Part III: The terrifying realities of antimicrobial resistance that will keep you up at night

As promised, today’s post will focus on 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.

The terrifying realities of antimicrobial resistance that will keep you up at night

CRE: Carbapenem resistant enterobacteriaceae This week, 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 21st century. 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.

Part II: Evidence of the link between animal agriculture and antimicrobial resistance

Yesterday, I wrote about the basics of animal agriculture and antimicrobials. Today, I’ll dive deeper into the issues.

Part II: Evidence of the link between animal agriculture and antimicrobial resistance

What is antimicrobial resistance and why should I care about it? Antimicrobial resistance occurs when microbes have developed the ability to evade antimicrobials, survive antimicrobial treatment, multiply, and infect others. Microbes are able to survive partly because antimicrobial treatment may kill off the sensitive microbes and leave the more adapted ones to adapt to the antimicrobial and multiply.

Microbes can become resistant to multiple drugs. This makes the infection difficult or impossible to treat. By its very nature, an infection will spread to others, endangering more people with resistant infections.

The FDA has a pretty great video explaining the process of antimicrobial resistance.

Is there any evidence of association between antimicrobial use in animal agriculture and antimicrobial resistance in humans? Yes. Most of the evidence is based on studies of foodborne illness such as Salmonella and Campylobacter because the foodborne route is the most common way that resistant microbes are transferred from animals to humans.

Some resistant bacteria will themselves endanger human health. Others which cannot make humans ill will share their resistant genetic code with microbes that can make humans ill. These previously vulnerable, pathogenic microbes become resistant when they receive the resistant genes.

Using antimicrobials at sub-therapeutic levels to enhance growth means that all bacteria in an animal’s body is regularly exposed to low levels of antimicrobials. The most susceptible microbes will be killed or incapacitated, but the surviving ones will become increasingly resistant to the antimicrobial used.

How does using antimicrobials in animal agriculture contribute to human foodborne illness? The CDC report “Antibiotic resistance threats in the United States, 2013” outlines exactly how these two issues are related:

  1. Antimicrobial-resistant microbes may be formed through biological (e.g. selective pressure, mutations) or human (e.g. antimicrobial misuse, inadequate diagnostics) avenues.
  2. Antimicrobials used in animal agriculture kill off susceptible microorganisms while allowing resistant microbes to survive.
  3. Resistant microbes can be passed from animals to humans through fecal or other forms of contamination of food.
  4. When humans eat contaminated food, they develop infections (e.g. coli) that cannot be treated with antimicrobials. For generally healthy people, this may not be problematic, as their immune system will fight the infection itself. However, some people will need a boost from antimicrobials—antimicrobials that are now useless.

Beacause of this strong connection between animal antimicrobial use and human illness, CDC recommends that antimicrobials are used only to treat infections rather than to enhance growth. The CDC calls this antibiotic stewardship. 

What are some other ways animal agriculture-induced antimicrobial resistance affects human health?

  • Infections that would not have otherwise occurred
  • Treatment failures
  • Increased severity of infections (Source.)

Is animal agriculture the only cause of antimicrobial resistance? Definitely not. The other major contributor to antimicrobial resistance is improper human medical use. For example, when doctors prescribe antibiotics for a viral infection, the antibiotic will not treat the viral infection. However, the antibiotic may kill off a few bacteria from a minor bacterial infection, leaving only the remaining bacteria resistant to the drug.

 

Come back tomorrow for Part III: The Stuff That Will Keep You Up At Night

Part I: The basics of animal agriculture + antimicrobial resistance

Before antimicrobials, strep throat could be fatal. Nearly every child who had bacterial meningitis died. A small cut, once infected, could kill a person. In my mind, antimicrobials are neck-and-neck with vaccines and basic sanitation as the most important health and medical discoveries. And yet we are quickly losing our grasp on treating infections. Multi-drug resistant tuberculosis is on the rise, as is drug resistant gonorrhea, and MRSA strikes fear into anyone working or staying in a hospital.

Animal agriculture may have something to do with this. Antimicrobials are used extensively in the livestock and poultry industries. This piece is Part I of my exploration of the links between animal agriculture and the looming public health crisis of antimicrobial resistance.

The basics of animal agriculture and antimicrobial resistance

What is the difference between antibiotics and antimicrobials? Strictly speaking, an antibiotic is a substance produced by a microorganism that is used to kill or inhibit the growth of other microorganisms. Penicillin, grown from fungus, is an antibiotic.

An antimicrobial can be naturally-occurring, semi-synthetic, or entirely synthetic compound that it used to kill or inhibit the growth of other microorganisms. Antimicrobials include sulfonamides and amoxicillin. Antimicrobials can be used against bacteria, viruses, fungi, and protozoa such as malaria and toxoplasma gondii.

