mec(SCCmec). MRSA clones are defined by the type of SCCmec element and the genotype of the methicilline-susceptible Staphyococcus aureus chromosome in which the SCCmec element is integrated.

• Journal of Microbiology
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• 제35권2호
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• pp.103-108
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• 1997

To improve the detection of methicillin resistant staphylococci, lowered incubation temperature (30.deg.) and inclusion of sodium chloride in media have been empirically recommended. However, in this study, we found that sodium chloride in Peptone-Yeast Extract-K$\_$2/HPO$\_$4/ (PYK) medium decreased methicillin minimum inhibitory concentrations. Divalent cations were shown to restore the expression of staphylococcal methicillin resistance. However, when it was determined by efficiency of plating, sodium chloride increased methicillin resistance expression on agar medium in which higher divalent cations were contained in the agar medium. The decrease of minimum inhibitory concentrations at 30.deg.C by sodium chloride occurred in Brain Heart Infusion but did not occur in other media investigated. Interestingly, both PYK and Brain Heart Infusion media had peptone, which contain cholic acids having detergent activities. Inclusion of sodium chloride in PYK caused a higher rate of autolysis. Penicillin binding protein 2a that has a low affinity to beta-lactam antibiotics, was highly inducible in methicillin resistant Staphylococcus epidermidis strains. In this study, we found that autolysins that are activated by the sodium chloride decreased the minimum inhibitory concentration at 30.deg.C, and peptidoglycan is weakened due to the presence of methicillin. Peptone in the media may aggravate the fragile cells. However, stabilization due to the presence of divalent cations and production of penicilin binding protein 2a increase the survival of staphylococci.

• 한국동물위생학회지
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• 제39권3호
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• pp.175-181
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• 2016

Staphylococcus pseudintermedius is an important opportunistic pathogen of dog and cats. Since 2006 there has been a significant emergence of methicillin-resistant S. pseudintermedius (MRSP) mainly due to clonal spread. The aim of this study was to investigated the prevalence of antibiotic resistance and presence of mecA and femA gene in 91 S. pseudintermedius isolates isolated from dogs and cats associated with various clinic infections. Methicillin resistance was confirmed by oxacillin disc diffusion method. MRSP isolate was detected 19 isolates (20.9%). MRSP and methicillin-resistant S. pseudintermedius (MSSP) isolates were highly resistant to penicillin, kanamycin, tetracycline, erythromycin, trimethoprim-sulfamethoxazole, clindamycin, ciprofloxacin, enrofloxacin and choloramphenicol (100~47.3% and 90.3~33.3%, respectively). About 90% of MRSP isolates were multi-drug resistance (resistance to at least five or more antimicrobials), and MSSP isolates was ca 74%. Among the 91 isolates, mecA gene was detected in 25 isolates (27.5%, 19 in MRSP isolates and 6 in MSSP isolates), but none carried the femA gene. Our results indicated MRSA isolates show a strong resistance to antimicrobials commonly used in veterinary medicine. A continuous surveillance and monitoring should be called for to prevent the contamination and spread of MRSP in dogs and cats.

• Journal of Animal Science and Technology
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• 제64권3호
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• pp.515-530
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• 2022

Sequence type (ST) 5 methicillin-resistant Staphylococcus aureus (MRSA) with staphylococcal cassette chromosome mec (SCCmec) type II (ST5-MRSA-II) and ST72-MRSA-IV represent the most significant genotypes for healthcare- (HA) and community-associated (CA) MRSA in Korea, respectively. In addition to the human-type MRSA strains, the prevalence of livestock-associated (LA) MRSA clonal lineages, such as ST541 and ST398 LA-MRSA-V in pigs and ST692 LA-MRSA-V and ST188 LA-MRSA-IV in chickens, has recently been found. In this study, clonotype-specific resistance profiles to cathelicidins derived from humans (LL-37), pigs (PMAP-36), and chickens (CATH-2) were examined using six different ST groups of MRSA strains: ST5 HA-MRSA-II, ST72 CA-MRSA-IV, ST398 LA-MRSA-V, ST541 LA-MRSA-V, ST188 LA-MRSA-IV, and ST692 LA-MRSA-V. Phenotypic characteristics often involved in cathelicidin resistance, such as net surface positive charge, carotenoid production, and hydrogen peroxide susceptibility were also determined in the MRSA strains. Human- and animal-type MRSA strains exhibited clonotype-specific resistance profiles to LL-37, PMAP-36, or CATH-2, indicating the potential role of cathelicidin resistance in the adaptation and colonization of human and animal hosts. The ST5 HA-MRSA isolates showed enhanced resistance to all three cathelicidins and hydrogen peroxide than ST72 CA-MRSA isolates by implementing increased surface positive charge and carotenoid production. In contrast, LA-MRSA strains employed mechanisms independent of surface charge regulation and carotenoid production for cathelicidin resistance. These results suggest that human- and livestock-derived MRSA strains use different strategies to counteract the bactericidal action of cathelicidins during the colonization of their respective host species.

