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[An ultrastructural evaluation of Pneumocystis carinii]
D Parada1, E Caleiras, R M Farías
1Unidad de Investigación, Instituto de Anatomía Patológica Dr. J. O'Daly, Caracas, Venezuela.
Abstract:
The pneumocystis carinii (PNC) is a challenge, because its taxonomy has not been completely explained. PNC seems to be a chimera with fungal and parasitic characteristics. The objective of the present study is to analyze the different stages observed in PNC using transmission electron microscopy in order to correlate them with bibliographic reports regarding a possible taxonomic classification. The trophic stage was the form most frequently encountered in alveolar spaces and their organisms varying in size and shape from 6 to 20 microns. Cyst were round or oval, with diameters ranging between 4 and 12 microns, showing four intracystic bodies were individually limited by a membrane. Connections between the membrane of intracystic bodies and junctions between them and the inner cell membrane of the cyst wall were also observed. Our ultrastructural findings appear to be in agreement with several reports which considered PNC among the fungi, most likely related them to the non-gemating Ascomycetes.
Insights
Pneumocystis carinii (PNC) remains taxonomically challenging due to its mixed characteristics. Ultrastructural analysis suggests PNC aligns with non-gemating Ascomycetes fungi.
Area of Science:
- Mycology
- Parasitology
- Microbiology
Context:
- The taxonomic classification of Pneumocystis carinii (PNC) is complex, presenting as a chimera with both fungal and parasitic traits.
- Accurate classification is crucial for understanding its biology and pathogenesis.
Purpose:
- To analyze the ultrastructural morphology of different Pneumocystis carinii stages using transmission electron microscopy.
- To correlate these ultrastructural findings with existing literature for taxonomic classification.
Summary:
- Trophic forms of PNC, varying from 6 to 20 microns, were most prevalent in alveolar spaces.
- Cyst forms, 4–12 microns, displayed four membrane-bound intracystic bodies with observed connections to the cyst wall.
- Ultrastructural evidence supports classifying PNC among fungi, specifically related to non-gemating Ascomycetes.
Impact:
- Provides ultrastructural evidence to support the fungal classification of Pneumocystis carinii.
- Contributes to resolving the taxonomic ambiguity surrounding this opportunistic pathogen.
- Informs future research into the biology and treatment of Pneumocystis pneumonia.