Combining Antibiotics Changes How Effective They Are

The implications from this should be studied more in light of the major antibiotic resistance problem this century. Among other things, the research found that the compound vanillin (which gives vanilla its taste) combined with an antibiotic that has mostly stopped being used (spectinomycin) increased the effectiveness of the antibiotic.

The effectiveness of antibiotics can be altered by combining them with each other, non-antibiotic drugs or even with food additives. Depending on the bacterial species, some combinations stop antibiotics from working to their full potential whilst others begin to defeat antibiotic resistance, report EMBL researchers and collaborators in Nature on July 4.

In the first large-scale screening of its kind, scientists profiled almost 3000 drug combinations on three different disease-causing bacteria. The research was led by EMBL group leader Nassos Typas.

Overcoming antibiotic resistance

Overuse and misuse of antibiotics has led to widespread antibiotic resistance. Specific combinations of drugs can help in fighting multi-drug resistant bacterial infections, but they are largely unexplored and rarely used in clinics. That is why in the current paper, the team systematically studied the effect of antibiotics paired with each other, as well as with other drugs and food additives in different species.

Whilst many of the investigated drug combinations lessened the antibiotics’ effect, there were over 500 drug combinations which improved antibiotic outcome. A selection of these positive pairings was also tested in multi-drug resistant bacteria, isolated from infected hospital patients, and were found to improve antibiotic effects.

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According to Nassos Typas, combinations of drugs that decrease the effect of antibiotics could also be beneficial to human health. “Antibiotics can lead to collateral damage and side effects because they target healthy bacteria as well. But the effects of these drug combinations are highly selective, and often only affect a few bacterial species. In the future, we could use drug combinations to selectively prevent the harmful effects of antibiotics on healthy bacteria. This would also decrease antibiotic resistance development, as healthy bacteria would not be put under pressure to evolve antibiotic resistance, which can later be transferred to dangerous bacteria.”

General principles

This research is the first large-scale screening of drug combinations across different bacterial species in the lab. The compounds used have already been approved for safe use in humans, but investigations in mice and clinical studies are still required to test the effectiveness of particular drug combinations in humans. In addition to identifying novel drug combinations, the size of this investigation allowed the scientists to understand some of the general principles behind drug-drug interactions. This will allow more rational selection of drug pairs in the future and may be broadly applicable to other therapeutic areas.