Table 1. MIC and therapeutic indices of 3 and various antibiotics.
Different Gram-positive, Gram-negative bacteria, and mycobacteria strains, including laboratory strains and clinical isolates with multidrug resistance, were covered in the evaluation. B. s, Bacillus subtilis; S. a, Staphylococcus aureus; E. c, Escherichia coli; E. fa, Enterococcus faecalis; E. fi, Enterococcus faecium; K. p, Klebsiella pneumoniae; A. b, Acinetobacter baumannii; P. a, Pseudomonas aeruginosa; M. s, Mycobacterium smegmatis; M. tb, Mycobacterium tuberculosis; and E. cl, Enterobacter cloacae. USA300 and USA400 are methicillin-resistant S. aureus strains. ND, not determined.
| Bacteria* |
MIC of 3 (μg/ml) |
MIC† of antibiotics (μg/ml) |
Therapeutic index‡ of 3 (HC50/MIC) |
||||||
| Ampicillin | Gentamycin | Erythromycin | Ciprofloxacin | Trimethoprim | Colistin | ||||
| Gram positive | S. a | 0.5 | <1 | <1 | <1 | <1 | >128 | >128 | >10,000 |
| S. a USA300 | 2 | ND | >2500 | ||||||
| S. a USA400 | 2 | >2500 | |||||||
| S. a -1 | 4 | >128 | 32 | >128 | 16 | >128 | >128 | >1250 | |
| S. a -2 | 4 | >128 | 32 | 128 | 16 | >128 | >128 | >1250 | |
| B. s | 4 | ND | >1250 | ||||||
| E. fa | 4 | <1 | 8 | <1 | <1 | >128 | >128 | >1250 | |
| E. fi -1 | 2 | >128 | ND | >128 | 32 | >128 | >128 | >2500 | |
| Gram negative | K. p | 4 | >128 | <1 | 64 | <1 | 32 | <1 | >1250 |
| K. p -1 | 2 | >128 | >128 | 32 | <1 | >128 | <1 | >2500 | |
| K. p -2 | 2 | >128 | <1 | 64 | <1 | <1 | <1 | >2500 | |
| K. p -3 | 2 | >32 | >32 | >32 | <1 | >32 | 32 | >2500 | |
| K. p -4 | 4 | >32 | >32 | >32 | 32 | >32 | >32 | >1250 | |
| K. p -5 | 4 | >32 | >32 | >32 | 16 | >32 | 32 | >1250 | |
| K. p -6 | 2 | >32 | >32 | >32 | 32 | >32 | 32 | >2500 | |
| A. b | 2 | >128 | 32 | 16 | <1 | 16 | <1 | >2500 | |
| A. b -1 | 2 | >128 | >128 | >128 | 32 | 128 | <1 | >2500 | |
| A. b -2 | 2 | >128 | <1 | 16 | <1 | 16 | <1 | >2500 | |
| P. a | 4 | 128 | <1 | 128 | <1 | >128 | <1 | >1250 | |
| P. a -1 | 4 | >128 | 4 | >128 | <1 | >128 | <1 | >1250 | |
| P. a -2 | 4 | >128 | 4 | 32 | <1 | >128 | <1 | >1250 | |
| E. cl -1 | 2 | >128 | <1 | 128 | <1 | 8 | <1 | >2500 | |
| E. cl -2 | 4 | >128 | <1 | 128 | <1 | 64 | >128 | >1250 | |
| E. cl -3 | 4 | >32 | >32 | >32 | 2 | >32 | 16 | >1250 | |
| E. cl -4 | 2 | >32 | >32 | >32 | >32 | >32 | 8 | >2500 | |
| E. cl -5 | 4 | >32 | 4 | >32 | >32 | >32 | 16 | >1250 | |
| E. c (K12) | 2 | 16 | <1 | 32 | <1 | >128 | >128 | >2500 | |
| E. c -1 | 2 | >128 | <1 | 64 | 4 | <1 | <1 | >2500 | |
| E. c -2 | 4 | >128 | 64 | 64 | 16 | >128 | <1 | >1250 | |
| Mycobacterium | M. s | 2.5 | 62 | ND | 15 | 0.5 | ND | ND | >2000 |
| M. tb H37Rv | 25 | 160 | 4 | 128 | 2.5 | >128 | 16 | >200 | |
| M. tb Erdman | 25 | ND | >200 | ||||||
*Strains having their names ending with -x are clinical isolates with multidrug resistance, and ESKAPE strains are shown in bold.
†Minimal inhibitory concentration.
‡The HC50 measured for 3 was >5000 μg/ml.