Staphylococcus aureus carrying Panton-Valentine leukocidin genes nasal colonization and skin infection: screening in case of outbreak in a school environment

Objectives

An outbreak of Staphylococcus aureus (SA) carrying the gene coding for Panton-Valentine leukocidin (PVL) skin infections in a primary school was investigated and monitored in the Val-d’Oise region (Greater Paris) in 2006.

Patients and methods

Skin infections reported after the beginning of the school year in primary-school teachers, students and their relatives were diagnosed and treated at the local hospital and screening for nasal colonization was implemented. A patient presenting with folliculitis, an abscess or furuncle with a positive-skin test or nasal swab for SA-PV was considered to be a case of infection. Colonization was defined as identification of SA-PVL in a nasal swab in the absence of skin lesions. In addition to recommended control measures, treatment by topical intranasal mupirocin was prescribed to all colonized patients and relatives of infected patients.

Results

Over five months, 22 cases of PVL-positive SA skin infections, including a case of simple folliculitis, were confirmed in 15 primary-school students (attack rate = 18.5%) and seven relatives. The occurrence of nasal colonization in relatives not attending the same school ranged from 0 to 30% according to the number of cases of skin infection in the family (p < 0,01). Two-thirds of patients treated with mupirocin were decolonized.

Conclusion

Transmission of this SA strain in school and family environments confirms the epidemic potential of PVL-positive isolates; however, screening for nasal colonization should be restricted to cases of skin infection and people in their immediate environment.     

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.     

Panton-Valentine leukocidin producing Staphylococcus aureus nasal carriage,in North-Lebanon

Objectives

We investigated the prevalence and the risk factors of nasal carriage of Staphylococcus aureus carrying Panton-Valentine leukocidin genes [Sa PVL(+)] in pupils.

Study population and methods

Two hundred and fifty-seven pupils were screened by nasal swabbing. The detection of 16S rRNA, mecA and luk-PV genes was performed by PCR and the risk factors were assessed with the statistical analysis of a questionnaire.

Results

Thirty-one percent of pupils were colonized, with 16.4% of isolates carrying the luk-PV gene and 8.8% the mecA gene. Children aged 7 years or more and living in a boarding school were the factors promoting nasal carriage 60% of children who presented with an abscess in the previous year were carriers of luk-PV gene Sa.

Conclusion

The study revealed a high prevalence of luk-PV gene among methicillin-susceptible strains and a statistically significant correlation between the presence of this gene and presenting with an abscess.     

Community-acquired methicillin-resistant Staphylococcus aureus carrying Panton-Valentine leukocidin genes: worldwide emergence

Infections caused by community-acquired (CA)-methicillin--resistant Staphylococcus aureus (MRSA) have been reported worldwide. We assessed whether any common genetic markers existed among 117 CA-MRSA isolates from the United States, France, Switzerland, Australia, New Zealand, and Western Samoa by performing polymerase chain reaction for 24 virulence factors and the methicillin-resistance determinant. The genetic background of the strain was analyzed by pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST). The CA-MRSA strains shared a type IV SCCmec cassette and the Panton-Valentine leukocidin locus, whereas the distribution of the other toxin genes was quite specific to the strains from each continent. PFGE and MLST analysis indicated distinct genetic backgrounds associated with each geographic origin, although predominantly restricted to the agr3 background. Within each continent, the genetic background of CA-MRSA strains did not correspond to that of the hospital-acquired MRSA.     

Methicillin-resistant Staphylococcus aureus in Dutch soccer team

An outbreak of community-acquired methicillin-resistant Staphylococcus aureus occurred among members and close contacts of a soccer team. Typing of the isolates showed the outbreak was caused by the well-known European ST80-IV strain. To our knowledge, this is the first report of an outbreak of this strain among members of a sports team.     

A history of Panton-Valentine leukocidin (PVL)-associated infection protects against death in PVL-associated pneumonia

Panton-Valentine leukocidin (PVL) is a Staphylococcus aureus toxin associated with skin and soft-tissue infections (SSTIs) and life-threatening necrotizing pneumonia in humans. Recent reports have demonstrated that neutralizing antibody to PVL is not protective against SSTI recurrence, thus raising a controversy about the expected clinical benefits from the use of PVL as a vaccine target. To investigate the impact of pre-existing immunity to PVL on the outcome of necrotizing pneumonia, we conducted a retrospective study of 114 cases and searched for an association between the history of PVL-associated infection and outcome. Death and severity factors, such as the need for mechanical ventilation and inotrope support, were significantly less frequent in patients with prior PVL-associated infection than in those without. These findings indicate a protective role of PVL-directed immunity in severe systemic PVL-associated disease, suggesting that anti-PVL vaccine could provide strong clinical benefits in this setting.     

