This quiz accompanies the article ‘We’re breaking antibiotic resistance’ and links to the themes of cell biology, genetics, and immunity.
QUESTIONS
1. Microbiologist Liselot Dewachter’s research has identified a promising approach to breaking antibiotic resistance. Explain how the pneumococcus bacterium becomes resistant to the antibiotic amoxicillin.
2. The researcher explains that clomifene, as well as amoxicillin, can be used against resistant bacteria. Explain the two different processes by which amoxicillin and clomifene weaken the cell wall.
3. The article explains that researchers initially focus primarily on the bacterial cell wall. Why is the cell wall a good target for medicines?
4. The research shows that the combined effect of amoxicillin and clomifene is far greater than the sum of the two agents individually. In addition, it becomes harder for bacteria to develop resistance to both agents simultaneously. Explain why this is more difficult.
ANSWERS
1. Within a population of pneumococci, a small number of bacteria may be less sensitive to amoxicillin as a result of random mutations. When patients take amoxicillin, it is primarily the sensitive bacteria that are killed. The resistant bacteria survive and continue to divide. As a result, those resistant bacteria increasingly predominate in the population, and amoxicillin resistance eventually emerges.
2. Amoxicillin prevents the formation of cross-links between the long chains in the cell wall, causing the cell wall to weaken. Clomifene, by contrast, inhibits the production of Und-P, which transports the building blocks of the cell wall to the outside. Without this molecule, the cell wall can no longer be properly assembled.
3. The cell wall is a good target because only bacteria have a cell wall – human cells do not. A medicine that attacks the cell wall can therefore damage the bacterium without harming human cells.
4. With a single antibiotic, one mutation may be sufficient for a bacterium to survive. When two agents are used simultaneously, bacteria must develop two successful adaptations, which is far less likely. This is why resistance to the combination of amoxicillin and clomifene is harder to achieve.