Textbook Problem

Bacteriophage-Inspired Antibiotics Although bacteriophages have been infecting bacteria for billions of years, no mechanism, has evolved in bacteria to prevent the viruses from lysing the cell walls of their hosts. Now, scientists are targeting the same bacterial wall components that bacteriophages do. The goal is to develop antibiotics that bacteria will be less likely to develop resistance to. 

FIGURE 20.22 shows the results of a study to test Epimerox, a new bacteriophage-inspired antibiotic, against Bacillus anthracis, the bacterial species that causes the disease anthrax.

FIGURE 20.22 Effect of Epimerox on the survival of mice with anthrax. Mice were infected with the bacteria B. anthracis. One group of 15 then began receiving a drug-free buffer solution 3 hours later. Another 15 were treated with Epimerox beginning 3 hours after infection. A third group of 15was treated with Epimerox beginning 24 hours after infection.

How long did it take for all the mice that received the drug-free buffer alone to die? What function did this group play in the experiment?

Summary Introduction

To determine: The days taken for all the mice to receive the drug-free buffer alone and die.

Introduction: Scientists developed an investigational broad spectrum of an antibiotic compound called Epimerox that inhibits or blocks the activity of an enzyme called epimerase. Epimerase is an enzyme found in Bacillus anthracis that is required to synthesize a polysaccharide in their cell wall. It is also essential for bacterial growth and for receptor expression. Epimerase is used as a model to produce the drug Epimerox. The bacteriophage-lysin enzyme has the capability to specifically bind with epimerase of bacteria and cause cell lysis. Bacillus could not develop a resistant mechanism to prevent the viruses from lysing their host cell wall. This was the idea behind to produce an antibiotic epimerase that could be effective against Bacillus anthracis.

Explanation of Solution

In the given case study, scientists had conducted certain experiments to determine the action of the Epimerox drug. The experimental groups of mice were infected with the bacteria Bacillus anthracis. The mice were grouped into 15 member groups. The first set of mice began to receive drug-free buffer after three hours of infection. At the same time, another set was treated with Epimerox antibiotics. The third set of mice was treated with Epimerox after 24 hours of infection. They observed the survival rate of mice of different groups, and the results were plotted in a graph (Refer Fig 20.2) showing the time (days) of survival versus percentage of survival. Refer Fig 20.2, “Effect of Epimerox on the survival of mice with anthrax”, in the textbook. The graph shows that the group of mice that were injected with drug-free buffer solution died within five days of infection.

Conclusion

The group of mice that were injected with drug-free buffer solution died within five days of infection.

Summary Introduction

To determine: The role of drug-free buffer in the given experiment.

Introduction: Epimerox inhibits or blocks the activity of an enzyme called epimerase. Epimerase is an enzyme found in Bacillus anthracis that is required to synthesize a polysaccharide in their cell wall. It is also essential for bacterial growth and for receptor expression. Epimerase is used as a model to produce the drug Epimerox.

Explanation of Solution

A solution that will resist the pH change by the addition of either acid or base is called buffer. The buffers are important to maintain the pH of a solution. In the given experiment, drug-free buffer serves as a control group to check the efficiency of the drug Epimerox against the Bacillus anthracis in other groups.

Conclusion

The drug-free buffer served as the control group.