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Pneumocystis carinii

Pneumocystis carinii. Katrina Kittleson Steda Lundak Parasitology 2007. Introduction . Fungus or Protozoan?? Orphan organism, phylogenic position has not yet been established Opportunistic Parasite Severe pathology in immunodeficient hosts Severely malnourished newborns

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Pneumocystis carinii

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  1. Pneumocystis carinii Katrina Kittleson Steda Lundak Parasitology 2007

  2. Introduction • Fungus or Protozoan?? • Orphan organism, phylogenic position has not yet been established • Opportunistic Parasite • Severe pathology in immunodeficient hosts • Severely malnourished newborns • One of the initial signs of AIDS emergence • Lives in interstitial tissue of lungs • Rarely disseminates to spleen, lymph nodes, bone marrow, eyes

  3. Fungus from nucleic acid and biochemical analysis rRNA homologous to that found in fungi stains with some fungal stains Affinity for Grocott’s methenamine silver stain Produces chitin has ultrastructural characteristics similar to some fungi Protozoan other structures similar to Toxoplasma and Plasmodium is sensitive to a variety of antiprotozoal agents. It’s membrane properties resemble those of amebas Shows surface antigenic variation which occurs in protozoa and has not been established in fungi Fungus vs. Protozoan

  4. Geographic Distribution • Worldwide • Most children exposed by the age of 3-4 years • Commonly found in the lungs of healthy individuals, but no disease occurs • Widespread in mammals

  5. Hosts • Humans • Pneumocystis jiroveci(i) alternate names • Pneumocystis carinii hominis • Elderly, malnourished children, primary immunodeficiency disorders, AIDS • Patients receiving cytotoxic or immunosupressive drugs for lymphoresticular cancers or transplants • Other mammals: rabbits, dogs, goats, swine, cats, chimpanzees, owl monkeys, horses

  6. Transmission • Aerosol droplets • Direct contact • Congenital infection • Household pets • Interspecies transmission? • Reactivation of latent infection when immunocompromised • Or, new infection?

  7. Life Cycle • Life cycle is not fully known • Asexual and sexual reproduction (CDC) • Four general morphological forms in mammals • Trophozoite (has amoeboid trophozoite form) • Precysts • Cysts • Sporozoites (intracystic bodies) • Cyst (diagnostic form) • chitinous membrane and 8 intracystic bodies • Pore in cyst wall used for releasing sporozoites. • Can be spherical or collapsed.

  8. Life Cycle

  9. Clinical Presentation • Causes Pneumonitis, Pneumocystis pneumonia (PCP) • Lung epithelium becomes desquamated • alveoli fill with foamy exudate containing parasites • Fever, non productive cough, breathing difficulty on exertion, respiratory failure, cyanosis • Death by asphyxia

  10. Diagnosis • Clinical symptoms • Sputum or bronchial lavage • Special staining with toluidine blue, methenamine silver • Gram-Weigert stain for cysts • ELISA, immunofluorescence assay, DNA amplification being developed

  11. Diagnosis

  12. Trophozoites in BAL material. Cysts in BAL material Pictures

  13. Treatments • Trimethoprim-sulfamethoxazole (TMP-SMZ) • Pentamidine isethionate inhalant • Treatments can be toxic and patient must be monitored closely • Prophylactic treatment if CD4 count is low (<200) • HAART regimen to boost immune system function, corticosteroids

  14. Pneumocystis carinii Infection: Update and Review • Questions • Relationship with immunosupression • Taxonomic classification • Morphology • Latent infection or new infection? • Diagnosis, treatment, prophylaxis • Research into a vaccine

  15. More information/References • Parasitology textbook • Discussion article • Familydoctor.org • Aafp.org • National Library of Medicine http://www.nlm.nih.gov/ • Center for Disease Control and Prevention http://www.cdc.gov

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