Efficacy of Common Laboratory Disinfectants on the Infectivity of
            <i>Cryptosporidium parvum</i>
            Oocysts in Cell Culture

Weir, Susan C.; Pokorny, Nicholas J.; Carreno, Ramon A.; Trevors, J. T.; Lee, Hung

doi:10.1128/aem.68.5.2576-2579.2002

Cited by 56 publications

(25 citation statements)

References 11 publications

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“…Hydrogen peroxide is one of the few commonly used surface disinfectants with proven effectiveness against C. parvum oocysts: exposure to H 2 O 2 (6%, 4 min) reduced the oocysts infectivity in HCT-8 cells an order of magnitude (Weir et al, 2002) while a 99% loss of oocysts infectivity was also observed in MDCK cells following exposure to 3% H 2 O 2 (20 min, 20 C) and 3% H 2 O 2 was thus recommended to inactivate C. parvum oocysts in laboratory settings (Barbee et al, 1999). Gaseous H 2 O 2 has also been shown effective at sterilizing endoscopic material containing oocysts (Vassal et al, 1998).…”

Section: Discussionmentioning

confidence: 99%

Comparison of propidium monoazide-quantitative PCR and reverse transcription quantitative PCR for viability detection of fresh Cryptosporidium oocysts following disinfection and after long-term storage in water samples

Liang

Keeley

2012

Water Research

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Section: Discussionmentioning

confidence: 99%

Comparison of propidium monoazide-quantitative PCR and reverse transcription quantitative PCR for viability detection of fresh Cryptosporidium oocysts following disinfection and after long-term storage in water samples

Liang

Keeley

2012

Water Research

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“…Considering the resistance of these fish microsporidia to chlorine, other disinfectants that do not injure fish embryos within eggs should be evaluated for killing spores. Hydrogen peroxide has been used to kill resistant stages of other protozoa, such as Cryptosporidium species (Weir et al 2002). Dilute formalin (e.g.…”

Section: Discussionmentioning

confidence: 99%

Spores of two fish microsporidia (Pseudoloma neurophilia and Glugea anomala) are highly resistant to chlorine

Ferguson¹,

Watral²,

Schwindt³

et al. 2007

Dis. Aquat. Org.

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Pseudoloma neurophilia (Microsporidia) is the most common pathogen found in zebrafish Danio rerio research facilities. The parasite is associated with marked emaciation. Zebrafish laboratories usually disinfect eggs to prevent transmission of pathogens, typically with chlorine at 25 to 50 ppm for 10 min. The ability of chlorine to kill spores of P. neurophilia and 2 other microsporidia, Glugea anomala and Encephalitozoon cuniculi, was evaluated using 2 viability stains. SYTOX ® Green was used to visualize dead spores, and live spores were identified by their ability to extrude polar tubes in Fungi-Fluor™ solution following UV exposure. Results with both stains were similar at various chlorine concentrations for P. neurophilia and G. anomala, but Fungi-Fluor was not useful for E. cuniculi, due to the much smaller spore size. Using the SYTOX stain, we found that 5 ppm chlorine for 10 min causes 100% death in spores of E. cuniculi, which was similar to findings in other studies. In contrast, the spores of P. neurophilia and G. anomala were much more resistant to chlorine, requiring >100 or 1500 ppm chlorine, respectively, to achieve > 95% spore death. Repeating chlorine exposures with spores of P. neurophilia using solutions adjusted to pH 7 increased the efficacy of 100 ppm chlorine, achieving > 99% spore inactivation. We corroborated our viability staining results with experimental exposures of zebrafish fry, achieving heavy infections in fry at 5 to 7 d postexposure in fish fed spores treated at 50 ppm (pH 9). Some fish still became infected with spores exposed to 100 ppm chlorine (pH 9.5). This study demonstrates that spores of certain fish microsporidia are highly resistant to chlorine, and indicates that the egg disinfection protocols presently used by most zebrafish research facilities will not prevent transmission of P. neurophilia to progeny.KEY WORDS: SYTOX Green · Fungi-Fluor · Pseudoloma neurophilia · Glugea anomala · Encephalitozoon cuniculi · Chlorine toxicity · Viability staining Resale or republication not permitted without written consent of the publisher

