Part III: The terrifying realities of antimicrobial resistance that will keep you up at night
This post is all about the terrifying realities of antimicrobial resistance. I’m generally not an alarmist, but these two issues are Not Good. We are on our way to a post-antibiotic age of medicine.
CRE: Carbapenem resistant enterobacteriaceae
Recently, I saw headlines about a “nightmare bacteria” that killed two people and infected at least five more. Turns out the nightmare wasn’t such a surprise — the infections were caused by carbapenem-resistant enterobacteriaceae, or CRE.
Enterobacteriaceae are a family of bacteria that includes familiar disease-causing bugs including as Salmonella, E. coli, Enterobacter, and Shigella as well as other bacteria that don’t make us sick. In fact, some of the bacteria found in this family live benignly in the digestive tracts of humans and animals. Others, however, can cause serious illness or death.
What’s particularly frightening is that carbapenems, a particular class of antimicrobials, are usually used as the last-ditch effort to fight infection when other antimicrobials have failed. Bacterial infections treated with carbapenems are nearly always resistant to multiple other drugs. This means that if bacteria are resistant to carbapenems, they’re almost certainly resistant to all other antimicrobials. There are a few drugs that are used to treat CRE, though none of them are particularly effective. If those fail, you’re in big trouble.
That’s right: CRE are resistant to basically every antimicrobial. If you get a CRE infection, your chances of survival are 50–50.
CRE are a serious threat to hospital patients. People are unlikely to come across CRE in their daily lives. However, people who are receiving hospital treatment are vulnerable to CRE infections.
I haven’t found any direct evidence linking CRE directly to animal agriculture. However, because carbapenem is only used when all other antimicrobials fail, if the bacteria weren’t already resistant, carbapenem wouldn’t have to be used in the first place! If you’d like to learn more, I recommend starting with Carl Zimmer’s piece “The ‘Nightmare Bacteria:’ An Explainer.”
Foodborne illness is a direct result of animal agriculture
When you get food poisoning, it doesn’t matter whether the culprit is ground beef or cantaloupe: the microbes that traveled from your salad to your stomach came from the fecal matter of an animal. Maybe it was the cow you were eating, or one of its neighbors, or maybe it was an animal whose manure runoff contaminated the ground that the cantaloupe grew on. Either way, your gastrointestinal distress is tied directly to the bugs living in the digestive systems of agricultural animals.
CDC estimates that 48 million, or 1 in 6, Americans get a foodborne illness each year. Antimicrobial-resistant infections from food cause 430,000 illnesses each year in the US. Multi-drug resistant Salmonella causes 100,000 illnesses annually. Some strains of illness-causing microbes are becoming less resistant, while others are getting stronger.
A white paper from the Center for Science in the Public Interest shows a bleaker picture. It identifies 55 foodborne illness outbreaks from 1973 to 2011 that were associated with antimicrobial resistant microbes. Foods most likely to be implicated in these outbreaks were dairy, ground beef, and poultry. More than half of the outbreaks were due to multi-drug resistant microbes.
Maybe even more concerning is the fact that 58% of the outbreaks in that 38 year period occurred between 2000 and 2011. That’s right — more than half of foodborne illness outbreaks caused by drug resistant microbes since 1973 have occurred in the 21stcentury. The number of human illnesses caused by food contaminated by resistant microbes is on the rise.
This series has raised a lot of questions for me, and I plan to continue exploring this issue. Are there any related questions you’d be interested in having me research? I’ll totally do the work for you!
Special thank you to John Phillips for setting me straight on carbapenems. He’s going to be a great pharmacist.
Originally published at teagank.com on February 20, 2015.