The rise of the superbugs
How the widespread overuse of antibiotics is proving that too much of a good thing can be catastrophic
Why the overuse of antibiotics has led to new generations of drug-resistant deadly diseases
Antibiotics are without question the miracle drugs of the 20th century. Penicillin, the first widely produced antibiotic, saved more soldiers’ lives during World War II than the Sherman tank. Since the 1940s researchers have discovered newer, more powerful strains of antibiotics to treat everything from a common ear infection to the most exotic tropical disease.
When a young mother or father takes their sick child to the doctor complaining of high fevers, green mucus and listlessness, they don’t want to hear the standard speech about drinking lots of liquids and getting plenty of rest – they want something that will alleviate the symptoms almost instantly. They want to be given antibiotics. And sadly many doctors are more than happy to prescribe them, whether patients really need them or not.
According to the United States Centers for Disease Control, antibiotics are wrongfully administered in almost 50 per cent of cases. On an individual level there’s no real harm in unnecessarily taking an antibiotic. However, widespread abuse of antibiotics has a potentially catastrophic effect on society as a whole. The more antibiotics that humans – and the animals we eat – take, the quicker bacteria evolve and the stronger they become. And what happens when bacteria evolve so significantly that our beloved antibiotics no longer have any effect on them?
Antibiotic resistance is one of the world’s most serious health threats. We are already witnessing the rise of so-called ‘superbugs’, pathogenic bacteria that are immune to traditional antibiotic treatment. One of the best known superbugs is MRSA, short for methicillinresistant Staphylococcus aureus.
Like several other drug-resistant bugs, MRSA spreads quickly through hospitals on the unwashed hands of health workers and patients. Staph infections are nasty enough. If allowed to enter the body they can target the lungs (pneumonia), the heart (endocarditis) and even the bloodstream (bacteraemia). MRSA is staph on steroids, because it has evolved to be resistant to the most effective antibiotics for
curing the infection. Imagine going into the hospital with a sprained ankle and leaving with a drug-resistant case of pneumonia.
So how do common bacteria like S. aureus and E. coli evolve so quickly from a curable annoyance to a potential pandemic? Let’s start by dusting off our Darwin. Evolution by natural selection requires three things: reproduction, variety and selective pressure. Bacteria are masters of reproduction. Under the right conditions a bacterial colony will double in size every ten minutes. They do this through binary fission. Essentially the bacterium makes a copy of its own DNA, then splits in two. With so much copying and splitting, some mistakes – in the form of mutations – are going to be made. These genetic mutations increase the variety of traits that the bacteria can express. Variety is not only the spice of life, but also the engine of evolution.
When a doctor administers an antibiotic to kill off an infection of S. aureus, this applies a selective pressure to the bacterial colony. Bacteria that express beneficial traits – such as the ability to pump antibiotics out of their system – will survive, while the others will be wiped out. The surviving bacteria will then
repopulate the colony, and the next time the antibiotic is applied, it will be completely useless.
Bacteria are not only evolutionarily efficient, they are also cheaters. Through a process called conjugation, two bacteria can share slices of genetic material that carry beneficial traits, skipping the randomness of natural selection altogether. By this method, some bacteria have developed techniques for disguising themselves to antibiotics, blocking the entrance to the cell wall and even tricking the body’s own immune system to release toxic levels of proteins.
The best weapon against the spread of superbugs is to reduce our overall consumption of antibiotics – including the beef, pork and dairy industries, which are responsible for administering approximately 80 per cent of the antibiotics in America – and to improve hygiene and sanitation at hospitals, where these infections thrive and spread.