Pneumo Cist Is

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Pneumocystis carinii was previously classified asa protozoa. Currently, it is considered a fungusbased on nucleic acid and biochemicalanalysis.


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Worldwide, in humans and animals.

Serologic evidence indicates that most healthy children havebeen exposed by age 3 to 4.

Pneumocystis pneumonia (PCP) occurs in immunosuppressedindividuals and in premature, malnourished infants.

Geographic Distribution


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Life Cycle


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These fungi are found in the lungs of mammals where they reside without causing overtinfection until the host's immune system becomes debilitated. Then, an oftentimeslethal pneumonia can result. Asexual phase: trophic forms The number

1 replicate by mitosis The number 2 to The number 3. Sexual phase: haploid trophicforms conjugate The number 1 and produce a zygote or sporocyte (early cyst) Thenumber 2.

The zygote undergoes meiosis and subsequent mitosis to produce eight haploid nuclei(late phase cyst) The number 3.

Spores exhibit different shapes (such as, spherical and elongated forms). It ispostulated that elongation of the spores precedes release from the spore case. It isbelieved that the release occurs through a rent in the cell wall. After release, theempty spore case usually collapses, but retains some residual cytoplasm The number 4.

A trophic stage, where the organisms probably multiply by binary fission is alsorecognized to exist. The organism causes disease in immunosuppressed individuals.


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Clinical presentation

The symptoms of Pneumocystis pneumonia (PCP) include dyspnea,

nonproductive cough, and fever.

Chest radiography demonstrates bilateral infiltrates.

Extrapulmonary lesions occur in a minority (


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The chest radiographtypically shows diffuse

infiltrates in both lungsextending from theperihilar region.


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Cysts of P. Carinii in lung tissue,stained with methenamine silverand hematoxylin and eosin

(H&E). The walls of the cysts arestained black; the intracysticbodies are not visible with thisstain.

Diagnosis

At diagnosis, because the organism

does not grow on ordinary media,

generally reached by microscopicvisualization using appropriate staining

sputum, bronchoalveolar lavage or

transbronchial biopsy.


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Gomori methenamine silver stain at high

magnification demonstrates cysts ofPneumocystis jiroveciin lung


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References:

http://www.cdc.gov/dpdx/pneumocystis/index.html

Ruffolo JJ. Pneumocystis cariniiCell Structure. In: Walzer, PD, editor.

Pneumocystis cariniiPneumonia. 2nd ed. Marcel Dekker; 1994. p. 25-43.

Cushion MT, Ruffolo JJ, Walzer PD. Analysis of the developmental stagesof Pneumocystis cariniiin vitro. Lab Invest 1988;58:324-331.

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Pneumo Cist Is