3 Current status of antibiotics

The heyday of antibiotics was from the 1940s to the 1960s and 1970s. This was a time when new antibiotic classes were identified and approved for clinical use, and antibiotic resistance was under control.

Since then, the stock of antibiotics able to cure bacterial infections has been seriously depleted. Antibiotic resistance has soared and the development of new drugs has not kept pace with the need to replace those which no longer work (Figure 4).

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Figure 4 Number of antibiotic classes discovered since the 1900s (Pew Charitable Trust, 2016).

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This figure comprises a bar graph showing the number of antibiotic classes discovered in each decade. The horizontal axis is labelled decade and marked from 1890s to 2010s in decade intervals. The vertical axis is labelled number of antibiotic classes discovered/patented and is marked from 0 to 10 in intervals of 1. The number of classes discovered is given above each bar. The highest number of antibiotic classes discovered were in the 1940s (7 classes) and the 1950s (9 classes) after this antibiotic discovery declined. On the right of the graph the last three decades (1990-2010s) are shaded in grey and this section of the graph is labelled no registered classes of antibiotics discovered after 1984.

Figure 4 Number of antibiotic classes discovered since the 1900s (Pew Charitable Trust, 2016).

In recent years, two potential new classes of antibiotic have been discovered from soil bacteria: teixobactin in 2015 (Ling at al., 2015) and the malacidins in 2018 (Hover, 2018).

In the next activity, you will explore how quickly bacteria develop resistance to newly introduced antibiotics.

Activity 2 Antibiotic activity and resistance timeline

Timing: Allow about 10 minutes

Review Figure 5 and then answer the questions below.

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Figure 5 Timeline of introduction and resistance, showing the main antibiotic classes. Introduction (or deployment) of each antibiotic class is shown above the timeline. The date when resistance was first observed for each class is shown below the timeline.

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This figure consists of a timeline showing the date of introduction and resistance of main antibiotic classes. The timeline runs from 1930 to 2005 and is marked in 5-year intervals. The date of introduction of antibiotics is marked above the timeline. The date resistance was observed is marked below the timeline.

Figure 5 Timeline of introduction and resistance, showing the main antibiotic classes. Introduction (or deployment) of each antibiotic ...

1. Which antibiotic class had the longest interval between its introduction and resistance appearing?

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2. What can you say in general about how long it takes resistance to develop once an antibiotic is brought into clinical use?

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3. In some cases, such as penicilin, resistance to the antibiotic is observed before use of the drug becomes widespread. Why is this?

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Answer

1. It took 13 years before resistance to imipenem, the first carbapenem, to be observed.
2. Resistance can develop quickly once an antibiotic becomes widely used. In most cases, resistance develops within two years of the antibiotic being introduced.
3. As you learned in Week 3, bacteria may have an intrinsic resistance to an antibiotic. It is not too surprising then that resistant bacteria are observed during the period between the initial discovery of an antibiotic and the point at which it is approved for clinical use.

Research and development into new drugs is an essential component of strategies to tackle the antibiotic resistance crisis. Unfortunately, as you will see in Section 4, this is not straightforward.