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[Pneumocystis jirovecii: what does this mean?]

M Herrag1, M T Elfassy Fihry, A Alaoui Yazidi

  • 1Service de pneumologie, hôpital Ibn Nafis, CHU Mohammed VI, faculté de médecine et de pharmacie, université Cadi Ayyad, Marrakech, Maroc. herrag.repir@gmail.com

Revue De Pneumologie Clinique
|December 21, 2010
PubMed

Insights

Pneumocystis pneumonia (PCP) is caused by Pneumocystis jirovecii, a diverse fungal species. Recent studies show PCP results from new infections, not reactivation, and transmission is host-specific.

Area of Science:

  • Medical Mycology
  • Infectious Diseases
  • Molecular Biology

Background:

  • Pneumocystis causes fatal pneumonia in immunocompromised individuals, particularly AIDS patients.
  • Historically, Pneumocystis was considered a zoonosis, with limited understanding of its species diversity.
  • Advances in DNA analysis have revealed extensive genetic diversity within Pneumocystis organisms.

Purpose of the Study:

  • To clarify the nomenclature and species diversity of Pneumocystis.
  • To understand the transmission dynamics and host-pathogen relationship of Pneumocystis jirovecii.
  • To investigate the source of Pneumocystis jirovecii pneumonia (PCP) in immunosuppressed patients.

Main Methods:

  • DNA sequencing and genotyping of Pneumocystis organisms from various hosts.
  • Comparative analysis of genetic sequences to determine species and variations.
  • Review of existing literature on Pneumocystis transmission and pathogenesis.

Main Results:

  • Pneumocystis is not a zoonosis; distinct host-specific species exist.
  • The organism causing human PCP is now named Pneumocystis jirovecii.
  • Genetic variations within P. jirovecii samples have been identified.
  • Transmission is limited to the same host, suggesting exogenous reinfection for PCP.

Conclusions:

  • The renaming of the human pathogen to Pneumocystis jirovecii provides clarity and an international standard.
  • Understanding P. jirovecii's genetic diversity aids in studying host-pathogen interactions and resistance.
  • Current evidence suggests PCP in immunosuppressed patients arises from new, exogenous infections rather than reactivation.

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