TABLE 6.

Proportional odds models for E. coli MIC responses for two antimicrobials

Antimicrobial	Independent variable	Beta	CI		Pa
			Lower	Upper
Gentamicin	Continuous tylosin	0.56	−0.01	1.13	0.0534
	Continuous CTC	0.59	−0.11	1.30	0.0989
	Pulse tylosin	0.18	−0.59	0.95	0.6456
	Pulse CTC	0.56	−0.11	1.22	0.0986
	Period 2	1.70	1.21	2.19	0.0000*
	Continuous tylosin*period 2	−1.12	−1.77	−0.47	0.0011*
	Continuous CTC*period 2	−1.09	−1.97	−0.20	0.0167*
	Pulse tylosin*period 2	−1.00	−1.70	−0.31	0.0055*
	Pulse CTC* period 2	−1.21	−2.00	−0.43	0.0030*
Streptomycin	Continuous tylosin	−0.34	−0.85	0.16	0.1801
	Continuous CTC	−0.88	−1.45	−0.31	0.0020*
	Pulse tylosin	−0.30	−0.98	0.38	0.3794
	Pulse CTC	−0.56	−1.14	0.02	0.0575
	Period 2	−2.09	−2.72	−1.46	0.0000*
	Continuous tylosin*period 2	0.84	0.03	1.66	0.0431*
	Continuous CTC*period 2	1.85	1.00	2.70	0.0001*
	Pulse tylosin*period 2	1.21	0.25	2.17	0.0144*
	Pulse CTC*period 2	1.15	0.24	2.06	0.0141*

^a*, significant at P = 0.05 level.