Emergence of two populations of methicillin-resistant Staphylococcus aureus with distinct epidemiological, clinical and biological features, isolated from patients with community-acquired skin infections

Increased incidence of cutaneous Staphylococcusaureus infections after the 2010 floods in the Var department of France: Rumour or reality?

BACKGROUND

Natural disasters are typically associated with the emergence of infectious diseases. On 15 June 2010, severe storms caused flooding in the Var department (France). A rumour about increased risk of Staphylococcusaureus skin infections after bathing in the sea began to circulate on Internet a few days after the floods. The aim of this study was to compare the rumour with the true incidence of cases of infection.

METHODS

Since 1999, we have been conducting a prospective survey of S. aureus skin infections in our hospital to study their clinical, laboratory and epidemiologic features. We compared data on cases of Staphylococcus skin infection recorded in our institution from 2008 to 2012.

RESULTS

We found that there was no increase in S. aureus skin infections after the floods compared to the previous and subsequent years.

CONCLUSION

We had a unique opportunity to check the rumoured increase in incidence of infectious disease with the true incidence. In our study, the fear of S. aureus skin infections following flooding proved to be unfounded.

Reduced Susceptibility to Chlorhexidine among Staphylococcus aureus Isolates in Israel: Phenotypic and Genotypic Tolerance

Antiseptic use for body decolonization is the main activity applied to prevent healthcare-associated infections, including those caused by S. aureus. Consequentially, tolerance to several antiseptics such as chlorhexidine gluconate (CHG) has developed. This study aimed to estimate the prevalence of CHG tolerance among S. aureus strains in Israel and to evaluate factors that may affect this tolerance. Furthermore, it tested the associations between phenotypic and genotypic CHG tolerance. S. aureus strains (n = 190) were isolated from clinical samples of patients admitted to various medical institutions in Israel. Phenotypic susceptibility to CHG was assessed by determining minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Genotypic tolerance was detected using real-time PCR for detection of qac A/B genes. MIC for the antibiotic mupirocin was determined using the Etest method. Presence of the Panton-Valentine Leucocidin (pvl) toxin, mecA and mecC genes was detected using an eazyplex® MRSAplus kit (AmplexDiagnostics GmbH, Gars, Germany). CHG tolerance was observed in 13.15% of the isolates. An association between phenotypic and genotypic tolerance to CHG was observed. Phenotypic tolerance to CHG was associated with methicillin resistance but not with mupirocin resistance. Additionally, most of the CHG-tolerant strains were isolated from blood cultures. In conclusion, this work shed light on the prevalence of reduced susceptibility to CHG among S. aureus strains in Israel and on the characteristics of tolerant strains. CHG-tolerant strains were more common than methicillin-resistant ones in samples from invasive infections. Further research should be performed to evaluate risk factors for the development of CHG tolerance.

Antibiotic susceptibility profile and prevalence of mecA and lukS-PV/lukF-PV genes in Staphylococcus aureus isolated from nasal and pharyngeal sources of medical students in Ecuador

BACKGROUND

Staphylococcus aureus is a common nasal colonizer in 20-30% of the general population. When mucosal and cutaneous barriers are disrupted, S. aureus can cause severe infections. While MRSA nasal carriers have an increased risk of infections when compared to non-carriers, prolonged exposure to the hospital environment may cause an increase in carriage of MRSA.

MATERIALS AND METHODS

A survey questionnaire was filled for analyzing risk factors of colonization. Swab isolates were identified as S. aureus by traditional microbiological assays. Antibiotic susceptibility profiles were performed following the CLSI standard guidelines. Multiplex PCR was conducted to determine the presence of genes mecA and lukS-PV/lukF-PV. Chi-squared, univariate, and multivariate logistic regressions were applied to find statistically significant associations between risk factors and the presence of S. aureus and MRSA.

RESULTS

One hundred and eighty-six isolates were identified as S. aureus. The strains showed high resistance to penicillin, oxacillin, azithromycin, erythromycin, clindamycin (inducible), and tetracycline. The overall prevalence of MRSA in medical students was 45.9% [40.4-51.6] 95% CI. PCR showed a prevalence of mecA gene in MRSA isolates of 6.1% while lukS-PV/lukF-PV gene was present in 3.2% [1.2-6.9] 95% CI of the S. aureus samples. The risk factors frequency of antibiotic intake and repeated visits to hospitals demonstrated statistical significance.

