• 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.

• Pediatric Infection and Vaccine
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• 제26권3호
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• pp.148-160
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• 2019

목적: 본 연구에서는 신생아실과 신생아 중환자실에서 발생한 methicillin-resistant Staphylococcus aureus (MRSA) 유행에서 환자와 보균자에서 분리된 MRSA의 분자역학적 연관성을 조사하여 유행의 감염원과 전파경로를 파악하고자 하였다. 방법: MRSA 유행기간인 2017년 8월부터 9월까지 피부감염 및 패혈증 환자들과 보균자로부터 분리된 MRSA 균주를 대상으로 유전형 및 병원성 인자를 분석하고 항생제 감수성 결과를 수집하였다. 결과: 연구기간 동안 신생아실(n=27)과 신생아 중환자실(n=14)에 총 41명의 신생아들이 입원하였다. 그 중, 7명(피부감염[n=6], 패혈증[n=1])에서 MRSA 감염이 확진되었고, 보균자 4명이 발견되었다. 신생아와 접촉이 있는 의료진 32명 중 3명이 MRSA를 비강에 보균하였다. 피부감염 유행 원인 균주는 Staphylococcal chromosomal cassette mec (SCCmec) type II, sequence type (ST) 89, spa type t375였고, 뮤피로신 저농도 내성을 포함하여 항생제 다제내성을 보였다. 패혈증을 일으킨 균주는 SCCmec type IVa, ST 72, 새로운 spa type인 t17879였다. 신생아 4명에게 집락된 MRSA 균주들은 다양하였으나 SCCmec type IVa, ST 72, spa type t664가 의료진과 신생아 2명에서 공통적으로 분리되었다. Panton-Valentine leukocidin (PVL) toxin 유전자가 신생아에게 집락된 모든 균주에서 발견되었다. 결론: 피부감염 유행을 일으킨 MRSA 균주는 항생제 다제내성을 보이는 균주였다. 신생아 MRSA 보균자에게서 분리된 균주는 모두 PVL 독소 유전자를 보유하였다. 유행기간 동안 다양한 MRSA 균주가 신생아들에게서 분리되기 때문에, 효과적인 감염 관리 및 추가 환자발생의 차단을 위하여 분자역학조사를 통하여 원인균을 확인하고 전파경로를 파악하는 것이 중요하다.

• Tuberculosis and Respiratory Diseases
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• 제75권2호
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• pp.75-78
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• 2013

Methcillin-resistant Staphylococcus aureus (MRSA) has emerged as an important cause of community-acquired infections, which has been recently designated as community-associated (CA) MRSA. Panton-Valentine leukocidin (PVL)-negative multilocus sequence type 72 (ST72)-staphylococcal cassette chromosome mec (SCCmec) type IV has been reported as the predominat CA-MRSA strain in Korea and is commonly associated with skin and soft tissue infections in addition to healthcare-associated pneumonia. However, community-acquired pneumonia (CAP) for this strain has not yet been reported. We hereby report two cases of CAP caused by PVL-negative ST72-SCCmec type IV strain in patients who had no risk factors for MRSA acquisition. While CA-MRSA infections are not yet prevalent in Korea, our cases suggest that CA-MRSA should be considered in cases of severe CAP, especially for cases associated with necrotizing pneumonia.

• 한국식품위생안전성학회지
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• 제34권6호
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• pp.576-582
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• 2019

