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ST59 is the predominant pathotype of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) in China. As a variant of ST59, there is relatively little known about the detailed information of ST338. To address this issue, here, we described thirteen ST338 CA-MRSA strains isolated from severe bloodstream infection cases, and focused on their epidemiology, genetic features and virulence potential. Phylogenetic analysis showed the earliest isolated strain of this study is likely a predecessor of recent ST338 lineage (after year of 2014). Furthermore, the phylogenetic reconstruction and time estimation suggested that ST338 evolved from ST59 in 1991. Notably, the carrying patten of virulence factors of all ST338 strains were similar, and the genomic islands νSaα, νSaγ and SaPI and the core virulence factors like hla and psm were detected in ST338 isolates. However, all ST338 isolates lacked some adhesion factors such as clfA, clfB, eap, cna and icaD. Additionally, among these ST338 strains, one PVL-negative ST338 isolate was detected. Experiment on mice nose and human alveolar epithelial cell showed that the nasal colonization ability of ST338 was weaker than that of CA-MRSA MW2. In a mouse bloodstream infection model and skin infection model, PVL+ and PVL− strains had the similar virulence, which was dependent on upregulation of toxin genes rather than the presence of mobile genetic elements such as ΦSa2 carrying PVL. Our findings provide important insight into the epidemiology and pathogenicity of the novel and highly virulent ST338-SCCmec Vb clone.

Previous studies have shown that livestock (LA)-MRSA ST398 evolved from a human-adapted methicillin-susceptible S. aureus (MSSA) clone. However, detailed information regarding ST9 is still unclear. Here, we characterized a community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) ST9-SCCmec XII isolate that has not been previously reported to cause serious disease in China. We obtained whole-genome sequences of one ST9-t899-XII isolate—ZY462471—from a patient with bloodstream infection without livestock contact. The antibiotic susceptibilities of ZY462471 were determined and the clinical information was extracted from medical notes and compared with twenty-seven previously sequenced genomes. Phylogenetic reconstruction was performed to investigate the probable host evolutionary origins of ZY462471, and the difference in resistome and virulence factors were investigated. Virulence assay was performed to evaluate the high virulence potential of ZY462471 and compare the virulence between the closest ST9 MSSA neighbours. Clinical data suggested that ZY462471 is a CA-MRSA. Phylogenetic analysis showed a much closer relationship of ZY462471 with human-associated MSSA ST9 isolates than other LA-MRSA ST9 isolates, suggesting that ZY462471 probably evolved from ST9 MSSA predecessors by acquiring an SCCmec cassette. Importantly, virulence assays indicated that ZY462471 was highly virulent and compared with the MSSA ST9 predecessors, ZY462471 did not show attenuated virulence. Finally, we found that ZY462471 harboured an immune evasion cluster (IEC)-carrying βC-Φ, which is typically found in human clinical S. aureus rather than LA-MRSA isolates, suggesting that ZY4762471 obtained the IEC-carrying βC-Φs from human clinical S. aureus strains. Considering its high virulence potential, this strain should be monitored to prevent more widespread dissemination.

Community-associated, methicillin-resistantStaphylococcus aureus(MRSA) lineages have emerged in many geographically distinct regions around the world during the past 30 years. Here, we apply consistent phylodynamic methods across multiple community-associated MRSA lineages to describe and contrast their patterns of emergence and dissemination. We generated whole genome sequencing data for the Australian sequence type (ST) 93-MRSA-IV from remote communities in Far North Queensland and Papua New Guinea, and the Bengal Bay ST772-MRSA-V clone from metropolitan communities in Pakistan. Increases in the effective reproduction number (Re) and sustained transmission (Re> 1) coincided with spread of progenitor methicillin-susceptibleS. aureus(MSSA) in remote northern Australia, dissemination of the ST93-MRSA-IV geno-type into population centers on the Australian East Coast, and sub-sequent importation into the highlands of Papua New Guinea and Far North Queensland. Analysis of a ST772-MRSA-V cluster in Pakistan suggests that sustained transmission in the community following importation of resistant genotypes may be more common than previously thought. Applying the same phylodynamic methods to existing lineage datasets, we identified common signatures of epidemic growth in the emergence and epidemiological trajectory of community-associatedS. aureuslineages from America, Asia, Australasia and Europe. Surges in Rewere observed at the divergence of antibiotic resistant strains, coinciding with their establishment in regional population centers. Epidemic growth was also observed amongst drug-resistant MSSA clades in Africa and northern Australia. Our data suggest that the emergence of community-associated MRSA and MSSA lineages in the late 20th century was driven by a combination of antibiotic resistant genotypes and host epidemiology, leading to abrupt changes in lineage-wide transmission dynamics and sustained transmission in regional population centers.

