Category: Public Health

Quick-and-Dirty Antibiotic Resistance Cheat Sheet

Spurred by a post over at BioMed Central blogs, which outlined challenges in effectively communicating to non-experts the risk of antimicrobial resistance, I decided to put together a little resistance cheat sheet for my mother, the legions of fans who read this blog, or at least the handful of folks who might see this on Facebook. This is by no means an in-depth list, nor does it cover every area of interest (e.g., farm use of antibiotics in livestock). It's meant to provide a quick-and-dirty back-of-the-hand reference of the broad strokes.

What is antibiotic resistance?

When a given drug, in this case an antibiotic, is effective at killing a certain strain of bacteria, that bacteria is considered susceptible to the drugWhen the bacteria evolves such that the drug is no longer effective against it, or becomes less effective, that bacteria is considered resistant. 

Synonyms for antibiotic resistance:

  • Antimicrobial resistance (AMR)
    • This is a broader term that refers to resistance against drugs used to treat other microbes, like viruses
  • Drug resistance
  • Superbug (refers to highly resistant bacteria)

What do antibiotics treat?

Bacteria! That's it.

What do patients do in order to make the problem worse?

(Or, worded more positively: Things you can avoid doing in order to help!)

  1. Don't take the full course
  2. Take the drugs inconsistently
  3. Share antibiotics
  4. Pressure doctors to prescribe antibiotics, even for viral infections

You can actually create an antibiotic-resistant strain by failing to take a full course of drugs. In essence, say you come down with an infection that is susceptible to drugs, but you only take half the course. By doing that, you may have allowed some of the hardier bacteria to survive. This subset of organisms will then continue to reproduce, eventually creating a population of bacteria that is less susceptible to the drug you're on.

Why is resistance bad or worrisome?

  1. Bacteria that are resistant to antibiotics are more difficult to treat.
  2. Your risk of serious, or even catastrophic, infection increases.
  3. Bacteria can share their resistance genes with other bacteria, even across species.
  4. Antibiotics are required for all sorts of procedures, such as surgery. The more resistance that emerges, the greater the chances are that in the coming years it will be took risky to do even simple operations.
MRSA (yellow) being ingested by neutrophil (purple). Photo Source: National Institute of Allergy and Infectious Diseases (NIAID).

MRSA (yellow) being ingested by neutrophil (purple). Photo Source: National Institute of Allergy and Infectious Diseases (NIAID).

What are some of the most worrying antibiotic-resistant bacteria?

CRE (Carbapenem-resistant enterobacteriaceae)

A strain of this bacteria caused a deadly outbreak in an Illinois hospital last year. Most of these infections are hospital-acquired, often through endoscopic procedures when the scope has not been cleaned properly.

MRSA (Methicillicin-resistant Staphylococcus aureus)

You may have heard of MRSA before. That's partly because staph is incredibly common: about 33% of people are non-symptomatic carriers, and something like 2–3% are carrying MRSA at any given time. However, MRSA has been making news over the past several years because what was once a primarily hospital-based infection has increasingly caused what are called "community-acquired" MRSA infections — infections picked up outside the hospital.

Tuberculosis

That's right. While you may know it because you read Angela's Ashes in high school, TB is still with us and gaining resistance to the antibiotics used to treat it. It is a much larger problem in certain populations, such as the homeless, and in developing countries. Resistant TB strains can be classified as "multidrug-resistant" (MDR) or "extensively drug-resistant" (XDR) when certain classes of drugs are no longer effective against a given strain.

Gonorrhea

The bacteria that causes gonorrhea (Neisseria gonorrhoeae) garners resistance quickly, and we may be approaching an era of untreatable gonococcal infections. Currently, the Centers for Disease Control and Prevention (CDC) run a program called the Gonococcal Isolate Surveillance Project (GISP, for short), which monitors the emergence of resistant gonorrhea strains around the United States. Physicians and public health experts have had to continually revise treatment protocols over the past 30 years in order to maintain the effectiveness of antibiotics currently in use.

Tip of the iceberg

There are other issues not directly related to patient behavior, but there are a few things you (and I) can do to help. If you want to know a little more about antimicrobial resistance in general, refer to entities like the World Health Organization or the CDC.

No Big Deal, Vaccines Have Just Almost Eliminated Polio

Vaccines are the best. Seriously, the first thing you would ever ask for — if charged with eradicating or decreasing the incidence of a given disease — is an effective vaccine against it, which makes anti-vaccination movements all the more perplexing, and vexing. Plenty have written about what fuels some of this animus: distrust of the medical establishment, ignorance about risk-benefit calculations, and general suspicion of the pharmaceutical industry. Yet, what makes some of these narratives occasionally difficult to refute convincingly are the nuggets of truth they sometimes contain.

