We sometimes hear about health scares involving so-called superbugs such as MRSA, Clostridium and E.coli, but what are they and how do they develop?

Superbugs are bacteria resistant to almost all antibiotics. Since the first antibiotic, Penicillin, was discovered in 1928, several different types of the medicine have been developed which work in two main ways:

• By making bacterial cell walls leaky, so bacteria absorb excess water and burst (penicillins and cephalosporins)
• By interfering with protein production so bacteria fail to grow or reproduce (tetracyclines, macrolides, aminoglycosides)

Bacteria are among the most primitive life forms on the planet, and reproduce when their cells divide to form two identical clones. The way their genes are copied is unsophisticated, and errors regularly occur. Some of these mutations make the bacterium resistant to certain antibiotics.

This may occur by secreting an enzyme that destroys the antibiotic, or by changing its metabolism to bypass the antibiotic's action. This resistance is most likely to develop when bacteria are exposed to low, sub-lethal doses of antibiotic, when antibiotics are used inappropriately (to treat a viral cold, for example) or when a course of antibiotics is stopped too soon.

Antibiotic resistance is most likely to develop in the most primitive parts of bacterial genetic material, known as plasmids. These are separate from the main bacterial genes and bacteria readily swap these plasmids among themselves.

This allows bacteria to pass on resistance genes quickly, even to unrelated species. So, once a bacterium acquires resistance to an antibiotic, the trait quickly spreads, especially as the antibiotic in question promptly kills off non-resistant bugs, allowing the resistant strains to thrive.

MRSA

Staphylococcus aureus lives on the skin and in the nose, and is a common cause of hospital wound infections. Methicillin-resistant Staphylococcus aureus (MRSA) was first detected in the UK in 1961. MRSA has now also acquired resistance to most other commonly used antibiotics, including vancomycin. It remains sensitive to new antibiotics such as linezolid, quinupristin and dalfopristin, although linezolid resistance was reported in one strain in 2003. Good hygiene practices, washing of hands, and using alcohol-based cleaning solutions helps to keep this superbug at bay.

Escherichia coli

We live with E.coli every day and have up to 11 trillion - weighing 1.5kg - in our gut. Some strains develop increased disease-causing potential, known as virulence, due to the same process that produces antibiotic resistance: genetic mutation. The mutation may be a simple change allowing the bug to stick to the gut wall more easily, or a more complex change such as producing a new poison that helps it overcome our immune defences.

A new E.coli superbug was identified in 2000, called extended spectrum beta-lactamase (ESBL), producing E.coli which is resistant to all but two oral antibiotics. This strain of E.coli mainly causes urinary tract infections and septicaemia (blood poisoning) in elderly or chronically ill people. Most people affected have recently taken antibiotics or been admitted to hospital.

Clostridium

Clostridium difficile (C.difficile) is a virulent strain of intestinal bacterium that produces 20 times more toxins than normal, leading to severe diarrhoea, gut inflammation and dehydration. It was responsible for almost 4000 deaths in 2005, twice as many as MRSA. Most victims have previously been treated with broad-spectrum antibiotics that kill off common gut bacteria and allow antibiotic-resistant virulent strains of C.difficile to flourish.

It is resistant to the alcohol-based cleaning fluids now routinely used to help combat MRSA and must be controlled by soap and water as well as steam cleaning. It is causing particular problems in hospitals in Norfolk at present and is also widespread in the community.

Prevention

Good hygiene with frequent hand-washing is important to reduce infection rates in hospitals. Scientists recently found that bacteria such as MRSA survive for several days on stainless-steel, but die within minutes when exposed to copper, which has natural, anti-bacterial properties.

A piece of copper measuring just one square centimetre can kill 10 million MRSA bacteria in just 90 minutes. Birmingham's Selly Oak hospital is currently fitting copper door knobs, taps, toilet handles and grab rails in an attempt to reduce superbug infections.

Wound dressings containing medicinal honeys, such as Medihoney® Wound Gel, are also effective against antibiotic-resistant superbugs. Honey has a high concentration of natural sugars that absorb fluid, creating a strong, osmotic environment in which bacteria does not thrive. They also release low levels of antiseptics, such as hydrogen peroxide and gluconic acid, which inhibit bacterial growth.

In addition, medicinal honey contains powerful antibiotics derived from the nectar of plants native to New Zealand and Australia, such as Manuka. Research shows medicinal honeys are effective against more than 250 clinical strains, including MRSA and vancomycin-resistant enterococci (VRE).

Maintaining a healthy immune system through good nutrition and a healthy lifestyle also increases your resistance against infections.