Cost of the meticillin-resistant Staphylococcus aureus search and destroy policy in a Dutch university hospital

Costs related to a search and destroy policy and treatment for Staphylococcus aureus bacteraemia in the University Hospital Maastricht were calculated for the period 2000 and 2004. The financial cost-benefit break-even point of the search and destroy policy was determined by modelling. On average 22,412 patients were admitted per year for an average of 8.7 days. Each year 246 patients were screened for meticillin-resistant Staphylococcus aureus (MRSA) and 74 patients were decolonised and nursed in preventive isolation. The prevalence of MRSA in the University Hospital Maastricht was 0.7%, as calculated from positive blood cultures, and mean length of stay for all patients with S. aureus bloodstream infections was 39.9 days. The annual cost of pro-active searching for MRSA in the University Hospital Maastricht was euro 1,383,200, and euro 2,736,762 for MRSA prevention and treatment of S. aureus bloodstream infections. Simulation of a variety MRSA/meticillin-susceptible S. aureus (MSSA) ratios showed that even if the MRSA prevalence reaches 8%, prevention costs are still lower than the cost of treating S. aureus infections. In conclusion, the total cost of a search and destroy policy is lower than the cost of treating S. aureus bloodstream infections in the University Hospital Maastricht. At an MRSA prevalence of 相似文献   

Postpartum mastitis and community-acquired methicillin-resistant Staphylococcus aureus

This single-center, case-control study documents a relative increase in methicillin resistance among 48 cases of Staphylococcus aureus-associated postpartum mastitis during 1998-2005. Of 21 cases with methicillin resistance, 17 (81%) occurred in 2005. Twenty (95%) isolates contained the Staphylococcus cassette chromosome mec type IV gene; this suggests that the increase is due to community-acquired methicillin-resistant S. aureus.     

Low prevalence of methicillin-resistant Staphylococcus aureus (MRSA) at hospital admission in the Netherlands: the value of search and destroy and restrictive antibiotic use

In the Netherlands, less than 1% of clinical isolates of Staphylococcus aureus are methicillin-resistant (MRSA). A national search and destroy policy prevents MRSA from becoming endemic. Some MRSA outbreaks cannot be related to patients at risk for MRSA carriage. This study was designed to measure the prevalence of MRSA among patients without risk factors for MRSA carriage at the time of admission to the hospital. In four Dutch hospitals, patients admitted to non-surgical departments in the period 1999-2000 were screened for MRSA nasal carriage. Nasal swabs were streaked on 5% sheep blood agar (BA), submerged in a selective broth, and incubated for two to three days at 35 degrees C. Colonies suspected of being S. aureus were identified with an agglutination test. Susceptibility testing was performed by an automated system and additional oxacillin disk diffusion. Methicillin resistance was confirmed by a DNA hybridization test and mecA PCR. MRSA strains were genotyped by pulsed-field gel electrophoresis (PFGE). Twenty-four percent (2332/9859) of the patients were S. aureus nasal carriers. Only three (0.03%) patients were MRSA carriers. These patients were not repatriated, nor known to be MRSA carriers before screening. Genotyping revealed that the strains were not clonally related and were not related to MRSA outbreaks in the hospital where the patients were admitted. We conclude that at routine admission to a Dutch hospital (excluding high-risk foreign admissions) the MRSA prevalence is low (0.03%), due to the Dutch search and destroy policy and restrictive antibiotic prescribing.     

Surveillance of methicillin-resistant Staphylococcus aureus in England and Wales, 1986–1990

The incidence of methicillin-resistant Staphylococcus aureus in England and Wales was monitored by a weekly reporting scheme from early 1986 to March 1990. Potential coverage was approximately two-thirds of hospital beds. Reporting centres fell from a peak of 210 in 1986 to a low of 101 centres early in 1989 with later recovery. There were 2367 positive reports in 1986, 2174 in 1987, 1700 in 1988, 1701 in 1989 and 632 in the first quarter of 1990. Colonizations outnumbered infections by 2:1. There were marked regional differences: North-East Thames was dominant in 1986 and 1987, and then declined; South-East Thames showed a dramatic increase in 1988 which continued. Other regions showed less significant changes but there were continuing problems in the South-Western Region and in the West Midlands. Some of these changes were related to the decline of EMRSA-1, possibly due to the introduction of effective control measures, and to the emergence of EMRSA-3 in South-East Thames and its spread to Wessex.     

