Specimen Collection and Processing (Parasitology)

COLLECTION

STOOL COLLECTION (TYPICAL)

• one spx. collected every other day 
• total of three collected in 10 DAYS

Diagnosis of Amoebiasis 

• six specimens in 14 DAYS

If patient in therapy of BISMUTH, BARIUM, & MINERAL OIL

• collect PRIOR TO THERAPY 
• not until 5-7 or 4 – 5 DAYS after completion of therapy

DELAYED FOR 2 WEEKS 

• if patient’s in antibiotic/antimalarials
• 2-5g – acceptable amount of stool (walnut-size)

Stool 

• Bacterial infection – 1 a day for 3 days 
• Parasitic infection – 3 specimens in 10 days
• Stool to preservative ratio – 1:3

FOR TROPHOZOITE MOTILITY DEMONSTRATION 

• FRESH SPX. IS REQRUIED 
• Examined in 30 MINS.
• STOOL FIXATIVES – 3:1 fixative : stool ratio

FORMALIN 

• 5% – protozoan cyst 
• 10% – helminth eggs & larvae 
• must be fixed within 30 MINS.
• ADVANTAGES 
  
  • easy to prepare 
  • preserves spx. for up to several years 
  • long shelf-life

POLYVINYL ALCOHOL 

• for permanent-stained smear 
• has plastic powder 
• most often combined with schaudinn solution
• SCHAUDINN SOLUTION 
  
  • Zinc sulfate 
  • Copper sulfate 
  • Mercuric chloride (base)

SODIUM ACETATE FORMALIN 

• for concentration technique & permanent stained smear 
• Can be used for modified-acid fast stain for coccidian oocysts

MACROSCOPIC

• must be FRESH, UNPRESERVED. 
• Consistency 
  
  • FULLY-FORMED – possible to see cyst 
  • LIQUID – trophozoite 
• Color – brown (normal color)

MICROSCOPIC EXAM 

DIRECT WET PREP

• To detect motile trophozoite 
• Used unfixed specimen 
• 0.85% saline 
• Glass slide – 3 x 2 inch-size 
• 22-mm square cover slip 
• PETROLEUM JELLY – temporary seal 
• Enhance details of cyst 
• Drop of lugol’s or D’ Antoni’s Formula 

BUFFY COAT SLIDES 

• Oxalated / citrated blood 
• Placed in wintrobe tubes 
• 30 mins. @ 100 x g 
• For Leishmania & Trypanosoma

CONCENTRATION TECHNIQUE

• Detects small no. of parasite
  
• Best to detect helminth eggs and larvae
  
• Types
  
  • Floatation
    
  • Sedimentation
    
• FECT (FORMALIN – ETHYL ACETATE SEDIMENTATION)
  
  • Most widely used
    
• ZINC SULFATE FLOATATION TECHNIQUE
  
  • Zn sulfate SG – 1.18 – 1.20
    
• KNOTT TECHNIQUE
  
  • 1 ml blood
    
  • 10 ml 2% formalin
    
  • 1 min @ 500 x g

PERMANENT STAINS

• Sample of choice – PVA-preserved
  
• Wheatly Trichrome – most widely used
  
• Iron Hematoxylin – for excellent morphology of intestinal protozoa

Other Specimens aside  from Stool

DUODENAL MATERIAL

• G. lamblia trophozoite
  
• Cryptosporidium
  
• Isospora belli
  
• S. stercoralis
  
• Fasciola hepatica
  
• C. sinensis
  

SIGMOIDAL MATERIAL (COLON)

• E. histolytica
  
• Coccidian parasite
  
• Microsporidia
  

CELLOPHANE TAPE PREP

• E. vermicularis
  
• Taenia spp

BLOOD – Giemsa stain is preferred.

• L. donovani
• Trypanosoma spp.
• Plasmodium spp.
• Babesia spp.
• Microfilaria

CSF

• Naegleria spp.
• Acanthamoeba
• T. gondii
• Microsporidia
• T. solium cysticercus
• Echinococcus spp

TISSUE

• Leishmania
• T. gondii
• Trypanosoma
• T. spiralis

SPUTUM

• P. westermani
  
• S. stercoralis
  
• Microporidia
  
• E. histolytica
  
• E. gingivalis
  
• A. lumbricoides
  
• Hookworm
  

URINE

• S. haematobium
  
• T. vaginalis
  
• Microfilaria
  

EYE SPECIMENS

• Acanthamoeba spp.
  
• T. gondii
  
• Loa loa
  

SKIN SNIPS

• O. volvulus
  

SKIN SNIPS

• O. volvulus
  

MOUTH SCRAPINGS

• E. gingivalis
  
• T. tenax