title: [Biological diagnosis of Mycoplasma pneumoniae respiratory infections].
abstract: Mycoplasma pneumoniae is a frequent causal agent of respiratory infections. A recent french survey was carried out on adults in hospital for an acute pneumonia which was acquired outside hospital. This study showed Mycoplasma pneumoniae in third position, behind the pneumococcus and Legionella pneumophila, accounting for 17% of those cases with an established aetiology. Nevertheless its exact importance is difficult to establish on account of the high frequency of very benign forms in which a clinical diagnosis is not achieved. M. pneumoniae pneumonia occurs particularly in young subjects without any seasonal or geographical predominance. The infection is endemic with little epidemic peaks every four to five years. It is weakly contagious and is limited to close contacts. The laboratory diagnosis of M. pneumoniae pneumonia can be made by isolating the germ responsible or by a serological examination. Isolation is rarely performed. It is lengthy and difficult and may be obtained from sputum or better from throat swabs. Several serological examinations have been performed. The presence of cold agglutinins is non specific. A search for anti M. pneumoniae antibodies is much more helpful. It is done by complement fixation in most laboratories. The diagnosis of a M. pneumoniae infection can be confirmed by a significant change in antibody level between the first and second blood specimens 15 days apart (at least a four fold rise in the antibody level) if the first specimen was taken at the beginning of the illness. If a single serum specimen is examined a minimum titre of 1/64 may be taken as a presumptive diagnosis.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000373:Agglutinins / Q000032:analysis; D003080:Cold Temperature; D003168:Complement Fixation Tests; D004797:Enzyme-Linked Immunosorbent Assay; D005455:Fluorescent Antibody Technique; D006801:Humans; D009177:Mycoplasma pneumoniae / Q000302:isolation & purification; D011019:Pneumonia, Mycoplasma / Q000175:diagnosis*
chemical_list: D000373:Agglutinins
vernacular_title: Diagnostic biologique des infections respiratoires à Mycoplasma pneumoniae.