Prevalence of the Panton-Valentine Leukocidin in Staphylococcus aureus associated with Upper Respiratory Tract Infections
Authors: Gonçalves, M.; Eira, D.; Tomé, R.; Mendes, F.; Valado, A., Armando C., Gabriel, A. and Osório N.
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S. aureus with lukS-PV and lukF-PV genes, responsible for encoding the cytotoxin panton valentine leukocidin (PVL) becomes a growing problem throughout the world. Initially, this pore-forming cytotoxin in human leukocytes was associated with skin and soft tissue infections, especially in recurrent abscesses. However, in the last decade a growing association of these PVL positive strains has been verified, with devastating pneumonia with a high mortality rate affecting mainly young adults, apparently healthy. In this study we were to determine the prevalence of PVL in S. aureus associated with upper respiratory tract infections. We were isolated 60 strains of S. aureus from respiratory tract infections in humans; these were tested for different antibiotics. Then, from DNA we analyzed the presence or absence of the lukS-PV and lukF-PV using the PCR technique. The phenotypic profile for different antibiotics tested revealed only one strain sensitive for all, 59 strains showed resistance: 2 (34%) to gentamicin and trimethoprim/sulfamethoxazole, 46 (78%) to levofloxacin, 51 (86.4%) to oxacilin and all (100%) to Penicilin G. The lukS-PV gene was detected only in 2 strains (3.3%), the lukF-PV gene was detected in 20 strains (33.3%) and both genes were detected simultaneously in only two strains, which were classified as PVL positive (3.3%). The average age of the infected individuals with PVL positive strains is 11 years, which may indicate that PVL positive strains infect younger individuals. The 18 positive strains for the lukF-PV gene suggest the use of other techniques to confirm the non - gene amplification for lukS-PV gene. The 60 strains showed a high resistance pattern to β-lactam antibiotics including penicillin and oxacillin, however, it was not established a link between PVL positive strains and resistance to a specific antibiotic or MRSA phenotype.
Keywords: S. aureus, LukS-PV, LukF-PV, PVL.