Staphylococcus pseudintermedius는 개에서 기회감염을 유발하는 병원체이며, 공중보건학적으로도 주요한 인수공통 병원체이다. 개에서 분리된 S. pseudintermedius 균주들은 주로 항생제 내성 및 개에서 피부 감염을 유발하는 주요 원인균으로 연구되어 왔지만, 가축에서 분리된 S. pseudintermedius 균주들의 항생제 내성 및 장내 독소 생성에 대한 정보는 매우 제한적이다. 본 연구에서는 개, 돼지, 육우에서 분리된 S. pseudintermedius 균주들에서 18가지의 장내 독소 (staphylococcal enterotoxin; SE) 유전자와 toxic shock syndrome toxin 유전자(tst-1)의 분포양상을 조사하였다. 또한, S. pseudintermedius 균주들의 항생제 내성 양상과 더불어 mecA 유전자 및 SCCmec type 또한 확인하였다. 육우에서 분리한 하나의 균주를 제외한 모든 개와 돼지 분리주 들이 4개 이상의 항생제에 내성을 보였으며, 개에서 분리된 6개의 균주 중 4개의 S. pseudintermedius 균주들이 메티실린 내성과 더불어 SCCmec V를 가진 것으로 확인 되었다. 총 11개의 SE 유전자들 (seb, sec, see, seg, sei, sej, sel, seo, sep, seq, seu) 및 tst-1가 개, 돼지 및 육우로부터 분리된 S. pseudintermedius 균주들에서 확인 되었으며, 대부분의 분리주들 (83%)에서 2개 이상의 SE 유전자들이 확인 되었고, 그 중 sel (42%) 및 sep (42%)가 가장 빈번하게 검출 되었다. 본 연구를 통하여 반려견에서 뿐만 아니라 주요 가축에서 존재하는 S. pseudintermedius 균주들에서 높은 항생제 내성 양상을 확인 하였으며, 항생제 내성과 더불어 여러 staphylococcal enterotoxin 및 tst-1 유전자들을 전파할 가능성을 확인 하였다.

• 대한의생명과학회지
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• 제26권3호
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• pp.230-237
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• 2020

Staphylococcus aureus (S. aureus) is known as a bacterium that can cause skin infections, respiratory system infections, and sinusitis; however, it can exist as a normal flora rather than a pathogen. Recently, methicillin-resistant S. aureus (MRSA) infections have emerged in the community as a new variant of community-associated (CA)-MRSA. In the present study, S. aureus and MRSA were isolated and cultured by collecting samples from facilities and environments where students and educational personnel have multiple contacts on university campuses; specifically, the nostrils and hands of college students were tested from July to September of 2019. The molecular properties of the isolated MRSA were analyzed, and the one MRSA strain was isolated from the university campuses. One MRSA that was isolated and cultured on campus was the mec complex group A and staphylococcal cassette chromosome (SCC) mec type II, which is a characteristic of healthcare-associated (HA)-MRSA, and SCCmec type V, which is a characteristic of CA-MRSA. This result was similar to other studies wherein the SCCmec type II was detected in SCCmec typing analysis in CA-MRSA. To confirm whether there is a new variant of CA-MRSA in the Republic of Korea, additional follow-up studies on the analysis of virulence factors of MRSA are needed by additionally separating CA-MRSA from the body parts of university students and educational personnel.

• Journal of Microbiology and Biotechnology
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• 제20권3호
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• pp.637-642
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• 2010

We investigated the prevalence and the molecular characteristics of vancomycin-intermediate Staphylococcus aureus (VISA) among methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from clinical samples at tertiary or general hospitals participating in a nationwide surveillance program for VISA and vancomycin-resistant Staphylococcus aureus (VRSA) in Korea during an 8-week period in each year from 2001 to 2006. Of 41,639 MRSAs isolated, 37,856 were screened and 169 grew on brain heart infusion agar supplemented with 4 ${\mu}g/ml$ vancomycin. A vancomycin MIC of 4 ${\mu}g/ml$ was confirmed for 33 VISA isolates of the 169 isolates. Eighteen of the 33 isolates were classified as hetero-VISA (hVISA) by the population analysis profile (PAP) method. All VISA isolates were susceptible to linezolid, tigecycline, and quinupristin-dalfopristin. Most VISA isolates (MIC 4 ${\mu}g/ml$) showed a PFGE C pattern with sec, seg, and sei enterotoxin genes, including ST5-SCCmec type II, or a PFGE A pattern with sea, including ST239-SCCmec type III.