When discussing animal agriculture, the term antibiotic resistance is often used. However, because it doesn’t include synthetic or semi-synthetic antimicrobials, I’m going to follow the lead of the United Nations, the World Health Organization, and the World Organization for Animal Health and use antimicrobial resistance.

How are antimicrobials used in animal agriculture? Antimicrobials are primarily used as growth promoters and are given to livestock and poultry at sub-therapeutic levels, meaning that the levels at which the antimicrobials are administered are below the threshold that would fight off infection. Using antimicrobials as growth promoters is a direct result of the ever-increasing demand for meat and animal products.

Antimicrobials increase animal growth rate by 2-10% and feed conversion efficiency 3-9%. It’s unclear how or why this happens, but some researchers suggest that cytokines released when the immune system fights off infection may stimulate growth-inhibition hormones. Others suggest that antimicrobials keep animals’ gut bacteria in check, allowing the energy that would have been used to stave off infection to instead be used for growth.

Because nearly all animals raised for food are kept in cramped, stressful conditions, antimicrobials are also used for disease prevention and control (metaphylaxis). The animals live in such a way that makes infectious disease likely—packed in very closely, standing their own excrement—and rather than make changes to their living conditions, the various industries choose to feed the animals preventative antimicrobials.

Antimicrobials are also used when animals get sick, or after an injury or surgery. However, these uses make up just a small portion of the antimicrobials used.

Does animal agriculture really use 80% of the world’s antimicrobials? This statistic is often cited. However, there doesn’t seem to be much evidence to support it. However, this figure includes ionophores, which are not used in human medications but are used as growth promoters.

Which antimicrobials are used in animal agriculture? This table shows a selection of the antimicrobials identified as both critical to human medicine and regularly used in animal agriculture in the Congressional Research Service brief “Antibiotic use in agriculture: Background and legislation” by Geoffrey S. Becker. I added the columns “Common drugs in this class” and “Human infections treated by this class (selected).”

Antimicrobial class Common drugs in this class Human infections treated by this class (selected) Use in animal agriculture Level of importance for human medicine as defined by the FDA, based on level of difficulty of transmitting resistance across genera and species
Cephalosporin (3rd generation) Cedax, Fortaz, ceftriaxone Gonorrhea; urinary tract; respiratory; pelvic inflammatory disease; pneumonia Disease treatment in cattle and swine Critical
Fluoroquinolone Cipro, Floxin, Avelox Anthrax; hospital-acquired infections, especially pneumonia; urinary tract Disease treatment in cattle Critical
Penicillin penicillin, amoxicillin, flucoxacillin Meningitis; syphilis; Lyme disease; strep throat Disease treatment in cattle; growth and disease treatment in swine High
Macrolide Zithromax, erythromycin Legionnaire’s Disease; chlamydia Disease treatment and prevention in cattle; growth, disease treatment and prevention in swine Critical
Tetracycline doxycycline, tetracycline, Chlamydia; acne and rosacea; typus; plague Disease treatment and prevention in cattle; growth, disease treatment and prevention in swine High
Lincosamide clindamycin, lincomycin Toxic Shock Syndrome Disease treatment in swine High
Streptogramin pristinamycin, quinupristin Vancomycin-resistant Staphylococcus aureus (VRSA) and enterococcus (VRE) Growth, disease prevention in chickens High

How does antibiotic resistance happen? The National Institute of Allergy and Infectious Disease (NIAID) cites seven ways that microbes can become drug resistant:

Biological causes

  • Selective pressure: only the microbes with genes that make them resistant to antimicrobials are able to survive
  • Mutations: random changes in the genetic code protect some microbes from antimicrobials
  • Gene transfer: microbes can get genes from other, drug-resistant microbes

Human causes

  • Inappropriate use: prescribing antimicrobials for a disease that cannot be cured by them—for example, prescribing an antibiotic for a cold
  • Inadequate diagnostics: using a broad-spectrum antimicrobial when a specific one may be more effective, or being unsure of the underlying cause of illness and prescribing a drug “just in case”
  • Hospital use: hospital patients are susceptible to infections, but giving them high doses of antimicrobials puts them at risk for resistant infections
  • Agricultural use: NIAID states that agricultural use of antimicrobials is still debatable as a public health issue.

Now that we’ve covered the basics, check out Part II!

Action Phase Podcast Episode 26

johnrossi_headshotJohn Rossi is an Assistant Teaching Professor in Bioethics and Public Health Ethics as well as a veterinarian. He gives me an excellent introduction to animal ethics and the public health implications of animal agriculture, as well as sharing his personal story of following a vegetarian/vegan diet. Special thanks to Phoebe for connecting me with John.

