In microbiology, what does the term ID_{50} refer to?

• A. The concentration of an antibiotic that inhibits 50% of bacterial growth
• B. The dose of a pathogen required to infect 50% of a test population
• C. The dose of a pathogen required to kill 50% of a test population
• D. The time required for a population of microbes to double in number

Answer: (B)

Verified step by step guidance

1. Understand that the term ID_{50} is used in microbiology and infectious disease studies to quantify the infectiousness of a pathogen.
2. Recognize that ID_{50} stands for the "Infectious Dose 50," which is the amount of a pathogen (such as bacteria or virus particles) needed to cause infection in 50% of a test population under controlled conditions.
3. Differentiate ID_{50} from other related terms: for example, the concentration of an antibiotic that inhibits 50% of bacterial growth refers to MIC (Minimum Inhibitory Concentration), and the dose required to kill 50% of a population is called LD_{50} (Lethal Dose 50).
4. Note that ID_{50} specifically measures infectivity, not lethality or growth inhibition, and is a key parameter in understanding how contagious or infectious a pathogen is.
5. Summarize that ID_{50} is the dose of a pathogen required to infect 50% of a test population, which helps researchers compare the infectious potential of different microorganisms.