Topic:
A new chemotherapeutic drug kills bacteria but not humans. Discuss the possible ways the drug may selectively act on bacterial cells.
Teacher comments:
Hi everyone…. just to get this week going, let's discuss the key term…. which is….. SELECTIVE TOXICITY !
Selective toxicity refers to the ability of the drug to targets sites that are relative specific to the microorganism responsible for infection. Sometimes these sites are unique to the microorganism or simply more essential to survival of the microorganism than to the host. This is an important quality for an antimicrobial drug, as it means that it selectively kills or inhibits the growth of microbial targets while causing minimal or no harm to the host.
In practice, this is expressed by a drug's therapeutic index (TI) - the ratio of the toxic dose (to the patient) to the therapeutic dose (to eliminate the infection). The larger the index, the safer is the drug (antibiotic) for human use.
From a patient point of view, the most important property of an antimicrobial agent is that the agent acts in some way that inhibits or kills bacterial pathogens but has little or no toxic effect on the patient.