With antbiotic use becoming more widespread and frequent than ever before, many forms of bacteria are developing a resistance to these drugs, and it's become one of the biggest challenges facing public health today. But new findings suggest that old, ineffective antibiotics could be altered to fight this global problem.

Researchers in the US have found that if they slightly modify an old antibiotic, it could be made effective again in treating six different drug-resistant bacteria that cause various respiratory and sexually transmitted diseases. 

The antibiotic, called spectinomycin, was originally developed as a treatment for gonorrhoea. It worked by interrupting how cells create proteins, which was supposed to halt the growth of the bacteria. The thing was, while the drug was safe, it wasn't all that effective, so was eventually removed from the market.

More recently, researchers at St Jude Children's Research Hospital in Memphis revisited the drug, with an interest in increasing its potency. They were looking specifically at how the drug binds itself to the part of a cell that synthesises proteins, known as the ribosome. 

They found that by substituting a benzyl molecule into the antibiotic, it could more easily bind to the cell's ribosomes to fight a range of bacterial infections. "This study demonstrates how classic antibiotics derived from natural products can be redesigned to create semi-synthetic compounds to overcome drug resistance," one of the team, biological chemist Richard Lee, said in a press release.

The team went on to develop six compounds that form a new class of antibiotics called aminomethyl spectinomycins. Further testing showed that these new compounds were effective against a range of bacteria, including "a particularly resistant strain of Streptococcus pneumoniae that resists many existing drugs", they report.

The antibiotics also were effective in treating five other bacteria that cause the sexually transmitted diseases  gonorrhoea and chlamydia, as well as respiratory tract infections, including pneumonia and influenza. Publishing the results in Science Translational Medicine, the team observed no serious side effects. 

Studies on mice and rats showed the drug could also be used to prolong survival in particularly severe pneumonia, while previous research published last year in Nature Medicine has shown this class of drugs could also be effective in treating tuberculosis. The particular variety - known as 1599 - appears to be just as effective as current TB drugs on the market, but without the side effects.

"I hope the result will be drugs that are more effective against tuberculosis and offer a faster route to a cure with fewer side effects," said Lee. With TB remaining a leading cause of global illness and death, killing roughly 1.3 million people each year, we certainly hope so too.