Table 3.

Antimicrobial (n = 16) minimum inhibitory concentration (MIC) distribution data obtained for 144 Enterococcus spp. isolated from 150 rectal faecal samples obtained at feedlot exit. The vertical line within each MIC distribution indicates the resistance breakpoint (see Table 1) for each antimicrobial except for tigecycline, where it indicates the susceptible breakpoint.

Antimicrobial Class	Antimicrobial Agent	Resistance (95% CI)	Percentage of Isolates Yielding Each MIC Value (µg/mL)
			0.015	0.03	0.06	0.12	0.25	0.5	1	2	4	8	16	32	64	128	256	512	1024
Aminoglycosides	Gentamycin	0.0 (0.00–2.60)														100.0
	Kanamycin	0.7 (0.10–4.76)														70.1	25.7	3.5	0.7
	Streptomycin	0.7 (0.10–4.76)																99.3	0.7
Beta-lactam	Penicillin	0.0 (0.00–2.60)					8.3	12.5	11.1	23.6	43.8	0.7
Fluoroquinolones	Ciprofloxacin	7.6 (4.28–13.27)					1.4	13.2	38.2	39.6	7.6
Glycopeptides	Vancomycin	0.0 (0.00–2.60)						60.4	34.0	4.2	1.4
Glycylcyclines	Tigecycline	1.4 (0.35–5.38)		0.7	3.5	52.1	38.2	4.2		1.4
Lincosamide	Lincomycin	84.0 (77.11–89.15)							13.2	2.8		1.4	82.6
Lipopeptides	Daptomycin	22.9 (16.77–30.48)							1.4	12.5	63.2	22.2	0.7
Macrolides	Erythromycin	4.2 (1.88–8.96)					60.4	1.4	3.5	22.2	8.3	1.4	2.8
	Tylosine tartrate	3.5 (1.45–8.07)							0.7	25.7	24.3	45.8			3.5
Nitrofurantoins	Nitrofurantoin	53.5 (45.30–61.46)												3.5	43.1	53.5
Oxazolidinones	Linezolid	0.0 (0.00–2.60)							0.7	97.2	2.1
Phenicols	Chloramphenicol	0.0 (0.00–2.60)									10.4	89.6
Streptogramins	Quinupristin/dalfopristin	18.1 (12.59–25.20)						13.2	4.2	64.6	17.4	0.7
Tetracycline	Tetracycline	6.9 (3.78–12.43)							93.1					0.7	6.3