CONCLUSION

S. aureus and MRSA isolates have a high prevalence of colonization, and antibiotic resistance in the population studied. MRSA resistance was not related to the presence of the mecA gene. The prevalence of PVL genes was low, but it could represent a risk because they are circulating in the community.

Recommendations for approaches to meticillin-resistant staphylococcal infections of small animals: diagnosis, therapeutic considerations and preventative measures.: Clinical Consensus Guidelines of the World Association for Veterinary Dermatology

BACKGROUND

Multiple drug resistance (MDR) in staphylococci, including resistance to the semi-synthetic penicillinase-resistant penicillins such as meticillin, is a problem of global proportions that presents serious challenges to the successful treatment of staphylococcal infections of companion animals.

OBJECTIVES

The objective of this document is to provide harmonized recommendations for the diagnosis, prevention and treatment of meticillin-resistant staphylococcal infections in dogs and cats.

METHODS

The authors served as a Guideline Panel (GP) and reviewed the literature available prior to September 2016. The GP prepared a detailed literature review and made recommendations on selected topics. The World Association of Veterinary Dermatology (WAVD) provided guidance and oversight for this process. A draft of the document was presented at the 8th World Congress of Veterinary Dermatology (May 2016) and was then made available via the World Wide Web to the member organizations of the WAVD for a period of three months. Comments were solicited and posted to the GP electronically. Responses were incorporated by the GP into the final document.

CONCLUSIONS

Adherence to guidelines for the diagnosis, laboratory reporting, judicious therapy (including restriction of use policies for certain antimicrobial drugs), personal hygiene, and environmental cleaning and disinfection may help to mitigate the progressive development and dissemination of MDR staphylococci.

Secondary bacterial infections and antibiotic resistance among tungiasis patients in Western, Kenya

Tungiasis or jigger infestation is a parasitic disease caused by the female sand flea Tunga penetrans. Secondary infection of the lesions caused by this flea is common in endemic communities. This study sought to shed light on the bacterial pathogens causing secondary infections in tungiasis lesions and their susceptibility profiles to commonly prescribed antibiotics. Participants were recruited with the help of Community Health Workers. Swabs were taken from lesions which showed signs of secondary infection. Identification of suspected bacteria colonies was done by colony morphology, Gram staining, and biochemical tests. The Kirby Bauer disc diffusion test was used to determine the drug susceptibility profiles. Out of 37 participants, from whom swabs were collected, specimen were positive in 29 and 8 had no growth. From these, 10 different strains of bacteria were isolated. Two were Gram positive bacteria and they were, Staphylococcus epidermidis (38.3%) and Staphylococcus aureus (21.3%). Eight were Gram negative namely Enterobacter cloacae (8.5%), Proteus species (8.5%), Klebsiellla species (6.4%), Aeromonas sobria (4.3%), Citrobacter species (4.3%), Proteus mirabillis(4.3%), Enterobacter amnigenus (2.1%) and Klebsiella pneumoniae (2.1%). The methicillin resistant S. aureus (MRSA) isolated were also resistant to clindamycin, kanamycin, erythromycin, nalidixic acid, trimethorprim sulfamethoxazole and tetracycline. All the Gram negative and Gram positive bacteria isolates were sensitive to gentamicin and norfloxacin drugs. Results from this study confirms the presence of resistant bacteria in tungiasis lesions hence highlighting the significance of secondary infection of the lesions in endemic communties. This therefore suggests that antimicrobial susceptibility testing may be considered to guide in identification of appropriate antibiotics and treatment therapy among tungiasis patients.

Some Virulence Factors of Staphylococci Isolated From Wound and Skin Infections in Shahrekord, IR Iran

Background:

Staphylococci release a large number of enzymes. Some of these, such as coagulase, beta- lactamase, hemolysins and biofilms are considered indices of pathogenicity.

