[When to ask a microbiological diagnostic test in pneumonia and how to interpret the results].

Gaillat, Jacques

Pneumonia is a leading cause of death in adults in the industrialised countries and in the rest of the world in infants. Most of the time the pathogens stay unkown and the current recommendations for the treatment of pneumonia are mainly based on a severity score to adapt the treatement to the risk. Nonethless new pathogens have recently been identified, coronavirus for SRASS, H5N1 for avian Flu, N1N1 for pandemic Flu, 35 years after the identification of Legionella pneumophila. These exemples stress the necessity to do and continue to identify pathogens in these clinical situations. Those last years new diagnostic tests have been elaborated: antigen detection in urines or in nasopharyngeal samples, molecular methods allowing to look at one or several pathogens at the same time on a single sample (Multiplex) with an increased sensitivity with regard to the more classical methods. Indirect methods have been developed to quantify inflammation in correlation with a bacterial or not infection. All these tests contribute to a better understanding but can and/or could be used in new algorithms to treat patients with pneumonia.