Viability Assessment of Cryptosporidium parvum Oocysts by Vital Dyes: Dry Mounts Overestimate the Number of “Ghost” Oocysts

Heidi Huus Petersen, Heidi L. Enemark

    Research output: Contribution to journalJournal articleResearchpeer-review

    Abstract

    Viability assessment of Cryptosporidium parvum oocysts is crucial for evaluation of the public health significance of this important zoonotic protozoon. Viability is commonly assessed in wet mounts after acid pretreatmentand staining with fluorogenic vital dyes. However, in some studies, oocyst viability is evaluated in dry mounts after staining in suspension. Here, we evaluate the effect of acid pretreatment in nine replicate samples and compare the assessment of oocyst viability after evaluation in wet and dry mounts, respectively. Although acid pretreatment had no significant effect on the viability scores, data obtained by scoring oocysts in drymounts resulted in∼25% underestimation of the proportion of viable oocyst (82.5% –+ 0.9% [wet mount + acid],57.7% –+ 2.3% [dry mount - Oacid], 76.0% –+ 1.7% [wet mount, - Oacid]), while the proportions of nonviable oocysts (DAPI+/PI+) were comparable for wet and dry mounts (9.7% –+ 0.4% [wet mount +acid], 12.1 –+ 1.5%[dry mount, - acid], 15.5% –+ 1.1% [wet mount, - acid]).
    Original languageEnglish
    JournalFoodborne Pathogens and Disease
    Volume15
    Issue number3
    Pages (from-to)141-144
    ISSN1535-3141
    DOIs
    Publication statusPublished - 2017

    Keywords

    • Cryptosporidium parvum
    • Viability
    • DAPI/PI staining

    Cite this

    @article{663bd2e2f1d44d1bb9faf45407509bd7,
    title = "Viability Assessment of Cryptosporidium parvum Oocysts by Vital Dyes: Dry Mounts Overestimate the Number of “Ghost” Oocysts",
    abstract = "Viability assessment of Cryptosporidium parvum oocysts is crucial for evaluation of the public health significance of this important zoonotic protozoon. Viability is commonly assessed in wet mounts after acid pretreatmentand staining with fluorogenic vital dyes. However, in some studies, oocyst viability is evaluated in dry mounts after staining in suspension. Here, we evaluate the effect of acid pretreatment in nine replicate samples and compare the assessment of oocyst viability after evaluation in wet and dry mounts, respectively. Although acid pretreatment had no significant effect on the viability scores, data obtained by scoring oocysts in drymounts resulted in∼25{\%} underestimation of the proportion of viable oocyst (82.5{\%} –+ 0.9{\%} [wet mount + acid],57.7{\%} –+ 2.3{\%} [dry mount - Oacid], 76.0{\%} –+ 1.7{\%} [wet mount, - Oacid]), while the proportions of nonviable oocysts (DAPI+/PI+) were comparable for wet and dry mounts (9.7{\%} –+ 0.4{\%} [wet mount +acid], 12.1 –+ 1.5{\%}[dry mount, - acid], 15.5{\%} –+ 1.1{\%} [wet mount, - acid]).",
    keywords = "Cryptosporidium parvum, Viability, DAPI/PI staining",
    author = "Petersen, {Heidi Huus} and Enemark, {Heidi L.}",
    year = "2017",
    doi = "10.1089/fpd.2017.2348",
    language = "English",
    volume = "15",
    pages = "141--144",
    journal = "Foodborne Pathogens and Disease",
    issn = "1535-3141",
    publisher = "Mary AnnLiebert, Inc. Publishers",
    number = "3",

    }

    Viability Assessment of Cryptosporidium parvum Oocysts by Vital Dyes: Dry Mounts Overestimate the Number of “Ghost” Oocysts. / Petersen, Heidi Huus; Enemark, Heidi L.

    In: Foodborne Pathogens and Disease, Vol. 15, No. 3, 2017, p. 141-144.

    Research output: Contribution to journalJournal articleResearchpeer-review

    TY - JOUR

    T1 - Viability Assessment of Cryptosporidium parvum Oocysts by Vital Dyes: Dry Mounts Overestimate the Number of “Ghost” Oocysts

    AU - Petersen, Heidi Huus

    AU - Enemark, Heidi L.

    PY - 2017

    Y1 - 2017

    N2 - Viability assessment of Cryptosporidium parvum oocysts is crucial for evaluation of the public health significance of this important zoonotic protozoon. Viability is commonly assessed in wet mounts after acid pretreatmentand staining with fluorogenic vital dyes. However, in some studies, oocyst viability is evaluated in dry mounts after staining in suspension. Here, we evaluate the effect of acid pretreatment in nine replicate samples and compare the assessment of oocyst viability after evaluation in wet and dry mounts, respectively. Although acid pretreatment had no significant effect on the viability scores, data obtained by scoring oocysts in drymounts resulted in∼25% underestimation of the proportion of viable oocyst (82.5% –+ 0.9% [wet mount + acid],57.7% –+ 2.3% [dry mount - Oacid], 76.0% –+ 1.7% [wet mount, - Oacid]), while the proportions of nonviable oocysts (DAPI+/PI+) were comparable for wet and dry mounts (9.7% –+ 0.4% [wet mount +acid], 12.1 –+ 1.5%[dry mount, - acid], 15.5% –+ 1.1% [wet mount, - acid]).

    AB - Viability assessment of Cryptosporidium parvum oocysts is crucial for evaluation of the public health significance of this important zoonotic protozoon. Viability is commonly assessed in wet mounts after acid pretreatmentand staining with fluorogenic vital dyes. However, in some studies, oocyst viability is evaluated in dry mounts after staining in suspension. Here, we evaluate the effect of acid pretreatment in nine replicate samples and compare the assessment of oocyst viability after evaluation in wet and dry mounts, respectively. Although acid pretreatment had no significant effect on the viability scores, data obtained by scoring oocysts in drymounts resulted in∼25% underestimation of the proportion of viable oocyst (82.5% –+ 0.9% [wet mount + acid],57.7% –+ 2.3% [dry mount - Oacid], 76.0% –+ 1.7% [wet mount, - Oacid]), while the proportions of nonviable oocysts (DAPI+/PI+) were comparable for wet and dry mounts (9.7% –+ 0.4% [wet mount +acid], 12.1 –+ 1.5%[dry mount, - acid], 15.5% –+ 1.1% [wet mount, - acid]).

    KW - Cryptosporidium parvum

    KW - Viability

    KW - DAPI/PI staining

    U2 - 10.1089/fpd.2017.2348

    DO - 10.1089/fpd.2017.2348

    M3 - Journal article

    C2 - 29185793

    VL - 15

    SP - 141

    EP - 144

    JO - Foodborne Pathogens and Disease

    JF - Foodborne Pathogens and Disease

    SN - 1535-3141

    IS - 3

    ER -