WE ARE RUNNING OUT OF ANTIBIOTICS.

To be fair, plenty of antibiotics still exist-–it’s just that they are no longer effective against bacterial infections.  

Why? Due to the overuse (and misuse) of antibiotics, many bacteria have become resistant to all available antibiotics. The Center for Disease Control (CDC) considers antibiotic-resistant bacteria “a global threat” and “one of the biggest public health challenges of our time”.  According to the CDC, at least 2 million people in the U.S. become infected with antibiotic-resistant bacteria each year, resulting in at least 23,000 deaths.  How did this happen? What can we do?

What are Antibiotics and How Do They Work?

Prior to the discovery of antibiotics and the advent of the antibiotic age, it was not uncommon for people to die from diseases caused by bacteria.  People died from strep throat, scarlet fever, pneumonia, wound infections, tetanus, gangrene, bacterial meningitis, tuberculosis, whooping cough…you get the picture. That all changed with the accidental discovery of penicillin.

A picture of the original culture plate on which Fleming first observed the growth of Penicillin notatum and its inhibition of nearby bacterial growth.  Image from HistoryChannel.com 
A picture of the original culture plate on which Fleming first observed the growth of Penicillin notatum and its inhibition of nearby bacterial growth.  Image from HistoryChannel.com

In 1928, Alexander Fleming left for vacation without tidying up his lab space.   When he returned two weeks later, he noticed that some of the petri dishes on which he had been growing bacteria had become contaminated by mold.  To his amazement, the area surrounding the mold was free of bacterial growth—as if the mold had produced something that inhibited bacteria from growing.  Fleming had accidentally discovered the first naturally-occurring antibiotic: penicillin. Mass production of penicillin went into effect to meet the needs of injured soldiers in World War II and saved many lives from the once-fatal infections.

During World War II, penicillin was used to combat infections in soldiers
During World War II, penicillin was used to combat infections in soldiers.

Since Fleming’s discovery, many other antibiotics have been discovered—both naturally-occurring and those which have been synthesized in the lab. Not all antibiotics work alike. Different classes of antibiotics target different aspects of bacterial growth. Some antibiotics target the synthesis of bacterial cell walls, causing bacterial cells to lyse. Other antibiotics specifically disable the ribosomes found only in bacteria. Still others prevent bacterial DNA replication, transcription, or metabolite synthesis. The great thing about antibiotics is that they only target components of bacterial cells; they don’t harm our cells at all.  

The following table summarizes how different classes of antibiotics work to kill or disable bacteria.

Classes of antibiotics, examples from each class, and the mechanism of action by which each class targets bacterial infections.
Classes of antibiotics, examples from each class, and the mechanism of action by which each class targets bacterial infections.

The following video summarizes the different ways that antibiotics work against bacterial infections.

Antibiotic Resistance

How did bacteria become resistant to antibiotics? Ultimately, all antibiotic resistance is due to genetic changes in the bacteria. Mutations in bacterial DNA lead to changes in the targets of the antibiotics, rendering the bacteria impervious to the action of the drugs.   DNA mutations in bacteria are not uncommon and happen randomly. However, the increased use of antibiotics give bacteria containing mutations leading to antibiotic resistance a selective advantage. These antibiotic resistant bacteria can easily grow and thrive, even in the presence of the drug.

Antibiotic resistance occurs following random mutations in bacterial DNA.  Bacteria containing these mutations will have a selective advantage when exposed to antibiotic treatment.
Antibiotic resistance occurs following random mutations in bacterial DNA. Bacteria containing these mutations will have a selective advantage when exposed to antibiotic treatment.

Perhaps the most frightening aspect of antibiotic resistance is how easily it is spread from one type of bacteria to another. When bacteria grow and divide, several mechanisms exist through which genetic information can be exchanged between bacteria. This transfer of genetic information, called horizontal transfer, can quickly allow the genes for antibiotic resistance to spread from one bacterium to another. Some of these mechanisms even allow the exchange of genetic information between bacteria of completely unrelated species. Therefore, antibiotic resistance can quickly spread from one bacterial species to another, especially within environments where multiple species of bacteria can be found (such as hospitals).