Background The global emergence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has seen the dominance of specific clones in different regions around the world with the PVL-positive ST93-IV as the predominant CA-MRSA clone in Australia. In this study we applied a genome-wide association study (GWAS) approach on a collection of Australian ST93-IV MRSA genomes to identify genetic traits that may have assisted the ongoing transmission of ST93-IV in Australia. We also compared the genomes of ST93-IV bacteraemia and non-bacteraemia isolates to identify potential virulence factors associated with bacteraemia.Results Based on single nucleotide polymorphism phylogenetics we identified two distinct ST93-IV clades circulating concurrently in Australia. One of the clades contained isolates primarily isolated in the northern regions of Australia whilst isolates in the second clade were distributed across the country. Analyses of the ST93-IV genome plasticity over a 15-year period (2002-2017) revealed an observed gain in accessory genes amongst the clone’s population. The GWAS analysis on the bacteraemia isolates identified two genes that have also previously been associated to this kind of infection. Conclusions The emergence of a ST93-IV clade containing additional virulence genes may explain the high prevalence of ST93-IV infections amongst the indigenous population living in the northern regions of Australia. In summary, this study has shown ST93-IV is evolving with multiple additional genes possibly contributing to its dominance in the Australian community.

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is threatening public health as it spreads worldwide across diverse environments. Its genetic hallmark, the mecA gene, confers resistance to many β-lactam antibiotics. Here, we show that, in addition, mecA provides a broad selective advantage across diverse chemical environments. Competing fluorescently labelled wild-type and mecA-deleted CA-MRSA USA400 strains across ~57,000 compounds supplemented with subinhibitory levels of the β-lactam drug cefoxitin, we find that mecA provides a widespread advantage across β-lactam and non β-lactam antibiotics, non-antibiotic drugs and even diverse natural and synthetic compounds. This advantage depends on the presence of cefoxitin and is strongly associated with the compounds’ physicochemical properties, suggesting that it may be mediated by differential compounds permeability into the cell. Indeed, mecA protects the bacteria against increased cell-envelope permeability under subinhibitory cefoxitin treatment. Our findings suggest that CA-MRSA success might be driven by a cell-envelope mediated selective advantage across diverse chemical compounds., The mecA gene confers resistance to many β-lactam antibiotics in community-associated MRSA bacteria. Here, Snitser et al. show that mecA also provides broad selective advantage across diverse chemical environments in the presence of subinhibitory β-lactam concentrations, by protecting the bacteria against increased cell-envelope permeability.

Background : Over the past few decades, methicillin-resistant Staphylococcus aureus (MRSA) has become a major cause of nosocomial infection and has recently emerged in the community. Community associated MRSA (CA-MRSA) have grown drastically over the years and have mostly manifested as a form of skin infection. The MRSA infection usually occurs in individuals with skin lesions serving as a site of entry for the bacteria. The aim of this study was to determine if MRSA is presence on the acne extractor used by some beauty salons in Jatinangor. Methods : A total of 40 samples were taken from 14 beauty salons in Jatinangor from September to October 2013. The samples were then cultured on mannitol salt agar. The isolated colonies were then gram stained, followed by catalase and coagulase test. The colonies having positive for Staphylococcus aureus (S. aureus) were then tested for cefoxitin susceptibility. Results : Overall 3 of the isolates were positive for S. aureus and none were positive for MRSA. Conclusions : Only a small fraction of the isolates are positive for S. aureus and no MRSA is detected.. [AMJ.2017;4(1):64–8] DOI : 10.15850/amj.v4n1.163

Community-associated MRSA (CA-MRSA) represents a global epidemic which beautifully encapsulates the fascinating ability of bacterial organisms to adapt quickly on an evolutionary basis to the extreme selective pressure of antibiotic exposure. In stark contrast to Healthcare-associated MRSA (HA-MRSA), it has become apparent that CA-MRSA is less straight forward of a challenge in terms of controlling its transmission, and has forced clinicians to adjust empiric management of clinical syndromes such as skin and soft tissue infection (SSTI) as well as pneumonia.This review details the history and epidemiology of CA-MRSA, while covering both current and future treatment options that are and may be available to clinicians. The authors reviewed both historic and more recent literature on this ever-evolving topic.While development of new anti-MRSA agents should be encouraged, the importance of antimicrobial stewardship in the battle to stay ahead of the curve with regards to the ongoing control of the MRSA epidemic should be emphasised.

