Carbon monoxide may improve effectiveness of antibiotics: study

Carbon monoxide may significantly improve the effectiveness of antibiotics, according to a study which may open up novel ways to fight antibiotic resistance.

The study led by researchers at Georgia State University in the US paired carbon monoxide with the antibiotic metronidazole. The researchers found carbon monoxide enhanced the efficacy of the antibiotic against H pylori, a type of bacteria that infects the stomach and causes peptic ulcers.

"We found that if you administer carbon monoxide together with an antibiotic called metronidazole, it can sensitise bacteria towards the same antibiotic by 25-fold," said Binghe Wang from Georgia State.

"It makes the bacteria much, much more sensitive to the antibiotic," he said.

"We always hear about the discussions of drug resistance. When we have drug resistance, itâs not because these bacteria will not respond to antibiotics anymore," said Wang.

"Most of the time, it means there is decreased sensitivity. If you can resensitise bacteria or sensitise them, then that would allow you to either use a smaller amount of antibiotic or use the same amount that would kill many, many more bacteria," he



said.

Carbon monoxide is infamous for its toxicity at high concentrations, but it also has promising potential as a medical gas, researchers said. 

Produced naturally in the human body, carbon monoxide is essential for survival and plays an important role in reducing inflammation, promoting cell proliferation and regulating cellular immune response to pathogens, they said.

Studies have found carbon monoxide has antimicrobial effects. In the study published in the journal Organic Letters, the researchers developed a prodrug system that releases three components: carbon monoxide, an antibiotic (metronidazole) and a fluorescent molecule used to monitor the release of carbon monoxide.

A prodrug is the precursor of a drug and must undergo a chemical conversion before becoming an active pharmacological agent. This prodrug system has a three-reaction sequence and becomes active when placed in water, which sets the reaction in motion.

They studied H pylori bacteria in a culture dish and compared the effect of only the antibiotic metronidazole against the bacteria versus the prodrug system with metronidazole and carbon monoxide combined.