This infographic shows the many ways antibiotic resistance can occur and spread.
This infographic shows the many ways antibiotic resistance can occur and spread.
Infographic from the CDC Threat Report 2013, Antibiotic resistance threats in the United States, 2013

Humans contain an incredible number of bacteria at any given time, collectively termed our microbiome. These microbes live in symbiosis with us, and changes to our microbiome have been shown to have negative effects on our health. The bacteria of our microbiome help us in many ways, including preventing colonization by pathogenic organisms, aiding in the digestion of our food, and producing vitamins and other factors.  Each time we take a course of antibiotics, the bacteria of our microbiome are adversely affected too. This is one more reason to limit the use of antibiotics.

What Can be Done?

While the problem of emerging antibiotic-resistant superbugs is a serious one, we still have time to make a difference. Here are some steps you can take right now to prevent the further spread of antibiotic resistance.

  • Avoid using antibacterial soaps.  Studies have demonstrated that proper handwashing with regular soap and water is just as effective as using antibacterial soaps and won’t contribute to the increase of antibiotic resistant strains of bacteria.  
  • When possible, avoid buying or eating animal products which have been fed antibiotics.  In 2013, the Food and Drug Association (FDA) reported that 81 percent of ground turkey, 69 percent of pork chops, 55 percent of ground beef, and 39 percent of chicken sampled in grocery stores were contaminated with drug-resistant strains of bacteria.
  • Only take antibiotics when necessary and only those prescribed to you by a doctor for your specific infection.  Not all antibiotics are alike, and not all can kill the bacteria responsible for each infection. But EVERY time you take a course of antibiotics, you increase the risk of selecting for the growth of resistant bacteria.
  • Antibiotics are not “cure-alls” and won’t help you recover from viral infections. Many ailments, such as the cold, flu, and sore throats are viral in origin. (In fact, did you know that between 70-95% of all sore throats are caused by viruses?) Why are antibiotics ineffective for viral infections? Remember that antibiotics work by targeting cell components found only in bacteria.  Scientifically-speaking, viruses are not alive. Viruses can only replicate and cause disease by infecting host cells—our cells.  Since both viruses and our cells lack the specific components that antibiotics target, viruses are impervious to the action of these drugs.
  • If antibiotics are necessary, request the shortest dose course as possible.  This limits the amount of time bacteria in your body are exposed to selective pressure that increases development of antibiotic resistance


Some of you might be thinking, “So, what’s the big deal? Drug companies can just come up with new antibiotics.” Unfortunately, it’s not that simple. Not only are new antibiotics needed, but so are new ways of targeting resistant bacteria. Many of the genetic mutations that drug-resistant bacteria have acquired make them much harder to kill. Antibiotics with novel mechanisms of action must be developed, and that takes time. It typically takes years for new antibiotics to go from the research lab to the pharmacy shelves. So the best course of action is to develop better practices as consumers and patients and to do our part to limit the spread of antibiotic resistance.

Further Information

Pre-Antibiotic Era Looming Large – The World is Almost out of Time

Infection in a Pre-Antibiotic Era

10 Most Dangerous Antibiotic-Resistant Bacteria

Content in this post was taken from the course Microbiology, available here. In it, students learn about the different types of microscopic life: viruses, prokaryotes, fungi, algae, and protozoa. The benefits of these microorganisms as well as the diseases they cause will be examined. Students will also learn how the Germ Theory of Disease came to be accepted, how infectious diseases spread, and how our immune system functions to protect us from disease. Videos, labs, and other hands-on activities are included. This course can be used alone or in conjunction with any science course your student may be taking.

WE ARE RUNNING OUT OF ANTIBIOTICS. To be fair, plenty of antibiotics still exist-–it’s just that they are no longer effective against bacterial infections. What are Antibiotics and How Do They Work? How did bacteria become resistant to antibiotics? What Can be Done? #superbugs #antibioticresistance

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