科研之友
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摘要
The genus Pneumocystis designates atypical and opportunistic micromycetes infecting mammals. Its life-cycle in the pulmonary alveoli includes several forms, which sizes are comprised between 2 and 8 pm: trophic forms, intermediate stages called precysts and mature cysts. Pneumocystis jirovecii designates the human specific species of Pneumocystis. In immunocompromised patients, this species is responsible for a severe interstitial alveolar lung disease, Pneumocystis pneumonia (PCP), which is fatal without specific treatment. P jirovecii can also colonize immunocompetent subjects, including health care workers. In patients with underlying chronic pulmonary diseases, this colonization contributes to the worsening of respiratory functions. Pneumocystis transmission occurs by the airborne route and there are several genotypic evidence that P. jirovecii is responsible for nosocomial outbreaks. Pneumocystis cannot be cultured but its DNA can be detected in air. Recent studies allowed quantifying Pneumocystis DNA in the surrounding air of hospitalized patients with PCP, showing its diffusion even outside the patient's room. However, the morphology of the airborne stage(s) of Pneumocystis is still not known. Several lines of evidence indicate that colonized hosts contribute to the widespread of Pneumocystis and to its transmission, but no study has been realized so far on the excretion and diffusion of Pneumocystis from colonized subjects. The new knowledge of airborne diffusion and genotyping of P. jirovecii, led to update the recommendations for prevention of P jirovecii transmission in the hospital setting.
- 出版日期2011-12
