Microscopy
Trophozoites of Pneumocystis jirovecii
are 1-5 µm, pleomorphic and contain a single nucleus. Trophozoites are
found in the lungs and many other extrapulmonary specimens, especially in
immunocompromised patients.
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A |
A:
P. trophozoites in a bronchoalveolar lavage (BAL) specimen of an AIDS
patient, stained with Giemsa.
Pneumocystis
jirovecii cysts are thick-walled, rounded and approximately 5-8 µm in
size, although thin-walled cysts exist also. Cysts contain up to eight
intracystic bodies. Precysts have also been described for this
organism. Precysts are spherical, 4-7 µm in diameter and do not
contain intracystic bodies (but may contain one or more nuclei). Cysts
are found in the lungs and many other extrapulmonary specimens, especially
in immunocompromised patients.
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B |
C |
B:
Three cysts of P. jirovecii in a bronchoalveolar lavage (BAL) specimen, stained
with Giemsa. Note the presence of several smaller, isolated trophozoites.
C: Cysts of P. jirovecii in
lung tissue, stained with silver stain. The walls of the cysts are stained black; the intracystic
bodies are not visible with this stain.
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D |
D: Cysts
of P. jirovecii
cysts in a bronchoalveolar lavage (BAL) specimen, stained with silver stain.
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E |
F |
E: Indirect immunofluorescence
using monoclonal antibodies against Pneumocystis jirovecii.
F: Direct immunofluorescence antibody stain using monoclonal
antibodies that target Pneumocystis jirovecii. This image is from a bronchoalveolar lavage
(BAL) specimen from a patient with a malignancy. Image courtesy of Brigham &
Women's Hospital, Boston, MA.
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