Collection and Handling of Stool Specimens

Refrigerated

Beyond 1 hour, the stool must be:

Amoebas

Incubation using a temperature of 37C destroys:

It allows visualization of motility in trophozoites

Which of the following is the main advantage of using a saline preparation when examining stool specimens?

10x low power

In a saline stool preparation, what magnification is typically used first to scan for potential parasitic organisms?

2 mg

How much stool is used in a saline wet mount?

Trophozoite movement

What can you see in a saline prep that you cannot see in an iodine prep?

Yellow-brown

In iodine-stained stool prep, what color does the cyst cytoplasm appear?

They are destroyed

What happens to trophozoites in iodine stain?

Nuclear chromatin

Which structure is easiest to see in iodine-stained stool?

10-20 minutes

A Kato-thick smear preparation is best examined within:

Kato-thick smear

• Useful in mass stool examinations

• Very good in detecting eggs with thick shells but not eggs with thin shells

Hookworm eggs may become too transparent or distorted

What would happen if Kato-thick smear preparation is kept too long before examination?

Zinc sulfate method

Flotation method of choice for protozoan cysts and many helminth eggs

Sheather’s Sugar Flotation

It is considered the best flotation method for the recovery of coccidian cysts, mainly Cryptosporidium, Cyclospora and Isospora

Ether

What reagent dissolves neutral fats in stool?

Acid Ether Concentration Technique (AECT)

Sedimentation technique recommended for the recovery of Trichuris, Capillaria and trematode eggs, especially Schistosoma

Loss of parasite to the plug of debris

What is the disadvantage of AECT?

Iron hematoxylin

It serves as a very useful stain for fresh and PVA- or SAF-preserved fecal specimens

Modified Ziehl-Neelsen technique

Technique used for the detection of oocysts of Cryptosporidium, Cyclospora and other coccidians

Giemsa

What is the preferred stain for a thin blood smear?

Microscopic examination

What is the gold standard for Malaria diagnosis?

Identify the parasite species

A thick blood smear is useful for detecting the presence of parasites. A thin smear is needed to:

Acridine orange

In the Quantitative buffy coat test, DNA of parasites take up which dye?

Concentrate parasites or microorganisms from a liquid sample

The Swinnex filter holder is used in membrane filtration primarily to:

First morning

What is the best specimen for sputum examination?

It is more concentrated

Why is a first morning specimen considered the best for urine examination?

Liver aspirate

Tissue aspirate usually requested to rule out hepatic amebic abscess

Duodenal aspirate

What type of aspirate is best used for the diagnosis of G. lamblia and S. stercoralis?

Rectal biopsy

What type of biopsy is used for the recovery of Schistosoma eggs?

Muscle biopsy

What type of biopsy is used for the recovery of encysted larvae of Trichinella spiralis?

Copro culture

In which stool culture method are larvae harvested using the Baermann procedure?

Larvae of hookworms and Strongyloides stercoralis

The Harada-Mori filter paper culture technique is primarily used for the detection of:

Histidine-rich protein 2 (HRP-2)

Which protein detected by malaria RDTs is produced only by Plasmodium falciparum?

All four human Plasmodium species

Parasite lactate dehydrogenase (pLDH) detected by malaria RDTs is produced by: