Table 5.

Distribution of minimum inhibitory concentrations among Pasteurella multocida isolates (n = 113 animals and 117 samples; lung samples = 85, nasal swabs = 30, laryngeal swabs = 1, joint fluid = 1).

					Distribution (%) of MICs (µg/mL)
Class	Categorya	Antimicrobial	MIC 50	%Rb	≤0.12	0.25	0.5	1	2	4	8	16	32	64
Aminoglycoside	II	GEN	4	8.5c					8.5	53.0	29.9	8.5
	II	NEO	16	65.8c						5.1	29.1	28.2	37.6
	III	SPE	32	27.4							1.7	36.8	32.5	64 >64 1.7 27.4
Fluorquinolone	I	ENRO	0.12	0	91.5	6.0	1.7	0.9
	I	DANO	0.12	1.7c	88.9	6.8	2.6	1.7
Macrolide	II	TYLT	32	99.1c							0.9	6.8	92.3
	II	TUL	4	29.9				13.7	30.8	11.1	5.1	7.7	1.7	29.9
	II	TIL	16	41.9						12.9	33.3	12.0	0.9	41.0
B lactams	I	XNL	0.25	0.9		94.9	0.9	2.6		0.9	0.9
	II	PEN	0.25	1.7	30.8	56.4	11.1				1.7
	II	AMP	0.25	1.8c		72.6	24.8	0.9	0.9		0.9
Lincosamides	II	CLIN	16	100c							1.7	98.3
Phenicol	III	FFN	0.5	1.7		10.3	58.1	25.6	4.3		1.7
Tetracycline	III	OXY	8	55.6			29.1	7.7	3.4	4.3	55.6
	III	CTET	4	43.6			16.2	21.4	11.1	7.7	43.6
Pleuromutilin		TIA	32	86.3c						0.9	0.9	12.0	86.3

Trimethoprim sulpha (Category II): <2/38 = 76.1%, >2/38 = 23.9%.

Sulphahdimethoxine (Category III): <256 = 35.9%, >256 = 64.1%.

GEN, gentamycin/NEO, neomycin/SPE, spectinomycin; DAN, danofloxacin/ENRO, enrofloxacin; TYLT, tylosin/TUL, tulathromycin/TIL, tilmicosin; PEN, penicillin/AMP, ampicillin/XNL, ceftiofur; CLI, clindamycin; FFN, florfenicol; SXT, trimethoprim sulpha/SDM, sulphadimethoxine; OXY, oxytetracycline; CTET, chlortetracycline; TIA, tiamulin.

^aCategorization of antimicrobial drugs based on importance in human medicine—Veterinary Drug Directorate.

^bPathogen minimum inhibitory concentration breakpoints from CLSI standards.

^cNo CLSI breakpoint for this bovine respiratory disease pathogen/antimicrobial combination, simply notes susceptibility.

Values in red indicate resistant proportion of samples.

Shaded areas indicate concentrations not tested.