• 대한의생명과학회지
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• 제26권3호
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• pp.244-248
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• 2020

Skin and soft tissue infections caused by methicillin-resistant Staphylococcus aureus (MRSA) can occur especially in community populations such as military training camps. We investigated antimicrobial resistance patterns and molecular epidemiological characteristics of MRSA isolated from nasal swabs in healthy army trainees. From January 2018 to March 2018, one MRSA strain was isolated from nasal swab and hand of healthy army trainees. mecA gene detection, SCCmec and mec complex typing were performed to analyze the antimicrobial resistance patterns and molecular epidemiological characteristics of MRSA isolates. As a result, SCCmec and mec complex type of MRSA isolate from military trainees was not-typeable (n=1). In conclusion, not-typeable subtype of MRSA isolate from military trainees need to be confirmed by continuous follow-up study to determine whether there is a different genotype or a new subtype of genotype present in the Republic of Korea.

• Journal of Veterinary Science
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• 제23권6호
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• pp.12.01-12.10
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• 2022

Background: Staphylococcus aureus and Streptococcus agalactiae are the main cause of clinical mastitis in dairy cattle in Argentina, whereas coagulase-negative staphylococci (CNS) and environmental streptococci are the main cause of subclinical mastitis. Bacteria isolated from infected animals show increasing antimicrobial resistance. Objectives: This study aims to determine the antimicrobial resistance of staphylococci and streptococci isolated from milk with mastitis, and to genotypically characterize the methicillin-resistant (MR) staphylococci. Methods: Isolation was performed on blood agar and identification was based on biochemical reactions. Antimicrobial susceptibility was according to the Clinical and Laboratory Standards Institute guidelines. The antimicrobial resistance genes, SCCmec type and spa type were detected by the polymerase chain reaction method. Results: We isolated a total of 185 staphylococci and 28 streptococci from 148 milk samples. Among the staphylococcal isolates, 154 were identified as CNS and 31 as S. aureus. Among the 154 CNS, 24.6% (n = 38) were resistant to penicillin, 14.9% (n = 23) to erythromycin, 17.5% (n = 27) to clindamycin, 6.5% (n = 10) to cefoxitin and oxacillin. Among the S. aureus isolates, 16.1% (n = 5) were resistant to penicillin, 3.2% (n = 1) to cefoxitin and oxacillin (MRSA). Six MR isolates (5 CNS and 1 MRSA) were positive to the mecA gene, and presented the SCCmec IVa. The MRSA strain presented the sequence type 83 and the spa type 002. Among the 28 streptococcal isolates, 14.3% (n = 4) were resistant to penicillin, 10.7% (n = 3) to erythromycin and 14.3% (n = 4) to clindamycin. Conclusions: The present findings of this study indicate a development of antimicrobial resistance in main bacteria isolated from cows with mastitis in Argentina.

• Journal of Microbiology and Biotechnology
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• 제20권4호
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• pp.775-778
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• 2010

A total of 2,858 meat samples collected during 2003-2008 in Korea were investigated, and methicillin-resistant Staphylococcus aureus (MRSA) isolates were isolated from 1.0% (9/890) of beef, 0.3% (4/1,055) of pork, and 0.3% (3/913) of chicken meat samples, respectively. MRSA isolates showed the two sequence types (STs), ST72 from beef and pork and ST692 from chicken meat. MRSA isolates from beef and pork were Panton-Valentine leukocidin-negative, staphylococcal cassette chromosome mec type IVa strain with ST72, which is the most prevalent type of communityacquired MRSA in Korea. An identical pulse-field gel electrophoresis pattern was detected among 10 of 16 MRSA isolates: 9 strains from beef (n=5) and pork (n=4) in 2008, and one strain from beef in 2005.

• 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.