Exercise 7: Ending Treatment Early Let's run the same scenario once more. This time, you end treatment early because you're feeling better. The last day that you take a pill is Day 6. So, you take nothing on Day 7, 8, 9, or 10.

You begin with the same numbers of bacteria as before: Strain A = 40, Strain B = 30, Strain C = 20, and Strain D = 10. Remember, these numbers represent thousands of bacteria.

Procedure:
1) Use our Model to determine what happens to the bacteria in your body over the course of ten days. Do your calculations by hand, with a calculator, with a spreadsheet program such as Excel, or with an online calculator such as www. easycalculation. com. Keep track of your data in a Data Table like the one described above. It's a good idea to try all mathematical calculations more than once, to be sure you don't make any mistakes. Here are some hints:

- At the end of Day 7, the final populations are Strain A (0), Strain B (0), Strain C (6), Strain D (10)
- At the end of Day 9, the final populations are Strain A (0), Strain B (0), Strain C (18), Strain D (34)
- Both Strain C and D are still present at the end of Day 10.

You won't be turning in your actual calculations for grading, but keep them. Your Instructor may ask to see them to ensure you did the exercise correctly.

2-4) Omitted

Answer the following questions. Record your answers in your Workbook:

5) Was the infection completely wiped out by the end of Day 10?

6) Which days were you contagious?

7) If we had continued to collect data past Day 10, would you have been contagious on future days?

8) If you answered "Yes" to question 7, then what kind of bacteria would you have become contagious with: a Strain that has resistance to Naquadria (such as Strain C or D), or one that doesn't have resistance to Naquadria (such as strain A or B)?

9) According to our Model, which of the following statements describes how antibiotic resistance builds up in a population of bacteria within ONE PATIENT?
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​a) Antibiotics cause individual bacteria to become more resistant. In other words, an individual bacterium may start out being susceptible to Naquadria, but after being exposed to it, the individual will become stronger, and more able to resist Naquadria's effects in the future.

​b) Antibiotics create resistance from scratch. In other words, even if a species of bacteria has no resistance to an antibiotic, exposing it to antibiotics will cause resistance to appear. For example, if we started out with a patient that had an infection containing only Strain A, resistant Strains, such as C and D, will automatically show up in this patient when we treat him with Naquadria.

​c) Antibiotics favor the survival and reproduction of any bacteria in a patient that already have resistance. If bacteria have resistance, they are more likely to survive, and pass that resistance on to their offspring. Over time, resistant bacteria become more common in the population, because they are the ones that are surviving and reproducing.

10) According to our Model, which of the following statements describes how antibiotic -resistant bacteria become more common among a population of SEVERAL PEOPLE?
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​a) Antibiotic-resistant bacteria are more likely to pass from person to person than non-resistant bacteria, because they are able to withstand the skin's external defenses better than non-resistant bacteria. Both resistant, and non-resistant bacteria will be passed from one person to another, but the stronger, resistant bacteria are the ones that survive the skin's defenses.

​b) Antibiotic-resistant bacteria are more likely to pass from person to person than non-resistant bacteria, because their numbers continue to increase, even when dosed with an antibiotic. Non-resistant bacteria quickly die out when dosed with an antibiotic, while resistant bacteria populations can continue to grow larger. If their numbers increase enough, they will reach the contagious threshold, and be passed on to other people.