[Severe community-acquired pneumopathy. What initial antibiotics to use?]

Even if they represent only a minor percentage of all respiratory infections, acute pulmonary infections are the leading mortality cause from infectious diseases. Epidemiologic data amongst hospitalized patients with acute infections reveal mean mortality figures of 20%. The adequate assessment of severity criteria is fundamental so that patients can be oriented towards suitable hospitalized units. Risks factors to be considered are: other illnesses, age (greater than 60 years), breathing frequency greater than 30/min, diastolic blood pressure less than 60 mmHg, confusion, a PaO2 less than 60 Torr, a leukocytosis greater than 30,000 or less than 4,000/mm3, albuminemia less than 35 g/l and blood urea greater than 7 mmol/l. The association of these factors increases the risk of complications and mortality in a linear way. By contrast, the type of responsible organism is not relevant. Five microorganisms are responsible for 80 to 90% of documented acute pulmonary infections: pneumococci, Mycoplasma pneumoniae, Haemophilus influenzae, Legionella pneumophila, Myxovirus influenzae. However, direct examination of bacteriologic smear allows for a proper identification of the infectious agent in only 15% of cases. The clinician can therefore use epidemiologic, clinical and radiological findings to propose an oriented, though probable, antibiotic treatment. In these conditions, the initial treatment remains the association of an A type penicillin with an inhibitory effect on beta-lactamases and of a macrolide (or, eventually, of a fluoroquinolone) until results of bacteriologic investigations is known. No data is available to suggest the use of new third generation oral cephalosporins in the first intention treatment of acute severe pulmonary infections due to their low and inconsistent effect on pneumococcus.