Prevalence of Panton Valentine Leukocidin in Carriage and Infective Strains of Staphylococcus aureus at a Referral Hospital in Kenya

Panton valentine leukocidin (PVL) is a pore forming exotoxin that is expressed by some Staphylococcus aureus (S. aureus) strains and is thought to add to its virulence. The prevalence of PVL in carriage and disease causing strains varies considerably from region to region. This study compared the prevalence of the PVL gene in S. aureus isolates obtained from healthcare workers and from patients seen at the Aga Khan University Hospital Nairobi (AKUHN). S. aureus isolates obtained from healthcare workers and patients attended to at AKUHN between July 2010 and March 2011 were used for this study. Forty five S. aureus isolates from healthcare workers and 63 from clinical specimens obtained from 59 patients were analysed for the PVL gene. The prevalence of PVL in isolates from healthcare workers was 24.4% compared to 39.7% in the isolates causing infection (P = 0.098). PVL prevalence was 58.8% in S. aureus isolates obtained from skin and soft tissue infections (SSIs) compared to 25.0% in carriage isolates (P = 0.002, OR 4.29). Prevalence in isolates from invasive infections was 11.1%. Patients with PVL positive S. aureus were younger than those with PVL negative isolates (P = 0.082). The high prevalence of PVL is comparable with that reported in other African countries. The significance of the high prevalence of PVL in S.aureus isolates carried by health care workers at AKUHN is unclear at the moment. PVL prevalence is significantly higher in S. aureus isolates causing SSIs compared to carriage and invasive isolates.