Are methicillin-resistant Staphylococcus aureus that produce Panton-Valentine leucocidin (PVL) found among residents of care homes?

OBJECTIVES: Panton-Valentine leucocidin (PVL)-positive Staphylococcus aureus are responsible for causing skin and soft tissue infections, with the potential to cause severe invasive disease. Recently, methicillin-resistant Staphylococcus aureus (MRSA) strains that produce PVL have emerged in the community. As residents of care homes are a key group at risk of MRSA colonization and infection, we have examined the epidemiology of MRSA in three large cohorts of residents in urban care homes to establish whether PVL-positive MRSA strains are present in this setting. METHODS: Nasal swabs (n = 3037) collected from consenting residents of 69 care homes in Leeds, UK, were screened for MRSA using chromogenic agar over three periods (June-August 2005, November-December 2006 and October-November 2007). PCR amplification was used to detect genes encoding PVL. Antibiogram profile and PFGE were also used to characterize MRSA isolates (n = 601). RESULTS: MRSA prevalence was 21%, 20% and 19% in each cohort, respectively. The majority of the isolates were related epidemiologically to the predominant local nosocomial epidemic MRSA strain, EMRSA-15 (78%). No isolate carried the genes encoding PVL. Twelve percent of the isolates (n = 74) had increased susceptibility to non-beta-lactam agents and were distributed across 31 care homes. CONCLUSIONS: MRSA strains that produced PVL were not found to be colonizing residents of care homes between 2005 and 2007. Continued surveillance is, however, necessary to understand the interaction between MRSA in care homes and hospitals, especially to reduce the chance that the former may amplify community-associated MRSA strains.

Prevalence of methicillin-resistant Staphylococcus aureus colonization among older residents of care homes in the United Kingdom.

OBJECTIVE: To determine the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) colonization among older residents of care homes in Leeds, United Kingdom, and to identify resident and care home risk factors for carriage. DESIGN: We conducted a cross-sectional prevalence survey of 715 residents from 39 care homes. All participants were tested for nasal colonization with S. aureus, including MRSA. A short questionnaire was completed about each participant and each care home. A multivariable model was used to determine which risk factors were independently associated with MRSA colonization. SETTING: Care homes for older residents in Leeds, United Kingdom. PARTICIPANTS: All residents in participating homes who were able to give informed consent. RESULTS: A total of 159 of 715 residents tested positive for MRSA, for a prevalence of 22% (95% confidence interval, 18%-27%) The resultant multivariate model showed that residence in a home with a low ratio of nurses to beds, residence in a care home in a deprived area, male sex, presence of an invasive device, and a hospitalization duration of more than 10 days during the previous 2 years were independently associated with MRSA colonization. CONCLUSIONS: This study found a large reservoir of MRSA within the care home population. Control strategies need to be coordinated between care homes and hospitals. Increasing the ratio of nurses to beds, reducing the duration of hospitalization, and improving the management of invasive devices could help reduce the prevalence of MRSA colonization. Further research is required to ascertain the potential health benefits of reducing the rate of MRSA colonization among care home residents.