With a fecal specimen, which procedure is most dependable for the accurate diagnosis of an intestinal amebic infection?

• A. Direct saline wet mount
• B. Direct iodine wet mount
• C. Permanently stained smear
• D. Formalin-ethyl acetate sedimentation technique

Answer: (C)

The most dependable way to diagnose an intestinal amebic infection from a fecal specimen is to rely on permanently stained smears. These stains, such as trichrome or iron-hematoxylin, fix and color the parasite well, preserving fine morphological details that are essential for accurate identification. With a permanently stained smear you can clearly visualize the cysts and trophozoites and distinguish Entamoeba histolytica from nonpathogenic amebae by features like the nuclear structure in cysts and the presence of ingested red blood cells in trophozoites. Direct saline or iodine wet mounts show only living forms and are highly operator-dependent, with lower sensitivity because trophozoites are fragile and debris can obscure identification. Concentration methods like formalin-ethyl acetate sedimentation aid in collecting organisms but rely on subsequent staining for proper identification; they don’t by themselves provide the diagnostic detail that a well-prepared permanent stain does. Thus, the Permanently stained smear offers the most reliable morphological basis for diagnosis.