DETECTION OF PNEUMOCYSTIS-CARINII DNA BY FILTRATION OF AIR

The high incidence of pneumonia caused by Pneumocystis carinii in immu nosuppressed patients makes it the most important parasite in non-trop ical geographical regions, It has recently been shown to be a fungus, but several aspects of this organism are still poorly understood. A ma jor question of clinical relevance is the nature of transmission and, thereby, the related problem of prevention. The mode of P. carinii tra nsmission is thought to be air, but this is based on circumstantial ev idence; the transmissive stage has not been identified. We attempted t o capture P. carinii by filtration of air in the vicinity of cages con taining P. carinii infected Wistar rats. Using nested polymerase chain reaction amplification or the thymidylate synthase gene to demonstrat e P. carinii we were able to demonstrate P. carinii DNA on such filter s, This strongly supports the suggested mechanism of transmission of P neumocystis by means of airborne spores and suggests an approach to th eir isolation and characterization.