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No need to add rifampicin to standard antibiotic treatment for Staphylococcus aureus blood infections

15 December 2017

Adding the drug rifampicin to standard antibiotic treatment does not improve outcomes from blood infections caused by the Staphylococcus aureus bug, according to the results of the largest ever trial on how to treat the infection, which were published last night in The Lancet journal.

ARREST tested whether adding an antibiotic drug called rifampicin (or rifampin) to standard antibiotic treatment for Staphylococcus aureus (S. aureus) blood infections, would reduce:

  • deaths
  • the infection not being cured
  • the infection coming back

S. aureus blood infection is common and can be life-threatening. Around one in every five people who have a S. aureus blood infection die from it. Yet, until now, there has been very little good quality evidence on how best to treat it.

Some doctors believed that adding rifampicin to standard antibiotic treatment might improve how well patients with S. aureus blood infections did. The ARREST trial set out to find out if that was the case. The ARREST trial took place between December 2012 and January 2017. People who agreed to take part in the trial were randomly split into 2 groups:

  • 388 people received standard antibiotic treatment for as long as they needed plus an extra placebo (dummy) treatment for 2 weeks
  • 370 people received standard antibiotics for as long as they needed plus additional rifampicin for 2 weeks

The trial followed up how people were doing for 12 weeks. Many of the people taking part in ARREST had other illnesses as well. These included heart failure, lung disease, cancer, moderate or severe renal (kidney) disease, and diabetes.

The ARREST trial found that people who had rifampicin in addition to standard antibiotic treatment did no better than people who had just standard antibiotic treatment. The overall proportion of people who

  • died within 12 weeks of starting the trial
  • or whose infection did not get better within 2 weeks
  • or whose infection came back again

was very similar in the two groups (17% in the rifampicin group versus 18% in the placebo group).

When the researchers looked at each of these aspects separately, they found rifampicin made no difference to the numbers of deaths, nor did it reduce the number of patients who did not get better within 2 weeks. There was some evidence that rifampicin may reduce the number of infections that came back again. But this improvement was not big enough to make a difference to the overall outcome of the trial.

People in the group who had rifampicin were no more likely to have a serious or severe side-effect than those in the group who had placebo. However, they were more likely to need to change their drugs because of side-effects, or experience drug interactions.

These results provide high quality evidence that adding rifampicin to standard antibiotic treatment provides no overall benefit for patients with S. aureus blood infections. This will enable doctors to be confident to not give rifampicin to their patients. This will reduce the complications patients experience from treatment. It will also reduce the risk of rifampicin resistance developing.