Practise antibiotic questions by explaining penicillin action, why bacterial targets differ from viruses or human cells, and how resistance evolves and is controlled.
In March 2019, a tropical cyclone in the south-west Indian Ocean caused widespread flooding in a number of countries.
The flooding and the damage caused by the cyclone meant that many people were at serious risk of cholera.
After the natural disaster occurred, many different areas reported outbreaks of cholera. Within a short time the disease had spread widely and large numbers of people were affected.
In addition to the standard treatment for cholera, antibiotics are recommended for people who are moderately ill or seriously ill with the disease.
Penicillin, which used to be prescribed for the treatment of cholera, has a different mechanism of action to doxycycline.
State which part of the bacterial cell is affected by the action of penicillin.
Tuberculosis (TB), influenza and polio are examples of infectious diseases.
Polio is a serious viral disease affecting young children. In 1996, polio caused paralysis in more than 75000 children across Africa. A long-term vaccination programme allowed the World Health Organization (WHO) to declare that Africa was largely free of polio in 2020.
Antibiotics, such as penicillin, do not help to prevent the spread of viral diseases, such as polio.
Explain why penicillin is not effective against viruses.
Fig. 4.1 is a transmission electron micrograph of the bacterium that causes cholera, Vibrio cholerae.
The flagellum shown in Fig. 4.1 allows movement of the bacterium within the gut and may also function to help it to bind to an intestinal epithelial cell. The organism does not enter the cell but the toxin it releases can enter and cause damage. Large quantities of water, chloride ions and sodium ions are lost from the cell.
Fig. 4.1
People with symptoms of cholera have severe watery diarrhoea and as a result can become very dehydrated.
Some strains of V. cholerae are antibiotic resistant.
Explain why this means that medical practitioners prefer to treat cholera with a single dose of antibiotic, rather than a multiple dose of the same antibiotic.