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بسم الله الرحمن الرحيم

بسم الله الرحمن الرحيم. GENUS: LEGIONELLA Prof. Khalifa Sifaw Ghenghesh. Gram-negative rods Requires iron and cysteine for growth Buffered charcoal yeast-extract agar (BCYE) Optimum growth temp. >> 35-36oC Grow better >> 2.5-5% CO 2 39 species Legionella pneumophila.

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بسم الله الرحمن الرحيم

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  1. بسم الله الرحمن الرحيم GENUS: LEGIONELLA Prof. Khalifa Sifaw Ghenghesh

  2. Gram-negative rods • Requires iron and cysteine for growth • Buffered charcoal yeast-extract agar (BCYE) • Optimum growth temp. >> 35-36oC • Grow better >> 2.5-5% CO2 • 39 species • Legionella pneumophila

  3. Legionella pneumophila • Divided into 3 subspecies • L. pneumophila ssp. pneumophila • L. pneumophila ssp. fraseri • L. pneumophila ssp. pascullei • L. pneumophila divided to >14 serogroups • Most infections caused by: • L. pneumophila, serogroup 1 (SG1)

  4. Legionella pneumophila (TEM)

  5. CLINICAL SYNDROMES 1. Legionnaires’ Disease • Pneumonia • Incubation period >> 2-10 days • High fever, respiratory distress, cough, confusion and local neurological signs. • Mortality • 10% in healthy individuals

  6. 2. Pontiac Fever • A brief febrile influenza-like illness • A high attack rate with no mortality • Source of infection usually is not identified

  7. Impression smear from the lung of a patient fatally infected with L. pneumophila serogroup 1, demonstrating many thin, Gram-negative bacilli (arrows).

  8. Lung cross-section of patient with L. pneumophila infectionGram-negative, coccoid rods

  9. LABORATORY DIAGNOSIS • SPECIMENS • Sputum, bronchial aspirate or washings • Pleural fluid, lung biopsy or autopsy material >> Microscopy examination • CULTURE • BCYE with or without antibiotics • Incubate for 48 hours at 36oC aerobically with 2.5% CO2 • Plates kept for least 10-14 days before discarded as negative • Colonies >> “cut-glass” appearance by plate microscopy or fluorescing blue-white under UV light • IDENTIFICATION • Specific antisera in an immunofluorescence test.

  10. ANTIGEN TESTS • Urine for legionella antigen by ELISA for identifying L. pneumophila SC1 • SEROLOGY • Not reliable

  11. Charcoal-yeast extract agar plate culture of Legionella pneumophila.

  12. Charcoal-Yeast extract agar plate culture of Legionella pneumophilia - Circular off-white colonies (day 6, at 36oC)

  13. L. pneumophila stained using direct FA technique (400x)

  14. TREATMENT • Erythromycin in high dosage (IV) • Rifampicin, Ciprofloxacin

  15. EPIDEMIOLOGY • Disease occurs in outbreak form due to dissemination of the bacteria in aerosols • Infected aerosols generated from warm water sources: • Ponds of cooling towers of refrigeration plants in air-conditioning systems • Domestic hot water systems in hotels and hospitals • Warm water in nebulizers and oxygen line humidifiers • Whirlpool spa baths and showers

  16. CONTROL • Eradication of Legionella organisms in various kinds of water sources that may give rise to aerosol production. • Eradication by • Heat or disinfection with chlorine or other biocides • Hot water should be above 60oC before distribution

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