Pneumocystis jirovecii

Pneumocystis jirovecii

Pneumocystis jirovecii is a fungus of the genus Pneumocystis and the excitation of interstitial pneumonia ( Pneumocystispneumonie, PCP ), which occurs particularly in infants, immunocompromised and AIDS patients. The pathogen is now no longer associated with the protozoa, but the sac fungi ( Ascomycota ) and is named after Otto Jírovec.

Previously Pneumocystis jirovecii was called Pneumocystis carinii; this was originally held for the pathogen of pneumonia in immunodeficiency.

This name is nowadays still widely used, but formally no longer allowed. It could be shown that the occurring in the human pathogen is different from the Pneumocystis carinii detected in rats.

Features

The trophozoites have a diameter of about 1 micron. Their shape is oval to oblong. By repeated division cysts arise with six to eight spores (diameter: about 5-7 microns ). The species differs from other fungi, among other things, that the cell membrane does not contain ergosterol but cholesterol.

Nomenclature

Pneumocystis jiroveci common name is used for the type. The correct name is but jirovecii.

Clinic

Infected patients often complain of dyspnea, tachypnea, dry cough. There is usually fever. Auscultation is unremarkable, the X-ray image of the lungs shows only in the course changes the meaning of the reticulo - nodular densities of the interstitium. Typical is also an increase of LDH in the blood.

Proof

Proof is by direct microscopy of a specimen of induced sputum, bronchoalveolar a lavage (BAL) or transbronchial biopsy. For better illustration of the Pneumocysten doing a staining method is used (for example, optical brighteners, toluidine blue or immunofluorescence ). Alternatively, the quantitative real -time PCR is increasingly used as a detection method, a positive detection is not always easy to interpret here, since the fungus can colonize the respiratory tract in small amounts in healthy people. In the usual culture media Pneumocystis jirovecii can not be cultured.

Therapy

Treatment and prophylaxis (eg in AIDS patients ) comes standard actually effective against bacteria antibiotic cotrimoxazole to apply ( for therapy in very high doses ). In addition, antiparasitic agents such as pentamidine and atovaquone are used. Echinocandin caspofungin as could in principle also be used for the treatment of Pneumocystis jirovecii infection, but this has been very unusual. Antifungals from the classes of polyenes and triazoles are ineffective against Pneumocystis, as they inhibit the synthesis of ergosterol, which does not occur in this species ( see above).