In part one, we talked about the benefits of bacteria we live with every day. As you are likely aware, not all bacteria are friendly. In fact, there are plenty of bacteria that we never want to encounter. Nonpathogenic bacteria are the ones that are either necessary for survival, or simply not harmful; however, pathogenic bacteria are the ones that cause infections and disease. These are the ones we hear about when there is contamination of our food supply, a drug-resistant outbreak at a hospital, or when you get food poisoning. One of the most dangerous bacteria doesn’t even have to infect us at all. The toxins produced by Clostridium botulinum and its brethren are some of the most potent toxins known. Food contamination by these bacteria is sometimes noticed as those telltale bulges in canned food gone bad.

Mealtime for Macrophage

Sometimes it is necessary to get rid of certain problematic bacteria in or around us. When you have a bacterial infection or have handled raw meat, it is usually a good idea to kill off those less friendly varieties. Our bodies usually do a great job of this on the inside, otherwise we’d be sick all of the time. Our immune systems recognize foreign invaders and destroy them, often by gobbling them up. Your skin keeps most things from getting in at all and produces its own defensive antibiotics called defensins. When it comes to washing your hands, most bacteria get removed by scrubbing your hands in water, while soap removes and kills even more. (Washing your hand also removes some of those defensins.)

Although it’s sometimes hard to find soaps without “antibacterial” slapped across the label and antibiotics added to them, these chemicals have no proven benefit. Soap is already harmful to bacteria and the most common of these antibiotics (triclosan) take a full two minutes of contact to work effectively anyway. Overuse of antibiotics is known to lead to antibiotic resistance and superbugs, and the health effects of some of these antibacterial soap additives on us is unknown. The FDA recently announced that the safety and efficacy of these additives must be proven to keep using them. In lieu of evidence that it is effective, Procter & Gamble has announced that they are removing triclosan from all of their products by this year. (*See update at the end of this post for new FDA rulings.)

Sometimes we have little choice but to kill off some friendly bacteria in order to stop the bad ones from running amok. Anyone who has had a high dose of antibiotics knows that there is a price to pay. Without the friendly bacteria left to keep things in check, you can find yourself stricken by a systemic yeast infection, thrush, or unusually sensitive bowels. Avoiding antibiotics when they are necessary carries a far greater risk, but this is another reason to only use them when necessary and follow the directions.

We are now faced with “superbugs” – bacteria that have evolved resistances to our common antibiotics. There’s the hospital-borne MRSA and multidrug-resistant tuberculosis just to name a few. Some of these resistant bacteria will evolve naturally, but just as we’ve accelerated changes in domesticated plants and animals, our actions are making rapid changes in these bacteria. When less resistant bacteria are killed off, there is little competition left for the stronger ones. It’s survival of the fittest, and they are the ones that will pass on their more resistant genes. Evolution is inevitable, but we don’t need to help these bacteria evolve any faster.

*Update: In September 2016, the FDA issued an updated ruling on 19 active ingredients in antibacterial soaps. Manufacturers have one year to stop using these ingredients in consumer antibacterial soaps, while another three chemicals are still under review. This does not apply to hand sanitizes or soaps used in medical settings.

Useful links:

Simple tips on antibiotics and their use: http://www.cdc.gov/getsmart/antibiotic-use/antibiotic-resistance-faqs.html
All about germs: http://www.mayoclinic.org/diseases-conditions/infectious-diseases/in-depth/germs/art-20045289
Better antibiotic stewardship may decrease infections: http://www.cdc.gov/media/dpk/2014/dpk-vs-safer-health-care.html
Alterations in gut microbiome by antibiotics in pigs: http://www.nature.com/ismej/journal/vaop/ncurrent/full/ismej201412a.html