Diagnosis of the primary infection by pneumocystis in autopsy specimens from two infants using lung impression smears (touch preps)

Abstract

The primary infection by Pneumocystis of normal, healthy infants is asymptomatic and goes undiagnosed. Microscopy diagnosis of Pneumocystis was sought in lung impression smears (LIS) from two ~3-month-old infants dying unexpectedly in the community. Pneumocystis nuclei and cysts were identified using Hema-Gurr with subsequent Gomori-Grocott staining in the same spot documenting that these stains may be complementary. LIS provide for an observer-dependent, inexpensive, and ready-available method for detection of Pneumocystis in infant lungs.

Keywords: Infant; Lung; Microscopy diagnosis; Pneumocystis; Primary infection.

Fig. 1

Representative microscopic findings. Lung impression smears of case 1 (A–D) and case 2 (E–F). The same spots are presented as stained with Hema-Gurr (A, B, C, etc.), and GMS (Adjacent below A1, B1, C1, etc.). The Hema-Gurr stained slides allow visualization of trophic forms with their nuclei and cytoplasm (black arrows). They are more abundant than cysts. The GMS stain allows visualization of cyst forms that are easier to see with green contrast. Mature cysts with 8 intracellular bodies as stained with Hema-Gurr (A, B, C) are stained with GMS (A1, B1, C1) (yellow arrows). The Hema-Gurr stain may suggest that cyst forms are present in a given spot. However, cysts were barely detected (C1), or not detected (F1) by GMS stain. This can be explained because cyst walls were either not reached by GMS for impregnation, or the cysts were not yet mature cysts with enough mucopolysaccharide in their wall. Vice versa, an empty cyst whose cell wall is well-stained in D1 is barely suggested in D (white arrows) . (All photos 1000X (Oil); Bar=10 μm). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)