🦠microbiology review

Pneumocystis

Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025

Definition

Pneumocystis is a genus of fungi, primarily known for causing Pneumocystis pneumonia (PCP) in immunocompromised individuals. It is often resistant to conventional antifungal treatments, necessitating specific antimicrobial drugs.

5 Must Know Facts For Your Next Test

  1. Pneumocystis jirovecii is the species responsible for PCP in humans.
  2. PCP is an opportunistic infection commonly seen in patients with HIV/AIDS.
  3. Trimethoprim-sulfamethoxazole (TMP-SMX) is the first-line treatment for PCP.
  4. Pneumocystis lacks ergosterol in its cell membrane, which makes it resistant to many antifungal drugs that target ergosterol synthesis.
  5. Diagnosis of PCP often involves bronchoalveolar lavage and staining techniques to identify the organism.

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