A new study by researchers in the UK, Canada and U.S. shows new hopes of restoring penicillin’s full antibiotic effect after discovering how a bacterium which causes pneumonia has become resistant.

Scottish scientist Sir Alexander Fleming discovered penicillin in 1928, but the development of penicillin for use as a medicine is attributed to the Australian Nobel Laureate Howard Walter Florey.

By 1940, penicillin became the first widely used antibiotic to treat pneumococcal infections. During the 1960s, however, the first pneumococcal bacteria that were not susceptible ("resistant") to penicillin were discovered in humans. Since then, penicillin resistant pneumococcal bacteria have been reported all over the world. By the late 1970s, pneumococci that were resistant to other types of antibiotics in addition to penicillins were reported. These "multidrug resistant" pneumococci have now been reported all over the world.

Streptococcus pneumoniae is responsible for 5 million child deaths every year worldwide. It also kills 7 percent of the 1 million elderly Americans that catch pneumococcal pneumonia every year.

The study was led by Dr Adrian Lloyd, of the Department of Biological Sciences at Warwick University, UK, and other colleagues from Warwick, the Université Laval, Ste-Foy in Quebec, and The Rockefeller University in New York.

Lloyd and his team targeted a protein called MurM that is essential for clinically observed penicillin resistance and has also been linked to changes in the chemical make up of the peptidoglycan that appear in penicillin resistant Streptococcus pneumoniae isolated from patients with pneumococcal infections.

The researchers found that the protein acted as an enzyme, playing a role in the formation of structures within the peptidoglycan, which build up its strength. The higher the levels of MurM activity, the stronger the peptidoglycan became, and the more likely the bacterium would be drug resistant as a result.

The researchers were able to replicate the activity of MurM in a test tube, allowing them to study in close detail exactly how it is deployed by Streptococcus pneumoniae to neutralise penicillin.

The researchers hope the results will allow them to develop new drugs, which can block bacterial resistance by disrupting the chemistry of MurM. These treatments could be for Streptococcus pneumoniae, but also for other bacteria such as MRSA, which also appears to rely on the same chemistry to build resistance.

“Because we now know in detail what this protein needs to be able to do its job and promote bacterial resistance we should be able to develop drugs to stop it from doing so." Lloyd told BBC News.

Professor Kevin Kerr, a consultant microbiologist at Harrogate District Hospital, told BBC News the findings were interesting, but much more work was needed.

"Solving the problem of penicillin resistance in pneumococci is a key priority for modern medicine and these results provide an important piece in the puzzle.

"The challenge must now be to see if this discovery can be exploited through the identification and development of new drugs which can inhibit this enzyme," he said.