Adult community-acquired pneumonia in central London.

Strep. pneumoniae was diagnosed as the cause of pneumonia in 40 (50%) of 80 consecutive adults admitted to St Stephen's Hospital with community-acquired pneumonia. None of the patients had evidence of Mycoplasma pneumoniae infection, and Legionella pneumophila serology was positive on only one occasion. In 29 patients (36%) no causative organism was demonstrated. The diagnosis of pneumococcal infection was obtained in 15 cases by isolating Strep. pneumoniae from the sputum, in 13 further cases by demonstrating pneumococcal capsular antigen in sputum, and in 12 other cases by detecting pneumococcal antigen in serum only. Only 2 cases with pneumococcal pneumonia were bacteraemic and 3 patients (7%), all aged more than 75 years, died. The relatively low bacteraemic and mortality rates suggest that community-acquired pneumococcal pneumonia currently seen in patients admitted to hospital in central London may not be so severe as in some other areas.