Rapid dissemination of Staphylococcus aureus with classic oxacillin resistance phenotype at a new university hospital

To determine the prevalence rates of oxacillin-resistant Staphylococcus aureus (ORSA) at a new university hospital since its opening, the results of disk diffusion tests on all clinical isolates, recovered between 1990 and 1998 at the National Cheng Kung University Hospital, were reviewed. In order, to investigate the mechanisms of oxacillin resistance among strains of S. aureus in Taiwan, MICs were determined by an agar dilution method, and polymerase chain reaction and colony hybridization assays were performed on 288 isolates collected during November 1998 to detect the mecA gene. The prevalence rates of ORSA increased rapidly from 14.1% in 1990 to 61.0% in 1998. The increasing rates were most rapid in the first four-year period, ranging from 11.6 to 106.7% per year, and became steady after 1994, ranging from 1.8% to 11.6%. Of 288 clinical isolates collected in November 1998, 206 (71.5%) were resistant to oxacillin (MIC >/= 16 mg/L), and four were borderline resistant (MIC 2-8 mg/L). All 210 strains possessed the mec A gene (classic resistance). The present study demonstrated that ORSA could disseminate in a new hospital with great speed, and indicated that all ORSA strains in Taiwan revealed classic resistance phenotype.     

Emergence and spread of low-level mupirocin resistance in methicillin-resistant Staphylococcus aureus isolated from a community hospital in Japan

The objective of this study was to investigate the state of mupirocin resistance in methicillin-resistant Staphylococcus aureus (MRSA) in a community hospital in Japan. Ninety strains of MRSA were isolated from the respiratory tract of 56 patients (group I, Jun 1990-Aug 1996) before introduction of mupirocin in Japan, which were compared with 168 strains from 48 patients (group II, Sept 1996-Jan 1998) and 146 strains from 85 patients (group III, Feb 1999-Dec 1999) isolated after introduction of mupirocin. Comparisons were made by determining the minimum inhibitory concentrations (MIC) against nine antibiotics. Fifty-five MRSA isolates from 27 patients [13 (27.1%) of 48 in group II and 14 (16.5%) of 85 in group III] after introduction of mupirocin showed low-level resistance to mupirocin (MIC, 6.25 to 50 microg/ml) but the remaining isolates were sensitive to mupirocin (MIC < or =3.13 microg/ml). Most patients colonized with low-level mupirocin-resistant MRSA were elderly (> or =65 years of age), on total parenteral nutrition or nasal feeding and had other underlying diseases. The proportion of patients colonized with low-level mupirocin-resistant MRSA following repeated use of mupirocin was higher in patients of group II than those of group III. Molecular typing by pulsed-field gel electrophoresis (PFGE) demonstrated that the pattern of 13 MRSA isolates from 13 patients of group II consisted of three patterns (A, B, C) with predominance of pattern A, while the pattern of 13 MRSA isolates from 13 patients of group III consisted of three patterns (A, C, D) with predominance of patterns A and D. Our results indicated that resistance of MRSA to mupirocin remains at a low level at present in Japan. However, we should be aware of the possible emergence of MRSA highly resistant to mupirocin in the future.     

Retrospective study of pneumonia due to Panton-Valentine leukocidin-producing Staphylococcus aureus in Reunion

ObjectivePanton-Valentine leukocidin-producing Staphylococcus aureus necrotizing pneumonia is an unusual cause of community-acquired pneumonia, although associated with a high case fatality. This infection mainly affects young individuals, without any history, and is most often preceded by flu-like symptoms.MethodWe focused on patients presenting with Staphylococcus aureus necrotizing pneumonia in Reunion (Indian Ocean) admitted to the emergency department. We performed a retrospective study based on data collected from laboratory registers and medical files of patients presenting with Staphylococcus aureus necrotizing pneumonia in Reunion between December 2014 and December 2017.ResultsA total of 16 patients were recruited for this study, with a median age of 40.5 years. More than half of patients had previously been admitted to the emergency department for acute respiratory distress syndrome or severe sepsis. Fourteen patients were admitted to the intensive care unit and six patients died (five premature deaths).ConclusionPhysicians should be aware of this infection during the flu season and quickly adapt the specific antibiotic treatment, including a drug inhibiting toxin production. As methicillin-resistant Staphylococcus aureus is very rarely observed in Reunion, physicians can still adapt the empirical treatment, without glycopeptides.     

