1.2.4 When Antibiotics Fail

If you have been prescribed an antibiotic lately, your doctor probably told you to finish the entire prescription even if all your symptoms clear up before they are gone. Have you ever wondered why this was necessary? The misuse of antibiotics is one of the main causes of antibiotic resistance. Imagine that you are sick with pneumonia caused by a bacterial infection. Your doctor prescribes an antibiotic to be taken every day for eight days. In this activity, you will model the effect of the antibiotic on the pneumococcal bacteria. The bacteria causing the infection have varying degrees of antibiotic resistance. What would happen if you did not properly take your antibiotics? What role would this play in the development of antibiotic-resistant bacteria? CAREER CONNECTIONS Pharmaceutical Scientist Meet Jyothy John, a pharmaceutical scientist working to make sure drugs are safe and regulated. She says, “At the start of my career, there were limited opportunities, but now colleges offer undergraduate and graduate programs that prepare students for future careers in pharmacy, medicine, and biomedical research.” ● Computer with graphing software ● Natural Selection & Antibiotic Resistance Set Career Profile: Jyothy John Data Visualization 1 Procedure The pneumococcal bacteria causing the infection vary in their level of antibiotic resistance, from a low level to extremely resistant. Each of these types is seen in various amounts in your simulation. For this procedure, you will roll a die to represent that it is time to take the antibiotic. Each roll will tell you whether or not you actually take the antibiotic each day and determine what happens to the bacteria population in your body as a result. With a partner, obtain a bag containing 20 blue stones, 15 yellow stones, 15 red stones and a die from your teacher. The colored stones represent the pneumococcal bacteria that are in your body. Each stone actually represents thousands of bacteria, not just one. ● Blue stones represent the least resistant pneumococcal bacteria. ● Yellow stones represent the resistant pneumococcal bacteria. ● Red stones represent the extremely resistant pneumococcal bacteria. ● Tossing the die represents that it is time to take the antibiotic. 2 Use the table below for your data. Round [Days] Least Resistant Resistant Extremely Resistant Total Bacteria Initial 13 6 1 20 1 8 6 1 15 2 3 6 1 10 3 0 4 1 5 4 0 0 0 0 5 0 0 0 0 6 0 0 0 0 7 0 0 0 0 8 0 0 0 0 Before you begin the simulation, read through steps 3–6. Roll a die. Use the chart to determine what happens to the bacteria population. 3 If one or more bacteria of a particular type are still alive in your body, add one of that type to each population and record the new totals in your data table. This represents the bacteria reproducing. Repeat the previous steps until you have completed the process eight times or until all of your bacteria are dead. Graph your data and place a copy of it in the space below. Your graph should include the number of: ● ● ● ● ● ● Least resistant bacteria Resistant bacteria Extremely resistant bacteria Bacteria per round (total) Use different colored lines to represent each type of bacteria. Include a key, title, and a label for each axis. Graphing: Refer to the Line Graph section of the Data Visualization resource as needed. 4 Share your results with the rest of the class. Summarize your results in several sentences in space below. Every single day I killed off the 5 weakest bacteria, and my experiment only lasted 5 days. After the 5th day, there was no more bacteria. Answer the Conclusion questions. 1. How did your results compare to the results of others? Explain why others obtained different results. My results differ from others because I killed off the max amount of bacteria everytime, and some people may have “forgot to take the antibiotic” which would allow the bacteria to stay longer for more days, 5 2. Given what you know about antibiotics, what other variables, besides missing doses, might affect the effectiveness of an antibiotic? Some other variables that might affect the effectiveness of an antibiotic are the patient’s diet, genes, age, and overall health. 3. Sue Smith wants to know why she has to continue taking her antibiotics even though she is feeling better. Explain the importance of Sue completing her full course of antibiotics as prescribed. Sue needs to continue taking her antibiotics even though she is feeling better because all the bacteria may not be gone, and you should kill off all the bacteria before there is a chance for more to come back and become resistant to an antibiotic. 4. Patients forgetting to take their antibiotics are not the sole cause of antibiotic resistance. Explain at least two other possible causes of the development of antibiotic-resistant bacteria. Two other possible causes of antibiotics are overuse of antibiotics and poor hygiene and self-care. 6