Table 1.

Macrolide and lincosamide MICs for the P. multocida and M. haemolytica strains used in this study^a

Pasteurellaceae strain	MIC (mg/liter)b				Macrolide resistance class	Presence erm(42) gene	Presence msr(E)/mph(E) genes
	Tulathromycin	Gamithromycin	Tilmicosin	Clindamycin
P. multocida 4407	0.5	0.5	4	4	Sensitive	–	–
M. haemolytica 11935	2	0.5	4	4	Sensitive	–	–
P. multocida 6052	8	8	>128	1,024	Class 1	+	–
P. multocida 6053	8	16	128	1,024	Class 1	+	–
P. multocida 6054	8	8	>128	1,024	Class 1	+	–
P. multocida 3361	64	32	32	16	Class 2	–	+
P. multocida 12602	>128	32	32	16	Class 2	–	+
M. haemolytica 12548	128	64	32	16	Class 2	–	+
P. multocida 3358	>128	64	128	>1,024	Class 3	+	+
M. haemolytica 6055	>128	128	128	>1,024	Class 3	+	+
M. haemolytica 6056	>128	128	>128	>1,024	Class 3	+	+

^aThe nomenclature for P. multocida and M. haemolytica strains has recently been changed: strains 6052 through 6056 were respectively called R11093 to R11097; strain 3358 was called R8331; strain 4407 was called R9441; and strains 3361, 11935, 12548, and 12602 have not previously been reported in the literature. All strains were tested for the presence of erm(42) and the msr(E)/mph(E) genes by PCR amplification and sequencing.

^bAll measurements were performed a minimum of three times and were highly reproducible.