TABLE 1.
MIC of erythromycin, clindamycin, and pristinamycin Ia for different Staphylococcus strains, as determined by broth microdilution
| Strain | Characteristic(s) or origin | Reference or source | Antibiotic resistance gene(s)a | MIC (μg/ml)b |
||||
|---|---|---|---|---|---|---|---|---|
| ERY | CLI | iCLI | PIA | iPIA | ||||
| S. aureus | ||||||||
| 80CR5 | Recipient strain for conjugation, plasmid free | 22 | ≤0.25 | ≤0.25 | NA | 4 | NA | |
| RN4220 | Recipient strain for electrotransformation, plasmid free | 21 | 0.25 | ≤0.25 | NA | 4 | NA | |
| RN4220/pBUS1 | RN4220 with cloning vector pBUS1 | 28, this study | tet(L) | 0.25 | ≤0.25 | NA | 4 | NA |
| RN4220/pBUS1-Pcapc | RN4220 with pBUS1 containing cap promoter | S. Schwendener | tet(L) | 0.25 | ≤0.25 | NA | 4 | NA |
| RN4220/pBJW5 | RN4220 with erm(44) and its regulatory region cloned into pBUS1 | This study | tet(L), erm(44) | 8 | ≤0.25 | 8 | 4 | 8 |
| RN4220/pBJW13 | RN4220 with erm(44) cloned into pBUS1-Pcap | This study | tet(L), erm(44) | >256 | >256 | >256 | 16 | 32 |
| S. xylosus | ||||||||
| JW4341 | Subclinical bovine mastitis milk | 10, this study | erm(44), mph(C) | 16 | 0.5 | 8 | 8 | 128 |
| JW1049 | Subclinical bovine mastitis milk | 10, this study | erm(44) | 16 | 1 | 8 | 16 | 256 |
| JW3659 | Subclinical bovine mastitis milk | This study | erm(44) | 128 | 0.5 | 16 | 32 | 256 |
| JW4305 | Subclinical bovine mastitis milk | This study | erm(44) | 32 | 0.5 | 8 | 16 | 256 |
a
Antibiotic resistance genes and functions: tet(L), tetracycline efflux gene; mph(C), macrolide phosphotransferase gene; erm(44), 23S rRNA methylase gene.
b
Abbreviations: ERY, erythromycin; CLI, clindamycin; PIA, pristinamycin IA; iCLI and iPIA, 2 μg/ml erythromycin added to the broth for the detection of inducible resistance to clindamycin (iCLI) and pristinamycin IA (iPIA); NA, not applicable.
c
Vector pBUS1-Pcap is a pBUS1 derivate that harbors the cap promoter of the S. aureus type 1 capsular polysaccharide biosynthesis gene cluster.