Purpose: The objective of this study was to determine the effect of sample size and volume of elution solutions on the recovery of oocysts from experimentally spiked cilantro.
Methods: Cilantro bunches (100 and 250 g) were inoculated with 100 Cyclospora and 100 Cryptosporidium oocysts. Cilantro bunches were processed at zero and seven days post-inoculation using 100 ml, 250 ml, and 1 liter of 0.1% Alconox or elution buffer (PBS pH 7.0, Tween 80, antifoam). Oocysts were concentrated by centrifugation or by hollow fiber filtration. Triplicate samples representing all combinations of test parameters in two independent trials were analyzed for the presence of oocysts by nPCR targeting the18S rRNA gene.
Results: Oocyst recovery from 100 and 250 g cilantro (spiked with 100 oocysts) previously rinsed with 60 ppm peroxiacetic acid was higher. When samples were prerinsed with chlorine, higher number of positive samples were obtained using Alconox. Higher recoveries were obtained after seven days postinoculation compared to recoveries on the same day of inoculation. Washes using 200 ml detected more positive samples (69%) compared to 500 ml washes (33%). Cyclospora oocyst recovery (50%) was higher than Cryptosporidium oocysts when using Alconox (18%).
Significance: Testing of foods containing coccidian parasites require multiple wash steps and concentration processes making the methodology tedious and time consuming. Consideration should be given to the sample size, wash solution, and concentration methodologies.