December 1, 2015
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Antibiotic Resistance (cont.)


Antibacterial is the term given to substances that kill or slow the growth of bacteria when treating human and environmental surfaces. These include substances that aid in proper hygiene.

Examples of antibacterial-containing commercial products are:

  • Hand soaps, gels, foams
  • Dishwashing detergents
  • Mattresses


Examples of antimicrobial (drug) resistance:

  • Methicillin-Resistant Staphylococcus aureus (MRSA)
  • Vancomycin-Resistant Enterococci (VRE)

What is drug resistance?

Antimicrobial resistance is the ability of microbes, such as bacteria, viruses, parasites, or fungi, to grow in the presence of a chemical (drug) that would normally kill it or limit its growth.

Picture of antibiotic resistant loop

Diagram showing the difference between non-resistant bacteria and drug resistant bacteria. Non-resistant bacteria multiply, and upon drug treatment, the bacteria die. Drug resistant bacteria multiply as well, but upon drug treatment, the bacteria continue to spread.
Credit NIAD

The History of Antimicrobial (Drug) Resistance


Microbes are living organisms that reproduce, thrive, and spread quickly and efficiently. Microbes include bacteria (e.g., Staphylococcus aureus, which causes some staph infections), viruses (e.g., influenza, which causes the flu), fungi (e.g., Candida albicans, which causes some yeast infections), and parasites (e.g., Plasmodium falciparum, which causes malaria).

Antimicrobial is a general term given to medicines that kill or slow the growth of microbes.

Antimicrobial drug resistance is the ability of a microbe to grow in the presence of a substance that would normally kill it or limit its growth.


In 1928 while working with Staphylococcus bacteria, Scottish scientist Alexander Fleming noticed that a type of mold growing by accident on a laboratory plate was protected from, and even repelled, the bacteria. The active substance, which Fleming called penicillin, was literally an antibiotic-it killed living organisms.

Thus began the age of using natural and, later, synthetic drugs to treat people with bacterial infections. Though not widely popular until the 1940s, antibiotics and other antimicrobials have saved countless lives and blunted serious complications of many feared diseases and infections. The success of antimicrobials against disease-causing microbes is among modern medicine's great achievements.

The Problem

After more than 70 years of widespread use, evolution of disease-causing microbes also has resulted in many antimicrobials losing their effectiveness.

As microbes evolve, they adapt to their environments. If something stops them from growing and spreading-such as an antimicrobial-they evolve new mechanisms to resist the antimicrobials by changing their genetic structure. Changing the genetic structure ensures that the offspring of the resistant microbes also are resistant.

Antimicrobial resistance makes it harder to eliminate infections from the body. As a result of a microbe's ability to survive in the presence of antimicrobials, some infectious diseases are now more difficult to treat than they were just a few decades ago. In fact, antimicrobials have helped people so effectively that humans are hurting the protective value of medicines through overuse and misuse.

More prudent use of antimicrobials will help to slow the development of resistance.


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