Objectives:

The aim of the current study was based on the isolation and identification of Staphylococcus aureus and coagulase negative Staphylococci (CNS) strains from various skin lesions and examining their biofilms, beta- lactamase, hemolysins production and antibiotic resistance pattern.

Materials and Methods:

Sixty one infected wounds and 39 skin infections samples were collected and examined. After the culture and identification, examination for production of hemolysins, beta- lactamase, biofilm and susceptibility toward 9 antimicrobials was performed.

Results:

Out of 75 isolated Staphylococci, sixty (80%) were biofilm producers. Two overall prevalence of 28.5% and 100% of ß-lactamase production were recorded for isolated S. aureus and CNS, respectively. Twenty out of 49 (40.8%), the same number of α- and β- hemolytic S. aureus, were isolated while six (12.24%) were ∂ -hemolysin producers. Twenty two of Twenty six (84.6%) isolates of CNS, were hemolysin producers that all were ∂ type. The S. aureus isolates from wound infections, show a high sensitivity pattern to all examined antibiotics, this sensitivity pattern for isolates from skin dermatitis is relatively low, though.

Conclusions:

High percentage of hemolysins, biofilm and beta lactamase production by isolated Staphylococci, suggests an important role of these virulence factors in the pathogenesis of isolated Staphylococci from dermatitis lesions. The S. aureus isolates from wound infections, show a high sensitivity pattern to all examined antibiotics. Only ciprofloxacin was found to be active against all isolates from dedermatitis lesions.

Methicillin-Resistant Staphylococcus aureus Associated with Animals and Its Relevance to Human Health

Staphylococcus aureus is a typical human pathogen. Some animal S. aureus lineages have derived from human strains following profound genetic adaptation determining a change in host specificity. Due to the close relationship of animals with the environmental microbiome and resistome, animal staphylococcal strains also represent a source of resistance determinants. Methicillin-resistant S. aureus (MRSA) emerged 50 years ago as a nosocomial pathogen but in the last decade it has also become a frequent cause of infections in the community. The recent finding that MRSA frequently colonizes animals, especially livestock, has been a reason for concern, as it has revealed an expanded reservoir of MRSA. While MRSA strains recovered from companion animals are generally similar to human nosocomial MRSA, MRSA strains recovered from food animals appear to be specific animal-adapted clones. Since 2005, MRSA belonging to ST398 was recognized as a colonizer of pigs and human subjects professionally exposed to pig farming. The “pig” MRSA was also found to colonize other species of farmed animals, including horses, cattle, and poultry and was therefore designated livestock-associated (LA)-MRSA. LA-MRSA ST398 can cause infections in humans in contact with animals, and can infect hospitalized people, although at the moment this occurrence is relatively rare. Other animal-adapted MRSA clones have been detected in livestock, such as ST1 and ST9. Recently, ST130 MRSA isolated from bovine mastitis has been found to carry a novel mecA gene that eludes detection by conventional PCR tests. Similar ST130 strains have been isolated from human infections in UK, Denmark, and Germany at low frequency. It is plausible that the increased attention to animal MRSA will reveal other strains with peculiar characteristics that can pose a risk to human health.

Pulmonary infections and community associated methicillin resistant Staphylococcus aureus: a dangerous mix?

The incidence of complicated pneumonias in children is increasing with a concurrent increase in the incidence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections. CA-MRSA is distinct from hospital associated MRSA [HA-MRSA] in regards to its genotype, epidemiology, and clinical course. Unlike HA-MRSA, CA-MRSA often strikes young, previously healthy children. Pneumonias caused by CA-MRSA have a rather distinct presentation. Because of its pore-forming toxins, namely Panton-Valentine leukocidin (PVL) and alpha-hemolysin, extensive necrotizing disease with corresponding hypoxaemia and hypercarbia is common. Other features include multilobar disease, leucopenia, haemoptysis, and high mortality rates. A previous influenza-like illness or skin and soft tissue infection [SSTI] often precede the development of pneumonia due to CA-MRSA. Vancomycin is recommended as first-line empiric therapy for suspected CA-MRSA infections. However, vancomycin is not an ideal agent for the treatment of pneumonia given its poor concentrating ability in alveolar fluid. Linezolid and clindamycin have also been used in the treatment of CA-MRSA pneumonia and ongoing research is looking for alternative antimicrobials. Recent studies have continued to report a lack of correlation between nasal colonization and active infections due to CA-MRSA. Given that the role of nasal colonization in CA-MRSA infection is not clear, the utility of decolonization treatment has been a point of debate. Finally, patients with cystic fibrosis are becoming increasingly colonized with MRSA as opposed to MSSA. There is some accumulating evidence that patients with MRSA show a more rapid deterioration in their degree of obstructive disease as measured by forced expiratory volume in one second (FEV(1)). However, it still is not clear whether MRSA is a marker for worsening disease or whether it actually is a cause of disease progression in cystic fibrosis. More longitudinal data is needed to understand how MRSA colonization impacts the course of disease in cystic fibrosis.