Pneumonia and new methicillin-resistant Staphylococcus aureus clone

Necrotizing pneumonia caused by Staphylococcus aureus strains carrying the Panton-Valentin leukocidin gene is a newly described disease entity. We report a new fatal case of necrotizing pneumonia. An S. aureus strain with an agr1 allele and of a new sequence type 377 was recovered, representing a new, emerging, community-acquired methicillin-resistant clone.     

Emergence of vancomycin-resistant Staphylococcus aureus identified in the Tlemcen university hospital (North-West Algeria)

Introduction

Nosocomial infections are a matter of concern in surgical wards. Their incidence is constantly increasing, especially among immunocompromised patients who are vulnerable to colonization by opportunistic pathogens such as Staphylococcus aureus. The bacterium accumulates resistance mechanisms against antibiotics such as vancomycin. The objective of our study was to explore this resistance, to screen for Staphylococcus aureus strains resistant to vancomycin, and to try various antibiotic combinations against these strains.

Patients and methods

The antibiotic susceptibility of 220 S. aureus strains was determined by agar diffusion and evaluation of minimal inhibitory concentrations (MICs), by dilution technique on solid medium according to clinical and laboratory standard institute (CLSI) standards. The screening of strains resistant to vancomycin was performed on brain heart infusion agar medium, supplemented with 6 μg/mL of vancomycin according to CLSI standards, and confirmed by determining MICs. The effectiveness of various antibiotic combinations was assessed by the checkerboard microplate method.

Results

The results show multidrug resistance to agents known for their antistaphylococcal activity with fluctuations in the level of resistance.

Conclusion

Three strains proved resistant to vancomycin. The vancomycin/gentamycin combination was the most effective.     

Clinical experience and outcomes of community-acquired and nosocomial methicillin-resistant Staphylococcus aureus in a northern Australian hospital

Methicillin-resistant Staphylococcus aureus (MRSA) is a well-recognized cause of hospital-acquired sepsis. We reviewed the clinical features of a new variant of community-acquired MRSA originally described from the Kimberley region of northern Western Australia (WA MRSA). This strain has become an increasing cause of community- and hospital-acquired sepsis at Royal Darwin Hospital (RDH) in the Northern Territory, especially in Aboriginal Australians from remote communities. Fifty percent of WA MRSA was community-acquired, with 76% in Aboriginals. Like the MRSA from eastern Australia (EA MRSA), WA MRSA commonly caused skin sepsis but was less likely to cause respiratory or urinary infections compared with EA MRSA. Twelve out of 125 (9·6%) WA MRSA and 7/93 (7·5%) EA MRSA infections were septicaemias. Septicaemia due to WA MRSA occurred in adult medical patients, especially those with temporary haemodialysis catheters, while EA MRSA septicaemia occurred throughout the hospital. Aboriginal people were more likely to develop both community- and hospital-acquired WA MRSA septicaemia [overall relative risk (RR) 12·3 (95% CI 3·7–40·7)]. Control of WA MRSA requires policies to reduce transmission in both hospitals and communities. Community-based control programmes need support for individual patient management, improved housing and hygiene, control of skin sepsis and appropriate use of antibiotics, especially in rural Aboriginal communities in northern Australia.     

Vancomycin susceptibility within methicillin-resistant Staphylococcus aureus lineages

Methicillin-resistant Staphylococcus aureus (MRSA) with reduced vancomycin susceptibility vancomycin-intermediate S. aureus (VISA) has been reported from many countries. Whether resistance is evolving regularly in different genetic backgrounds or in a single clone with a genetic predisposition, as early results suggest, is unclear. We have studied 101 MRSA with reduced vancomycin susceptibility from nine countries by multilocus sequence typing (MLST), characterization of SCCmec (staphylococcal chromosomal cassette mec), and agr (accessory gene regulator). We found nine genotypes by MLST, with isolates within all five major hospital MRSA lineages. Most isolates (88/101) belonged to two of the earliest MRSA clones that have global prevalence. Our results show that reduced susceptibility to vancomycin has emerged in many successful epidemic lineages with no clear clonal disposition. Increasing antimicrobial resistance in genetically distinct pandemic clones may lead to MRSA infections that will become increasingly difficult to treat.