This study investigated the prevalence of MRSA in samples taken in households, with and without backyard pigs in villages in a rural area of Shandong Province, China. Community-associated MRSA and livestock-associated MRSA, belonging to ST59 and ST9, respectively, were identified in both humans and pigs. The genotypic and phenotypic comparison of isolates indicates that bidirectional transmission of MRSA has occurred between humans and pigs in the villages.

Sam Abraham, Stephen Jagoe, Stanley Pang, Geoffrey W.Coombs, Mark O'Dea, Jonathon Kelly, Manouchehr Khazandi, Kiro R.Petrovski, Darren J.Trott

More than half a century has passed since MRSA emerged in the world, and the characteristic nature of MRSA keeps changing. Initially healthcare-associated MRSA prevailed in hospital and healthcare facilities, and thereafter community-associated MRSA emerged and spread in communities. Reports of severe case infection by CA-MRSA are gradually increasing in Japan. Now MRSA can be classified into 11 types according to its staphylococcal cassette chromosome (SCCmec) type. Together with the variety of virulence gene repertoire, clinically important MRSA is the group with diverse genotypes. In this chapter, we focused on CA-MRSA and summarized its history, diversity, and virulence factors.

Methicillin-resistant Staphylococcus aureus (MRSA) is a common hospital pathogen, but now its prevalence in the community is increasing. Community-associated MRSA (CA-MRSA) is the causative agent in many outpatient skin and soft tissue infections. Within the women's health population, CA-MRSA infection can result in a variety of genital skin infections, including boils, furuncles, and abscesses. Antibiotic-resistant strains, reinfection, and transmission among close contacts contribute to difficulty in controlling the spread of this pathogen. This article provides an overview of CA-MRSA, its clinical presentation, diagnosis, treatment, and implications for clinical practice in women's healthcare settings.

There is evidence of a growing incidence of resistant microorganisms in the United States, and nurse practitioners (NPs) are in a pivotal position to lead in the delivery of health care related to this problem. Recently, the incidence of community-associated methicillin-resistant Staphylococcus aureus has increased, which requires urgent attention to safe practice and prevention. Because this is a relatively new public health problem, the evidence to support management is evolving. NPs are positioned to examine the evidence and incorporate findings into practice.

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) emerged unexpectedly in the 1990s and is now a problem worldwide. CA-MRSA is epidemic in the United States and is the most common cause of community-associated bacterial infections. Here, we provide a basic overview of CA-MRSA epidemiology and discuss molecules that contribute to the enhanced virulence phenotype of this pathogen.

Community-associated MRSA (CA-MRSA) strains have rapidly emerged worldwide as a cause of skin and soft tissue infections and occasionally severe disease. Although there have been relatively few reports from the UK, it is clear that the incidence of CA-MRSA infections is rising. Several distinct clonal CA-MRSA lineages have been identified causing infections in individuals both in the community and in UK hospitals. Their prevalence is likely to be considerably higher than reported. In this review article we clarify the terminology and definitions used for CA-MRSA, detail their emergence, and summarise the available information regarding their current epidemiology and clinical impact in the UK. We discuss management and preventative strategies, highlight limitations in existing surveillance and the future challenges posed by CA-MRSA in the UK.

Introduction In today's world of medicine, the state of the art for diagnosis has reached levels of accuracy never dreamed. Nevertheless, diagnostic error still is encountered frequently. Regardless of whether the diagnosis is made based on clinical evaluation, imaging, or laboratory studies, when the diagnosis is wrong, patient injury can result. This report describes a case of methemoglobinemia after starting dapsone for a presumed spider bite.

