(Rev Méd Chile 2007; 135: 517-28).

Tobacco smoke is a proven risk factor for viral and bacterial respiratory infection. In adults without COPD, smoking is associated with a significant increase in the relative risk of pneumonia (OR = 2.0;, invasive pneumococcal disease (OR = 2.6; and Legionella infection (OR =3.48; 1). Plausible explanations of the increased risk of infection in active or passive smokers include increased bacterial adherence, decrease of lung and nasal clearance, and changes in the immune response. Conclusions: Exposure to tobacco smoke approximately doubles the risk of infection. This increased burden of infection has significant healthcare cost implications. Each infectious episode in an individual should prompt an attempt at smoking cessation.Key words: respiratory infection, influenza, tuberculosis, pneumonia, risk factors, smoking. (OR: 2,0; IC95%: 1,24), enfermedad neumocócica invasiva (OR: 2,6; IC95%: 1,5) e infección por Legionella spp. (OR: 3,48; IC95%: 2,79). Además, el tabaquismo está asociado a mayor riesgo de influenza (OR: 2,4; IC95%: 1,8), tuberculosis (OR: 2,6; IC95%: 2,(2)(3)1) Resumen La exposición a humo de tabaco constituye un importante factor de riesgo para adquirir infecciones respiratorias bacterianas y virales. En adultos sin enfermedad pulmonar obstructiva crónica, el tabaquismo está asociado a un aumento significativo del riesgo de neumonía