Action Phase is on iTunes. Subscribe so you never miss an episode. Ratings help other people find the show and have the added benefit of giving me a little ego boost!

You can also stream the episode here.

https://ia902506.us.archive.org/24/items/26-JohnRossi-ActionPhasePodcast/26-JohnRossi-ActionPhasePodcast.mp3

Teagan Goes Vegan

Or, Why a burger-loving lady is going to learn how to grill tempeh  

This will be my vegan bible.

I love food. I love cooking, I love eating, I love entertaining. I grew up around chefs and servers and sometimes made cookies in professional kitchens just for fun. In college, I majored in Religion and created a course just about Judaism and Food. Before I started my MPH, I worked as a catering cook and personal chef. Preparing and eating food has been, and likely will continue to be, an integral part of my happiness.

 

And I’ve always been a voracious meat eater. In elementary school, my mom would make chicken in lemon sauce and I would eat my whole plate before she even sat down. Burgers are my #1 favorite entrée to order in restaurants. Just last week, I declared that the only thing that would fix my bad mood was a Wawa meatball hoagie.

 

But morally, I’m evolving. As my college friends can attest, I had an awakening when I read Michael Pollan’s The Omnivore’s Dilemma. After a brief corn obsession, I turned my attention to factory farms. I became vegetarian. I loved it—I felt like I was making a good choice not only for myself, but also for animals and the environment. However, I fell back into eating meat after a series of family crises, moving halfway across the country, and starting a new job. I was unstable in just about every way, and being vegetarian seemed like too much work.

 

Now, I feel solid. I’m about to graduate with my MPH and have a job lined up already. I’m getting married in September. I’m managing anxiety and learning healthy boundaries. I am strong, and now that I am strong, I want to be compassionate and responsible for my impact on the world.

 

Raising animals for food has significant public health implications. Infectious diseases like MRSA and influenza thrive in factory farms and are easily transmitted to humans. Antibiotics are used as prevention rather than treatment because the animals easily fall ill, and this indiscriminant use is the major contributor to antibiotic resistance. The massive amounts of waste produced in these Concentrated Animal Feeding Operations (CAFOs) contaminate water, air, and soil.

 

The animals on factory farms are treated as commodities rather than living beings. A quick Google search will lead to graphic videos and images of slaughterhouses (euphemistically called “processing plants”) that will haunt you. The abuse inflicted upon these animals is outrageous.

vegan_farms

I had believed that ethically sourced meat was the best option for me, since I really like eating meat but have trouble with the ways in which it is produced. But alas, a student budget does not allow for pasture-raised steaks and farmer’s market eggs. I found myself eating way more meat than I wanted to be, and it was all from factory farms.

 

So I’ve decided to do an experiment. From yesterday, May 6, through June 3, I am going to eat a vegan diet. I plan to keep the blog updated about my experiences. Maybe I’ll throw in a recipe or two if I make something really tasty. I am tracking my food intake so I can share what I learn about balancing macronutrients and calorie consumption while eating vegan. I hope to have a series of guests on the podcast who can talk about the public health and ethical issues around this topic. The first episode, with Allyson Kramer, vegan and gluten free cookbook author, will be up tomorrow.

 

I hope you’ll come along on this adventure with me. It should be fun, it will probably be difficult, and it will hopefully be interesting.

Friday Five: Merck for Mothers, Gates Foundation, mental health, antibiotics, housing

Each Friday, I use five sentences to summarize and comment on five important, interesting, or just plain amusing health stories from the week. Merck for Mothers expands to the US

The US’s high infant mortality rate is often cited as an indicator of our nation’s poor health. However, the maternal mortality rate is often ignored while the number of pregnancy-related deaths has doubled since 1990. Pharmaceutical giant Merck established its Merck for Mothers overseas to help reduce maternal mortality and has just announced it will import those programs to work with expectant mothers in the US. It will provide $6 million in funding for initiatives in ten states and three cities, including Baltimore and Philadelphia. The project will also work to standardize procedures for pregnancy-related emergencies.

Maternal mortality by GDP per capita. I've highlighted a few countries for comparison. While the US does have a comparatively low maternal mortality rate, it is far above other countries with similar GDPs. The size of the circles represent the size of the population, and the color indicates the geographic region. Source: Gapminder

 

The Gates Foundation funds all kinds of new public health ideas

The Bill and Melinda Gates Foundation is dedicated to improving public health around the world, and its Grand Challenges Explorations is a way to promote innovation. This week, the Foundation announced the 81 winners of this year’s $100,000 grants. All of the grants awarded fall into these categories:

