Tea Can Reverse Antibiotic Resistance in MRSA
JMT Hamilton-Miller
Department of Medical Microbiology
Royal Free Hospital School of Medicine
Pond Street London NW3 2QG UK
44-171-794-0500 ext 3271
Paper A-11, Session 129-A
I t has been known from anecdote for thousands of years, and from the scientific literature since 1906, that extracts of the dried leaves of the evergreen shrub Cajaellia sinensis - what the world knows as the beverage called "tea" - has the ability to kill various disease-causing microbes. There is thus a good basis for the folk remedy of using cold tea to relieve inflamed and sore eyes (a microbial infection is often the cause of this condition). What scientists at The Royal Free Hospital School of Medicine and the University of Cambridge, England, have now discovered is that tea also exerts two other antibacterial effects, unrecognized previously, that have potentially important implications in the on-going fight against antibiotic resistance. Most of the work described here was done in the Department of Medical Microbiology at The Royal Free Hospital School of Medicine (a College of London University) by Tat Yam, Saroj Shah and Jeremy Hamilton-Miller. Other experiments were carried (yut by Peter Reynolds at the Department of Biochemistry, University of Cambridge, England. The findings were presented on Tuesday 19th May at the 98th General Meeting of the American Society for Microbiology, held in Atlanta GA. The bacteria known as "methicillin-resistant Staphylococcus aureus", or MRSA for short, have sometimes been called "superbugs" by the media. This is because they have become resistant to virtually all available antibiotics, while retaining their ability to cause serious infections. Their presence in a hospital disrupts normal routines and causes considerable extra expenditure. Staphylococci developed the ability to destroy penicillins, and so become resistant to them, not long after the introduction of Penicillin into medical practice in the 1940s. This destructive mechanism ("penicillinase") can be counteracted by the use of modified penicillins (such as methicillin) and by cephalosporins, which are stable in the presence of penicillinase. In the late 1970s, however S. aureus found a way to alter the method by which it put together a rigid cellwall (which is the target of penicillins and cephalosporins), so that none of these antibiotics could any longer be relied upon to kil! l the bacteria. MRSA have now become widespread throughout the world. The discovery described here is that a component of tea prevents the MRSA using this altered method of making its cell wall, and thus reverses the resistance to methicillin and other related antibiotics. Furthermore, another activity discovered in the same extracts of tea interferes with the action of penicillinase. Thus, a component in tea has the potential to counteract both mechanisms of antibiotic resistance found in MRSA, and might also prevent sensitive staphylococci developing mechanisms of resistance. Much further investigation is needed to clarify exactly how these processes work, and isolation and chemical modification of the active component in tea extracts may produce a compound that will have clinical value in the future.
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