I’ve spent a lot of time in meetings listening to people debating whether to use the word “antibiotic” vs “antimicrobial.” I tend to stay out of those discussions because I don’t care too much either way.

  • Yes, they mean somewhat different things.
  • Yes, we want to be precise when writing guidance documents where the difference might be relevant.

However, 99% of the time, it doesn’t matter which term we use.  Their definitions are pretty variable depending on where you look, but commonly it’s something along the lines of:

  • Antimicrobials: substances that inhibit or kill microbes, including bacteria, viruses, fungi and protozoa (microscopic parasites).
  • Antibiotics:  substances that inhibit or kill bacteria.

So, antibiotics are a subset of antimicrobials. Most of the time, when we’re talking about use, resistance or stewardship, we’re focused on bacteria, and therefore antibiotics. However, it’s not all about bacteria, and some substances that inhibit bacteria also inhibit other types of microbes.

  • I tend to use antimicrobial when I’m writing scientifically.
  • I tend to use antibiotic and antimicrobial rather interchangeably otherwise.

Why not just use the “proper” term all the time?

  • Part of it is habit.
  • Part of it is a lack of motivation.
  • Part of it is using a term people are most likely to understand.

If you asked 100 people “What kind of drug do you usually get if you have a urinary tract infection?” I’d guess almost all would say “An antibiotic.

If you asked 100 veterinarian or physicians “What kind of drug do you usually prescribe for a urinary tract infection?” I’d bet over 90% would also say ” An antibiotic.” Maybe even 100%.

That doesn’t mean we should avoid using the proper term when it’s important. If we’re working on international guidelines, we need to be absolutely clear what we’re talking about.  But beyond that…

TomAYto, tomAHto. PotAYto, PotAHto.

I don’t really care what we call them most of the time, I just want us to use them better.