• 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.

• Pediatric Infection and Vaccine
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• 제16권1호
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• pp.1-5
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• 2009

Methicillin-resistant Staphylococcus aureus (MRSA), a leading cause of nosocomial infections, has been increasingly recognized in communities of the United States. This article will review the clinical spectrum and treatment of MRSA infections in children in the context of recent epidemiological changes of MRSA infections. In general, community-associated (CA) MRSA most frequently causes skin and soft tissue infections and has an increased association with invasive infections, particularly pneumonia and musculoskeletal infections. Hospital-associated (HA) MRSA strains tend to be associated with bloodstream infections, pneumonia, and surgical site infections. Different from the United States, CA-MRSA infections are not common in Korea (only 5.9%); however, there are some CA-MRSA clones that are different from HA-MRSA clones in Korea and from CA-MRSA clones in other countries. The treatment of MRSA infections should be guided by antimicrobial susceptibility testing, the site of infection, and the infection severity. Vancomycin is the treatment of choice for invasive MRSA infections. Other agents such as trimethoprim-sulfamethoxazole, clindamycin, linezolid, quinupristin-dalfopristin, and daptomycin have been used for some conditions.

• 대한의생명과학회지
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• 제27권4호
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• pp.195-207
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• 2021

Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterial pathogen capable of causing human diseases, such as soft tissue infection, bacteremia, endocarditis, toxic shock syndrome, pneumonia, and sepsis. Although the incidence rate of diseases caused by MRSA has declined in recent years, these diseases still pose a clinical threat due to their consistently high morbidity and mortality rates. However, the role of virulence factors in staphylococcal infections remains incompletely understood. Methicillin resistance, which confers resistance to all β-lactam antibiotics in cellular islets, is mediated by the mecA gene in the staphylococcal cassette chromosome mec (SCCmec). Differences in SCCmec types and differences in their sizes and structures serve epidemiological purposes and are used to differentiate between hospital-associated (HA)-MRSA and community-associated (CA)-MRSA. Some virulence factors of S. aureus are also providing a distinction between HA-MRSA and CA-MRSA. These factors vary depending on the presence of toxins, adhesion, immune evasion, and other virulence determinants. In this review, we summarized an overview of MRSA such as resistance mechanisms, SCCmec types, HA- and CA-MRSA, and virulence factors that enhance pathogenicity or MRSA epidemiology, transmission, and genetic diversity.

• Tuberculosis and Respiratory Diseases
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• 제80권2호
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• pp.201-209
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• 2017

Background: Methicillin-resistant Staphylococcus aureus (MRSA) infection is a severe and life-threatening disease in patients with community-onset (CO) pneumonia. However, the current guidelines lack specificity for a screening test for MRSA infection. Methods: This study was retrospectively conducted in elderly patients aged ${\geq}65years$, who had contracted CO-pneumonia during hospitalization at the Jeju National University Hospital, between January 2012 and December 2014. We analyzed the risk factors of MRSA in these patients and developed a scoring system to predict MRSA infection. Results: A total of 762 patients were enrolled in this study, including 19 (2.4%) with MRSA infection. Healthcare-associated pneumonia (HCAP) showed more frequent MRSA infection compared to community-acquired pneumonia (4.4% vs. 1.5%, respectively; p=0.016). In a multivariate logistic regression analysis, admissions during the influenza season (odds ratio [OR], 2.896; 95% confidence interval [CI], 1.022-8.202; p=0.045), chronic kidney disease (OR, 3.555; 95% CI, 1.157-10.926; p=0.027), and intensive care unit admission (OR, 3.385; 95% CI, 1.035-11.075; p=0.044) were identified as predictive factors for MRSA infection. However, the presence of HCAP was not significantly associated with MRSA infection (OR, 1.991; 95% CI, 0.720-5.505; p=0.185). The scoring system consisted of three variables based on the multivariate analysis, and showed moderately accurate diagnostic prediction (area under curve, 0.790; 95% CI, 0.680-0.899; p<0.001). Conclusion: MRSA infection would be considered in elderly CO-pneumonia patients, with three risk factors identified herein. When managing elderly patients with pneumonia, clinicians might keep in mind that these risk factors are associated with MRSA infection, which may help in selecting appropriate antibiotics.

