Previous Article | Next Article ![]()
Appl. Environ. Microbiol., 05 1995, 1714-1719, Vol 61, No. 5
EC Nieminski, FW Schaefer 3rd and JE Ongerth
The steps of two immunofluorescent-antibody-based detection methods were
evaluated for their efficiencies in detecting Giardia cysts and
Cryptosporidium oocysts. The two methods evaluated were the American
Society for Testing and Materials proposed test method for Giardia cysts
and Cryptosporidium oocysts in low-turbidity water and a procedure
employing sampling by membrane filtration, Percoll-Percoll step gradient,
and immunofluorescent staining. The membrane filter sampling method was
characterized by higher recovery rates in all three types of waters tested:
raw surface water, partially treated water from a flocculation basin, and
filtered water. Cyst and oocyst recovery efficiencies decreased with
increasing water turbidity regardless of the method used. Recoveries of
seeded Giardia cysts exceeded those of Cryptosporidium oocysts in all types
of water sampled. The sampling step in both methods resulted in the highest
loss of seeded cysts and oocysts. Furthermore, much higher recovery
efficiencies were obtained when the flotation step was avoided. The
membrane filter method, using smaller tubes for flotation, was less
time-consuming and cheaper. A serious disadvantage of this method was the
lack of confirmation of presumptive cysts and oocysts, leaving the
potential for false-positive Giardia and Cryptosporidium counts when
cross-reacting algae are present in water samples.
Copyright © 1995, American Society for Microbiology
Comparison of two methods for detection of Giardia cysts and Cryptosporidium oocysts in water
Utah Department of Environmental Quality, Salt Lake City 84114-4830, USA.
This article has been cited by other articles:
| J. Bacteriol. | Microbiol. Mol. Biol. Rev. | Eukaryot. Cell | All ASM Journals |
|---|