Foundations in Microbiology 9th Edition by Kathleen Park Talaro, Barry Chess

Exercise 4

Critical thinking is the ability to reason and solve problems using facts and concepts. These questions can be approached from a number of angles, and in most cases, they do not have a single correct answer.
An infectious dose of several million cells in enteric infections seems like a lot.
a. In terms of the size and abundance of microbes, could you see a cluster containing that many cells with the naked eye?
b. Refer to chapter 7 on microbial growth cycles. About how long would it take an average bacterial species to reach the infectious dose of a million cells starting from a single cell?
c. Why do enteric diseases require a relatively higher infectious dose than nonenteric diseases?
d. Explain why antimicrobic therapy used on gram-negative bacterial infections could actually lead to illness rather than cure it.