Community-associated methicillin-resistant Staphylococcus aureus: epidemiology and clinical consequences of an emerging epidemic

Staphylococcus aureus is an important cause of skin and soft-tissue infections (SSTIs), endovascular infections, pneumonia, septic arthritis, endocarditis, osteomyelitis, foreign-body infections, and sepsis. Methicillin-resistant S. aureus (MRSA) isolates were once confined largely to hospitals, other health care environments, and patients frequenting these facilities. Since the mid-1990s, however, there has been an explosion in the number of MRSA infections reported in populations lacking risk factors for exposure to the health care system. This increase in the incidence of MRSA infection has been associated with the recognition of new MRSA clones known as community-associated MRSA (CA-MRSA). CA-MRSA strains differ from the older, health care-associated MRSA strains; they infect a different group of patients, they cause different clinical syndromes, they differ in antimicrobial susceptibility patterns, they spread rapidly among healthy people in the community, and they frequently cause infections in health care environments as well. This review details what is known about the epidemiology of CA-MRSA strains and the clinical spectrum of infectious syndromes associated with them that ranges from a commensal state to severe, overwhelming infection. It also addresses the therapy of these infections and strategies for their prevention.

Clinical manifestations and outcome of skin infections caused by the community-acquired methicillin-resistant Staphylococcus aureus clone ST80-IV

BACKGROUND

Several Panton-Valentin leukocidin-positive clones of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) are spreading worldwide. The European clone ST80-IV is the main CA-MRSA clone in Europe. There is no reported study of the specific clinical manifestations and outcome of skin infections caused by the clone ST80-IV, using strict definitions of skin diseases.

METHODS

Single-centre observational prospective cohort of S. aureus skin infections caused by the clone ST80-IV.

RESULTS

From November 1999 to October 2009, we diagnosed skin infections due to the clone ST80-IV in 20 patients (median age 28 years, median 27; range 1-66). All the isolates had all the following characteristics: lukPV, etd and edin gene-positive, agr 3 allele, spa-type t044 and ST80. All the isolates were resistant to beta-lactam agents, kanamycin, tetracycline and fusidic acid. During the study period, the 20 patients had the following manifestations: 19 primary abscesses (18 single abscess and one patient with two), eight furuncles, four folliculitis, one case of cellulitis, one wound infection and one felon. Surgical treatment and drainage was required for all the primary abscesses. The infections occurred mainly in the perineal area (50%). No secondary infections occurred in family members. Despite strict hygiene measures, systemic antibiotics and nasal mupirocine, four patients (20%) had recurrent skin infections over a period of a few months to 6 years.

CONCLUSIONS

The CA-MRSA clone ST80-IV is responsible for suppurative skin infections such as furuncles and abscesses, which can recur over a period of several years.

Community-associated meticillin-resistant Staphylococcus aureus

Meticillin-resistant Staphylococcus aureus (MRSA) is endemic in hospitals worldwide, and causes substantial morbidity and mortality. Health-care-associated MRSA infections arise in individuals with predisposing risk factors, such as surgery or presence of an indwelling medical device. By contrast, many community-associated MRSA (CA-MRSA) infections arise in otherwise healthy individuals who do not have such risk factors. Additionally, CA-MRSA infections are epidemic in some countries. These features suggest that CA-MRSA strains are more virulent and transmissible than are traditional hospital-associated MRSA strains. The restricted treatment options for CA-MRSA infections compound the effect of enhanced virulence and transmission. Although progress has been made towards understanding emergence of CA-MRSA, virulence, and treatment of infections, our knowledge remains incomplete. Here we review the most up-to-date knowledge and provide a perspective for the future prophylaxis or new treatments for CA-MRSA infections.

