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Understanding antibiotic resistance
Understanding antibiotic resistance

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5 Case study: the link between antibiotic use and antibiotic resistance

In this case study you will further explore the link between antibiotic use and antibiotic resistance, by looking at a specific class of antibiotics, the cephalosporins.

Cephalosporins are a group of ß-lactam antibiotics which target cell wall synthesis. Discovered in the late 1940s, cephalosporins have a wide range of activity, have few side effects, and are one of the most commonly used antibiotics in the world.

Activity 7 Finding out about cephalosporins

Timing: Allow about 25 minutes

The images provided for this case study are taken from Resistance Map, a web-based programme that allows antibiotic use and antibiotic resistance data from different countries to be compared.

Study Figures 6a and 6b which compare cephalosporin use from 2000 to 2015 in the UK and South Africa. Then answer the following questions.

  • a.How did cephalosporin use change over time in each country?
  • b.Which country had the lowest consumption of cephalosporins in 2015?
  • c.What factor is most likely to have accounted for the change in cephalosporin consumption in the UK since 2007?
A line graph showing cephalosporin use in the UK between 2000 and 2015.
Figure 6a Cephalosporin use in the UK. (Data source: CDDEP, 2017)
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This figure comprises a line graph showing cephalosporin use in the UK between 2000 and 2015. The horizontal axis is labelled year and is marked from 2000 to 2016 in 2-year intervals. The vertical axis is labelled standard units per 1000/pop UK and is marked from 0 to 2000 in intervals of 500. The blue line on the graph crosses the vertical axis at approximately 1750. It remains fairly constant between 2000 and 2007 before sloping downwards towards the horizontal axis. It ends in 2015 at approximately 750 standard units/1000 pop UK.

Figure 6a Cephalosporin use in the UK. (Data source: CDDEP, 2017)
A line graph showing cephalosporin use in South Africa between 2000 and 2015.
Figure 6b Cephalosporin use in South Africa. (Data source: CDDEP, 2017)
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This figure comprises a line graph showing cephalosporin use in South Africa between 2000 and 2015. The horizontal axis is labelled year and is marked from 2000 to 2016 in 2-year intervals. The vertical axis is labelled standard units per 1000/pop South Africa and is marked from 0 to 900 in intervals of 100. The orange line on the graph crosses the vertical axis just below 800. It remains fairly constant with a small peak in 2011. It ends in 2015 at approximately 700 standard units/1000 pop South Africa.

Figure 6b Cephalosporin use in South Africa. (Data source: CDDEP, 2017)

Discussion

  • a.Over the period 2000 to 2015, antibiotic consumption decreased in the UK and remained relatively stable in South Africa.
  • b.In 2015, the UK and South Africa had similar levels of cephalosporin consumption – about 700 standard units per 1000 population.
  • c.The fall in cephalosporin consumption use in the UK since 2007 was probably due to a switch in prescribing away from cephalosporins towards other antibiotic alternatives.

Now study Figures 7a and 7b which compare cephalosporin resistance among K. pneumoniae and E. coli clinical isolates in the UK and South Africa. Then answer the following questions.

  • a.What was the resistance pattern for each organism in each country?
  • b.Which country had the highest levels of cephalosporin resistance for these bacterial species in 2015?
A line graph showing cephalosporin resistance in K.pneumoniae and E.coli in the UK between 2001 and 2015.
Figure 7a Cephalosporin resistance among K. pneumoniae and E. coli clinical isolates in the UK. (Data source: CDDEP, 2017.)
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This figure comprises a line graph showing cephalosporin resistance in K. pneumoniae and E. coli in the UK between 2001 and 2015. The horizontal axis is labelled year and is marked from 2001 to 2015 in 1-year intervals. The vertical axis is labelled resistance (%) and is marked from 0 to 16 in intervals of 2. The blue line represents percentage resistance of E. coli. It crosses the vertical axis is at 2% and gradually slopes upwards to a peak of 15% in 2013 before sloping downwards to end at 12% in 2015. The orange line represents percentage resistance of K. pneumoniae it starts at 13% in 2005 and remains relatively constant until 2015.

Figure 7a Cephalosporin resistance among K. pneumoniae and E. coli clinical isolates in the UK. (Data source: CDDEP, 2017.)
A line graph of cephalosporin resistance in K.pneumoniae and E.coli in South Africa between 2011 and 2015.
Figure 7b Cephalosporin resistance among K. pneumoniae and E. coli clinical isolates in South Africa. (Data source: CDDEP, 2017.)
Show description|Hide description

This figure comprises a line graph showing cephalosporin resistance in K. pneumoniae and E. coli in South Africa between 2011 and 2015. The horizontal axis is labelled year and is marked from 2011 to 2015 in 1-year intervals. The vertical axis is labelled resistance (%) and is marked from 0 to 100 in intervals of 10. The blue line represents percentage resistance of E. coli. It crosses the vertical axis at 15% and remains relatively constant until 2015. The orange line represents percentage resistance of K. pneumoniae it crosses the vertical axis at 60% and remains relatively constant until 2015.

Figure 7b Cephalosporin resistance among K. pneumoniae and E. coli clinical isolates in South Africa. (Data source: CDDEP, 2017.)

Discussion

  • a.In the UK, cephalosporin resistance remained relatively stable in K. pneumoniae over the period 2000–2015, but increased from about 2% to 12% in E. coli.

    In South Africa, there was a slight increase in cephalosporin resistance in both K. pneumoniae and E. coli from 2011 to 2015.

  • b.Levels of cephalosporin resistance were higher in South Africa than in the UK – considerably so for K. pneumoniae.

What conclusions, if any, can you draw from the data in Figures 6 and 7?

Discussion

The link between antibiotic use and antibiotic resistance is complex and factors other than the amount of antibiotics used can affect the levels of resistance found. For example, the underlying mechanism by which the bacterial population becomes resistant to the antibiotic and the frequency at which resistance spreads is also important. You will learn more about this in Weeks 3 and 4.

Note also that the resistance data in Figures 6 and 7 are for clinical isolates from healthcare settings, whereas antibiotics are increasingly used for non-therapeutic purposes such as agriculture.

In the next section you will explore what the rising global levels of antibiotic resistance mean for us now and in the future.