Superbugs: Science in the household

Prior to embarking on the adventure that is the PhD in neuroscience, I completed an undergrad in microbiology and immunology in Montréal. Microbiology, with its immediate medical and environmental applications, is a science that’s very relevant to everyone in many ways. Microbiology also gives us the two everyday staples that are beer and cheese. Why I would choose to move away from a potential career of making tasty, tasty cheese to poke at mouse brains, I’m still not sure. But today, I bring microbiology back to tell you about a nice study on how our everyday actions can directly impact our health. Now that’s relevant science.

I’m sure you’ve heard about superbugs, bacteria that are resistant to all the most powerful antibiotics known to man. These strains arise from natural selection (survival of the fittest bug!), either following a random mutation or environmental pressure. Say you have a viral infection, but the doctor prescribes you antibiotics anyways (as of 2002, 53% of Canadians still believe antibiotics kill viruses, by the way). You take them, and as a result, the bacteria of your natural flora (the “good” bacteria) become resistant to the antibiotic through survival of the fittest. In addition, instead of storing this resistance in their genome, they store it in this free-floating DNA loop called a plasmid. Then, let’s say you accidentally cut yourself while chopping up raw chicken on a dirty cutting board (bad day!). You get a bacterial infection. Bacteria are quite friendly with each other, and while they’re making you miserable, your good bacteria end up passing the resistance to the bad bacteria by literally fusing together and exchanging a copy of the plasmid (this is called horizontal transfer, as opposed to vertical transfer, when they pass it on to their offspring). Now when you get antibiotics for your very real bacterial infection, they won’t work. That’s just one simple example of superbugs in the making.

The problem is, even if you’re not sick, chances are you’re using antibiotics. In your home. Everyday. Cleaning products, disinfectants, hand soaps, many of those have biocide products in them. In 2008, a group of researchers wondered if maybe that was responsible for generating antibiotic-resistant strains of bacteria. They enrolled over 200 households split into two groups: one group would use cleaning products and hand soap with antimicrobial agents in them for one year, the other would not (well, they would still clean, just not with biocides). Before and after the study, the researchers took bacterial samples from the hands of the people from each household. As it turns out, the bacterial isolates from the group who used biocides had significantly more bacteria that were resistant to one or more antibiotics. Are you surprised? Me neither.

Now that doesn’t mean those were superbugs that would definitely cause health issues, but this should be reason for concern. Continuously exposing bacteria to antibacterial-containing products is pressuring them to select their “fittest bugs”, those who have reduced susceptibility to antibiotics. As it turns out, another study published in The Lancet in 2005 (I’ll spare you the details) showed that it makes no difference whether you use antibacterial soap or regular soap to wash your hands, they end up just as clean either way. And, as an added bonus, we’re doing the environment a favor when we use biocide-free cleaning products and soaps. That’s what we call a win-win situation!

Staphylococcus aureus, a bacterium that can be responsible for antibiotic-resistant infections in humans. Image from the Agricultural Research Service, the research agency of the United States Department of Agriculture.