Community-acquired methicillin-resistant Staphylococcus aureus: community transmission, pathogenesis, and drug resistance

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA) is able to persist not only in hospitals (with a high level of antimicrobial agent use) but also in the community (with a low level of antimicrobial agent use). The former is called hospital-acquired MRSA (HA-MRSA) and the latter community-acquired MRSA (CA-MRSA). It is believed MRSA clones are generated from S. aureus through insertion of the staphylococcal cassette chromosome mec (SCCmec), and outbreaks occur as they spread. Several worldwide and regional clones have been identified, and their epidemiological, clinical, and genetic characteristics have been described. CA-MRSA is likely able to survive in the community because of suitable SCCmec types (type IV or V), a clone-specific colonization/infection nature, toxin profiles (including Pantone-Valentine leucocidin, PVL), and narrow drug resistance patterns. CA-MRSA infections are generally seen in healthy children or young athletes, with unexpected cases of diseases, and also in elderly inpatients, occasionally surprising clinicians used to HA-MRSA infections. CA-MRSA spreads within families and close-contact groups or even through public transport, demonstrating transmission cores. Re-infection (including multifocal infection) frequently occurs, if the cores are not sought out and properly eradicated. Recently, attention has been given to CA-MRSA (USA300), which originated in the US, and is growing as HA-MRSA and also as a worldwide clone. CA-MRSA infection in influenza season has increasingly been noted as well. MRSA is also found in farm and companion animals, and has occasionally transferred to humans. As such, the epidemiological, clinical, and genetic behavior of CA-MRSA, a growing threat, is focused on in this study.

Evolution and virulence of Panton-Valentine leukocidin-positive ST30 methicillin-resistant Staphylococcus aureus in the past 30 years in Japan

“…CA-MRSA (34,37,38). In this study, we investigated PVL-positive ST30 MRSA since the 1980s in Japan focusing on its evolution and virulence.…”

Necrotizing Pneumonia in the Community

“…However, the role of PVL in necrotizing lesion development is still controversial (9), and is probably due to the species-specific susceptibility of neutrophils to the lytic effects of PVL (10). The prevalence of the PVL genes varies geographically (3,11). MRSA containing the PVL genes comprises 0.1% of MRSA isolates that have been collected in hospitals in Japan (12).…”

“…MRSA containing the PVL genes comprises 0.1% of MRSA isolates that have been collected in hospitals in Japan (12). Although there has been no large study conducted in Japan, it is thought that the prevalence of the PVL genes is significantly lower in Japan than in the USA (11,13). Most of the reported Japanese cases of CA-MRSA were not severe and included skin infections.…”

Relationship between antibiotic consumption, oropharyngeal colonization, and ventilator-associated pneumonia by Staphylococcus aureus in an intensive care unit of a Brazilian teaching hospital

“…In studies of intensive-care patients, ORSA colonizes the throat more frequently than it does either the nose or the groin/axilla [25][26][27][28] , and nasal colonization with ORSA is a poor predictor for the subsequent occurrence of ORSA lower respiratory tract infections that require antimicrobial treatment 29 . On the other hand, there is less information on the etiopathogenesis for the development of VAP by ORSA.…”