• Journal of Microbiology and Biotechnology
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• 제34권3호
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• pp.681-688
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• 2024

The accurate and rapid detection of methicillin-resistance of Staphylococcus aureus (SA) holds significant clinical importance. However, the methicillin-resistance detection strategies commonly require complicated cell lysis and gene extraction. Herein, we devised a novel colorimetric approach for the sensitive and accurate identification of methicillin-resistance of SA by combining allosteric probe-based target recognition with self-primer elongation-based target recycling. The PBP2a aptamer in the allosteric probe successfully identified the target MRSA, leading to the initiation of self-primer elongation based-cascade signal amplification. The peroxidase-like hemin/G-quadruplex undergo an isothermal autonomous process that effectively catalyzes the oxidation of ABTS2- and produces a distinct blue color, enabling the visual identification of MRSA at low concentrations. The method offers a shorter duration for bacteria cultivation compared to traditional susceptibility testing methods, as well as simplified manual procedures for gene analysis. The overall amplification time for this test is 60 min, and it has a detection limit of 3 CFU/ml. In addition, the approach has exceptional selectivity and reproducibility, demonstrating commendable performance when tested with real samples. Due to its advantages, this colorimetric assay exhibits considerable potential for integration into a sensor kit, thereby offering a viable and convenient alternative for the prompt and on-site detection of MRSA in patients with skin and soft tissue infections.

• 대한의생명과학회지
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• 제5권1호
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• pp.131-133
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• 1999

본 연구는 methicillin 내성 Staphylococcus aureus (MRSA)에 특이적인 유전자인 mecA 유전자를 검출하기 위하여 전라북도의 두 병원에서 황색포도상구균 31주를 분리하였다. 이중 penicillin에 내성인 20균주를 디스크 확산법을 이용하여 methicillin, oxacillin, ampicillin, vancomycin, penicillin에 대한 다약제 내성 성상을 확인하였고, 중합효소 연쇄반응(PCR)을 이용하여 mecA 유전자를 확인하였다. 디스크 확산법을 실시한 결과 methicillin 내성균주는 20균주 중 10주 (50%)였다. Methicillin에 내성인 10균주를 PCR법으로 확인한 결과 7주에서 554 bp의 DNA증폭이 관찰되어 mecA 유전자가 존재함을 확인하였다.

• Journal of Microbiology and Biotechnology
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• 제32권12호
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• pp.1537-1546
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• 2022

Staphylococcus aureus is a cause of high mortality in humans and therefore it is necessary to prevent its transmission and reduce infections. Our goals in this research were to investigate the frequency of methicillin-resistant S. aureus (MRSA) in Taif, Saudi Arabia, and assess the relationship between the phenotypic antimicrobial sensitivity patterns and the genes responsible for resistance. In addition, we examined the antimicrobial efficiency and application of silver nanoparticles (AgNPs) against MRSA isolates. Seventy-two nasal swabs were taken from patients; MRSA was cultivated on Mannitol Salt Agar supplemented with methicillin, and 16S rRNA sequencing was conducted in addition to morphological and biochemical identification. Specific resistance genes such as ermAC, aacA-aphD, tetKM, vatABC and mecA were PCR-amplified and resistance plasmids were also investigated. The MRSA incidence was ~49 % among the 72 S. aureus isolates and all MRSA strains were resistant to oxacillin, penicillin, and cefoxitin. However, vancomycin, linezolid, teicoplanin, mupirocin, and rifampicin were effective against 100% of MRSA strains. About 61% of MRSA strains exhibited multidrug resistance and were resistant to 3-12 antimicrobial medications (MDR). Methicillin resistance gene mecA was presented in all MDR-MRSA strains. Most MDR-MRSA contained a plasmid of > 10 kb. To overcome bacterial resistance, AgNPs were applied and displayed high antimicrobial activity and synergistic effect with penicillin. Our findings may help establish programs to control bacterial spread in communities as AgNPs appeared to exert a synergistic effect with penicillin to control bacterial resistance.

