The clinical spectrum and diagnosis of Mycoplasma pneumoniae infection.

The clinical, radiographic and microbiological data of 47 patients with Mycoplasma pneumoniae infection admitted to three Norfolk hospitals during a 20-month period between 1982 and 1983 have been reviewed. Thirty-nine presented with pneumonia and eight with non-pulmonary infection. The M. pneumoniae specific IgM test was positive in 42 of 45 patients tested (89 per cent); in 39 the levels were diagnostic on admission. Cold agglutinins were detected in 27 (57 per cent) and a fourfold rise in complement fixation titre was demonstrated in 13 (29 per cent). Sputum culture was positive in 12 (26 per cent). The extrapulmonary manifestations observed were haemolytic anaemia (17 per cent), Stevens Johnson syndrome (4.1 per cent), neurological abnormalities (4.1 per cent), arthritis (2.1 per cent), hepatitis (2.1 per cent) and pericarditis (2.1 per cent). One patient with multilobe pneumonia, pericardial effusion and haemolytic anaemia died. Six patients presented with a history of illness longer than a month; in three the clinical and radiographic picture suggested chronic disease (pulmonary tuberculosis, lymphoma and unresolving pneumonia). There were no distinctive clinical or radiographic features of M. pneumoniae infection. Diagnosis, therefore, relies on serological tests of which the most useful is the rapid, specific IgM test, positive in 86 per cent of the admission sera.