19 May 1998

A "Cuppa" Weakens Superbugs

Antibiotic resistant bacteria first emerged in the 1940s, shortly after the introduction of penicillin into medical practice. Using a mechanism called penicillinase, the staphylococci bacteria developed the ability to destroy penicillins, and so become resistant to them. Modified penicillins, such as methicillin, were effective against the new strain of the bacteria until the 1970s when yet another resistant strain emerged. The new strain of bacteria, known as methicillin-resistant staphylococcus aureus, or MRSA for short, had a different type of cell wall which antibiotics were ineffective against.

The media called MRSA a "superbug" - resistant to virtually all antibiotics and still capable of causing serious infection. Its presence became a problem for hospitals where expensive clean-up campaigns disrupted already busy wards.

Now, scientists at The Royal Free Hospital School of Medicine (London) and the University of Cambridge, have discovered that growing MRSA in the presence of tea (Camellia sinensis) extracts renders the bacteria susceptible to antibiotics again. The tea extract appears to do this by preventing the bacteria synthesizing the enzyme critical for building the antibiotic resistant cell wall.

Presenting their findings at the 98th General Meeting of the American Society for Microbiology in Atlanta, the researchers Tat Yam, Saroj Shah, Peter Reynolds and Jeremy Hamilton-Miller, said that the same extracts of tea also seemed to interfere with the action of penicillinase, the mechanism used by the bacteria to resist the first penicillins. The tea extracts may have the potential to counteract both mechanisms of antibiotic resistance found in MRSA. The researchers added that further investigation is needed to clarify exactly how the tea extracts work.