People LOVE antibiotics. Seriously – if there was one medication that people think of as having next to no side effects and magical powers that are able to crush diseases ranging from cancer to incurable flatulence, it is antibiotics. When I see a pet in the emergency room, even if infection is not anywhere on our radar, I get quizzical looks if don’t send the ailing pet home with the requisite little vial of pills. They do work wonders and have saved countless animal and human lives, but antibiotics have their limitations and they only work for a limited number of situations – all of them involving bacteria.

In terms of cavorting wee beasties that can make you sick, you have your choice of basically three things: bacteria, viruses or fungi. It’s a little like deciding on your pizza toppings.  Actually, on second thought, it’s not like that at all. There are a few other things out there (like prions, the agents that cause Mad Cow Disease. Prions are the zombies  of infectious disease – not alive, not dead, just sorta there), but the first three are the main players.  Antibiotics only work against bacteria – period. There are a few medications out there that combat viruses, but they are fairly lame and have a hefty side effect profile.  If you are afflicted with a virus, you pretty much have to just wait it out and hope your immune system is up to the task. Ditto with fungal infections.  But we have some powerful friends when it comes down to killing bacteria, and their amazing success at protecting us from infection has imbued them with almost magical properties in the collective mind of the public.

Given that there is so much confusion and misinformation out there about antibiotics, I thought I would jot down a few key points to help clear up the situation a bit. 

1. Where did they come from?

The original antibiotics were developed from mold. Yes, mold – that yucky stuff that grows on the leftover Chinese food in the back of your refrigerator and, if you are like me, in the corners of your shower (not big on routine household maintenance, am I).

Somewhere long ago in a lab someone discovered antibiotics (technically, Sir Alexander Flemming [1881-1955] didn't discover penicillin but rather in 1928 he discovered the antibiotic property of some icky ugly fungus that grew by accident in a petri dish that already had bacteria in it; it might have been his lunch, for all we know). He and his compatriots noticed that bacterial cultures did not grow as well when they became contaminated with mold.  Being smart, lab coat-wearing and bespectacled intellectual types, they thought there must be something in the mold that attacked the bacteria and inhibited their growth. And they were right! The mold was producing substances that killed off the bacteria, and the modern age of antibiotics was ushered in. The compounds produced by the mold were identified and isolated, and after a few fits and starts of failed attempts, antibiotics became a powerful tool in the fight against disease.

2. What do they do?

Some of the antibiotics produced today bear little resemblance to these first, humble compounds based on mold. Many of the initial antibiotics punched holes in the cell walls of bacteria (the little membrane surrounding bacteria that keep all the insides on the inside) and sort of deflated them.  Hard to cause disease and wreak mayhem with all your guts spilling  out. Many new and interesting ways of killing bacteria have since been found, so those same smarty-pants bespectacled types have taken the original properties of antibiotics and expanded on them, synthesizing many new compounds over the years.

3. OK – what’s the down side?

It’s not all moldy showers and fun, though. The cruel twist in all of this is that you absolutely can’t live without bacteria. Every single one of us has trillions of bacteria slaving away in our insides to help digest our food and perform countless other beneficial tasks. If antibiotics work too well and kill off these beneficial bacteria, your guts could be in a world of hurt. This is one reason why diarrhea is a common side effect of antibiotic use. The normal balance of bugs in your intestinal tract gets upset, and things go all wonky  and sideways for a bit.  Yogurt, made with the help of these same bacteria, is often recommended to help repopulate the gut with the beneficial types of bacteria. I don’t want to take all the fun out of your breakfast, but yogurt is pretty much bacteria stew. Good bacteria, but bacteria nonetheless. Yum!

Another class of substances, called probiotics, is intended to offset some of the potentially negative effects that antibiotics can have on the gastrointestinal tract. These come in pill, powder and liquid form, and are all aimed at replacing the beneficial bugs that line our guts.

Antibiotics also tend to become weaker over time, a phenomenon known as resistance.  This happens because they tend to kill off only the bacteria that are susceptible to them, leaving in their wake bacteria that are immune to their effects. If you look at the effects of antibiotics as a weapon in a war, the analogy would be that you have killed off all of the mediocre soldiers, leaving the Jean-Claude Van Damme and Rambo types behind.  In order to combat the effects of resistance, researchers have developed even stronger medications with new ways of killing the bugs.

Of course, with these new medicines come new side effects and risks, and the pressure mounts on bacteria to develop new ways of resisting the new drugs.  This arms race has led to the current sorry state of affairs wherein we have some nasty bacteria circling out there, like methicillin-resistant Staphylococcus aureus (MRSA), a particularly awful pathogen that eats most modern antibiotics for lunch. One tender caress from MRSA and you have likely entered into a long-term, and quite unhealthy, relationship.

Veterinarians are often faced with pet owners demanding antibiotics for conditions that don’t call for them.  A similar situation often exists in the pediatrician’s office, where parents demand antibiotics for situations that are probably not bacterial in origin, like ear infections.  It is hard to withstand the relentless requests for antibiotics for many conditions; many veterinarians and MDs will just give in to the pressure, causing further resistance patterns to develop. The problem of antibiotic overuse and misuse leading to widespread bacterial resistance has been dubbed a ‘doomsday scenario’ by the World Health Organization. It is possible that someday we will have killed off all the weak bacteria, but not yet developed the anti-Jean Claude Van Damme/Rambo medications of the future to beat back the resistant bugs: a scary proposition indeed.

4. What can we do to help?

Most nasty bacteria will relent if the right dose of antibiotic is used for the right amount of time. One of the worst things you can do, to yourself and to the world at large, is to stop your antibiotics before the full course is up – and the same goes for your pets.  Stopping them too soon only kills off the weakest and most susceptible bugs, while a full course has a better chance of eliminating all the baddies. If none are left, there is less chance for resistance to occur. All those half-empty pill vials you have in your medicine cabinet from when your sinus infection started to improve after 3 days? Naughty in the extreme! It may seem like a pain to keep popping those pills, but it’s the best way to make sure you don’t get a resistant infection in the future.

So, the next time your veterinarian or MD tells you that antibiotics probably won’t help with whatever ails you or your pet, or implores you to finish the full course of medications, listen and finish. The future might just depend on it.