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Unformatted text preview: lu like illness. • Clinically not distinguishable from other type of pneumonia.
• Appropriate microbiologic testing is the key to legionellosis diagnosis. University of Toronto, February 10, 2012
Toronto, Clinical presentation
• The case fatality rate of Legionellosis:
- 40 to 80% in untreated immuno-suppressed patients.
- 5 to 30% with appropriate case management .
• Epidemiology :
- 10 000 to 50 000 people contract Legionnaires’ disease every year in the United States
(WHO. 2005. Legionellosis ). - 8000 to 18000 persons are hospitalized annually with legionellosis in the United States
(Arch. Intern. Med. 1997, 157: 1709-1718). University of Toronto, February 10, 2012
University Toronto, Clinical presentation
• In industrialized countries, Legionella pneumophila is the second most common
pathogen detected in cases of pneumonia requiring admission to intensive care
units (MMWR Morb Mortal Wkly Rep, 2007 56:1261 3 ).
• Risk factors: increasing age, smoking, male sex, chronic lung disease, hematologic
malignancies, renal disease, lung cancer, immuno suppression and diabetes.
• Despite the use of antibiotics capable of intracellular penetration, the mortality
rate of legionellosis is still greater than 7% (Chest 2005, 128:1401 5 ). University of Toronto, February 10, 2012
University Toronto, Legionella genus
• The causative agents of legionellosis are gram-negative, non-sporeforming bacilli of the Legionella genus.
• This group of bacteria currently represents a genus of more than 53
species comprising 70 serogroups.
• Legionella pneumophila is the major cause of outbreaks (91.5%).
• Legionella pneumophila serogroup 1 is the predominant serotype
(84.2%). University of Toronto, February 10, 2012
Toronto, Microbial Ecology
• Natural reservoir : Water
Natural • Legionella bacteria are found worldwide Legionellae and can be detected in up to 80%
of freshwater sites (Fields, B. S. 1997. Manual of environmental microbiology). • Present as :
• Free planktonic cells.
• Surface-associated communities such as biofilms
(Rogers, J. 1994 Appl Environ Microbiol. ). • L. pneumophila is able to replicate in amoebae
and replication ins...
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This note was uploaded on 09/16/2012 for the course MICROBIOLO 101 taught by Professor Tom during the Spring '12 term at Arab Open University, Amman.
- Spring '12