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Understanding antibiotic resistance
Understanding antibiotic resistance

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4.2.1 Modern antibacterial applications of metals

Many modern applications of metals have focused on the use of nanoparticles (particles between 1 and 100 nanometres in size) (Figure 11).

An artist’s impression of silver nanoparticles destroying a bacterium.
Figure 11 Illustration of silver nanoparticles destroying a bacterium.

Activity 7 Using silver nanoparticles to improve the effectiveness of antibiotics

Timing: Allow about 10 minutes

Silver nanoparticles can be used to improve the effectiveness of antibiotics. Read the following short excerpt from an article in the Guardian newspaper and then answer the questions below.

At Boston University, a team of biomedical engineers found that conventional antibiotics could kill between 10 and 1,000 times as many bacteria, including many previously resistant strains, when boosted with silver ions. This ancient remedy for infection – described by the Greeks in 400 BC – works in two ways: first by disrupting bacterial metabolism, causing bacteria to self-destruct; and second by making their cell membranes more permeable to the antibiotic. However, while the research is promising, these drugs still have to pass safety testing, as ingesting too much silver can be toxic for humans.

(Cox, 2017)
  1. The researchers showed that silver nanoparticles enhanced the ability of antibiotics to treat Gram-negative bacterial infections. Why do you think this might be? (Hint: you may want to revisit some material in Weeks 2 and 3 to help you answer this question.)
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Answer

Gram-negative bacteria are resistant to many antibiotics because the antibiotics cannot cross their impermeable membrane. By disrupting the cell membrane of Gram-negative bacteria, silver nanoparticles make it easier for the antibiotic to enter the cell and reach its target.

  1. How would improving the effectiveness of antibiotics in treating Gram-negative infections help to tackle antibiotic resistance?
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Answer

Improving the effectiveness of an antibiotic could reduce either the dose of antibiotic required or the amount of time needed to treat the infection. Both of these will help to reduce antibiotic demand. The ability to treat infections caused by Gram-negative bacteria with new antibiotics may provide alternatives that could be used when the infection is resistant to routinely used antibiotic treatments.

Metals can also be used as antibacterial surfaces. Copper surfaces can kill microbes, including HCAIs such as MRSA, within minutes to hours. The use of antibacterial copper surfaces in hospitals has been suggested to reduce the spread of HCAIs.

Activity 8 Reducing the spread of HCAIs by using copper surfaces

Timing: Allow about 10 minutes

Read the following article which describes a trial using copper surfaces to reduce infection transmission in a Birmingham hospital.

Article 2 Copper fittings ‘all but eliminate superbugs’ [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)]

Where else do you think copper surfaces could be used to reduce infection transmission?

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Answer

Copper could be used to make medical devices. It could also be used in care homes, schools and other public places; in fact, anywhere that stainless steel is currently used. For example, one of South America’s largest theme parks – Fantasilandia in Chile – has recently replaced many of its most frequently touched surfaces with copper to try to reduce infection transmission (Keevil, 2017).

You have now looked at several different alternatives to antibiotics. Many of these alternatives are still a long way from being used routinely to treat infections. It is likely that a combination of these alternatives, together with new and existing antibiotics, will be required to treat infections in the future.

You should now complete this week’s quiz which covers material from the last four weeks of this course.