What is a key difference between the MIC and MBC in bacteriostatic drugs?

The minimum bactericidal concentration (MBC) represents the lowest concentration of an antimicrobial that consistently kills a specific bacterium, whereas the minimum inhibitory concentration (MIC) is the lowest concentration that inhibits bacterial growth without necessarily killing the bacteria. In bacteriostatic drugs, which inhibit bacterial growth rather than kill bacteria, the MBC is often significantly higher than the MIC. This is because bacteriostatic drugs prevent bacteria from multiplying, but in order to achieve actual death of the bacteria, a much higher concentration may be necessary.

This difference highlights the nature of bacteriostatic action—concentrations that stop growth (MIC) might not be sufficient to eradicate the bacteria (MBC). Therefore, the MBC's higher presence in comparison to the MIC provides insight into the drug's effectiveness in terms of bacterial eradication versus growth inhibition, which is particularly relevant in the therapeutic planning and selection of appropriate antimicrobial therapies.