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

Table 1

Parameter estimates (standard error—SE, odds ratio—OR and the OR 95% confidence interval—CI) of the proportional odds mixed model for changes on the fecal culture results across time for Mycobacterium avium subsp. paratuberculosis in dairy cows in Minnesota, USA.

Parameter	Levels	Estimate	SE	OR	CI	P value
Intercept*	0	−6.44	0.54			<0.01
	1	−2.43	0.34			<0.01
	2	Reference	—	—	—	—
Months, n	1	0.13	0.02	1.14	1.10, 1.18	<0.01
Temperature, C°	−18°	0.79	0.31	2.20	0.82, 5.99	0.08
	−70°	Reference	—	—	—	—
Initial bacterial load**	1	4.38	0.56	79.80	13.4, 478.02	<0.01
	2	2.47	0.53	11.82	2.21, 62.97	0.02
	3	1.65	0.46	5.18	1.19, 22.85	0.04
	4	Reference	—	—	—	—

*0: negative, 1: mean of 0.25–50 colonies/tube (CPT)), and 2: mean of >50 CPT.
**1: mean of 0.25–9 colonies/tube (CPT)), 2: mean of 10–49 CPT, 3: heavy (mean of 50–100 CPT), and 4: >100 CPT.