Reserch Progress of USA300 Clone of Community-Associated Methicillin-Resistant Staphylococcus Aureus / 现代检验医学杂志

Community associated methicillin-resistant Staphylococcus aureus is a human pathogen.It can cause a series of infections cause morbidity and mortality,including bacteremia,pneumonia and soft tissue infections.USA300 clone is highly toxic and contagious.Its prevalence in the United States continues to rise,and has begun to spread to the rest of the world.This article briefly reviews the recent research on relevant aspects of molecular epidemiological characteristics,grug resistance mechanisms and treatment of USA300 clone.

Multicenter study on the molecular characteristics of community-associated Methicillin-resistant Staphylococcus aureus in children with skin and soft tissue infection / 中华实用儿科临床杂志

Objective To explore the molecular characteristics of community-associated Methicillin-resistant Staphylococcus aureus (CA-MRSA) from children with skin and soft tissue infection (SSTIs) in China.Methods CA-MRSA was collected from the outpatients in Department of Dermatology in 13 Children's Hospitals of China.Genotypic characteristics of CA-MRSA isolates were tested by adopting mnltilocus sequence typing (MLST),staphylococcal protein A (spa) typing and Staphyloccoccal cassette chromosome mec (SCCmec) typing.And the presence of Panton-Valentine leukocidin genes(pvl) was determined also.Results Overall,1 705 strains of Staphylococcus aureus were isolated from SSTIs children,and CA-MRSA accounted for 2.6％ (44/1 705 strains).Two types of SCCmec were detected in all the CA-MRSA strains,and the main types were SCCmec Ⅳ and SCCmec Ⅴ,accounting for 45.5 ％ (20/44 strains) and 54.5 ％ (24/44 strains),respectively.Thirteen MLST types (STs) and 15 spa types were detected among CA-MRSA.The most prevalent MLST was ST121 (18/44 strains,40.9％),followed by ST59 (9/44 strains,20.5％).Additionally,t437 was predominant,accounting for 40.9％ (18/44 strains).ST121 strain had 8 spa types,and t2086 was the most common type (6/18 strains,33.3％);while ST59 had only 1 spa type,t437.No ST121,ST59 and t437 strains were found in Central and Eastern region of China.Only 4 (9.1％) of the 44 CA-MRSA strains harbored pvl genes which were all from Southern region.Conclusions The most common clone of SSTIs CA-MRSA in children is MRSA-ST121-SCCmec Ⅳ/Ⅴ,as the molecular epidemiology of CA-MRSA strain has changed,ST121 has replaced ST59 to become the main epidemic strains.

Molecular epidemiology of methicillin resistant staphylococcus aureus colonizing the anterior Nares of school children of Udupi Taluk.

Context: Community associated methicillin resistant Staphylococcus aureus (CA‑MRSA) cause serious skin and soft tissue infections including necrotizing fasciitis and necrotizing pneumonia. Production of Panton Valentine Leucocidine (PVL) toxin is implicated in its enhanced virulence. A variant of epidemic MRSA‑15 (EMRSA‑15) which produces PVL toxin has been isolated and characterized by pulsed-field gel electrophoresis (PFGE) method from the Indian population both in hospital and community settings. Aims: Identify the epidemiological type of MRSA colonizing the anterior nares of school children in Udupi taluk. Settings and Design: The study population included children of the age group of 5-16 years belonging to the Udupi taluk of Karnataka, India. A total of 1503 children were screened for MRSA colonization during July 2009 to December 2010. Materials and Methods: PVL assay, Staphylococcal Cassette Chromosome (SCC) mec typing and PFGE typing were carried out with all the MRSA isolates. Statistical Analysis Used: Frequency distribution of different variables was assessed by SPSS. Results: Among the 1.1% of MRSA, 58.8% (10/17) of isolates were positive for pvl and 41.7% (7/17) were identified as SCC mec type IV. PFGE patterns of all the strains were identical with Indian variant EMRSA‑15; however they were different from classical EMRSA‑15 in 3-4 bands. Conclusions: The Indian variant EMRSA‑15 gains much epidemiological relevance owing to the acquisition of pvl gene. In spite of low prevalence of nasal colonization of MRSA, emergence of the virulent Indian variant EMRSA‑15 in our community is a worrisome fact to be reckoned with.

