Laboratory Diagnostic Methods

How should Fecal specimens be collected?

Must be in a CLEAN DRY waterproof container

Fresh LIQUID or SOFT stool should be examined how quickly?

Within 30 minutes!!

What should be done if a LIQUID/SOFT stool sample cannot be examined immediately?

Must examine within 30 minutes or FIX IT

Fresh FORMED stool should be examined how quickly?

2-3 hours

What should be done if a FORMED stool sample cannot be examined immediately?

Examine 2-3 hours or REFRIGERATE overnight/FIX

Can stool be incubated?

NO stool should NEVER be incubated

What kind of stages can be found in LIQUID STOOL

MOTILITY = Trophozoites

What kind of stages can be found in FORMED STOOL?

Inside of FORMED STOOL you have EGGS and non motile things

How do we get optimal parasite recovery in stool?

Taking 3 specimens spaced a DAY or TWO apart

What is done in the Macroscopic (gross) examination of Stool?

Scanning for INTACT worms and proglottids

Also noting the CONSISTENCY of the stool

And the COLOR

What does BLACK stool indicate?

BLEEDING

What are the 3 microscopic preparations for stool?

1. Direct wet mount

2. Concentrates

3. Permanent stained smears

How are Direct wet mounts done?

1. Water on slide

2. Specimen in water

3. Coverslip carefully placed on specimen

What are your 2 types of Wet mounts?

1. Saline

2. Iodine

What is the Saline wet mount mostly used for?

Observing MOTILITY

What is the Iodine wet mount used for?

INTERNAL structures

DESTROY motility

What are the 2 CONCENTRATION techniques

1. Sedimentation - destroys motility

2. Flotation - preserve motility

Which is the main sedimentation method?

Formalin-ethyl acetate (FES) sedimentation method

Would you use a sedimentation method for observing Trophozoites/motility?

NO sedimentation makes TROPHS unrecognizable

Which Concentration method should be used to preserve trophs/motility?

Flotation method

This one is the opposite, it distorts the nonmotile stages

What is the GOLD STANDARD for stool specimens?

Stained smears

What are your 3 types of Permanently Stained Smears?

1. Trichrome (most preferred)

2. Iron hematoxylin stain

3. Kinyoun stains

What is the Trichrome stain?

BLUE/GREEN background

Most preferred permanent stain

Cytoplasm of cysts and trophs appear blue green

Which permanent stain smear provides high definition of parasitic structures?

Iron hematoxylin stain

Which stain detects Oocysts?

Kinyoun stain

How are permanent smears examined?

Thick and thin at low-high power

THIN at oil immersion 100x

How is the Cellophane tape test performed?

Pressing tape down on the perianal area

Which test is used for G. lamblia and S. stercoralis?

Enterotest capsule

Which specimens are used to diagnose amebiasis and cryptosporidiosis

Sigmoidoscopy specimens

Urine, vaginal, and urethral specimens can diagnose which parasites?

Schistosoma haematobium, Trichomonas vaginalis, and Enterobius vermicularis

Sputum specimens can be used to diagnose which parasites?

Strongyloides stercoralis and Wuchereria bancrofti

Entamoeba histolytica extraintestinal infections

Which specimens should be collected DURIN FEVER

Malaria, babesia, and Trypanosoma