Table 4.
The MIC and MBC values of temporin-PKE and its analogues against several pathogens 1.
| Bacteria | MIC 2/MBC 3 (μM) | |||||||
|---|---|---|---|---|---|---|---|---|
| Positive 4 | Temporin-PKE | 2K | K12 | 3K | 4K | i | 3i | |
| S. aureus (ATCC 6538) | 2/2 | 2/2 | 2/2 | 4/4 | 2/2 | 32/32 | 2/2 | 32/32 |
| E. coli (ATCC CRM 8739) | 1/1 | >512 | 4/4 | 8/8 | 2/2 | 4/4 | >512 | >512 |
| C. albicans (ATCC CRM 10231) | 4/4 | >512 | >512 | >512 | 32/64 | 64/64 | >512 | 128/256 |
| MRSA (NCTC 12493) | 2/2 | 2/2 | 2/2 | 4/4 | 2/2 | 32/32 | 4/4 | 64/64 |
| K. pneumoniae (ATCC 43816) | 2/2 | >512 | 16/32 | 32/64 | 4/4 | 16/16 | >512 | >512 |
| P. aeruginosa (ATCC CRM 9027) | 2/2 | >512 | 128/256 | 256/256 | 16/16 | 64/64 | >512 | >512 |
| E. faecalis (NCTC 12697) | 4/4 | 8/8 | 2/2 | 8/8 | 2/2 | 32/32 | 4/4 | 128/128 |
| Clinical strains | ||||||||
| MRSA (B042 V2E1 A) | 2/2 | 4/8 | 2/2 | 4/4 | 2/2 | 16/16 | 4/4 | 64/64 |
| E. coli (ATCC BAA-2340) | 2/2 | >512 | 8/8 | 16/16 | 2/2 | 32/64 | >512 | >512 |
| P. aeruginosa (B004 V2S2 B) | 1/1 | >512 | 32/32 | 64/64 | 8/8 | 32/32 | >512 | >512 |
| K. pneumoniae (ATCC BAA-1705) | 2/2 | >512 | 16/16 | 64/64 | 8/8 | 32/32 | >512 | >512 |
| HC50 (μM) | 6.58 | 19.87 | 122.7 | 87.47 | 1671 | 68.37 | 64.0 | |
| G+ bacteria GM (μM) | 3.36 | 2.00 | 4.76 | 2.00 | 26.91 | 3.36 | 32.00 | |
| Overall GM 5 (μM) | - | 7.46 | 17.15 | 4.26 | 26.49 | - | - | |
| TI (Gram+ bacteria) | 1.96 | 9.94 | 25.79 | 43.74 | 62.10 | 20.33 | 6.20 | |
| TI 5,6 (Overall) | - | 2.66 | 7.16 | 20.53 | 63.08 | - | - | |
1 The results were achieved from the 15 replicates in the three independent assays. 2 The MIC was the lowest concentration at which no bacterial growth could be observed. 3 The MBC was the lowest concentration without any bacterial colonies, which meant at this concentration, the peptide reduced the viability of the pathogen by more than 99.9%. 4 The positive control for C. albicans (ATCC CRM 10231) was amphotericin B. Gentamicin acted as the positive control for P. aeruginosa (B004 V2S2 B) and K. pneumoniae (ATCC BAA 1705). Norfloxacin was used as the positive control for other bacterial strains in the table. 5 As the antimicrobial activities of temporin-PKE, temporin-PKE-i, and temporin-PKE-3i were specifically against Gram-positive bacteria, their overall GM and TI scores were not calculated. 6 TI is the ratio between HC50 (µM) and the GM of MICs (µM), which represents the antimicrobial selectivity of the peptides, which is descried in a previous study [25].