Screening for Panton-Valentine Leukocidin Toxin Genes in Multi-Drug Resistant Methicillin-Resistant Staphylococcus aureus Nasal Isolates from Healthy School Children in Mariental, Namibia

Panton-Valentine leukocidin (PVL) is one of the toxins responsible for increased virulence of Staphylococcus aureus. In school settings where children are in close contact with each other, S. aureus strains, including those that may produce PVL, can be transmitted and spread in the community. Twenty-two multi-drug resistant MRSA nasal isolates from children enrolled in five schools in the town of Mariental and the multi-drug resistant American Type Culture Collection MRSA reference strain S. aureus ATCC 33591 (PVL-negative control) were used for molecular assays. Plasmid deoxyribonucleic acid (DNA) of isolates was amplified by polymerase chain reaction (PCR) and amplified PCR products were electrophoresed on a 2.5% (w/v) agarose gel containing 12 μl 0.5 μg/ml ethidium bromide and 1× TAE (Tris-acetate-EDTA) buffer at 90 volts for 50 minutes. The developed gel was viewed for the PVL-associated lukS and lukF genes that amplified at 151 bp and 406 bp, respectively. Our results indicated that seven nasal isolates had PVL toxin gene(s). From the seven isolates, three were tested positive for both lukS and lukFgenes, one tested positive for only lukS, and three tested positive for only lukF. Two of the isolates harbouring both lukS and lukF genes shared the same antibiotic resistance pattern and one of them could also produce enterotoxin A. One of the isolates with only lukF gene could produce enterotoxins B and C. These toxin-producing isolates can be expected to be more virulent than non-producers. Children should be educated on the importance of regular handwashing with soap and water to prevent the spread of potentially virulent staphylococci amongst them and the wider community. This work warrants a larger study to be carried out to investigate PVL toxin and its associated infections in Staphylococcus from school children in Namibia.