Exposure to cigarette
smoke has long been associated with increased frequency of respiratory
infections -- which are harder to treat in smoke-exposed people than in those
who lack such exposures. Now Ritwij Kulkarni of Columbia University, New York,
NY, and colleagues show that cigarette smoke actually boosts virulence of Staphylococcus
aureus bacteria.
Their study appears in the November 2012 issue of the journal Infection
and Immunity.
S. aureus is a normally harmless inhabitant of the upper respiratory
tract, but one which can morph into a dangerous pathogen capable of causing
severe, and even fatal infections, says Kulkarni. The new research shows that
cigarette smoke can aid and abet that transformation.
Cigarette smoke does so by enhancing S. aureus'
ability to form biofilms, which are an important virulence factor, according to
the study. The research showed further that reactive oxygen species, such as
H2O2, which are concentrated in cigarette smoke, drive biofilm formation, says
Kulkarni.
Kulkarni notes that a recent paper, from another group, showed
that reactive oxygen species suppress the gene regulator, "Accessory Gene
Regulator," or agr for short. "That fits nicely with our story,"
he says. "We think control of biofilm formation [and of numerous other
virulence factors inS. aureus] proceeds via agr."
Journal Reference:
1. R. Kulkarni, S. Antala, A. Wang, F. E. Amaral,
R. Rampersaud, S. J. LaRussa, P. J. Planet, A. J. Ratner.Cigarette Smoke
Increases Staphylococcus aureus Biofilm Formation via Oxidative Stress. Infection
and Immunity, 2012; 80 (11): 3804 DOI: 10.1128/IAI.00689-12
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