Final answer:
The answer is true because selective toxicity ensures effective treatment of infections with minimal harm to the host. Selectivity is easier to achieve with bacteria due to unique biological structures not present in human cells, and it is a critical factor in antimicrobial drug efficacy.
Step-by-step explanation:
The statement that selective toxicity is a key characteristic of a useful antimicrobial is indeed true. Selective toxicity refers to an antimicrobial's ability to target and eliminate harmful microbes without causing damage to the host. This is crucial as it ensures efficacy in eliminating the infection while preserving the health of the individual taking the medication. Antimicrobials achieve this selective toxicity because microbial cells, such as bacteria, significantly differ from human cells, allowing antimicrobials to target structures or processes unique to the microbes.
Furthermore, the choice between bacteriostatic and bactericidal drugs, as well as the spectrum of activity (narrow vs. broad), is important when prescribing an antimicrobial. The fitness of the immune system and the severity of the infection determine which type to use. The development of antimicrobial drugs often involves high-throughput screening and combinatorial chemistry, to identify compounds that can serve as effective treatments with minimal side effects to humans.
Lastly, the continuous evolution of antimicrobial resistance among microorganisms is a challenge in the development and use of antimicrobial drugs. This makes research and innovation in this field critically important for maintaining a robust arsenal against infectious diseases.