3.3.1 Case study – antibiotics relevant to your work

Throughout this module you have studied the mechanism of action of several classes of antibiotics. In Activities 10–12 you will use an online database and apply what you have learnt to find out about the mechanism of action of an antibiotic related to your work.

In the following activity you will use the online Comprehensive Antibiotic Resistance Database (CARD) to find out some basic information about the mechanism of action of antibiotics relevant to your work.

Activity 10: Identifying antibiotics relevant to your work

Timing: Allow about 15 minutes

You are asked to read a short paragraph and answer some questions about it. One paragraph is relevant to human health and the other to animal health. Select the paragraph that is most appropriate for your job and your interests. Identify three antibiotics that are relevant to your work.

Animal health

Mastitis is extremely common in dairy cattle, and is very costly for farmers. It is usually an infection of the mammary gland that can be caused by physical injury, but the most common cause is environmental contamination. Antibiotics available to treat bacterial mastitis include sulphonamides (an example of which is sulphanilamide), penicillin and streptomycin.

You can either use the mastitis example above or choose another disease from your work and the related antibiotics used to treat it. You may wish to talk to a colleague or supervisor to find out what diseases are commonly encountered in your workplace for ideas.

Use the space below to make a note of any antibiotics used in your work.

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Activity 11: Accessing CARD

Timing: Allow about 15 minutes

Now access the Comprehensive Antibiotic Resistance Database (CARD) [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)] .

Type the name of one of the antibiotics that you identified in Activity 10 into the search box on the top right of the CARD website (highlighted in Figure 29).

Figure 29 Screenshot of the CARD database. The search box on the top right is highlighted.

Select the antibiotic name from the resulting drop-down list (see Figure 30).

Figure 30 Screenshot from the CARD database showing the drop-down search menu.

This should open a webpage containing information about the antibiotic. An example is shown in Figure 31.

Figure 31 Screenshot of an antibiotic page in the CARD database. The drug class link is highlighted.

Explore the entry for the antibiotic that you have selected. Note down in the space below any information you can find about:

  • the drug class that the antibiotic belongs to
  • whether its action is bacteriostatic or bactericidal
  • whether it is active against Gram-negative or Gram-positive bacteria, or both
  • whether it is broad- or narrow-spectrum
  • the bacterial process that it interferes with.

Be aware that some information about the antibiotic may be given on the drug class page. To access this information you will need to click on the name of the drug class to open the link (highlighted in Figure 31).

Do not worry if you cannot find all of this information in the CARD database. You could also try searching online or asking your colleagues for information. Now repeat the process for two other antibiotics used to treat your chosen disease or pathogen.

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Activity 12: Showing what you have learnt

Timing: Allow about 15 minutes

Write a short summary (of four or five sentences) about what you have found out. Include the name of the antibiotic and why you have selected it. To help you, an example of a forum post is given below:

Animal health example

Bacterial diarrhoea, or scour, in piglets can be treated using cephalexin as long as the bacterial pathogen is susceptible to it. In my workplace we carry out regular tests to determine whether diarrhoeal samples from pigs from the local farms are resistant to cephalexin. Cephalexin is a cephalosporin antibiotic. It is a broad-spectrum, bactericidal antibiotic which acts by inhibiting bacterial cell wall synthesis. It is active against both Gram-positive and Gram-negative bacteria.

Human health example

In my workplace we carry out regular tests to determine whether diarrhoeal samples from the local community are resistant to cephalexin. Cephalexin is a cephalosporin antibiotic. It is a broad-spectrum, bactericidal antibiotic which acts by inhibiting bacterial cell wall synthesis. It is active against both Gram-positive and Gram-negative bacteria.

Once you have written your three summaries, spend a few minutes comparing the different antibiotics and how they act. Are they from different classes, or the same? Do they have the same mechanism of action or different? What else is similar or different about them?

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3.3 Evolving resistance to antibiotics

4 End-of-module quiz