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Genetic variation in Pneumocystis carinii isolates from different geographic regions: implications for transmission

C B Beard1, J L Carter, S P Keely

  • 1Centers for Disease Control and Prevention, Atlanta, Georgia 30341-3724, USA. cbb0@cdc.gov

Emerging Infectious Diseases
|May 29, 2000
PubMed

Insights

Pneumocystis pneumonia (PCP) transmission in AIDS patients involves diverse genetic strains, suggesting active acquisition from common sources rather than early-life infections. Human involvement is key in the P. carinii transmission cycle.

Area of Science:

  • Medical Microbiology
  • Infectious Diseases
  • Genetics

Background:

  • Pneumocystis carinii pneumonia (PCP) is an opportunistic infection common in individuals with Acquired Immunodeficiency Syndrome (AIDS).
  • Understanding the transmission dynamics of P. carinii is crucial for controlling PCP outbreaks in immunocompromised populations.

Purpose of the Study:

  • To investigate the transmission patterns of P. carinii in persons with AIDS.
  • To identify genetic variations in P. carinii isolates to infer transmission routes.

Main Methods:

  • Analysis of P. carinii isolates from 191 AIDS patients across five U.S. cities.
  • Evaluation of genetic variation at two loci: mitochondrial large subunit rRNA and dihydropteroate synthase.
  • Identification of 14 unique multilocus genotypes, with mixed infections found in 17.8% of cases.

Main Results:

  • Genotype frequencies differed based on the patient's place of diagnosis, not place of birth.
  • Mixed infections were significantly associated with primary PCP diagnoses.
  • Genetic diversity suggests P. carinii is acquired actively from a common source.

Conclusions:

  • PCP cases in AIDS patients likely arise from recent infections, not early-life acquisition.
  • Transmission involves a common source, potentially human or environmental.
  • Humans play a significant role in the P. carinii transmission cycle, even without direct person-to-person spread.

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