Toxin profiling of Staphylococcus aureus strains involved in varicella superinfection

The most common complications of varicella are bacterial skin and soft tissue infections, generally due to Staphylococcus aureus and group A beta-hemolytic streptococci. The aim of this study was to characterize the toxin and antibiotic resistance profiles of S. aureus isolates involved in varicella complications. Between 2002 and 2007, the French Reference Centre for Staphylococci collected 58 S. aureus isolates involved in varicella superinfection. All the isolates were characterized by screening for 12 toxin genes, agr typing, and mecA gene detection; some isolates were also studied by spa typing, multilocus sequence typing (MLST), and resistance profiling. A major toxin gene was detected in 53% (31/58) of the isolates (genes for exfoliative toxins A and B, 17.2%; Panton-Valentine leukocidin gene, 8.6%; toxic shock syndrome toxin 1 gene, 27.6%). Most clinical manifestations were directly compatible with the classical activity of these toxins. Nineteen isolates (33%) were resistant to methicillin, and 12 of these isolates belonged to an emerging agr-2, ST5 clone that harbors the toxic shock syndrome toxin 1 gene. These data should be considered in the management and treatment of patients with varicella complicated by S. aureus superinfection. Antibiotics that decrease toxin production, such as clindamycin, may provide benefit, and their efficacy against bacterial superinfections in children with varicella should be studied.

Methicillin-susceptible Staphylococcus aureus in skin and soft tissue infections, Northern Italy

Summary statement: A community outbreak with intrafamilial skin infections was associated with an MSSA clone.

During February 2004–September 2006, familial clusters and sporadic cases of Staphylococcus aureus skin and soft tissue infections were observed in a suburban area near Milan in northern Italy. Molecular typing of the isolates showed an epidemic methicillin-susceptible S. aureus (MSSA) strain, spa type 005 and sequence type 22 that harbored Panton-Valentine leukocidin (PVL) genes. The first case-patients were neonates or mothers who had recently delivered in the local hospital. Examination of the medical records showed a cluster of postpartum mastitis and neonatal skin infections antedating the emergence of infections in the community. Nasal swabs of neonates, mothers, and hospital staff were positive for the epidemic MSSA. Hospital circulation of the strain was interrupted by implementation of infection control measures, although infections continued to occur in the community. The PVL-positive MSSA strain resembles typical community-acquired methicillin-resistant S. aureus in its ability to cause prolonged community and hospital outbreaks of skin infections.

Staphylococcus aureus in dermatology outpatients with special emphasis on community-associated methicillin-resistant strains

Methicillin-resistant Staphylococcus aureus (MRSA) emerged as a community-associated pathogen (CA-MRSA) in the past 6 years. This prospective study investigated dermatology outpatients with inflammatory skin diseases, leg ulcers, and skin infections for Panton-Valentine leukocidin (PVL)-positive S. aureus, often associated with deep skin infection. In case of PVL positivity, molecular typing and PCR demonstration of resistance genes were performed. Out of 248 patients, 130 carried S. aureus, 24 being lukS-PV lukF-PV positive. Eighteen were MRSA, 11 of them belonging to the multilocus sequence typing clonal complex (CC)5, 1 to CC45, and 2/18 to CC8. Out of 18 patients, 4 were CA-MRSA containing lukS-PV lukF-PV as an important trait of CA-MRSA. Out of four CA-MRSA isolates, two were of type ST080 containing far-1 coding for fusidic acid (FUS) resistance and two were FUS sensitive (ST152 and ST001). The FUS-sensitive CA-MRSA, which corresponded to the CA-MRSA of ST001 from the United States, was detected in Germany for the first time, indicating that dermatologists are first in line to detect CA-MRSA. In contrast to CA-MRSA from other continents, far-1-coded FUS resistance represents a typical marker for the widespread CA-MRSA ST080 in Europe, especially in Germany. The significant risk factor for the acquisition of CA-MRSA was visits to foreign countries and/or professional or private contacts with foreigners.