For instance, vaccines can and do cause serious adverse effects, in very rare cases for the most part. Remaining vigilant about those risks is important, but so is the utilitarian concern that weighs the benefits (in lives saved or illnesses prevented) against the risks (in deaths, neurologic problems, and other adverse effects). In the vast majority of cases, that comparison works out overwhelmingly in favor of immunization as a category, even as the efficacy and risk profile varies depending on the vaccine.

This physical therapist is assisting two polio-stricken children holding on to a rail while they exercise their lower limbs.

This physical therapist is assisting two polio-stricken children holding on to a rail while they exercise their lower limbs. In the early 1950s there were more than 20,000 cases of polio each year. After the polio vaccination was introduced in 1955 that figure dropped to about 3,000 per year by 1960.
Image and Caption: CDC/Charles Farmer, ID# 2612

Today, for World Polio Day, the World Health Organization (WHO) posted a short informational page on poliomyelitis, a highly infectious disease that results in lower limb paralysis in a number of those who contract it (about 1 in 200). Once a common infection, vaccines have drastically reduced the burden of polio in both the developed and developing worlds.

The WHO:

Polio cases have decreased by over 99% since 1988, from an estimated 350,000 cases in more than 125 endemic countries then, to 416 reported cases in 2013. These included only 160 cases in endemic countries; international spread from endemic areas into polio-free areas accounted for the remainder.

In 2014, only parts of 3 countries in the world remain endemic for the disease–the smallest geographic area in history. Of the 3 strains of wild poliovirus (type 1, type 2, and type 3), wild poliovirus type 2 was eradicated in 1999 and case numbers of wild poliovirus type 3 are down to the lowest-ever levels with the no cases reported since November 2012 from Nigeria.

However, the oral polio vaccine contains a weakened strain of the virus itself, which can in rare instances lead to the establishment of a new circulating strain. As I learned today, this is referred to as vaccine-derived polio. Interested in the burden of such cases, I looked it up and came across a beautiful illustration of the risk-benefit issue. Again we turn to the WHO, this time to their Question & Answer on vaccine-derived polio:

When a child is immunized with OPV [oral polio vaccine], the weakened vaccine-virus replicates in the intestine for a limited period, thereby developing immunity by building up antibodies. During this time, the vaccine-virus is also excreted. In areas of inadequate sanitation, this excreted vaccine-virus can spread in the immediate community (and this can offer protection to other children through ‘passive’ immunization), before eventually dying out.

On rare occasions, if a population is seriously under-immunized, an excreted vaccine-virus can continue to circulate for an extended period of time. The longer it is allowed to survive, the more genetic changes it undergoes. In very rare instances, the vaccine-virus can genetically change into a form that can paralyse – this is what is known as a circulating vaccine-derived poliovirus (cVDPV).

How often does this happen? According to their Q&A:

Since 2000, more than 10 billion doses of OPV have been administered to nearly 3 billion children worldwide. As a result, more than 10 million cases of polio have been prevented, and the disease has been reduced by more than 99%. During that time, 20 cVDPV outbreaks occurred in 20 countries, resulting in 758 VDPV [vaccine-derived polio virus] cases.

Do that math.

 

Update (10/24): I should have been a little more precise in my wording. Polio infections have been eliminated in many areas, while eradication may remain a ways off. For a brief discussion of the obstacles still standing in the way of full eradication, I point you to this editorial in the Lancet. I have updated the title of this post to reflect what I think is a better approximation of the situation, but this page on disease elimination and eradication from the Centers for Disease Control and Prevention (CDC) discusses some of the ambiguities between the terms.

The ALS Ice Bucket Challenge: Money, Water, and the Social Game

Full disclosure: I did donate to the ALS (Amyotrophic Lateral Sclerosis) Association. It wasn't much, but it was a good cause, even if my reasons for doing so were partially irrational. On one hand, I thought, I'll enhance a small donation a bit because an offer to match was available [rational], but I am not doing so with due diligence, based on information about the disease or the charity [irrational], though I did head to Charity Navigator afterward to check them out, and I did already know about ALS. Furthermore, I fully anticipated being nominated for the Ice Bucket Challenge eventually, so somewhere deep down in my icky stuff I probably thought, hey, this insulates me from the inevitable inner conflict when I am finally implicated. Someone would get around to it, surely, and lo and behold, someone did—a close friend of mine, who also happened to make a pretty hilarious video out of his own Challenge. (He actually anticipated my discomfort, and cited it in his video as the reason for my nomination. I have some respect for this sort of trolling.)

But there is something that doesn't smell right. If it were simply the contrarian impulses that sit in my bowels, I'd be inclined to let the matter go without much more thought. On one hand, I do resent that a person can so easily be made to look like a heartless bastard, simply by not participating in a popular trend or meme, for charity or otherwise. In addition, I don't think we can ignore the oddity of wasting so much water—a back-of-the-envelope calculation by a Washington Post blogger estimates that 5 million gallons have been dumped—or the fact that by pouring ice water over your head you purportedly signal that you'd actually rather give less than the $100 "penalty" assessed in the event of refusal. Granted, many or most people just do both.

