Lecture's guest Feb_10_2012_Sequence_Based_typing_of_Legionella_spp

Clinically not distinguishable from other type of

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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 of Legionellosis • • 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 of Legionellosis • 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 : Present • 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.

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