Progress of virulence determinants in community-associated methicillin-resistant staphylococcus aureus / 国际儿科学杂志

Methicillin-resistant staphylococcus aureus (MRSA) remains a prominent human pathogen.Traditionally, MRSA infections occurred exclusively in hospitals and were limited to immunocompromised patients or individuals with predisposing risk factors. However, recently there has been a worldwide epidemic caused by community-associated (CA)-MRSA strains, which can cause severe infections that can result in necrotizing fasciitis or even death in otherwise healthy children or adults outside of healthcare settings. People have made great progress to explain the reasons for enhanced virulence of CA-MRSA, here we review the recent progress made towards four virulence determinants, which are Panton-Valentine leukocidin (PVL), α-Hemolysin (Hla),α-type phenol-soluble modulin ( PSMα) and arginine catabolic mobile element (ACM E) .

Incidence of Community-associated Methicillin-resistant Staphylococcus aureus Infections in a Regional Hospital / Journal of Rural Medicine

<b>Background and Objective:</b> Since the early 2000s, the incidence of methicillin-resistant <i>Staphylococcus aureus</i> (MRSA) infections among the community of people lacking known healthcare risk factors has increased. This MRSA infection is referred to as community-associated MRSA (CA-MRSA) infection and is distinct from hospital-associated MRSA (HA-MRSA) infection, which occurs among people with known healthcare risk factors. Understanding the epidemiology of CA-MRSA infections is critical; however, this has not been investigated in detail in Japan. Our objective was to investigate the incidence of CA-MRSA infections in a regional hospital. <BR><b>Patients and Methods:</b> We investigated CA-MRSA isolates and infections in a rural regional hospital by reviewing medical records of one year. Infections were classified as CA-MRSA if no established risk factors were identified. <BR><b>Results:</b> During 2008, 31 <i>Staphylococcus aureus</i> (<i>S. aureus</i>) isolates were detected in 29 unique patients, with 1 methicillin-sensitive <i>S. aureus</i> (MSSA) isolates obtained from 19 patients (66%) and MRSA obtained from 10 patients (34%). In the 10 patients with MRSA, the number of HA-MRSA and CA-MRSA cases were nine (32% of patients with <i>S. aureus</i> isolates) and one (3%), respectively. The patient with CA-MRSA was diagnosed with cellulitis due to CA-MRSA. All nine patients with HA-MRSA exhibited colonization. <BR><b>Conclusion:</b> We observed a CA-MRSA case in a regional hospital in Japan, suggesting that incidence trends of CA-MRSA should be considered in future research and treatment.

Two Cases of Bacteremia Caused by Community-Associated Methicillin-Resistant Staphylococcus aureus / 감염과화학요법

Recent reports have described an increasing incidence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) in patients who do not exhibit established risk factors for healthcare exposure. We report two cases of CA-MRSA bacteremia complicated by vertebral osteomyelitis. Both of CA-MRSA isolates were resistant to beta-lactam agents, but susceptible to clindamycin, trimethoprim-sulfamethoxazole, gentamicin, ciprofloxacin, and tetracycline. Both isolates carried staphylococcal cassette chromosome mec (SCCmec) type IVA, and were identified as sequence type (ST) 72 by mlultilocus sequence typing (MLST). However, the Panton-Valentine leukocidin (PVL) gene was not identified.

Two Cases of Bacteremia Caused by Community-Associated Methicillin-Resistant Staphylococcus aureus / 감염과화학요법

Recent reports have described an increasing incidence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) in patients who do not exhibit established risk factors for healthcare exposure. We report two cases of CA-MRSA bacteremia complicated by vertebral osteomyelitis. Both of CA-MRSA isolates were resistant to beta-lactam agents, but susceptible to clindamycin, trimethoprim-sulfamethoxazole, gentamicin, ciprofloxacin, and tetracycline. Both isolates carried staphylococcal cassette chromosome mec (SCCmec) type IVA, and were identified as sequence type (ST) 72 by mlultilocus sequence typing (MLST). However, the Panton-Valentine leukocidin (PVL) gene was not identified.

