Tags

Type your tag names separated by a space and hit enter

Pneumocystis jirovecii pneumonia

Shmuel Shoham, M.D., John G. Bartlett, M.D.
Pneumocystis jirovecii pneumonia is a topic covered in the Johns Hopkins ABX Guide.

To view the entire topic, please or purchase a subscription.

Official website of the Johns Hopkins Antibiotic (ABX), HIV, Diabetes, and Psychiatry Guides, powered by Unbound Medicine. Johns Hopkins Guide App for iOS, iPhone, iPad, and Android included. Explore these free sample topics:

Johns Hopkins Guides

-- The first section of this topic is shown below --

PATHOGENS

  • Causative organism of pneumocystis pneumonia (PCP) is the fungus called Pneumocystis jiroveci.
    • Closest relative is Taphrina deformans, a fungal pathogen of peach trees.
  • There are multiple species within the genus Pneumocystis
    • P. jiroveci (formerly identified as P. carinii and pronounced "yee row vet zee”) cause of disease in humans.
    • P. carinii and P. wakefieldiae infect rats, and P. murina infects mice.
      • Other species infect a range of animals (e.g. rabbits, sheep, monkeys, aquatic mammals).
  • Morphological forms:
    • Trophic form:
      • Predominant forms (>90% in the lungs), multiply through binary fission, heterogeneous in shape, about ∼2 µm at greatest diameter, have a cell membrane and a fragile (not rigid) cell wall.
    • Asci or spore form (also called cyst):
      • Formed by conjugation of two opposite mating type trophic forms (sexual reproduction), more uniform in shape, about 8–10 µm in greatest diameter.
      • Have a rigid cell wall that is important for protecting the organism from environmental conditions when outside of the host (during airborne transmission) and contains beta-glucans.
      • Mature cysts contain 8 intracystic bodies, which can be released to become trophic forms.
  • Important biochemical properties:
    • Cell membrane lacks ergosterol and hence antifungal agents such as azoles and amphotericin B products are not active against Pneumocystis.
    • The fungus must synthesize its own folic acid and hence this is a typical target for treatment (e.g TMP/SMX).
    • Cyst cell wall contains beta-glucans, which can be helpful for diagnosis and perhaps treatment.
  • Ecological niches and transmission
    • Specific environmental reservoirs are not well understood.
    • The organism grows well on epithelial cells within alveoli and fungal burden correlates with the degree of immune dysfunction.
    • P. jiroveci may be present at low levels in healthy humans, who may serve as a source of transmission.
    • Transmission is via airborne asci (cyst) forms passed from person to person.
    • There are constant inhalation and acquisition (transient or long term) of the organism. Clinical disease may be due to new acquisition of the fungus by a susceptible patient or from the transformation of long-term carriage into active disease.

-- To view the remaining sections of this topic, please or purchase a subscription --

Last updated: April 5, 2019

Citation

Shoham, Shmuel, and John G Bartlett. "Pneumocystis Jirovecii Pneumonia." Johns Hopkins ABX Guide, The Johns Hopkins University, 2019. Johns Hopkins Guide, www.hopkinsguides.com/hopkins/view/Johns_Hopkins_ABX_Guide/540439/all/Pneumocystis_jirovecii_pneumonia.
Shoham S, Bartlett JG. Pneumocystis jirovecii pneumonia. Johns Hopkins ABX Guide. The Johns Hopkins University; 2019. https://www.hopkinsguides.com/hopkins/view/Johns_Hopkins_ABX_Guide/540439/all/Pneumocystis_jirovecii_pneumonia. Accessed July 21, 2019.
Shoham, S., & Bartlett, J. G. (2019). Pneumocystis jirovecii pneumonia. In Johns Hopkins ABX Guide. Available from https://www.hopkinsguides.com/hopkins/view/Johns_Hopkins_ABX_Guide/540439/all/Pneumocystis_jirovecii_pneumonia
Shoham S, Bartlett JG. Pneumocystis Jirovecii Pneumonia [Internet]. In: Johns Hopkins ABX Guide. The Johns Hopkins University; 2019. [cited 2019 July 21]. Available from: https://www.hopkinsguides.com/hopkins/view/Johns_Hopkins_ABX_Guide/540439/all/Pneumocystis_jirovecii_pneumonia.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - Pneumocystis jirovecii pneumonia ID - 540439 A1 - Shoham,Shmuel,M.D. AU - Bartlett,John,M.D. Y1 - 2019/04/05/ BT - Johns Hopkins ABX Guide UR - https://www.hopkinsguides.com/hopkins/view/Johns_Hopkins_ABX_Guide/540439/all/Pneumocystis_jirovecii_pneumonia PB - The Johns Hopkins University DB - Johns Hopkins Guide DP - Unbound Medicine ER -