Chlorine dioxide inactivation of Cryptosporidium parvum oocysts and bacterial spore indicators

被引:92
作者
Chauret, CP
Radziminski, CZ
Lepuil, M
Creason, R
Andrews, RC
机构
[1] Indiana Univ, Biol & Phys Sci Unit, Kokomo, IN 46904 USA
[2] Univ Toronto, Dept Civil Engn, Toronto, ON M5S 1A4, Canada
关键词
D O I
10.1128/AEM.67.7.2993-3001.2001
中图分类号
Q81 [生物工程学(生物技术)]; Q93 [微生物学];
学科分类号
071005 ; 0836 ; 090102 ; 100705 ;
摘要
Cryptosporidium parvum, which is resistant to chlorine concentrations typically used in water treatment, is recognized as a significant waterborne pathogen, Recent studies have demonstrated that chlorine dioxide is a more efficient disinfectant than free chlorine against Cryptosporidium oocysts, It is not known, however, if oocysts from different suppliers are equally sensitive to chlorine dioxide, This study used both a most-probable-number-cell culture infectivity assay and in vitro excystation to evaluate chlorine dioxide inactivation kinetics in laboratory water at pH 8 and 21 degreesC, The two viability methods produced significantly different results (P < 0.05), Products of disinfectant concentration and contact time (Ct values) of 1,000 mg min/liter were needed to inactivate approximately 0.5 log(10) and 2.0 log(10) units (99% inactivation) of C. parvum as measured by in vitro excystation and cell infectivity, respectively, suggesting that excystation is not an adequate viability assay. Purified oocysts originating from three different suppliers were evaluated and showed marked differences with respect to their resistance to inactivation when using chlorine dioxide, Ct values of 75, 550, and 1,000 mg min/liter were required to achieve approximately 2.0 log,, units of inactivation with oocysts from different sources. Finally, the study compared the relationship between easily measured indicators, including Bacillus subtilis (aerobic) spores and Clostridium sporogenes (anaerobic) spores, and C. parvum oocysts. The bacterial spores were found to be more sensitive to chlorine dioxide than C. parvum oocysts and therefore could not be used as direct indicators of C. parvum inactivation for this disinfectant. In conclusion, it is suggested that future studies address issues such as oocyst purification protocols and the genetic diversity of C. parvum, since these factors might affect oocyst disinfection sensitivity.
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收藏
页码:2993 / 3001
页数:9
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