What are antibiotics, how do they work & when do we use them?

Imagine you were alive 100 years ago. A simple papercut could turn into septicaemia and cost you your hand or your life. An STD could result in permanent disfigurement and disability. If you contracted TB, you would likely be taken to an outdoor sanatorium in the hope that fresh air and your immune system could overcome the dreaded consumption. A strep throat could turn into rheumatic heart disease. If you survived an operation, you could still succumb to sepsis.

Therefore, one could say that the development of antibiotics and other antimicrobial therapies is arguably the greatest achievement of modern medicine. This World Antibiotic Awareness Week, our expert talks about the importance of this life-saving discovery.

What are antibiotics?

Antibiotics are medications that destroy (interfere with cell wall or contents) or contribute to the slow growth (prevent multiplication) of bacteria. Penicillin was the first one, discovered by Alexander Fleming in 1928. It is still highly regarded as an effective medication and used first line in appropriate doses for a multitude of different infections. Broad-spectrum antibiotics treat a wide range of bacterial infections.

Not all infections are bacterial

It is important to note that not every infection is caused by bacteria. Some infections are viral or fungal or even parasitic. A virus is a tiny infectious agent that replicates only inside the living cells of another organism. Viruses affect not only humans but plants, insects and animals. They do not have their own metabolism and cannot naturally reproduce outside of a host. They are much smaller than bacteria and have different shapes. Most viruses cause disease.

Examples of viral infections include the common cold, influenza, herpes (chickenpox, shingles, cold sores), measles, ebola, HIV and hepatitis A, B and C. Since viruses are so different structurally and metabolically from bacteria, antibiotics will not have any effect on those infections.

By comparison, bacteria are complex single-celled organisms that reproduce on their own. They are found everywhere and are not visible to the naked eye, but can be seen under a standard microscope. They live in our bodies and on our skin. In our gastrointestinal tract, they aid digestion and stave off colonisation by harmful germs. They also help us to develop our immune systems. Less than 1% of bacteria cause disease in humans.

Common bacterial infections include tonsillitis, strep throat, urinary tract infections and cellulitis (soft tissue infections).

By understanding that infections are caused by a large range of different organisms, it becomes clear why antibiotics cannot and should not be ubiquitously handed out every time we are feeling ill. Would you lay down rat poison to deal with a cockroach infestation at your house? Chances are the answer is no. The same theory applies with using antibiotics for viral infections.

What are superbugs and antibiotic resistance?

But besides the fact that antibiotics won’t have any therapeutic benefit in a non-bacterial infection, we have far larger issues to deal with, the most alarming being the emergence of superbugs and antibiotic resistance. If you get an infection and take antibiotics, you’re going to feel better in one or two days, but you still have to take the rest of the course to eliminate all the bacteria from your body. Otherwise, they can grow again and develop resistance to the drug. Antibiotics are actually curing your infection, not just treating your symptoms.

To prevent and control the spread of antibiotic resistance, you should:

  • Only use antibiotics when prescribed by a certified health professional.
  • Never demand antibiotics if your health worker says you don’t need them.
  • Always follow your health worker’s advice when using antibiotics and be sure to finish the course.
  • Never share or use leftover antibiotics.
  • Prevent infections by regularly washing hands, preparing food hygienically, avoiding close contact with sick people, practising safer sex, and keeping vaccinations up to date.

In the event that you actually do get ill with a bacterial infection, your doctor is likely going to take into account several factors such as location/source of infection, most likely infective organism, local antibiotic resistance patterns and any allergies or intolerances you may have. Based on that, they will prescribe you a broad-spectrum antibiotic to treat your infection.

“If you get an infection and take antibiotics, you’re going to feel better in one or two days, but you still have to take the rest of the course to eliminate all the bacteria from your body.”

Sometimes we need to be more specific with our choice of antibiotics. For example, if resistance patterns in certain infections are known to be high, if an infection doesn’t seem to be clearing on a broad-spectrum antibiotic or if we’re simply unsure about what we are treating. In such cases, your doctor will submit a specimen to the microbiology lab, identify the bug and try to destroy bacterial colonies using various antibiotics on culture medium to see which antibiotics are effective against that specific infection. These kinds of tests eliminate all the guesswork when treating infections.

When used correctly, antibiotics do more good than harm. However, they can have side effects and some people are even allergic to certain types of antibiotics. Common side effects include gastrointestinal upset (for example nausea, diarrhoea and cramping) and overgrowth of fungal flora, resulting in thrush.

This is not to be confused with true allergic reactions which could be potentially life-threatening. Such reactions could manifest with skin rashes/hives or swelling of lips/tongue/airway, possibly as severe as anaphylactic shock. If you or your doctor suspect that you’ve had an allergic reaction to an antibiotic, it’s not worth “giving it another try”. We have multiple classes of antibiotics to choose from and most people who are allergic to one specific antibiotic can safely tolerate another from a different class.

If you have any questions about suitability for antibiotics, optimal use and associated risk, please always contact your doctor. With the possibility of our world heading towards a post-antibiotic apocalypse (yes, it sounds dramatic but is it so far from the truth?), it is not only the responsibility of healthcare practitioners but also the general public to ensure that we’re not irresponsible in how we treat infection.