Question

1. What are the similarity and differences between the two graphs?

2. Does this data support the hypothesis that some reaistance genes evolved in bacteria that werent exposed to modern antibiotics? Why or Why Not?

3. Did any antibiotics affect gram-positive and gram- negative strains very differently? What is a possible explanaition for this?

4. Do the results of this study give us any insights into how we might combat antibiotic resistance going foward? If so, what?

Origins of Antibiotic Resistance Data Point Student Handout Gram +ve Folate Pathway ANAS Resistant Strains Gram -ve SOS boome Hot Pathway DNA/RNA Synthesis Call Wall Synthes ok (20 Caption: Different strains of bacteria found in Lechuguilla Cove in New Mexko were tested for resistance to a variety of antibiotics. The antibiotics are grouped by color to show the similor mode of action/target they employ to kill bacteria. (A) Resistance in Gram-positive strains of bacterie (8) Resistance in Gram negative strains of bacteria. BACKGROUND INFORMATION Since the discovery of the first antibiotic, penicillin, in 1928, antibiotics have revolutionized the fight against bacterial infections. Antibiotics are chemicals that specifically target and kill bacteria. Unfortunately, they are often prescribed unnecessarily and frequently misused by patients. Research has shown that these trends have contributed to the recent evolution of bacteria that are resistant to antibiotics. What is less clear is whether the bacterial genes that confer antibiotic resistance (collectively called the "resistome") are all newly evolved since the introduction of antibiotics or have evolved independently.

Answer 1

​​​​​​1. Similarities: The two graphs shows the pattern of antibiotic resistance in gram+ and gram- bacteria. As we can observe from the graph, that the response of bacterial growth to antibiotics follow a definite pattern. Antibiotics against cell wall synthesis provide more resistance then rest of the groups.

Differences: Gram negative strain is more susceptible to antibiotic classes which target the 50S and 30S units of ribosome. They show less resistance as compared to gram positive strain to the group which targets cell wall synthesis.

2. The data shows that some resistant genes, after being exposed to antibiotics have evolved themselves through various mutations like deletion, inversion etc. Such changes have rendered these genes ability to help bacteria survive when exposed to the antibiotics.

3. Yes. As evident from the graph, gram positive bacteria show almost nil resistance to rifampicin which affects the DNA/RNA synthesis pathway. This is because gram negative bacteria have impermeable cell wall. Since, the drug can't enter, it won't be able to inhibit RNA formation.

4. The data provided basis to tackle antibiotic resistance. By analyzing the graphs, we can decide the various drug combinations which can be effective against both the strains. Moreover, we could use the antibiotics cautiously to which bacterial strains are yet to develop resistance. And for those group of antibiotics to which resistance is already developed, we can look out for their alternatives or change their composition slightly with required trials.