  • Increasing the interoperability of good data (ex: improving humanitarian information management in crises)
  • Develop the next generation of condom (ex: condom applicator that can minimize interruption)
  • Labor saving innovations for women smallholder farmers (ex: participatory reality TV show encouraging the use of draught animals)
  • New approaches for the detection and treatment of selected neglected tropical diseases (ex: artificial snail decoy to confuse a parasite)
  • The ‘One Health’ concept: bringing together human and animal health for new solutions (ex: new canine rabies vaccine)

Non-specialist health care workers in developing nations are successful at mental health care

A report published this week shows good news for mental health in low- and mid-income countries. Examining 38 studies, researchers found that non-specialists (such as doctors and nurses rather than psychologists and psychiatrists), who have some mental health training, have been successful in alleviating mental, neurological, and substance abuse issues. Compared to untrained health care workers, patients of trained workers had a positive affect on depression, youth PTSD, and problem drinkers. The researchers caution against making assumptions about what kinds of interventions might work. But the bright side is that training primary care workers to consider mental health needs could help get much-needed care to people who may otherwise go without. You can read the report—and a plain language summary—here.

Tonight’s nightmare is…bacteria that no antibiotic can kill

New Zealander Brian Pool died in July, but the specifics of his death were just reported this week. While in teaching in Vietnam, he underwent surgery and contracted KPC-Oxa 48, a strain of bacteria that is resistant to all antibiotics. That’s right, all of them. New Zealand authorities were strict about quarantine, so there’s little worry that the bug will spread from this particular incident. If you’d like to learn about all the things at risk if we lose the ability to kill bacteria, Maryn McKenna has a terrifying run down.

Why we need public housing

I’ve recently become interested in the importance of safe, stable, and affordable housing as a prerequisite for good health. Ensuring everyone has their basic needs met is perhaps the most important public health issue. How can anyone expect to have a successful smoking cessation intervention if participants don’t know where they’ll sleep tonight? Now that I’m paying attention to the issue, I’m seeing it everywhere. This infographic explains how public housing can be a part of the solution.

public_housing_info

Friday Five: Lea-Ann Ellison, antibiotic resistance, apps, medical marijuana, adorableness

Each Friday, I use five sentences to summarize and comment on five important, interesting, or just plain amusing health stories from the week.  

Surprise! Lifting weights while pregnant is controversial

Americans do a great job of finding reasons to criticize women, especially when it comes to reproduction and motherhood. This week, we were subjected to a wave of judgment about Lea-Ann Ellison, who has the audacity to lift weights while 33 weeks pregnant. She says her doctor is fine with her exercise. Pregnant women are told to continue being active, and that’s exactly what she’s doing. If her doctor—not the ones quoted by media outlets—deem her exercise intensity level safe, then we should butt out.

 

Antibiotic resistance is going to be a big problem

A first-of-its-kind report from the CDC on the status of antibiotic resistance classifies 18 microorganisms as “urgent,” “serious,” or “concerning” in their ability to fight antibiotics. The list includes everyone’s favorite infections: gonorrhea, typhoid, and tuberculosis. Antibiotics are one of the most important reasons our life expectancy has grown, and losing the ability to kill bacteria will certainly mean more severe illness. This is a great opportunity for primary prevention (preventing illness before it starts); strategies such as advocating for condom use, safe food handling practices, and vaccines will be necessary. Meanwhile, doctors should be discerning about prescribing antibiotics, and we must invest more money and effort into developing new drugs.

 

Now some apps will come with an “FDA approved” message

The FDA has made its final decision about which mobile health apps it will regulate. It is focusing on apps that could cause significant risk to users if the app does not function correctly. Apps that allow the user to check blood glucose levels or turn the phone into an ultrasound machine could be game changers for providers and patients. However, when I looked for these apps on the iTunes store, I couldn’t find any. Is this because they won’t be released until after the FDA approves them?

 

Egg Harbor dispensary is set to open

The long-awaited South Jersey medical marijuana dispensary run by the Compassionate Care Foundation is set to open in just a few weeks in Egg Harbor. Sales will be by appointment only and the building cannot have any illuminated signs, ostensibly to reduce the inevitable interest of recreational users. Interestingly, the non-profit Compassionate Care Foundation will have to pay federal income taxes because the federal government does not recognize its non-profit, leading to a projected cost to consumers of $400 per ounce, with a limit of two ounces per month. Could the rules and restrictions placed on the Egg Harbor dispensary be a model for regulating dangerous yet legal painkillers? We have a lot to learn from the state-by-state legalization of marijuana, and I’m interested to see how this evolves.

 

Adorable Care Act. That’s right. Adorable.

The Adorable Care Act has stolen my heart. These animals are just too damn cute. And they’re advocating for the Affordable Care Act on Tumblr and Twitter? Oh man, sign me up for insurance right now. Observe these baby animals that I poached right from the Tumblr:

This kitten is so excited she can stay on her parents' insurance for a few more years.

adorable_care_piglet