A Case of Primary Infective Endocarditis Caused by Community-Associated Methicillin-Resistant Staphylococcus aureus in a Healthy Individual and Colonization in the Family

Primary community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) endocarditis has rarely been reported in healthy individuals without risk factors, such as skin and soft tissue infections, and intravenous drug abuse. We describe a case of infective endocarditis by CA-MRSA (ST72-PVL negative-SCCmec IVA) in previously healthy individuals with no underlying medical condition and CA-MRSA colonization in the family.

Multicenter Study for Frequency and Clinical Features of Community-Associated Methicillin-Resistant Staphylococcus aureus in Korea / 감염과화학요법

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) infection has emerged in patients who do not have the established risk factors. In Korea, little is known about the epidemiology and clinical features of community-associated MRSA (CA-MRSA). MATERIAL AND METHODS: Clinical microbiology laboratory databases of 7 hospitals were reviewed to identify the patients from whom MRSA was isolated during the period of January to July 2005. Only one isolate per patient was enrolled. In order to identify the risk factors of MRSA acquisition, the medical records and the Health Insurance Review Agency databases were reviewed. CA-MRSA was defined as MRSA isolated from patient without established risk factors. We analyzed patient demographics, underlying medical conditions, characteristics of infection, and antimicrobial susceptibility profiles. RESULTS: Of total 3,251 S. aureus isolates, 1900 (58.4%) were MRSAs. Of the MRSA isolates, 114 (6.0%) were CA-MRSA. Of 114 CA-MRSA isolates, 22 (19.3%) were colonizers, 22 (19.3%) were pathogens, and the clinical significance of remaining 70 (61.4%) could not be determined. Median age of the 22 patients with CA-MRSA disease was 47 years. Nine patients had skin and soft tissue infections, 9 ear infections, 3 bacteremia, 1 septic arthritis. Seven patients had underlying medical disease. None died of the CA-MRSA infections. Of the 73 isolates of CA-MRSA, 47 (64.4%) were resistant to more than 3 classes of antibiotics besides beta-lactams. CONCLUSION: Although MRSA is highly prevalent among hospital-associated S. aureus infection, CA-MRSA infections are not common.

Multicenter Study for Frequency and Clinical Features of Community-Associated Methicillin-Resistant Staphylococcus aureus in Korea / 감염과화학요법

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) infection has emerged in patients who do not have the established risk factors. In Korea, little is known about the epidemiology and clinical features of community-associated MRSA (CA-MRSA). MATERIAL AND METHODS: Clinical microbiology laboratory databases of 7 hospitals were reviewed to identify the patients from whom MRSA was isolated during the period of January to July 2005. Only one isolate per patient was enrolled. In order to identify the risk factors of MRSA acquisition, the medical records and the Health Insurance Review Agency databases were reviewed. CA-MRSA was defined as MRSA isolated from patient without established risk factors. We analyzed patient demographics, underlying medical conditions, characteristics of infection, and antimicrobial susceptibility profiles. RESULTS: Of total 3,251 S. aureus isolates, 1900 (58.4%) were MRSAs. Of the MRSA isolates, 114 (6.0%) were CA-MRSA. Of 114 CA-MRSA isolates, 22 (19.3%) were colonizers, 22 (19.3%) were pathogens, and the clinical significance of remaining 70 (61.4%) could not be determined. Median age of the 22 patients with CA-MRSA disease was 47 years. Nine patients had skin and soft tissue infections, 9 ear infections, 3 bacteremia, 1 septic arthritis. Seven patients had underlying medical disease. None died of the CA-MRSA infections. Of the 73 isolates of CA-MRSA, 47 (64.4%) were resistant to more than 3 classes of antibiotics besides beta-lactams. CONCLUSION: Although MRSA is highly prevalent among hospital-associated S. aureus infection, CA-MRSA infections are not common.