Drug resistance may be reversed using hydrogen sulphide

Antibiotic resistance in some kinds of bacteria may be reversed using hydrogen sulphide (H₂S), according to a new study.

Prior to the release of the study, published in Frontiers in Microbiology this month (August), it was believed that H₂S, a gas that smells of rotten eggs, served as a "universal defence mechanism" in bacteria against antibiotics.

Researchers from the Singapore-MIT Alliance for Research and Technology (SMART) tested this concept on Acinetobacter baumanii, a pathogenic bacteria that does not naturally produce H₂S. A. baumanii causes infections of the blood, urinary tract and lungs, and is associated with pneumonia, meningitis and other diseases.

A 2019 report released by the UN Interagency Coordinating Group on Antimicrobial Resistance, says that, by 2050, as many as 10 million deaths may be attributable yearly to antimicrobial resistance (AMR), besides causing significant damage to economies. The report noted that AMR can drive around 24 million people into extreme poverty because treatment costs are higher.

When the researchers added H₂S releasing compounds to A. baumanii, instead of triggering antibiotic resistance, the bacterium became sensitive to multiple antibiotics, even reversing acquired resistance to gentamicin — a common antibiotic used to treat various infections.

Until now, H₂S was regarded as a universal bacterial defence against antibiotics. This is a very exciting discovery because we are the first to show that H₂S can, in fact, improve sensitivity to antibiotics and even reverse antibiotic resistance in bacteria that do not naturally produce the agent."

Wilfried Moreira, an author of the study and principal investigator of the SMART antimicrobial resistance interdisciplinary research group

The researchers believe that similar results can be achieved in an unknown number of bacterial species that do not produce H₂S. "More research is necessary as other bacteria may have alternative biochemistry and responses that affect the outcome," says Megan McBee, scientific director at SMART, adding that the study has opened up a treatment option against AMR.

"Our research has found a way to make the deadly bacteria and others like it more sensitive to antibiotics and provide a breakthrough in treating many drug-resistant infections," said Say Yong Ng, lead author of the paper and laboratory technologist at SMART.

AMR has become a serious threat to public health in the past years and, according to WHO, is a problem faced by every country. As of 2016, 490,000 people had contracted a strain of tuberculosis resistant to various drugs. Treatment of HIV and malaria has also been complicated by drug resistance.

"If findings hold true in animal models, a combination therapy of an H₂S donor drug and an antibiotic could be a treatment option for these increasingly common infections that rely heavily on only a few antibiotic options," says McBee.

In a statement to SciDev.Net, the WHO press office said the UN body "recognizes that the current research being undertaken on A. baumannii and hydrogen sensitisation is supporting building of the needed evidence base. "A. baumannii is one of the critical gram-negative pathogens for which new treatment options are needed".