• 생명과학회지
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• 제8권5호
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• pp.537-549
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• 1998

실험대상 병원내 27개소의 공기중에서 30분 동안 낙하균을 여름과 겨울에 채취하여, 총 세균 수와 포도상 구균속 및 진균의 수를 비교하고, 각각의 균을 동정하고, 분리된 주요 세균에 대한 항생물질 감수성 검사를 실시하였다. 분리된 총 세균 수, 포도구균속의 수, 진균의 수는 여름에 각각 26개, 17개, 2개였으며, 겨울에는 각각 19개, 8개, 2개로 여름이 더 많았다. 분리 동정된 세균 종은 Staphylococcus dpidermidis가 가장 많았으며, 그 다음이 Staphylococcus aureus, Aerococcus spp., Staphylococcus saprophyticus, Micrococcus spp., Bacilluc spp. 등의 순이 었다. 병원내 공기중에서 분리된 진균은 Aspergillus spp., Cephalosporium spp., Curvularia spp., Penicillium spp., Phialophora spp. 등의 순으로 많이 분리되었다. 분리된 109주의 Staphylococcus epidermidis는 tetracycline에 45.0%, methicillin에 40.4%, erythromycin에 31.2%, kanamycin에 24.8%, gentamy-cin에 16.5%가 저항성 균주이었다. 분리된 76주의 Staph-ylococcus aureus는 erythromycin에 71.1%, methicillin에 63.2%, kanamycin에 44.7%, tetracycline에 39.5%, ampicillin에 32.9%가 저항성 균주이었다. 분리된 67주의 Aerococcus spp.는 erythromycin에 26.9%, methicillin에 25.4%, tetracycline에 22.4%, kanamycin에 20.9%가 저항성 균주이었으나, vancomycin에는 저항성 균이 없었다. 분리된 48주의micrococcus spp.는 tetracycline에 27.0%, erythomycin과 methicillin에 각각 22.9%, kanamycin에 20.8%가 저항성 균주이었다. 분리된 37주의 Staphylococcus saprophyticus는 cephalothin에 35.4%, methicillin과 ampicillin에 32.4%, erythromycin과 kanamycin에 각각 27.0%, tetracycline에 21.6%가 저항성 균주이었다.

• 한국미생물·생명공학회지
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• 제51권4호
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• pp.545-547
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• 2023

Staphylococcus epidermidis is a normal flora of human skin and is occasionally associated with pathogenic infections. We report the complete genome sequence of methicillin-resistant Staphylococcus epidermidis strain Z0118SE0272 isolated from the residential environment sharing by a companion dog and dwellers. Resistance to cefoxitin was observed in the strain, whereas it was susceptible to erythromycin, clindamycin, quinupristin-dalfopristin, trimethoprim-sulfamethoxazole, mupirocin, vancomycin, teicoplanin, linezolid, and tigecycline. The strain Z0118SE0272 identified as sequence type 130 possessed the mecA gene responsible for methicillin resistance, which composed the new type of staphylococcal cassette chromosome mec elements lacking mecRI.

• 한국미생물·생명공학회지
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• 제52권1호
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• pp.99-101
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• 2024

Fluoroquinolones have been extensively used in treatment or prevention of serious infections in humans and food-producing animals, especially in poultry, due to their broad-spectrum activity to both Gram-positive and -negative pathogens. However, the use of fluoroquinolones in poultry production selects for bacteria carrying genetic determinants for quinolone resistance. Here, we present the complete genome sequences of two methicillin-resistant Staphylococcus aureus (MRSA) strains displaying quinolone resistance, which were isolated from healthy broilers in Korea.