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Resistance to antibiotics prompts new health threats

Experts think the age of the wonder drug may now be over because of antibiotic overuse

PUBLISHED : Sunday, 29 September, 2013, 12:00am
UPDATED : Sunday, 29 September, 2013, 12:46am

It has only been 70 years since work began on the first mass production of an antibiotic, penicillin. It was hailed as a "wonder drug" as it could treat a host of diseases including pneumonia and scarlet fever.

Yet within just two years, the man who had first noticed the anti-bacterial properties of a penicillin mould, Alexander Fleming, was warning: "It is not difficult to make microbes resistant to penicillin in the laboratory by exposing them to concentrations not sufficient to kill them, and the same thing has occasionally happened in the body."

Even by this time, bacteria outside laboratories were developing resistance to penicillin. They did so thanks to natural selection, with relatively tiny numbers of variants that were not killed by penicillin proliferating, and giving rise to populations that could survive the former wonder drug. These could then even swap genetic material with other bacteria, conferring resistance on those bacteria as well.

Staphylococcus aureus was to give rise to one of the most infamous antibiotic-resistant strains. "Staph" is common in healthy humans - you surely have it on your skin or in your nose. But it can lead to severe infections in wounds, such as after surgery.

As resistant strains became an issue, a penicillin derivative was introduced as a countermeasure. This was methicillin, first licensed in 1959, and with resistant strains first noted the following year. Since then, methicillin-resistant Staphylococcus aureus - MRSA - has become a severe problem, especially in hospitals.

More antibiotics were developed, and a growing list of bacterial diseases in turn evolved resistance to them. Initially, resistance caused little concern. But the antibiotics "pipeline" has lately almost ground to a halt: though 14 classes of antibiotics were introduced for human use from 1935 to 1968, only five have been introduced since, and two of these are for use on the skin.

Evolution, meanwhile, continues apace, with a growing roll call of drug-resistant diseases, including strains that are multiple-drug resistant or even exhibit total drug resistance. These strains are the superbugs: Tough to treat and capable of causing severe infections and even death.

"Global action is needed to tackle the catastrophic threat of anti-microbial resistance," England's chief medical officer Professor Dame Sally Davies said earlier this year.

"CRE [Carbapenem-resistant enterobacteriaceae, including gut bacteria like E. coli] are nightmare bacteria," said Tom Frieden, director of the United States' Centres for Disease Control and Prevention (CDC). "Our strongest antibiotics don't work and patients are left with potentially untreatable infections."

In an e-mailed reply to questions from the Sunday Morning Post, Professor Margaret Ip of the Chinese University of Hong Kong's Department of Microbiology noted: "Hong Kong has seen high resistance rates to some of the traditionally used oral anti-microbial agents.

"The condition has improved somewhat with an overall increased awareness of their use, better hygiene and infrastructure for controlling drug-resistant bacteria. It is pertinent to reduce and contain these resistant bacteria, so as to preserve the choices of antibiotics that are available and effective."

Similar action is advocated by the CDC, which on September 16 released a landmark report on antibiotics resistance, with a conservative estimate that antibiotic-resistant bacteria kill 23,000 people in the US every year. According to the CDC, "up to half of antibiotic use in humans and much of antibiotic use in animals is unnecessary".

The age of the wonder drug may be over. As Hong Kong's Dr Margaret Chan, director-general of the World Health Organisation, observed last year: "A post-antibiotic era means, in effect, an end to modern medicine as we know it. Things as common as strep throat or a child's scratched knee could once again kill."

Martin Williams, a Hong Kong-based writer, holds a PhD in physical chemistry from Cambridge University

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