Legionnaires' Disease

Abstract

To identify the etiologic agent of Legionnaire's disease, we examined patients' serum and tissue specimens in a search for toxins, bacteria, fungi, chlamydiae, rickettsiae and viruses. From the lungs of four of six patients we isolated a gram-negative, non-acid-fast bacillus in guinea pigs. The bacillus could be transferred to yolk sacs of embryonated eggs. Classification of this organism is incomplete. We used yolk-sac cultures of the bacillus as antigen to survey suspected serum specimens, employing antihuman-globulin fluorescent antibody. When compared to controls, specimens from 101 to 111 patients meeting clinical criteria of Legionnaires' disease showed diagnostic increases in antibody titers. Diagnostic increases were also found in 54 recent sporadic cases of severe pneumonia and, retrospectively, in stored serum from most patients in two other previously unsolved outbreaks of respiratory disease. We conclude that Legionnaires' disease is caused by a gram-negative bacterium that may be responsible for widespread infection.

Microbiological and Clinical Studies of Legionellosis in 33 Patients with Cancer

“…he genus Legionella was proposed in 1979 as the causative agent of Legionnaires' disease, a form of severe pneumonia (1,2). Currently, this genus contains 58 species and three subspecies (www.bacterio.net).…”

Validation of a Microbead-Based Format for Spoligotyping of Legionella pneumophila

“…egionella pneumophila is a Gram-negative facultative intracellular pathogenic bacterium, identified as the infectious agent of Legionnaires' disease (LD) in 1977 (1). Several species of the Legionella genus are responsible for LD; however, L. pneumophila is responsible for the majority of cases of LD, with Ͼ90% of all identified clinical cases within serogroup 1, which accounts for ϳ85% of all cases (2,3).…”

Pulmonary Collectins Protect Macrophages against Pore-forming Activity of Legionella pneumophila and Suppress Its Intracellular Growth

“…L. pneumophila is found ubiquitously in freshwater environments, and its aerosolization causes opportunistic infections, including severe pneumonia, Legionnaire's disease, and a less severe flu-like disease, Pontiac fever (15,16). Phagocytosed bacteria are generally killed in phagolysosome, where an acidic pH and lysosomal enzymes digest the bacteria.…”