[Comparison of clinical presentation of mixed pneumonia with Chlamydia pneumoniae and Streptococcus pneumoniae and S. pneumoniae pneumonia].

Chlamydia pneumoniae is a significant cause of both lower and upper acute respiratory illnesses, including community-acquired pneumonia. Furthermore, C. pneumoniae has been reported to frequently cause pneumonia in association with other respiratory pathogens, mainly Streptococcus pneumoniae. In this study, we investigated the clinical presentation of mixed pneumonia with Chlamydia pneumoniae and S. pneumoniae and compared it with S. pneumoniae pneumonia. A total of 13 cases of mixed pneumonia and 58 cases of S. pneumoniae pneumonia identified at Kawasaki Medical School and related hospitals between April 1996 and March 2001 were analyzed. The diagnosis of C. pneumoniae infection was based on isolation and serologic testing of antibodies by the microimmunofluorescence test. The clinical presentation of mixed pneumonia and S. pneumoniae pneumonia was almost identical and no statistical differences were observed between the two groups. This is the same as what was observed before except eleven out of the 13 of the mixed pneumonia patients responded to treatment with only beta-lactam antibiotics. Our results indicated that C. pneumoniae may not be the primary cause of community-acquired pneumonia but it might descript the normal clearance mechanisms, enabling other pathogens to invade.