An uncommon presentation for a severe invasive infection due to methicillin-resistant Staphylococcus aureus clone USA300 in Italy: a case report

Background

Methicillin resistant Staphylococcus aureus (MRSA) has been considered for many years a typical nosocomial pathogen. Recently MRSA has emerged as a frequent cause of infections in the community. More commonly, community-acquired (CA)-MRSA is a cause of infections of the skin and soft-tissues, but life-threatening infections such as necrotizing pneumonia and sepsis can occasionally occur.

Case presentation

This report describes an uncommon presentation of invasive CA-MRSA infection in an adolescent without known risk factors. The presentation was typical for bacterial meningitis, but the clinical findings also revealed necrotizing pneumonia. Following the development of deep venous thrombosis, the presence of an inherited trombophilic defect (factor V Leiden) was detected. The patient was successfully treated with an antibiotic combination including linezolid and with anticoagulant therapy. CA-MRSA was isolated from both cerebrospinal fluid and blood. The isolates were resistant to oxacillin and other beta-lactam antibiotics and susceptible to the other antibiotics tested including erythromycin. Molecular typing revealed that the strains contained the Panton-Valentine leukocidin genes and type IV SCCmec, and were ST8, spa type t008, and agr type 1. This genetic background is identical to that of the USA300 clone.

Conclusion

This report highlights that meningitis can be a new serious presentation of CA-MRSA infection. CA-MRSA strains with the genetic background of the USA300 clone are circulating in Italy and are able to cause severe infections.

[Incidence of methicillin-resistant Staphylococcus aureus in community-onset paediatric skin infections: a retrospective study 2000-2005]

BACKGROUND

A dramatic increase in the incidence of methicillin-resistant Staphylococcus aureus (MRSA) in community-onset skin infections has been reported over the last 10 years in the USA. The emergence of MRSA has been recently described in France. The aims of this study were to assess the incidence of MRSA in community-onset skin infections and to analyse the characteristics of MRSA skin infections in a French paediatric population.

PATIENTS AND METHODS

This is a retrospective study covering the period January 2000 to December 2005. Patients aged under 15 years with S. aureus isolated from skin and a clinical diagnosis of skin infection were included.

RESULTS

One hundred and thirty-four children were included with a median age of 3.4 years. There were no significant differences in MRSA prevalence between the different years of the study. The overall prevalence of MRSA was 8.2% (n=11/134). None of the isolated strains presented an antimicrobial susceptibility profile suggestive of the ST80-type community-acquired MRSA described in France. Three MRSA strains were isolated from serious superantigen-mediated skin infections. The antimicrobial susceptibility and genetic profile (tst-positive agr2 MSRA) for one strain of S. aureus militated strongly in favour of an MRSA ST5 clone skin infection.

CONCLUSION

In this study we found no evidence of epidemic spread of MRSA in community-onset childhood skin infections between 2000-2005. Nevertheless, we report three cases of serious MRSA-induced superantigen-associated skin infection. This argues in favour of the presence of virulent community MRSA clones in France.

Community-acquired methicillin-resistant Staphylococcus aureus skin infections: implications for patients and practitioners

