Clinical Sydromes - Legionella pneumophila

Clinical Sydromes

L. pneumophila causes two distinct clinical entities - - Legionnaire’sdisease and Pontiac fever.

◗ Legionnaire’s disease

Incubation period varies from 2 to 10 days. Pneumonia is the primary manifestation of Legionnaire’s disease with multilob-ular consolidation, inflammation, and abscesses in the lung. Fever, chills, dry or nonproductive cough, and pleuritic or non-pleuritic chest pain are the common symptoms of the disease. Hemoptysis is rare. The condition becomes more severe and is associated with much morbidity and high mortality if not treated immediately.

    Decreased pulmonary function, pulmonary fibrosis or scarring, abscess formation in the lungs, and fulminant respiratory failure are the important complications of pul-monary disease. Progressive respiratory failure is the most common cause of death in patients with Legionnaire’s disease. The mortality may be as high as 80% in untreated patients. It may be nearly 50% in nosocomial infections of patients with underlying diseases. Extrapulmonary mani-festations include myocarditis, pericarditis, and prosthetic valve endocarditis. They also include peritonitis and acute renal failure.

◗ Pontiac fever

Pontiac fever is a mild, self-limiting condition. The condition presents as fever and myalgia that resolve without treatment. Table 47-2 compares the Legionnaire’s disease and Pontiac fever caused by L. pneumophila.