MD 3Y1-4
Clin Para – Case Study
Case Study:
Nathalie, a 17-year-old Haitian woman, presented to a women’s clinic complaining of watery and foamy
bowel movements 5 to 10 times a day. She had also experienced abdominal cramps and a low-grade
fever. The physician ordered a stool sample for routine fecalysis as well as for culture and sensitivity
tests.The culture and sensitivity tests were reported as negative for enteric pathogens. The
laboratory technician performed a routine fecalysis, including a permanent trichrome stain. No parasites
were observed.Two days later, a repeat fecalysis was ordered. The patient was now diagnosed as HIVpositive. The repeat sample was again examined for ova and parasites by routine
laboratory procedures. This time, the technologist noted oval forms of the wet preps that were highly
refractile and suggestive of fungal cells, but no budding was seen. The trichrome permanent stain did
not confirm the laboratory technician’s suspicions. Not satisfied that the sample was negative,
the laboratory technician performed an alternative permanent stain. The organisms seen on this stain
are illustrated in the diagram. These organisms were noted as 5 μm in size with one to six dark granules
within their cytoplasm.
Questions and Issues for Consideration*
1.What organism did the laboratory technician suspect, and why? What morphologic form is seen in
this diagram?
2.What was the alternative permanent stain, and how would these parasites appear following this stain
procedure?
3.What fungal elements might appear similar to this organism? How would they stain with
the alternative stain?
Answers:
1. The organism that the laboratory technician suspected is Cryptosporidium parvum the reason
why he suspects this is because there is a presence of the oocysts that looks like a yeast cells
when subjected in the wet preparations that indicates the presence of this parasite.
2. The alternative permanent stain that the laboratory technician used is the modified acid-fast
stain, wherein the Cryptosporidium parvum parasite will appear as acid-fast and will therefor
stain red. The Cryptosporidium oocysts under this stain will show a small and dark-staining
granule.
3. The fungal elements that might appear to be similar with C. parvum is the yeast, the yeast under
modified acid-fast stains will appear a color blue stain because their difference is that the yeast
is a non-acid-fast organism.