Long-Term Survival of Mycobacterium avium subsp. paratuberculosis in Fecal Samples Obtained from Naturally Infected Cows and Stored at −18°C and −70°C
2011

Survival of Mycobacterium avium in Cow Feces at Low Temperatures

Sample size: 69 publication 10 minutes Evidence: moderate

Author Information

Author(s): Eran A. Raizman, L. A. Espejo, S. J. Wells

Primary Institution: University of Minnesota

Hypothesis

Map long-term viability at −18°C and −70°C would not be significantly different.

Conclusion

Mycobacterium avium can survive for long periods in cow feces at both −18°C and −70°C, with no significant difference in survival between the two temperatures.

Supporting Evidence

  • Map survived at −18°C for an average of 540 days.
  • Samples stored at −70°C showed a trend for longer survival.
  • Statistical analysis indicated that the temperature effect on viability was not significant after adjusting for initial bacterial load.
  • The probability of a sample decreasing in bacterial load was 13% per month.
  • Overall survival in −18°C can ease fecal sample management in laboratories with low-processing capacity.

Takeaway

This study shows that bacteria from sick cows can live a long time in their poop when kept really cold, which helps labs that can't process samples right away.

Methodology

Fecal samples were collected from infected cows and stored at −18°C and −70°C, recultured every 3–6 months, and analyzed using a proportional odds mixed model.

Potential Biases

Nonrandom allocation of samples based on initial culture results could introduce bias.

Limitations

The study lacked constant time intervals between cultures and used a targeted sampling approach rather than random selection.

Participant Demographics

Fecal samples were collected from 51 cows across 17 herds, primarily those with high bacterial loads.

Statistical Information

P-Value

<0.01

Confidence Interval

95% CI 1.01 and 1.20

Statistical Significance

p<0.05

Digital Object Identifier (DOI)

10.4061/2011/341691

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