legionella Pneumophila
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History, transmission, pathogenesis, symptoms, treatment and prevention of disease caused by legionella pneumophila bacteria...
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legionella Pneumophila
- 1. Legionella Pneumophila By: Syeda Aiman
- 2. OBJECTIVES: The presentation is designed to talk about: History of Legionella Pneumophila outbreak. Genus Legionella and its species. Legionella Pneumophila’s characteristics virulence factors Habitat Mode of transmission. Persons at risk Pathogenisity of Legionellosis (Pneumonia & Pontiac fever) Lab Diagnosis Treatment Prevention
- 3. History, Mystery and Discovery Legionella: name from Legionnaire. Legionnaire ‘’soldier’’ was a member of legion (a division of army during Roman Empire) Pneumophila: • Pneumo = pneumonia • Phila = Philadelphia (name of city in US) Outbreak occurred among people attending a convention of American legion at the Stratford Hotel in Philadelphia.
- 4. GENUS LEGIONELLA There are 30 species of legionella that cause pneumonia. Legionella Pneumophila = 90% of pneumonia Legionella Micdadei and Legionella Bozemanii = remaining 10% cases of pneumonia
- 5. Characteristics: • Thin, pleomorphic, gram-negative rods. • Intracellular pathogens of macrophages. • Motile (flagellated) • Non-spore forming • Aerobic • 16 serogroups (most cases caused by serogroup 1 organisms) Virulence factors: • Lipopolysaccharide (endotoxin): adherence, invasion, iron acquisition, inhibiting the immune response • Flagella: movement • Pili: attach cell to host surface • Type II secretion system: secret proteins found in cytoplasm of bacteria to extracellular space
- 6. Habitat: Environmental water sources (Air conditioners, hot tubs, water-cooling towers) Hospitals (water taps, sinks, showers) Mode of transmission = air-borne (inhalation of aerosols from contaminated water) Person-to-person spread does not occur Portal of entry = respiratory tract Person at risk: Older man who smoke and consume alcohol Patients with o AIDS o Cancer o Transplant (especially renal transplant) o Being treated with corticosteroids.
- 7. Atypical (Lobar) Pneumonia Accompanied by: Cough: (prominent symptom) Sputum is scanty and non-purulent Hyponatremia Serum sodium <130 mEq/L Distinguish it from other pneumonia Cause mental confusion Non-bloody diarrhoea Proteinuria Microscopic hematuria RBCs in urine. So small that blood cannot be seen when you urinate. Legionella Pneumophila Infections (Legionellosis)
- 8. Pathogenesis of Pneumonia: 1) L. Pneumonia gets into lung, bacteria are phagocytosed by alveolar macrophage. 2) After internalization, bacteria triggers Legionella containing vacuole (LCV) biogenesis (a specialized vacuole for intracellular replication of bacteria) 3) Legionella multiply intracellularly by avoiding phagosome-lysosome fusion using type IV secretion system (main virulence system) 4) When legionella become motile, host cell become overwhelmed by infection and breakdown resulting in release of bacteria that cause infection of other macrophages.
- 9. Pontiac Fever A mild, flulike form of legionella infection that include fever, headache, muscle aches. It does not result in pneumonia or death. Symptoms usually go away on its own, no hospitalization or antibiotic therapies are required Pathogenesis: Involve a host response to endotoxin from lipopolysaccharide of legionella without replication of bacteria in the host.
- 10. LAB DIAGNOSIS L. Pneumophila grows on charcoal-yeast agar (a specialised medium supplemented with iron and cystein) Urinary antigen test (UAT) • Rapid means of making diagnosis • Available only for serogroup 1 organisms Grey/white coloured colonies
- 11. Prevention: • Reducing cigarette and alcohol consumption. • Eliminating aerosols from water sources. • Using hyperchlorination and high temperature in hospital water supplies. o No vaccine available Fluoroquinolones: Levofloxacin or Trovafloxacin Macrolides: Azithromycin or Eryhthromycin Treatment:
- 12. (1) How to differetiate? Atypical pneumonia caused by Legionella Vs Other atypical pneumonia (2) Why Penicillin and Cephalosporins are not effective in treatment for legionellosis? (3) What causes hyponatremia in legionellosis?
- 13. The End