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“…Ozone, another popular water disinfectant, has proven to be much more efficient in killing oocysts, although its instability makes it difficult to maintain high levels in water for periods of time sufficient for treatment under practical conditions (20). The oocysts are also unaffected by commonly used laboratory disinfectants such as 6% sodium hypochlorite, 70% ethanol, and a variety of commercial preparations used domestically or in animal husbandry (28), although exposure to 10% Formol, aqueous or gaseous ammonia, or hydrogen peroxide has been reported to greatly reduce or eliminate oocyst infectivity (1,9,23). Low concentrations of ammonia (0.007 M) significantly decrease the viability of oocysts after 24 h of exposure, as determined with in vitro assays (19), and a 4-min exposure to 6% hydrogen peroxide or a 13-min exposure to ammonium hydroxide-amended windshield washer fluid reduces infectivity of C. parvum oocysts in cell culture 1,000-fold (28).…”

mentioning

confidence: 99%

Efficacy of Two Peroxygen-Based Disinfectants for Inactivation of Cryptosporidium parvum Oocysts

Quílez

Sánchez-Acedo

Avendaño

et al. 2005

Appl Environ Microbiol

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Two commercial peroxygen-based disinfectants containing hydrogen peroxide plus either peracetic acid (Ox-Virin) or silver nitrate (Ox-Agua) were tested for their ability to inactivate Cryptosporidium parvum oocysts. Oocysts were obtained from naturally infected goat kids and exposed to concentrations of 2, 5, and 10% Ox-Virin or 1, 3, and 5% Ox-Agua for 30, 60, and 120 min. In vitro excystation, vital dyes (4,6-diamidino-2-phenylindole and propidium iodide), and infectivity in neonatal BALB/c mice were used to assess the viability and infectivity of control and disinfectant-treated oocysts. Both disinfectants had a deleterious effect on the survival of C. parvum oocysts, since disinfection significantly reduced and in some cases eliminated their viability and infectivity. When in vitro assays were compared with an infectivity assay as indicators of oocyst inactivation, the excystation assay showed 98.6% inactivation after treatment with 10% Ox-Virin for 60 min, while the vital-dye assay showed 95.2% inactivation and the infectivity assay revealed 100% inactivation. Treatment with 3% Ox-Agua for 30 min completely eliminated oocyst infectivity for mice, although we were able to observe only 74.7% inactivation as measured by excystation assays and 24.3% with vital dyes (which proved to be the least reliable method for predicting C. parvum oocyst viability). These findings indicate the potential efficacy of both disinfectants for C. parvum oocysts in agricultural settings where soil, housing, or tools might be contaminated and support the argument that in comparison to the animal infectivity assay, vital-dye and excystation methods overestimate the viability of oocysts following chemical disinfection.

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Efficacy of Common Laboratory Disinfectants on the Infectivity of Cryptosporidium parvum Oocysts in Cell Culture

Cited by 56 publications

References 11 publications

Comparison of propidium monoazide-quantitative PCR and reverse transcription quantitative PCR for viability detection of fresh Cryptosporidium oocysts following disinfection and after long-term storage in water samples

Comparison of propidium monoazide-quantitative PCR and reverse transcription quantitative PCR for viability detection of fresh Cryptosporidium oocysts following disinfection and after long-term storage in water samples

Spores of two fish microsporidia (Pseudoloma neurophilia and Glugea anomala) are highly resistant to chlorine

Efficacy of Two Peroxygen-Based Disinfectants for Inactivation of Cryptosporidium parvum Oocysts

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