Legionella

• What type of bacteria is Legionella pneumophila?

  Pleomorphic Gram-negative bacilli
• What is the motility characteristic of Legionella pneumophila?


  It is motile with a single polar flagellum
• Is Legionella pneumophila a sporulating bacterium?

  No, it is non-sporulating
• How many serotypes does Legionella pneumophila contain, and which is the most important?

  It contains more than 14 serotypes, with serotype-1 being the most important
• When was Legionella pneumophila first recognized, and where did the outbreak occur?

  It was first recognized in 1977 at a hotel in Philadelphia, USA
• What type of pneumonia is caused by Legionella pneumophila?


  It causes a type of epidemic atypical pneumonia called Legionnaire disease
• What are the risk factors for Legionnaire disease?

  Risk factors include being elderly (>50 years), immunocompromised (AIDS), smokers, diabetics, and men being more affected than women
• What are the main sources of infection for Legionnaire disease?


  Main sources of infection are water sources like air conditioners, cooling towers, and plumbing systems
• How does Legionella pneumophila survive in its environment?

  It multiplies inside free-living amoeba and survives with biofilms
• What is the pathogenesis of Legionella pneumophila?

  It is a facultative intracellular pathogen that multiplies in alveolar macrophages and blocks phagosome-lysosome fusion
• What role does the macrophage inhibitory protein (MIP) play in Legionella pneumophila infection?

  MIP facilitates phagocyte entry to a specialized vacuole
• What is the incubation period for Legionnaire disease?

  The incubation period is 2-10 days
• What are some clinical features of Legionnaire disease?

  Clinical features include dry cough, fever, headache, confusion and delirium, vomiting, and diarrhea
• What is Pontiac fever?

  It is a mild, flulike form of Legionella infection that does not result in pneumonia
• What are the diagnostic methods for Legionella infection?

  Diagnostic methods include sputum Gram staining, culture on buffered charcoal-yeast agar (BCYE), immunofluorescence staining, Legionella urine antigen, and PCR
• What is the treatment for Legionnaire disease?

  Treatment includes Azithromycin, Erythromycin, Rifampin, and Ciprofloxacin
• Why are penicillins and cephalosporins less effective against Legionella pneumophila?

  Because Legionella pneumophila produces B-lactamase
• What are the prevention methods for Legionnaire disease?

  Prevention methods include chlorination of water and heating water to >40°C followed by cooling to <20°C
• What are the key characteristics of Legionella pneumophila?

  • Pleomorphic Gram-negative bacilli
  • Motile with single polar flagella
  • Non-sporulating and non-capsulated
  • Fastidious and aerobic
  • Contains >14 serotypes, most important is serotype-1
  • More than 30 subtypes
• What are the clinical features and risk factors associated with Legionnaire disease?

  Clinical features:

  • Incubation period: 2-10 days
  • Symptoms: dry cough, fever, headache, confusion, delirium, vomiting, diarrhea

  
  

  Risk factors:

  • Elderly (>50 years)
  • Immunocompromised (AIDS)
  • Smokers
  • Diabetics
  • Men > women