Macrolide-lincosamide-streptogramin resistance phenotypes and genotypes of coagulase-positive Staphylococcus aureus and coagulase-negative staphylococcal isolates from bovine mastitis

Table 1 Minimum inhibitory concentrations (MICs) of 40 ER-R coagulase-positive S. aureus isolates

Antibiotic agents	The number of isolates inhibited in different MICs (μg mg^-1)^a												MIC50	MIC90
Antibiotic agents	≤0.125	0.25	0.5	1	2	4	8	16	32	64	128	≥256	MIC50	MIC90
Erythromycin^b	0	0	0	0	0	0	0	1	3	2	6	28	>256	>256
Clindamycin^b	24	7	0	1	6	0	0	0	0	0	0	2	0.125	2
Spiramycin^c	0	0	0	0	0	0	3	5	0	2	30	0	>128	>128
Tylosin^d	0	0	3	5	25	0	0	0	2	2	2	1	2	64
Azithromycin^b	0	0	0	0	0	0	0	0	0	4	0	36	>256	>256
Quinupristin-dalfopristin^b	23	11	6	0	0	0	0	0	0	0	0	0	0.125	0.25
Tulathromycin^e	0	0	0	0	0	0	0	0	0	0	5	35	>256	>256

^aSusceptibility, intermediate resistance and resistance are shown in normal, italic and boldface fonts, respectively
^bMIC breakpoints for erythromycin, azithromycin, clindamycin and quinupristin-dalfopristin were based on Clinical and Laboratory Standards Institute (CLSI) documents (CLSI, 2004, 2011)
^cMIC breakpoints of spiramycin were based on the SWEDRES-SVARM (2012)
^dMIC breakpoints of tylosin were based on the VADS according to a previous study [5]
^eMIC breakpoints of this antibiotic were not available
MIC₅₀, the MIC for 50 % of the organisms
MIC₉₀, the MIC for 90 % of the organisms

ISSN: 1746-6148