The recent emergence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) marked a quantum change in the biology and epidemiology of a major human pathogen. Various virulence determinants unique to CA-MRSA have been uncovered recently, which shed light on how these strains spread easily and sustainably among humans and frequently cause severe disease. The role of the Panton Valentine leukocidin (PVL) in CA-MRSA pathogenesis is a matter of much debate. Although epidemiological data have indicated a role for PVL in the CA-MRSA disease process, recent data from relevant animal models indicate that PVL does not impact virulence of prevalent CA-MRSA strains. Identifying specialized pathogenic traits of CA-MRSA remains a challenge that will yield new diagnostic tools and therapeutic targets for drug and vaccine development. Here, we discuss the roles of PVL, the arginine catabolic mobile element and phenol-soluble modulins in the pathogenesis of prevalent CA-MRSA strains.

B Cherie Millar, Anne Loughrey, Richard Bill and John E Moore investigate the prevalence of community-associated MRSA and infection prevention measures health professionals should practise

Community-associated strains of methicillin-resistant Staphylococcus aureus (CA-MRSA) have recently emerged as a major cause of serious infections among older children and are now being seen in NICU patients. We present the case of a preterm infant with CA-MRSA necrotizing pneumonia and secondary bacteremia.

While the potential for a devastating influenza pandemic has captured the imagination of the medical community and the population at large, another epidemic is currently raging in the United States and has already made inroads in Canada.[1][1] Clones of community-associated methicillin-resistant

Laypeople and health care professionals alike recognize Staphylococcus aureus as an important cause of disease and understand that antibiotic-resistant strains pose a threat to the community. Before the availability of antibiotics, invasive staphylococcal disease was often fatal, and the introduction of penicillin in the 1940s dramatically improved survival. Although penicillinase-producing strains soon emerged, methicillin and other penicillinase-stable β-lactam agents filled the breach. However, methicillin-resistant strains of S. aureus (MRSA), which are resistant to the entire class of β-lactam agents, were identified almost immediately and are now found in hospitals worldwide. Despite the growing prevalence of MRSA in hospitals, these strains . . .

However, owing to the absence of evidence for the, so far, elusive molec -ular mechanisms that are involved, the existence of nonheterogeneous, functionally oxacillin-sus -ceptible (OS)-MRSA strains, even carrying the mecA gene, could also be anticipated.In fact, during the last decade, reports of OS-MRSA isolates have increasingly appeared in the literature. These reports involved geo-graphically distant regions worldwide, including Germany, Japan, USA, Taiwan, India, Argentina, the UK and Greece. In an interesting study con -ducted between 1995 and 1996, seven out of 447 healthcare workers from three German hospitals were shown to be carrying OS-MRSA isolates, while only three of them carried true MRSA iso -lates, indicating that healthcare workers may be a silent reservoir of ‘dormant’ MRSA

Background Therapy for Staphylococcal infections may be complicated by the possibility of inducible macrolide-lincosamide-streptogramin B resistance (MLSBi). We studied the prevalence of MLSBi in community associated (CA) and hospital associated (HA) Staphylococcus aureus isolates from clinical samples. Methods A total of 305 strains of S. aureus comprising 140 (45.9%) [95% CI 40.36–51.52] methicillin resistant S. aureus (MRSA) and 165 (54%) [95% CI 48.48–59.64] methicillin-sensitive S. aureus (MSSA) were identified by conventional methods. The double disc test (D test) was applied by placing erythromycin and clindamycin discs to investigate inducible and constitutive MLSBi resistant phenotypes. Results 16.6% of MRSA showed constitutive resistance and 37.5% inducible MLSBi resistance. Community associated MRSA (CA-MRSA) represented 10% of all isolates and had lower prevalence of MLSBi than hospital associated MRSA (HA-MRSA). Conclusion Routine screening for inducible MLSBi resistance by double disc test can screen for potential treatment failures such that clindamycin can be used effectively and judiciously when indicated for staphylococcal infections especially for treating skin and soft tissue infections (SSTIs) in CA-MRSA due to low prevalence of MLSBi among CA-MRSA.