Besides the social pressure, though, one might also suggest those partaking in the Challenge are doing so out of sound self-interested decision-making: a person can mitigate both their financial and social losses.

More on that later.

You can, of course, donate whatever the hell you want, whether you decide to freeze your ass off or not. Explicitly calling on others by name to do so, however, puts undue pressure on that person for a number of reasons, not the least of which is that you have no clue what their financial situation might be.

Addressing practical considerations, Vox has an excellent piece about why donating to charity based on viral memes isn't a great idea—namely, because that sort of donation leads to inefficient allocation of resources—and I highly recommend you read this one to get an idea of the health burdens created by various diseases in comparison to ALS. The ALS Association is now going to have to figure out now how to use the unprecedented influx of cash, more than $20 million as of this writing, and I sincerely hope it is allocated well in order to support new and exciting research efforts. I really do. The fact that ALS affects such a small number of people, it should be stressed, does not make studying it worthless, nor should we fail to recognize those who have it. They deserve the hope and awareness that this Challenge, in its best iterations, provides. Neither is it heartless, though, to take utilitarian concerns into consideration, as I've seen suggested among acquaintances. Millions of people die every year from malaria, heart disease, lack of access to sanitary water, and a host of other causes. Something tells me Ice Bucketers won't be infusing charities that address those problems with loads of cash, despite the fact that the life-per-dollar ratio is undoubtedly much higher. This, from the Vox article's quoting of William MacAskill, illustrates the reasoning [emphasis mine]:

If you're concerned about the latter [maximizing impact], he suggested giving to diseases that impact the developing world. As a rule, he explained, "donating money to the best developing world health charities will reach at least 100 times as many people than if you donate to developed world health causes." For example, consider the potential public-health impact of your dollars spent, using a measure of disease burden like the quality-adjusted life year. With ALS, he said that $56,000 would provide one quality-adjusted life to a sufferer. On the other hand, he said, "the same amount of money could provide 500 quality-adjusted life years if you give money to bed nets for malaria."

"People can get upset when you say some causes are more effective than others. That's not true, because it's as tragic for someone to die of ALS as it is for someone to die of malaria. But wanting to respect and honor a particular tragedy is different from trying to help as many people as you can."

Also, while most Challenge videos do cite the reason for the stunt, some do not. In case your feeds have been replete with less-than-explicit explanations for why this challenge is going on (ignoring its real roots), please at least read the following passage entitled "What is ALS?" from the ALS Association's website:

Amyotrophic lateral sclerosis (ALS), often referred to as "Lou Gehrig's Disease," is a progressive neurodegenerative disease that affects nerve cells in the brain and the spinal cord. Motor neurons reach from the brain to the spinal cord and from the spinal cord to the muscles throughout the body. The progressive degeneration of the motor neurons in ALS eventually leads to their death. When the motor neurons die, the ability of the brain to initiate and control muscle movement is lost. With voluntary muscle action progressively affected, patients in the later stages of the disease may become totally paralyzed.

A-myo-trophic comes from the Greek language. "A" means no or negative. "Myo" refers to muscle, and "Trophic" means nourishment–"No muscle nourishment." When a muscle has no nourishment, it "atrophies" or wastes away. "Lateral" identifies the areas in a person's spinal cord where portions of the nerve cells that signal and control the muscles are located. As this area degenerates it leads to scarring or hardening ("sclerosis") in the region.

As motor neurons degenerate, they can no longer send impulses to the muscle fibers that normally result in muscle movement. Early symptoms of ALS often include increasing muscle weakness, especially involving the arms and legs, speech, swallowing or breathing. When muscles no longer receive the messages from the motor neurons that they require to function, the muscles begin to atrophy (become smaller). Limbs begin to look "thinner" as muscle tissue atrophies.

If you want a really thoughtful post about the social game involved, look no further than the Google+ post below. Before you read it, though, let me stress once again that donating to support ALS research or work on other rare diseases is important. I am certainly not trying to discourage people from giving generously to causes they feel strongly about. More people should give to charity more often, myself included.


ALS is a horrible illness that I cannot myself fathom going through. I feel for those who have it, and I do sincerely hope that these dollars, however wrought, will succeed in pushing ALS research forward. In the meantime, I will also suggest that you donate to a charity I support because of the fantastic work they do across the world in bringing basic medical services to dangerous and poverty-stricken parts of the world: Medecins Sans Frontieres / Doctors Without Borders.


Support Doctors Without Borders

All of the inevitable points and counterpoints have been bandied about, I know. Such are the social media cycles that revolve around hot topics, so if you made it to the end of this one, I thank you.