For decades, doctors have hid a stash of drugs in the back of their medical toolboxes with a pane of glass over the top that read, ‘only break in case of emergency’. Because they were rarely used, bacteria hadn't had a chance to evolve a defense against them. That lack of genetic evolution has made these drugs a go to against stubborn pathogens that showed immunity against other medicines. Doctors would only call on them in extreme, or sometimes even dire, circumstances. They were the medical equivalent of a last line of defense. Unfortunately, thanks to the apparent fall of colistin, those defenses aren't as strong as they once were.
Late in 2015, it was discovered that bacteria sampled from pigs and people in south China had become resistant to the colistin drug. Even though it’s been around since 1959, it had seen limited use because it can be toxic to the kidneys. It was included in a group of drugs that doctors had to choose from as a last resort for that reason. Even as a last resort option, it was rare to see it administered because of the damage it could cause on the body. This fact allowed it to remain usable following the last round of bacterial evolution that allowed some microbes to begin resisting a number of other last resort drugs. Once doctors had broken the glass on them, colistin was all that remained. At that point, it truly became the last resort for medical professionals, and now even that is slipping away.
One of the big questions that must be asked is, if colistin wasn’t being used commonly, how did bacteria suddenly evolve to defend against it? The answer actually falls outside of medicine and into the world of agriculture. According to National Geographic, coliston is a relatively cheap drug, and because of its affordability, it is used as an additive to animal feed. Once it is in the feed, it allows animals to put on muscle mass faster and helps to guard them against the rigors of intensive farming.
This resulted in the mass use of the drug in Chinese livestock, thus it’s appearance in pigs. As the food chain did it’s thing and pork was ingested by the Chinese, the resistance was able to transfer to people, which has led us to where we are today. What makes this even more concerning is that the gene that has granted resistance to the drug is able to freely move from one form of bacteria to another, meaning that the evolution process could very well work against the drug at a pace even faster than ones that came before. Below is a brief video that provides background on how bacteria becomes resistant and why it could matter in the 21st century.
For now, a rally cry has gone out to bring change to international agricultural regulations. Even if such a change can happen quickly, the fear is that we'll still eventually reach a point where doctors will be less willing to attempt surgery out of fear that a serious bacterial infection could develop. Without drugs to remove such harmful organisms, the mortality rate of even simple surgical procedures could see a drastic shift in the wrong direction and that’s something none of us will want to face. Only time will tell if Darwinism will ultimately prevail.