Methicillin-susceptible Staphylococcus aureus clone related to the early pandemic phage type 80/81 causing an outbreak among residents of three occupational centres in Barcelona, Spain

In the 1950s an unusually virulent and transmissible penicillin-resistant Staphylococcus aureus clone harbouring Panton-Valentine leukocidin (PVL) genes, known as phage type 80/81 and subsequently identified as multilocus sequence type (ST) 30, emerged and caused serious infections in hospitals and the community. We describe an outbreak of skin infections caused by a PVL-positive, methicillin-susceptible S. aureus (MSSA) strain of ST1472, related to phage type 80/81, in three associated occupational centres. After identification of the first patient an active case-finding strategy was initiated among the three centres. Epidemiological and clinical features were indistinguishable from outbreaks currently caused by community-acquired methicillin-resistant S. aureus. The S. aureus was cultured and identified from nasal swabs and skin lesions by conventional methods; PVL was detected using a PCR assay. Pulsed-field gel electrophoresis and DNA-array-based genotyping were applied to MSSA isolates. MSSA was identified in nasal swabs from 49 of 133 individuals (37%). A single pulsed-field gel electrophoresis pattern, belonging to ST1472 (CC30) and PVL positivity, were detected in 20 individuals, including eight of 18 skin cultures, i.e. 15% of the screened individuals were colonized by the epidemic strain. Nasal and cutaneous decontamination with 5% nasal mupirocin ointment and 2% aqueous chlorhexidine was implemented for all individuals. Patients with active skin infections were treated with a first-generation cephalosporin. General recommendations were made to prevent cross-transmission. No new cases were reported over the following 90 days.