SLIDE PREPARATION AND TROUBLESHOOTING

OBJECTIVES

• Student will properly prepare slides...
• Students will reject slides that do not meet quality standards.
• Students will identify and justify the correct preparation for the suspected parasite
• Students will identify and justify the correct preparation for the specimen source.
• Students will reject specimens that do meet histological standards.

NUMBER OF STOOL SPECIMENS

• Three pre-therapy specimens, three post therapy specimens
• If one is positive, future orders should be canceled
• Two of each should be normal bowel movements
• The third should be laxative induced if patient does not already have diarrhea
• Amebiasis may require up to six of each specimen

TIMING OF SPECIMENS

• Specimens should be ordered for alternating days within less than ten days
• Timing of post therapy specimens depends n the specimen

PRESERVED AND FRESH

• As a general rule Fresh should be examined within 30 minutes
• Preservatives are formalin, polyvinyl alcohol resin, or SAF
• SAF is preferred due to PVA's toxic qualities

GROSS EXAMINATION

• Color
• Consistency
• Foreign objects
• Blood&Mucus
• Visible parasites

CONSISTENCY

• Liquid or watery- protozoan trophozoites, no cysts
• Formed- protozoan cysts
• Helminth eggs and larvae, microsporidian spores, and coccidian oocysts are found in all

MICROSCOPIC EXAMINATION

• Direct wet mount
• Concentration
• Permanent Smear
• Snips/histological
• Peripheral Smear

DIRECT WET MOUNT

• Screening for motility and protozoan trophozoites
• One drop of specimen and one drop of saline(0.85%) or one drop Lugol's iodine
• Drip on slide and cover slip
• Seal cover slip edges with Vaseline--paraffin mixture
• Can also be used with aspirates and fluids

CONCENTRATION

• Removes debris
• Filtered then spun with ethyl acetate
• More commonly used than flotation

FLOTATION

• Sheather's Sugar Flotation
• Particularly effective for Cryptosporidia and Isospora oocysts
• Can only use formalin preservation

PERMANENT STAINS

• Iron hematoxylin
• Wheatley's trichrome
• Modified Acid-fast stain

OTHER SPECIMENS

• Scotch tape prep
• For pinworms

OTHER SPECIMENS

• Sigmoidoscopy material
• For amebiasis

OTHER SPECIMENS

• Aspirates
• Lung and liver abscesses
• Use TYI-S-33 medium for viability
• For entamoeba and Hydatid cysts