Dr Phil Kieran: My GP is reluctant to prescribe antibiotics 

We have been using them for treatment for less than a hundred years, and in that time, their benefits can’t be overstated.

My grandfather was a GP who in his career would have seen a chest infection change from a diagnosis with a pretty high mortality rate to one that is easily treatable and often wouldn’t even keep someone from working, thanks to antibiotics. In 1901, before antibiotics, infections caused 36% of all deaths and 51% of childhood deaths; in 2000, the mortality rate was 11% and 7%, respectively. This change is nothing short of miraculous.

When antibiotics became available, they were prescribed liberally, including for viral infections. Though doctors knew they wouldn’t improve viral symptoms, they reasoned they would reduce the risk of secondary bacterial infection. This was common practice before we knew about antibiotic resistance.

When you have a bacterial infection, the antibiotic you take will kill off almost all the specific bacteria. The infection may comprise billions of individual bacteria, and some will be genetically resistant to the antibiotic. Usually, your immune system will clear these remaining bacteria without difficulty because they are small in number. But every time an antibiotic is prescribed, we risk resistant bacteria replicating itself and causing an infection in other people. Eventually, this will lead to all bacteria in the community being immune to antibiotics.

Doctors are careful when prescribing antibiotics, not because they might stop working for an individual patient, but to prevent them from losing effectiveness for the public.

This resistance has happened with many infections already, the most well-known being MRSA (a resistant strain of a common bacteria) and with strains of TB. The worry is that this could happen to all infections, and we would be back to the same situation before the 1920s when penicillin was discovered.

Antibiotics work by stopping specific processes that bacteria need to reproduce. We can target these because bacterial cell machinery is different from human ones. Viruses use our cells to replicate, so antibiotics have no effect whatsoever on them. Also, by taking out a lot of healthy bacteria in your gut, antibiotics can lower your immune system. We are only now realising how much harm antibiotics do to gut bacteria. I hope this clarifies why a GP will not prescribe antibiotics when you don’t need them. Not needing them is a good thing. Antibiotics can make things worse, not just for you but for everyone if you take them when you don’t need to.

• I recommend looking at www.undertheweather.ie for good advice on common viral illnesses.
• If you have a question for Dr Phil Kieran, please send it to parenting@examiner.ie