COMPARISON OF PRIMERS AND OPTIMIZATION OF PCR CONDITIONS FOR DETECTION OF CRYPTOSPORIDIUM-PARVUM AND GIARDIA-LAMBLIA IN WATER

Eight pairs of published PCR primers were evaluated for the specific d etection of Cryptosporidium parvum and Giardia lamblia in water. Detec tion sensitivities ranged from 1 to 10 oocysts or cysts for purified p reparations and 5 to 50 oocysts or cysts for seeded environmental wate r samples. Maximum sensitivity was achieved with two successive rounds of amplification and hybridization, with oligonucleotide probes detec ted by chemiluminescence, Primer annealing temperatures and MgCl2 conc entrations were optimized, and the specificities of the primer pairs w ere determined with closely related species. Some of the primers were species specific, while others were only genus specific. Multiplex PCR for the simultaneous detection of Cryptosporidium and Giardia was dem onstrated with primers amplifying 256- and 163-bp products from the 18 S rRNA gene of Cryptosporidium and the heat shock protein gene of Giar dia, respectively. The results demonstrate the potential utility of PC R for the detection of pathogenic protozoa in water but emphasize the necessity of continued development.