Question

Bacterium ID50 E. coli O157:17 20 1 Legionella pneumophila Shigella 10 Treponema pallidum 57 Which organism in Table above most easily causes an infection? Select one: O a. E. coli O157:H7 O b. Legionella pneumophila O c. Shigella O d. Treponema pallidum e. The answer cannot be determined based on the information provided.

Answer 1

ID50 represents the total number of pathogens required to infect the host in the 50% of the sample population. ID50 value is used to measure the infectiousness of a pathogen. A lower ID50 value represents the higher infectiousness becasue less amount of pathogens are required to cause a particular disease. Legionella pneumophilla has lowest ID50 value hence can cause infection more easily.

So option B is correct.