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CYCLOSPORA
CAYETANENSIS: Diagnosis
The
coccidian oocysts stain orange with safranin and are acid-fast
variable; some organisms will stain deep red/purple with a
mottled appearance but no internal structures. Clean, wet
mounts show nonrefractile objects that appear as glassy, wrinkled
spheres. Using modified acid-fast stains, they may stain from
purple to pale (essentially no color). It is important
to remember that the stain decolorizer should be no stronger
than a 1% sulfuric acid. When modified acid-fast stains were
first used to stain Cryptosporidium parvum, the decolorizer
was a 3% to 5% sulfuric acid; this is too strong for Cyclospora
- too much color is removed. The 1% acid formula works well
for C. parvum, C. cayetanensis, and Isospora belli.
The oocysts often have a wrinkled appearance (like wrinkled
cellophane). The oocysts autofluoresce strong green or blue,
depending on the filters used (Green: 450-490 DM excitation
filter; Blue: 365 DM excitation filter) under UV epifluorescence.
During concentration of stool specimens, centrifugation speed
and time should be 500xg for 10 min. |
