Hollow-fiber ultrafiltration ofCryptosporidium parvumoocysts from a wide variety of 10-L surface water samples

Abstract

An optimized hollow-fiber ultrafiltration system (50 000 MWCO) was developed to concentrate Cryptosporidium oocysts from 10-L samples of environmental water. Seeded experiments were conducted using a number of surface-water samples from the southwestern U.S.A. and source water from four water districts with histories of poor oocyst recovery. Ultrafiltration produced a mean recovery of 47.9% from 19 water samples (55.3% from 39 individual tests). We also compared oocyst recoveries using the hollow-fiber ultrafiltration system with those using the Envirochek filter. In limited comparison tests, the hollow-fiber ultrafiltration system produced recoveries similar to those of the Envirochek filter (hollow fiber, 74.1% (SD = 2.8); Envirochek, 71.9% (SD = 5.2)) in low-turbidity (3.9 NTU) samples and performed better than the Envirochek filter in high-turbidity (159.0 NTU) samples (hollow fiber, 27.5%; Envirochek, 0.4%). These results indicate that hollow-fiber ultrafiltration can efficiently recover oocysts from a wide variety of surface waters and may be a cost-effective alternative for concentrating Cryptosporidium from water, given the reusable nature of the filter.

Optimization of a Reusable Hollow-Fiber Ultrafilter for Simultaneous Concentration of Enteric Bacteria, Protozoa, and Viruses from Water

“…Consistent with previous work (8,9,26), the washing procedures were effective in completely removing protozoa and viruses. When bacterial growth was observed, additional cycles of sanitization were done until the plate counts were zero.…”

“…Previous work has shown that Tween 80 stabilizes virus and improves elution (9,11), and the nonionic detergent probably prevented the adhesion of cells to the ultrafilter membrane surface in our study. However, though serovar Enteritidis recoveries doubled in the presence of Tween 80, recoveries remained highly variable, especially in contrast to the consistent recoveries of the two E. coli strains used.…”

“…The small-scale ultrafiltration system (filter surface area, 0.017 m 2 ) was evaluated by using 2 liters of sterile, deionized water and phosphate-buffered saline (PBS; pH 7) with and without 0.1% Tween 80 as the liquid medium. The 2-liter samples were processed at a transmembrane pressure of 80 kPa and were filtered as previously reported (9,26). The 10-liter volumes were processed by using the larger, 0.2-m 2 filter and filtered as outlined in Fig.…”

“…Ultrafiltration uses a sizeexclusion-based mode of concentration, where molecules smaller than the pore size of the filter pass through the membrane and out of the system and larger particles are concentrated in the retentate. The cross-flow circulation pattern with recirculation of the retentate reduces fouling of the membrane and makes it possible to filter large volumes of turbid water while maintaining the organisms in suspension (6,9,19,26).…”

Recovery of Cryptosporidium from spiked water and stool samples measured by PCR and real time PCR

“…The 1622 method detects and calculates only Cryptosporidium oocysts in water samples; the 1623 method -Cryptosporidium oocysts and Giardia cysts, and introduces some improvements. However, the recovery of oocysts from environmental water samples with the use of these both methods has been reported to be very variable (Simmons et al 2001;Kuhn and Oshima 2002;Wohlsen et al 2004;Krometis et al 2009;Karim et al 2010). With regard to this fact, matrix spikes are routinely analysed to determine the influence of environmental matrices on the effectiveness of the methods for detecting target organisms (Francy et al 2004).…”