• 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.

• Tuberculosis and Respiratory Diseases
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• 제67권5호
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• pp.409-412
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• 2009

Background: Several large outbreaks have demonstrated the threat of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) in close-contact environments, such as occurs during training and quartering of military recruits training. In South Korea, which is a hospital or healthcare-associated MRSA prevalent area, military service is compulsory for all healthy young men. We surveyed and determined the extent of CA-MRSA colonization in the upper respiratory tracts of Korean military recruits. Methods: The Korean military recruits who were enrolled in a military training facility from November 2004 to March 2005 were eligible for this study. Sputum or nasopharyngeal swap was obtained from randomly selected subjects who displayed upper respiratory tract symptoms. Results: Of the 181 participants, 32 participants (17.7%) were colonized with S. aureus, and 12 participants (6.6%) were colonized with MRSA. Among the cases that were colonized with S. aureus, 37.5% (12/32) were colonized with MRSA. Antimicrobial susceptibility testing showed resistant patterns that were suggestive of the CA-MRSA strains for all of the MRSA isolates. Conclusion: This study of Korean military recruits found a great deal of showed MRSA colonization in them, and the antimicrobial resistant profile that was suggestive of a CA-MRSA strain. Further efforts to prevent the spread of MRSA infections and careful monitoring for CA-MRSA outbreaks are warranted, especially in a high risk group such as military recruits.

• Pediatric Infection and Vaccine
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• 제16권2호
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• pp.150-161
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• 2009

목 적: 황색포도알균은 소아에서 피부 및 연부조직 감염과 침습성 감염을 일으키는 주요한 원인균이다. 최근 미국에서는 지역사회관련 메티실린 내성 황색포도알균(communityassociated MRSA, CA-MRSA)에 의한 심한 감염이 증가하는 추세로 알려졌지만, 우리나라에서는 소아에서의 황색포도알균 감염의 임상적 특성에 대한 체계적 연구 결과가 아직 없는 실정이다. 본 연구에서는 단일기관에서 경험한 소아 황색포도알균 감염을 CA-MRSA 감염을 중심으로 조사하였다. 방 법: 2004년 1월부터 2007년 12월까지 4년 동안 서울대학교 어린이병원에서 치료받은 소아로부터 분리되었던 황색포도알균의 항균제 감수성 결과 및 균주가 분리되었던 환자 429명의 후향적 의무기록을 통해 검체 부위, 병원 감염 여부, 기저질환, 면역상태, 임상 질환 및 임상 경과에 대한 자료를 분석하였다. 감염의 발생 장소와 위험인자의 유무에 따라 원내 발생(Hospital-onset, HO), 또는 지역사회 발생(community-onset, CO) 의료기관 관련 감염(healthcare-associated, HA)과 지역사회 관련 감염(community-associated, CA)로 구분하였다. 결 과: 1세 미만의 환자 206명 중에서는 HO-HA 감염이 72%, CO-HA 감염이 7%, 그리고 CA 감염이 21%였으며 1세 이상의 환자 223명 중에서는 각각 48%, 28%, 24%였다. HA감염 중 CO-HA 감염의 비율은 1세 이상 환자군에서 1세 미만에 비해 높았으며(8.6% vs. 37.1%, P <0.001), CO 감염 중 HA 감염의 비율 역시 1세 이상 환자군에서 높았다(24.5% vs.54.3%, P <0.001). 전체 분리된 균주의 57%가 MRSA였고 CA감염의 30% (29/96)가 MRSA였으며, CA-MRSA 중 가장 흔한 감염 형태는 피부 및 연조직 감염이었다. 결 론 : 지역사회에서 발생하는 감염을 일으키는 황색포도알균의 메티실린 내성율이 높으며, CA-MRSA는 피부 및 연조직 감염이 가장 흔히 일으켰다.

• 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.

