TABLE 3.
CYS can potentiate colistin and azithromycin in vitro; MICs of colistin and azithromycin with and without CYS against a selection of pathogensa
| Antibiotic | Bacterial species, strain, and genotype or phenotype | Median MIC (μg/ml)b |
% reduction in effective dose | |
|---|---|---|---|---|
| Without CYS | With CYS | |||
| Colistin | E. coli NEB pET-29B | 2 (S) | 1 (S) | 50 |
| E. coli NEB pET-29B mcr-1 | 8 (R) | 1 (S) | 87.5 | |
| E. coli RH14000226 mcr-1 | 4 (R) | 2 (S) | 50 | |
| K. pneumoniae NB01216 blaNDM-1, mgrB′ (70Ins_IS5-like) | 64 (R) | 16 (R) | 75 | |
| K. pneumoniae NB02216 blaKPC-2, mgrB′ (7A→T) | 32 (R) | 1 (S) | 96.9 | |
| Azithromycin | S. aureus SACF636 (MRSA) | 0.5 (S) | 0.25 (S) | 50 |
| S. aureus SACF652 (MRSA) | >256 (R) | 0.25 (S) | >99.9 | |
| S. aureus SACF662 (MRSA) | >256 (R) | 0.5 (S) | >99.8 | |
| S. aureus SACF667 (MRSA) | >256 (R) | 0.5 (S) | >99.8 | |
| S. aureus SACF660 (MSSA) | 0.5 (S) | 0.25 (S) | 50 | |
| S. aureus SACF661 (MSSA) | 1 (S) | 0.5 (S) | 50 | |
| S. aureus SACF663 (MSSA) | 128 (R) | 0.25 (S) | 99.8 | |
| S. aureus SACF665 (MSSA) | 0.5 (S) | 0.25 (S) | 50 | |
| S. aureus SACF666 (MSSA) | 1 (S) | 0.5 (S) | 50 | |
| S. aureus DSM 11729 (MRSA) | 16 (R) | 1 (S) | 93.8 | |
| S. aureus BAA-1717 (MRSA) | 8 (R) | 4 (I) | 50 | |
| N. gonorrhoeae NB04916 | 32 | 4 | 87.5 | |
| N. gonorrhoeae NB03916 | >256 | >256 | 0 | |
a
Including the interpretive criteria where possible when used alone and in combination.
b
S, susceptible; I, intermediate; R, resistant.