Diagnosis of pneumococcal pneumonia was made when at least one of the following criteria was present: (1) visualization of Cram-positive cocci in the Gram stain and isolation of more than 5 x10s CFU/ml of Streptococcus pneumoniae in quantitative sputum culture, or (2) isolation of S pneumoniae in blood cultures and/or pleural fluid. Similar criteria were used for other types of bacterial pneumonia. Pneumonia due to M pneumoniae, C bumeti and C psittaci were diagnosed when a fourfold or greater rise in antibody titer was detected.
Statistical analysis was done using the chi square test or Fishers exact test to compare categorical variables. Significant differences were considered if the p value was <0.05.
During the period of study, 400 community-acquired pneumonias were diagnosed; an etiology was obtained in 165 of these 400 cases (41.25 percent [Table 1]).
Thirty episodes (7.5 percent) were caused by L pneumophila. All patients (100 percent) were males with a mean age of 55.9 years (range, 36 to 81 years). No evident seasonal predominance was observed. Alcoholism was present in 18 patients with Legionnaires* disease (60 percent), while it was present in only 22 of84 (26.2 percent) patients with pneumococcal pneumonia (p<0.01).
Table 1—Etiology of Community-Acquired Pneumonia Requiring Hospitalization (Group A) and of Community-Acquired pneumonia with Respiratory Failure (Group B)
|Bacterium||Group A (%)||Group B (%)|
|S pneumoniae||84 (21)||19 (18.2)|
|L pneumophila||30 (7.5)||15 (14.4)|
|Haemophilus influenzae||13 (3.25)||3 (2.9)|
|C psittaci||11 (2.75)||5 (4.8)|
|M pneumoniae||9 (2.25)||—|
|Gram-negative bacilli||8 (2)||5 (4.8)|
|Others||10 (2.5)||8 (7.7)|
|Total||165 (41.25)||55 (52.8)|
|Unknown||235 (58.75)||49 (47.2)|