Part 4: Natural selection and antibiotic-resistant bacteria

What antibiotic resistance genes need to be present in Salmonella bacteria to enable them to survive and reproduce in the chickens that live on this farm?

Could the Salmonella bacteria that you modelled survive and reproduce in the intestines of chickens that live on this farm? Look at the cup with beads and the key from Part 3. Explain why or why not.

Did the use of antibiotics on the farm cause your Salmonella bacteria to become antibiotic resistant OR was your Salmonella bacteria resistant to antibiotics before the antibiotics were used on the farm? Support your answer with evidence from the model.

Natural selection occurs when genes for antibiotic resistance become more common in a population because they increase organisms’ abilities to survive and reproduce. What genes are likely to become more common in the population of Salmonella bacteria that live on the chicken farm?

The statements below describe events in the natural selection of bacteria that are resistant to the antibiotic penicillin. Indicate the order in which the events occurred by writing numbers (2, 3 or 4) in front of the statements in your Digital Lab Notebook.

___1__ Bacteria in the chickens’ intestines naturally have a variety of antibiotic resistance genes.

______ The bacteria are exposed to erythromycin when chickens drink their water.

______ Erythromycin-resistant bacteria become more common on the chicken farm.

______ Bacteria that are resistant to erythromycin survive and reproduce.

Describe what conditions in a manure lagoon are likely to result in the evolution (natural selection) of new antibiotic-resistant bacteria.

Describe two ways that people might be exposed to antibiotic-resistant bacteria from manure lagoons.