CYS can potentiate colistin and azithromycin in vitro; MICs of colistin and azithromycin with and without CYS against a selection of pathogensa

AntibioticBacterial species, strain, and genotype or phenotypeMedian MIC (μg/ml)b% reduction in effective dose
Without CYSWith CYS
ColistinE. coli NEB pET-29B2 (S)1 (S)50
E. coli NEB pET-29B mcr-18 (R)1 (S)87.5
E. coli RH14000226 mcr-14 (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
AzithromycinS. 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 NB0491632487.5
N. gonorrhoeae NB03916>256>2560
  • a Including the interpretive criteria where possible when used alone and in combination.

  • b S, susceptible; I, intermediate; R, resistant.