Dermatologists and other healthcare providers need to be aware of the epidemiology, clinical features, management, and prevention of community-acquired methicillin-resistant Staphylococcus aureus (CAMRSA) infection. Currently, infection caused by CAMRSA is considered to represent a worldwide epidemic and infectious skin lesions are a frequent occurrence. Athletes, certain ethnic populations, children, homeless persons, homosexual men, household members of infected people, HIV-infected patients, intravenous drug abusers, military personnel, newborns, pregnant and postpartum women, tattoo recipients, and urban dwellers of lower socioeconomic status in crowded living conditions are individuals at increased risk of developing CAMRSA infection. Although the observed incidence of cutaneous CAMRSA lesions in patients with atopic dermatitis or other conditions that are characterized by a non-intact skin barrier is less than that reported in other groups of people at risk for this skin infection, close surveillance for the emergence of CAMRSA skin infection in children and adults with atopic dermatitis and other patients whose skin barrier is disrupted is justified since colonization by S. aureus in these individuals represents a potential reservoir for CAMRSA. It is also important to note that infection-associated risk factors are absent in many individuals who develop cutaneous CAMRSA infection. CAMRSA skin lesions are pleomorphic. The most common presentations of CAMRSA infection are abscess, cellulitis, or both. These infectious lesions are not uncommonly misinterpreted by the patient as spider bites or insect bites. Other manifestations of cutaneous CAMRSA infection are impetigo, folliculitis, and paronychia. Incision and drainage of abscesses, systemic antibacterial therapy, and adjunctive topical antibacterial treatment are the essential components of management of CAMRSA skin infections. At the initial visit, a bacterial culture of the infectious lesion is recommended to confirm identification of the pathogen and to determine antimicrobial susceptibility. Subsequently, based upon the reported antibacterial sensitivity, alteration (if necessary) of the patient's empiric systemic antimicrobial treatment can be initiated. Direct skin-to-skin transmission of the causative bacteria, damage to the skin's surface, sharing of personal items, and a humid environment are potential mechanisms for the acquisition and transmission of CAMRSA skin infection. The spread of cutaneous CAMRSA infection can potentially be prevented by incorporating personal, environmental, and healthcare measures that strive to eliminate the causes of acquisition and transmission of the bacteria.

Global distribution of Panton-Valentine leukocidin--positive methicillin-resistant Staphylococcus aureus, 2006

We determined the agr type, multilocus sequence type, protein A gene type (spa typing), toxin gene profile, and antimicrobial drug resistance profile of 469 isolates of Panton-Valentine leukocidin-positive community-acquired methicillin-resistant Staphylococcus aureus isolates (PVL-positive CA-MRSA). The isolates had been collected from around the world from 1999 through 2005 by the French National Reference Center for Staphylococci. We found that some continent-specific clones described in 2003, such as clone ST8, have now spread all over the world. Likewise, some PVL-positive CA-MRSA have spread to several countries on various continents. New clones have emerged (e.g., ST377) on new genetic backgrounds. PVL-positive CA-MRSA that were usually susceptible to most antistaphylococcal antimicrobial agents have acquired new resistance determinants (e.g., to gentamicin) in certain countries. The major trait shared by all these clones is a short staphylococcal chromosomal cassette mec element of type IV or V.

Use of a single-nucleotide polymorphism genotyping system to demonstrate the unique epidemiology of methicillin-resistant Staphylococcus aureus in remote aboriginal communities

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) has emerged as a major public health problem in Australia, as in many other parts of the world. High rates of CA-MRSA skin and soft tissue infection have been reported from Aboriginal communities. We used a single-nucleotide polymorphism (SNP) genotyping typing system based on the multilocus sequence type (MLST) database to investigate the epidemiology of CA-MRSA and methicillin-sensitive S. aureus (MSSA) over a 12-month period in three remote Aboriginal communities of Northern Australia. This was supplemented by real-time PCR for Panton-Valentine leukocidin (PVL) genes, staphylococcal cassette chromosome mec (SCCmec) typing, and antimicrobial susceptibility testing. S. aureus was recovered from pyoderma lesions on 221 occasions and throat swabs on 44 occasions. The median monthly recovery rate of S. aureus from skin sores was 58% (interquartile range, 62 to 78%), and there was no seasonal variation. Twenty-three percent of isolates were CA-MRSA; the proportion was similar across the communities and did not vary over the study period. Erythromycin resistance was found in 47% of CA-MRSA and 21% of MSSA. SNP-based typing identified 14 different clonal complexes (cc); however, cc75 was predominant, accounting for 71% of CA-MRSA isolates. These were confirmed as ST75-like by using an additional SNP and MLST of selected isolates. All but one of the cc75 isolates had SSCmec type IV (one had type V), and all were PVL negative. Monthly tracking of SNP-based cc types showed a highly dynamic process. ST75-MRSA-IV appears to be unique to the region and probably evolved de novo in remote Aboriginal communities.