Fifteen patients with Legionnaires’ disease (50 percent) had respiratory failure, whereas only 19 of84 (22 percent) patients with pneumococcal pneumonia (p<0.01) had it. Some clinical, laboratory, radiographic and evolutive features of patients with Legionnaires’ disease are reflected on Table 3 depending on whether they did or did not have respiratory failure. Development of respiratory failure was associated with involvement of several lobes on the chest roentgenogram and isolation of L pneumophila in any clinical specimen (p<0.05).
The overall mortality of community-acquired pneumonia due to L pneumophila was 10 percent, but in those cases that were not treated with erythromycin initially it was 27 percent. The mortality for patients with pneumococcal pneumonia was 5 percent. The three patients who died suffered from heart disease, had multiple lobes involved, developed respiratory failure, did not receive erythromycin initially, and in all cases, L pneumophila was isolated.
The precise etiology of community-acquired pneu monia is unknown in as many as 50 percent of cases,* but recently Levy and colleagues observed that the prognosis was identical whether a bacteriologic diagnosis was made or not.
Table 3—Community-Acquired Pneumonia Caused by L pneumophila: Comparison between Patients with and without Respiratory Failure
|Salient Features||Group A (with Respiratory Failure) (%)||Group B (without Respiratory Failure) (%)||PValue|
|No. of Patients||15||15|
|Elevation of transaminase||46||40|
|Elevation of creatinine||33|
|Multiple lobes affected||53||46||<0.05|
|No. of deaths||3 (20)|