Which term describes an antimicrobial that kills bacteria directly?

Which term describes an antimicrobial that kills bacteria directly?

• A. Bacteriostatic
• B. Bactericidal
• C. Kirby-Bauer Test
• D. Minimum Inhibitory Concentration (MIC)

Answer: (B)

The main idea is how an antimicrobial affects bacterial cells. An agent that kills bacteria directly is described as bactericidal. It causes lethal damage to the cells, leading to their death, often by disrupting essential structures or functions (like the cell wall or critical enzymes). In contrast, bacteriostatic agents prevent bacteria from growing but don’t necessarily kill them outright; the immune system then clears the inhibited cells. The Kirby-Bauer test is a disk-diffusion assay that shows how susceptible bacteria are to an antibiotic, not whether the drug kills. The MIC indicates the lowest concentration that stops visible growth, not whether it kills; some drugs may be bactericidal at certain concentrations and bacteriostatic at others. So the term that best fits “an antimicrobial that kills bacteria directly” is bactericidal.

The main idea is how an antimicrobial affects bacterial cells. An agent that kills bacteria directly is described as bactericidal. It causes lethal damage to the cells, leading to their death, often by disrupting essential structures or functions (like the cell wall or critical enzymes). In contrast, bacteriostatic agents prevent bacteria from growing but don’t necessarily kill them outright; the immune system then clears the inhibited cells. The Kirby-Bauer test is a disk-diffusion assay that shows how susceptible bacteria are to an antibiotic, not whether the drug kills. The MIC indicates the lowest concentration that stops visible growth, not whether it kills; some drugs may be bactericidal at certain concentrations and bacteriostatic at others. So the term that best fits “an antimicrobial that kills bacteria directly” is bactericidal.