Objective To describe the changing prevalence of healthcare- and community-associated MRSA. Methods Susceptibility phenotypes of MRSA were observed from 2000 to 2012 using routine susceptibility data. Phenotypic definitions of major clones were validated by genotyping isolates from a nested period prevalence survey in 2011. Results The predominant healthcare-associated (AUS-2/3 like) MRSA phenotype decreased from 42 to 14 isolates per million occasions of service in outpatients (P < 0.0001) and from 650 to 75 isolates per million accrued patient days in inpatients (P 0.0005), while the respective rates of the healthcare-related EMRSA-15 like phenotype increased from 1 to 19 in outpatients (P < 0.0001) and from 11 to 83 in inpatients (P < 0.0001) and those of the community-associated MRSA phenotype increased from 17 to 296 in outpatients (P < 0.0001) and from 71 to 486 in inpatients (P < 0.0001). When compared with single nucleotide polymorphism genotyping the AUS-2/3 like phenotype had a sensitivity and positive predictive value (PPV) for CC239 of 1 and 0.791 respectively, while the EMRSA-15 like phenotype had a sensitivity and PPV for CC22 of 0.903 and 0.774. PVL-positive CA-MRSA, predominantly ST93 and CC30, accounted for 60.8% of MRSA, while PVL-negative CA-MRSA, mainly CC5 and CC1, accounted for 21.4%. Conclusions The initially dominant healthcare-associated MRSA clone has been progressively replaced, mainly by four community-associated lineages.

The predominant community-associated MRSA strains vary between geographic settings, with ST8-IV USA300 being the commonest clone in North America, and the ST30-IV Southwest Pacific clone established as the dominant clone in New Zealand for the past two decades. Moreover, distinct epidemiological risk factors have been described for colonisation and/or infection with CA-MRSA strains, although these associations have not previously been characterized in New Zealand. Based on data from the annual New Zealand MRSA survey, we sought to describe the clinical and molecular epidemiology of MRSA in New Zealand. All non-duplicate clinical MRSA isolates from New Zealand diagnostic laboratories collected as part of the annual MRSA survey were included. Demographic data was collected for all patients, including age, gender, ethnicity, social deprivation index and hospitalization history. MRSA was isolated from clinical specimens from 3,323 patients during the 2005 to 2011 annual surveys. There were marked ethnic differences, with MRSA isolation rates significantly higher in Māori and Pacific Peoples. Over the study period, there was a significant increase in CA-MRSA, and a previously unidentified PVL-negative ST5-IV spa t002 clone replaced the PVL-positive ST30-IV Southwest Pacific clone as the dominant CA-MRSA clone. Of particular concern was the finding of several successful and virulent MRSA clones from other geographic settings, including ST93-IV (Queensland CA-MRSA), ST8-IV (USA300) and ST772-V (Bengal Bay MRSA). Ongoing molecular surveillance is essential to prevent these MRSA strains becoming endemic in the New Zealand healthcare setting.

The control and prevention of meticillin-resistant Staphylococcus aureus (MRSA) is a major challenge for healthcare establishments, especially as this pathogen continues to evolve. The emergence and spread of community associated MRSA producing Panton-Valentine leukocidin (PVL) causing severe, sometimes fatal, infections in otherwise healthy people is a significant cause of concern. Patient screening to detect MRSA is now widely used as part of an effective control program to limit the spread of this pathogen. Real-time PCR targeting specific MRSA markers offers a rapid alternative to conventional methods enabling earlier intervention, such as patient isolation and decolonization treatment. Herein we describe a multiplex real-time assay that combines primers and probes to detect MRSA and the genes for PVL to provide a rapid and informative assay.

Community-associated MRSA differs from the better known healthcare-associated MRSA.

To the Editor: I read the article by Frei et al[1][1] with great interest and would like to emphasize the important role of incision and drainage (I&D) for management of skin and soft tissue infection (SSTI) caused by community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA). As a

Healthcare and community associated MRSA are meanwhile exchanged in all directions between hospitals, long-term care facilities, nursing homes, and the community. This article is focusing on the situation concerning MRSA, but the situation concerning other multidrug-resistant (MDR) pathogens such as vancomycin-resistant enterococci or MDR Gram-negative pathogens is similar. Some European countries have started national campaigns to improve the situation significantly. They require the successful cooperation between healthcare facilities, public health authorities, health insurances, quality management and patient safety organizations, educational facilities, the public, and the veterinarian sector. These activities in the society need scientific data to provide evidence for the intervention measures and support their implementation. To really support the activities in the society, intervention studies are urgently needed to provide a more robust basis for decisions to improve the situation.