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.1

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.


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.


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.