Describe four factors that may have an influence on the effectiveness of an antimicrobial treatment using various microbial control methods.

These are:
1. Number of microbes: if there is a lot of microbes, then more time is needed to kill all of them.
2. Characteristics of microbes: some microbes have resistance genes, so they will not react to agents they are resistant to; some microbes have protective structures so treatment will be inhibited.
3. Time of exposure: different agents will need different time to kill microbes.
4. Environment: the effect of temperature, pH, organics both on microbes and agents.