[Lower respiratory tract infections in immunocompetent adult].

Lower respiratory tract infections represent one of the main causes of mortality in the world. They essentially consist of bronchitis, acute exacerbations of chronic obstructive bronchopulmonary diseases (COPD) and acute pneumonia. If acute bronchitis is mainly of viral origin, acute exacerbations of COPD and pneumonia are mainly due to a trio of bacteria (Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis). Other pathogens as many viruses and atypical bacteria such as Mycoplasma pneumoniae, Legionella, some Enterobacteriaceae and very rarely Pseudomonas aeruginosa are also implicated. S. pneumoniae is the pathogen associated with the greatest morbidity and mortality and empirical antibiotic treatment should always be active on this germ. According to the type of infection and factors of comorbidity, empirical antibiotic treatment should cover a number of other pathogens. Beta-lactams, associated or not with macrolides/azalides are the first line treatment. Fluoroquinolones, although highly active against all pathogens, must be used only in restricted situations in order to avoid emergence of resistance to these antibiotics.