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

Abstract

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. 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). 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. 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.