Blastocystis presents in healthy and diseased persons so its role in disease development is a subject
of debate. This study compared between growth patterns of different symptomatic Blastocystis
subtypes. Morphometric measures of the vacuolar form of STs isolated from acute GIT symptomatic
patients showed that major diversity in size ranged from 4.928±1.77 among ST4 to 70.54±29.66
among wild ST3. Size in chronic group was 4±0.816 in ST-4 and 40.83±7.359 in heterozygous
ST3, and in intermittent group ranged from 5.5±0.707 in ST4 to 47.5±6.45 in heterozygous ST3
with significant differences. Phenotypic variations were commonly among inter-subtypes of ST3.
Generation patterns in re-culturing were 24.1% of isolates at 5th re-culturing and the 29.6% at 6th reculturing
loss of 90% viable vacuolar form numbers compared to that on first culture. Low percenta
ge (9.3%) reached to 9th re-culture. Majority of ST-1 (40%) was lost at the 5th re-culture while
58.8% of wild ST-3 was lost in the 7th & 8th, respectively, with 29.4% per each. Meanwhile, 66.6%
of ST-4 was lost in the 5th & 6th, respectively, with 33.3% per each, but without significant difference.
As to metronidazole® susceptibility, the majority of ST1, wild ST3, heterozygous ST3 and
ST4 isolates gave 60%, 58.7%, 57.2% & 79.9% sensitivity.