Long-Term Survival of Mycobacterium avium subsp. paratuberculosis in Fecal Samples Obtained from Naturally Infected Cows and Stored at −18°C and −70°C

The objective was to evaluate the survival of Mycobacterium paratuberculosis (Map) in naturally infected dairy cows feces under long periods of freezing at −18°C and −70°C. Samples were collected from cows previously tested positive with serum ELISA or fecal culture, or with clinical signs of Johne&...

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Main Authors: Eran A. Raizman, L. A. Espejo, S. J. Wells
Format: Article
Language:English
Published: Hindawi Limited 2011-01-01
Series:Veterinary Medicine International
Online Access:http://dx.doi.org/10.4061/2011/341691
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spelling doaj-59f082bf93b14f869bbd4c0d96d01a8c2020-11-24T22:54:28ZengHindawi LimitedVeterinary Medicine International2042-00482011-01-01201110.4061/2011/341691341691Long-Term Survival of Mycobacterium avium subsp. paratuberculosis in Fecal Samples Obtained from Naturally Infected Cows and Stored at −18°C and −70°CEran A. Raizman0L. A. Espejo1S. J. Wells2320 Fernleaf Dr West Lafayette, IN 47906, USADepartment of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, St. Paul, MN 55108, USADepartment of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, St. Paul, MN 55108, USAThe objective was to evaluate the survival of Mycobacterium paratuberculosis (Map) in naturally infected dairy cows feces under long periods of freezing at −18°C and −70°C. Samples were collected from cows previously tested positive with serum ELISA or fecal culture, or with clinical signs of Johne's disease. Samples were stored at −18°C and/or −70°C and recultured in Herrold's egg yolk media every 3–6 months. A proportional odds mixed model was used for data analysis. Sixty nine fecal samples were stored for different periods between September 2002 and January 2005. Of these, 45 (65%) were stored at −18°C and 24 (35%) at −70°C. Average number of days between repeated culture dates was 98 and 84 for −18°C and −70°C, respectively. Median number of repeated cultures was 6 and 4 for samples stored at −18°C and −70°C, respectively. After adjusting for initial sample bacterial load, the effects of temperature or number of thawing and refreezing cycles on Map viability were not significant. The probability that a sample decreases from high to moderate-low bacterial load and from moderate-low to negative bacterial load was 13.5% per month. Although this study found gradual reduction of Map concentration in stored fecal samples through time, overall survival in −18°C can ease fecal samples management in laboratories with low-processing capacity or lack of −70°C freezer.http://dx.doi.org/10.4061/2011/341691
collection DOAJ
language English
format Article
sources DOAJ
author Eran A. Raizman
L. A. Espejo
S. J. Wells
spellingShingle Eran A. Raizman
L. A. Espejo
S. J. Wells
Long-Term Survival of Mycobacterium avium subsp. paratuberculosis in Fecal Samples Obtained from Naturally Infected Cows and Stored at −18°C and −70°C
Veterinary Medicine International
author_facet Eran A. Raizman
L. A. Espejo
S. J. Wells
author_sort Eran A. Raizman
title Long-Term Survival of Mycobacterium avium subsp. paratuberculosis in Fecal Samples Obtained from Naturally Infected Cows and Stored at −18°C and −70°C
title_short Long-Term Survival of Mycobacterium avium subsp. paratuberculosis in Fecal Samples Obtained from Naturally Infected Cows and Stored at −18°C and −70°C
title_full Long-Term Survival of Mycobacterium avium subsp. paratuberculosis in Fecal Samples Obtained from Naturally Infected Cows and Stored at −18°C and −70°C
title_fullStr Long-Term Survival of Mycobacterium avium subsp. paratuberculosis in Fecal Samples Obtained from Naturally Infected Cows and Stored at −18°C and −70°C
title_full_unstemmed Long-Term Survival of Mycobacterium avium subsp. paratuberculosis in Fecal Samples Obtained from Naturally Infected Cows and Stored at −18°C and −70°C
title_sort long-term survival of mycobacterium avium subsp. paratuberculosis in fecal samples obtained from naturally infected cows and stored at −18°c and −70°c
publisher Hindawi Limited
series Veterinary Medicine International
issn 2042-0048
publishDate 2011-01-01
description The objective was to evaluate the survival of Mycobacterium paratuberculosis (Map) in naturally infected dairy cows feces under long periods of freezing at −18°C and −70°C. Samples were collected from cows previously tested positive with serum ELISA or fecal culture, or with clinical signs of Johne's disease. Samples were stored at −18°C and/or −70°C and recultured in Herrold's egg yolk media every 3–6 months. A proportional odds mixed model was used for data analysis. Sixty nine fecal samples were stored for different periods between September 2002 and January 2005. Of these, 45 (65%) were stored at −18°C and 24 (35%) at −70°C. Average number of days between repeated culture dates was 98 and 84 for −18°C and −70°C, respectively. Median number of repeated cultures was 6 and 4 for samples stored at −18°C and −70°C, respectively. After adjusting for initial sample bacterial load, the effects of temperature or number of thawing and refreezing cycles on Map viability were not significant. The probability that a sample decreases from high to moderate-low bacterial load and from moderate-low to negative bacterial load was 13.5% per month. Although this study found gradual reduction of Map concentration in stored fecal samples through time, overall survival in −18°C can ease fecal samples management in laboratories with low-processing capacity or lack of −70°C freezer.
url http://dx.doi.org/10.4061/2011/341691
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