| Year | Mupirocin Concentration | Bacteriostatic | Bactericidal | Observations | Ref |
| 1978 | 0.05 μg/ml | Yes |
| Cells treated with pseudomonic acid within the MIC range, once transferred to fresh media, will spontaneously recover after several hours, and that higher concentrations are necessary for a bactericidal effect. | [55] |
| 1985 | MIC, ≤0.5 μg/ml | Yes |
| Nearly all clinical isolates of Staphylococcus aureus and Staphylococcus epidermidis, including multiply resistant strains, were susceptible (Mupirocin MIC, ≤0.5 μg/ml) …and the activity of Mupirocin was not greatly influenced by inoculum size, but was significantly enhanced in acid medium.” Minimum bactericidal concentrations were 8- to 32-fold higher than MICs, and the antibiotic demonstrated a slow bactericidal action in time-kill tests, resulting in 90 to 99% killing after 24 hrs. incubatedat 37˚C. | [65] |
| 1985 | 1 μg/ml at 120 hours |
| Yes | Before the 120-hour mark, regrowth of surviving colonies would occur at 0.25 μg/ml without the presence of mutants, in an inoculum of 106 CFU. With higher inoculums of 109 CFU, resistant variables (on agar) were found at 2 μg/ml that had stable MICs at 1 - 4 μg/ml Mupirocin, as compared to 0.03 - 0.06 μg/ml for the original inoculum. Colonies also showed “striking orange/yellow” pigmentation, which was then lost on sub-culture, most likely due to the extra production of β-carotene. Casewell concluded that this level of resistance “may not be significant” as the topical 2% formulation of Mupirocin contains 20,000 μg/ml of the antibiotic. | [66] |