• Pediatric Infection and Vaccine
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• 제18권2호
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• pp.143-153
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• 2011

목 적 : 황색포도알균의 보균율은 신생아에서 가장 높다고 알려져 있고, 황색포도알균의 보균은 곧 그 균주에 의한 감염증으로 이어질 위험이 높아진다. 본 연구에서는 신생아황달로 입원한 환아에서의 황색포도알균과 MRSA의 보균율을 조사하였고, 신생아황달의 대부분이 모유황달이나 생리적황달임을 감안하여 이를 통해 간접적으로 건강한 신생아의 황색포도알균 및 MRSA 보균율을 추정하고자 하였다. 방 법: 2006년 1월부터 2010년 12월까지 성애병원과 광명성애병원 신생아집중치료실에 황달로 입원한 환아 545명을 대상으로 하였다. 입원 첫날 멸균된 면봉으로 비강과 서혜부를 도찰하여 얻은 검체를 세균배양을 통해 황색포도알균을 동정하고 다시 항생제감수성 검사를 통해 메티실린내성 여부를 판정한 결과를 후향적으로 조사하였다. 결 과:총 545명의 환아가 본 연구에 포함되었고, 이중 318명의 비강과 서혜부에서 황색포도알균이 분리되어 보균율은 58.3%였고 214명의 환아에서는 MRSA가 분리되어 MRSA 보균율은39.3%였다. 또한 분리된 MRSA를 항생제 감수성 결과를 토대로 분석하였을 때, CA-MRSA로 추정되는 균주는 65.7% (142/216), HA-MRSA로 추정되는 균주는 34.3% (74/216)였다. 결 론: 39.3%의 MRSA 보균율로 미루어볼 때, 외부에서 전원되는 신생아를 대상으로 한 MRSA 감시배양검사는 필요하다고 생각된다. 또한, MRSA 균주 중 CA-MRSA 가능성 균주가 65.7%로 높게 나와 이미 지역내산부인과 및 분만실 등에 CA-MRSA 균주가 정착해 있을 가능성이 높다고 생각되며 이에 대한 지속적이고도 정기적인 MRSA 감시배양검사도 필요할 것으로 생각된다.

• Pediatric Infection and Vaccine
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• 제19권3호
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• pp.111-120
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• 2012

목 적 : 단일 병원 신생아입원실에 입원한 신생아를 대상으로 환자의 임상적 특징에 따른 MRSA 보균율을 알아보고, 그 기원을 추정해 보며, MRSA 보균에 영향을 미치는 요소들을 살펴보고자 하였다. 방 법 : 2008년 1월부터 2011년 12월까지 을지대학교 서울 을지병원 신생아 입원실에 입원하여 MRSA 감시배양검사를 시행받은 1,733명의 신생아를 대상으로 의무기록을 후향적으로 조사하였다. MRSA 감시배양검사는 비강, 서혜부, 직장에서 시행하였고, 퇴원 시까지 매주 반복 시행 하였다. MRSA 감시배양결과에 따라서 보균자와 비보균자로 나누었다. 결 과 : 대상환자 1,733명 중에 415명(23.9%)이 MRSA 보균자였다. 제태기간, 출생체중, 분만 방식, 분만전 산모에게 항생제 투여 여부, 출생장소, 입원전 체류 장소에 따라서 MRSA 보균율에 차이를 보였다(P<0.001). 다변량 검사에서 분만전 산모에게 예방적 항생제를 투여하지 않은 경우가 투여한 경우에 비해서 신생아가 MRSA 보균자가 될 위험도가 2.8배(OR=2.77; 95% CI, 1.88-4.07), 출생장소가 외부인 경우가 본원인 경우에 비해서 2.3배(OR=2.28; 95% CI, 1.17-4.42) 높음을 확인하였다. 결 론 : 신생아 입원환자를 대상으로 한 MRSA 보균율은 23.9%로 상대적으로 높은 보균율을 확인하였다. 환자특성을 고려하여 추정한 HA-MRSA 보균율은 51/511명(10%), CA-MRSA 보균율은 309/858명(36%) 이었다. 본병원 신생아에서 MRSA 보균과 연관된 요인은 산모의 예방적 항생제 사용여부와 출생장소임을 확인하였다.