Our study was aimed at comparing the meticillin-resistant Staphylococcus aureus (MRSA) strains isolated from an anonymous group of health-care workers (HCWs) with those obtained from patient samples during a 3-month time interval. We employed spa typing and virulence gene profiling to characterize the MRSA strains. Our data revealed that a total of 14 discrete spa types were circulating in both patients and HCWs. The t032 spa type, characteristic of EMRSA15 and the Barnim EMRSA ST 22 clones, accounted for over 70 % of isolates, and was equally distributed between patients and HCW groups. In addition, a number of epidemic and sporadic strains were identified, which highlighted the diversity of spa types that can be found within a health-care setting. Virulence profiling for the carriage of 7 genes by the 14 different spa types demonstrated that 10 types carried the fnbA, cna, sdrE, hlg and ica virulence factors. We concluded that there was no significant difference between the MRSA strains found circulating in the patients and the HCWs, and noted that the dominant spa types carried an identical set of virulence genes that included the key adhesins fnbA, cna and sdrE.
INTRODUCTIONStaphylococcus aureus is an important human pathogen and is one of the most significant causes of health-careassociated infections in the UK. In an attempt to control the high mortality and morbidity of systemic meticillinresistant S. aureus (MRSA) infections, techniques have been developed to analyse the genetic relatedness of different strains and help inform infection control policies. The single most important identification method is PFGE; however, the complexity, cost and lack of inter-laboratory standardization have led to the appearance of alternative methods (Deurenberg et al., 2007). For long-term global studies on the evolution of strains, multilocus sequence typing is the most commonly used technique (Enright & Spratt, 1999), while for short-term studies on molecular evolution and nosocomial outbreaks, spa typing has proved an excellent tool (Koreen et al., 2004; Malachowa et al., 2005; Shopsin et al., 1999).Alongside the development of sequenced-based typing methods, attention has become focused on the comparison of different MRSA genomes. In particular, the number of studies on the distribution of genes that are directly involved in causing disease has increased (Kuhn et al., 2006;Nashev et al., 2004; Peacock et al., 2002). These genes encode a variety of products that are referred to as virulence factors. Examples include PVL, a toxin linked to the occurrence of necrotizing pneumonia (Brown et al., 2009;Labandeira-Rey et al., 2007); ETA, the toxin responsible for scalded skin syndrome (Amagai et al., 2000); and CNA, the collagen-binding protein that is associated with osteomyelitis (Elasri et al., 2002). , Peacock et al. (2002 compared the distribution of 33 putative virulence factors amongst S. aureus strains isolated from the nasal passages of blood donors and strains responsible for invasive disease. This work suggeste...