Pneumocystis pneumonia in hospitals: outbreaks or improved recognition?

A presumed outbreak of Pneumocystis carinii pneumonitis occurred at a large teaching hospital. The diagnosis was made by lung biopsy or at autopsy in seven patients over a 22 1/2-year period and only by percutaneous lung aspirate in seven patients over a 2 1/2-year period. Apparent outbreaks may be related to both an increase in the number of cases of disease and improved diagnostic methods.