Legionella

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Legionella
By
Dr. Emad AbdElhameed Morad
Lecturer of Medical Microbiology and Immunology
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Species

• There are about 40 species of legionella.
• Legionella pneumophila is a major cause of
  disease in man.

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Morphology culture

• Motile
• Weakly Gram negative
• Fastidious
• Cultured on buffered charcoal yeast extract agar
  (BCYE) agar. This medium contains L-cysteine,
  iron and a-ketoglutarate.

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Biochemical reactions
Catalase positive
Oxidase positive
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Pathogenesis

• Legionella lives in water sources.
• Mode of infection inhalation of water aerosols
  contaminated by the bacteria.
• So, infection is often related to contaminated
  air conditions, showers and sinks.
• Infection occurs in immunodeficient patients.

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Diseases

• Atypical pneumonia called Legionnaires disease.
• Flu like condition called Pontiac fever.

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Laboratory diagnosis

• Specimen
• Bronchial aspirate
• Pleural fluid
• Lung biopsy
• Culture on BCYE agar.
• Direct detection by PCR.
• Serological diagnosis by ELISA.

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Treatment

• Azithromycin or erythromycin is the treatment of
  choice.

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GOOD LUCK