Comparative radiographic features of community acquired legionnaires' disease, pneumococcal pneumonia, mycoplasma pneumonia, and psittacosis

Abstract

The features of the chest radiographs of 49 adults with legionnaires' disease were compared with those of 91 adults with pneumococcal pneumonia (31 of whom had bacteraemia or antigenaemia), 46 with mycoplasma pneumonia, 10 with psittacosis pneumonia. No distinctive pattern was seen for any group. Homogeneous shadowing was more frequent in legionnaires' disease (40/49 cases) (p < 0.005), bacteraemic pneumococcal pneumonia (25/31) (p < 0.001) and non-bacteraemic pneumococcal pneumonia (42/60) (p < 0.05) than in mycoplasma pneumonia (23/46). Multilobe disease at presentation was commoner in bacteraemic pneumococcal pneumonia (20/31) than in non-bacteraemic pneumococcal pneumonia (15/60) (p < 0.001) or legionnaires' disease (19/49) (p < 0.025). In bacteraemic pneumococcal pneumonia multilobe disease at presentation was associated with increased mortality. Pleural effusions and some degree of lung collapse were seen in all groups, although effusions were commoner in bacteraemic pneumococcal pneumonia. Cavitation was unusual. Lymphadenopathy occurred only in mycoplasma pneumonia (10/46). Radiographic deterioration was particularly a feature of legionnaires' disease (30/46) and bacteraemic pneumococcal pneumonia (14/27), and these groups also showed slow radiographic resolution in survivors. Radiographic resolution was fastest with mycoplasma pneumonia; psittacosis and non-bacteraemic pneumococcal pneumonia cleared at an intermediate rate. Residual intrapulmonary streaky opacities remained in over a quarter of survivors from legionnaires' disease (12/42) and bacteraemic pneumococcal pneumonia (5/19).