Immunology School Listings Home            

   Immunology Schools Feedback Feedback

Immunology Schools Feedback
ImmunologySchool Listings
Immunology Careers
Free Course on Immunology
Immunology Schools Examination
Immunology Schools FAQs
Anatomy Top Schools/School Rankings
Anatomy Top Schools/School Rankings

Legionella


ORGANISM:

  • Genus: Legionella
  • Species: pneumophila


GENERAL CONCEPTS:
  • Legionellae are ubiquitous aquatic saprophytes
  • Legionella is a relatively recent discovery in terms of human disease.
  • L. pneumophila, in particular, is the etiologic agent of Legionnaire's disease, first described in Philadelphia in 1976.
  • Legionnaire's disease is characterized by cough and fever with radiologic evidence of pneumonia.
  • Legionella is a unique, previously unrecognized bacterium. One might say it is a new organism for an old disease.


DISTINCTIVE PROPERTIES:
  • Legionella are motile, catalase-positive, Gram-negative bacilli. Some strains produce a yellow fluorescence under 366 nm ultraviolet light. Most are fastidious, requiring iron and L-cysteine for growth.
  • There are 25 species of Legionella and 42 serogroups. Most (85%) clinical isolates are L. pneumophila serotype 1.
  • The Legionella cell wall is mostly diaminopimelic acid (DAP) and contains little peptidoglycan. The LPS appears to lack the endotoxic lipid A moiety.
  • Several species produce hemolysins and there are some reports of exotoxins.
  • Legionella are capable of intracellular (macrophage) multiplication.


PATHOGENESIS:
  • Legionella have, in general, a low potential for virulence and most infections occur in persons having compromised immunity or pulmonary function.
  • There are two forms of disease produced by Legionella:

    1. Pontiac fever: An epidemic flu-like condition described in Pontiac Michigan in 1968 was later found to be due to Legionella. This condition was marked by fever, chills, headache and malaise that lasted 2-5 days and resolved.
    2. Legionnaire's disease: A severe pneumonia characterized by fever, chills and a non-productive cough. This multi-organ disease has significant mortality if not treated promptly.

  • The virulence of Legionella is dependent upon their ability to survive and multiply within macrophages.


HOST DEFENSES:
  • Most healthy individuals resist infection by Legionella but the mechanisms are not well understood.


EPIDEMIOLOGY:
  • Legionella are typically associated with aerosolized water (central air conditioning, cooling towers, showers, whirlpools).
  • Disease is generally waterborne; transmission occurs via airborne droplets.
  • The organisms exist in nature; humans are an accidental host.


DIAGNOSIS:

  • Clinical: Symptoms include headache, malaise, rapid fever, nonproductive cough, pneumonia. Generally, disease is difficult to diagnose but might be suspected in middle aged to older men who smoke and drink.
  • Laboratory: Bacteria can be grown on Buffered Charcoal-Yeast Extract (BCYE) agar. Direct immunofluorescent may be used to visualize the organisms. An increase in Legionella-specific serum antibody is evidence of infection.


CONTROL:

  • Sanitary: Regular maintenance of air conditioning or the inclusion of biocidal compounds into water cooling towers reduces the reservoir. Similarly, hyperchlorination of the water supply eliminates the source.
  • Immunological: None available.
  • Chemotherapeutic: Erythromycin is the drug of choice.

Our Network Of Sites:
Apply 4 Admissions.com               | A2ZColleges.com  | OpenLearningWorld.com  | Totaram.com
Anatomy Colleges.com                 | Anesthesiology Schools.com  | Architecture Colleges.com | Audiology Schools.com
Cardiology Colleges.com            | Computer Science Colleges.com | Computer Science Schools.com | Dermatology Schools.com
Epidemiology Schools.com          | Gastroenterology Schools.com  | Hematology Schools.com     | Immunology Schools.com
IT Colleges.com                | Kinesiology Schools.com  | Language Colleges.com  | Music Colleges.com
Nephrology Schools.com             | Neurology Schools.com  | Neurosurgery Schools.com | Obstetrics Schools.com
Oncology Schools.com    | Ophthalmology Schools.com | Orthopedics Schools.com       | Osteopathy Schools.com
Otolaryngology Schools.com | Pathology Schools.com  | Pediatrics Schools.com   | Physical Therapy Colleges.com
Plastic Surgery Schools.com | Podiatry Schools.com   | Psychiatry Schools.com   | Pulmonary Schools.com 
Radiology Schools.com | Sports Medicine Schools.com | Surgery Schools.com  | Toxicology Schools.com
US Law Colleges.com | US Med Schools.com | US Dental Schools.com

Copyright 2000-2011 Immunology Schools, All Right Reserved. | Site Map | Privacy Policy | Disclaimer