Why Some Infections Are Getting Harder to Treat

These four common—and dangerous—bacteria are becoming resistant to antibiotics. How does this affect you?

Why Some Infections Are Getting Harder to Treat

Penicillin ushered in the antibiotic era when it was discovered in 1928. Now, many experts are worried that we may be entering a post-antibiotic era, where bacteria become immune to drugs and standard treatments no longer work.

Though it’s not a reality yet, in years to come minor injuries and small cuts could turn deadly, and many forms of surgery might become extremely risky to safely perform. The World Health Organization (WHO), in its 2014 Antimicrobial Resistance: Global Report on Surveillance, called the post-antibiotic era “a very real possibility for the 21st century.”

What is antibiotic resistance and how does it happen? What bacteria have stopped responding to drugs? And what’s being done to address the problem? We got answers from infectious disease specialist Seema Shah, MD, of Texas Orthopedic Hospital in Houston.

What causes resistance?
Antibiotic resistance happens when bacteria change and antibiotics can’t kill them anymore. “Every type of bacteria has its own genome,” or set of genes and DNA, says Dr. Shah. “Mutations can occur in one bacterium that make it resistant to a type of antibiotics. Those start to multiply even if you’re taking antibiotics because they’re not affected. And, they can transfer that resistance to other bacteria.” In other words, overuse of antibiotics kills the bacteria that are not resistant, leaving only the types that are.

In 2014, healthcare providers in the US wrote 266 million outpatient antibiotic prescriptions, more than enough for every American over age 18. The Centers for Disease Control and Prevention (CDC) estimates that at least 30 percent of antibiotic prescriptions are unnecessary.

But that’s a pretty small chunk compared to the amount of antibiotics used for livestock. About 80 percent of antibiotics sold in the US are used for animals. Bacteria in farm animals stop responding to the treatments, then humans eat the farm animals and pick up the resistant bacteria.

What bacteria are fighting off antibiotics?
The CDC estimates that more than 2 million people per year get sick and 23,000 die in the US from resistant infections. Here are some antibiotic-resistant bacteria that are becoming more common—or more worrisome.

Staphylococcus aureus, commonly known as staph, lives on the skin and especially in the noses of many healthy people, says Shah. Staph infections are usually minor, but can be life-threatening if the bacteria enters your bloodstream, joints, bones or vital organs. One type, methicillin-resistant Staphylococcus aureus, known as MRSA, is resistant to a number of common antibiotics, is particularly hard to get rid of and can lead to sepsis or toxic shock syndrome. For now, MRSA can be treated with the antibiotic vancomycin, but Shah says it’s taking more and more to knock out infections.

Enterobacteriaceae includes E. coli—a cause of food poisoning, as well as urinary tract and deadly bloodstream infections—and Klebsiella pneumoniae, which can lead to pneumonia, meningitis and blood infections. Even the last-resort antibiotic carbapenem doesn’t work on some of these bacteria. Carbapenem-resistant Enterobacteriaceae top the WHO’s list of bacteria for which a new treatment is most desperately needed.

Gonorrhea—certain strains, at least—has become resistant to all but one class of antibiotics. “I don’t think it’s fair to say that resistant gonorrhea is common, but it’s becoming more and more of a problem in the last few years,” Shah says. The CDC has changed its treatment recommendations three times between 2010 and 2015 to account for increased resistance to a number of drugs.

Vancomycin-resistant Enterococci (VRE) has been troubling healthcare providers for years, according to Shah. Enterococci infections often strike people who have already been hospitalized, and are responsible for about 66,000 hospital-acquired infections in the US per year. Of those, about 20,000 are antibiotic-resistant, which cause about 1,300 deaths.

What’s being done?
The WHO’s Essential Medicines List got its biggest update in 40 years in June 2017, dividing antibiotics into three classes. Organizing the drugs into these categories aims to reduce overuse of last-resort antibiotics and lower the number of bacteria that become resistant to them.

  • The “access” group consists of the most commonly used antibiotics, such as amoxicillin and azithromycin. They’re used to treat a wide variety of illnesses and should be available at all times.
  • The “watch” group includes first- or second-line treatments for a smaller number of infections.
  • The “reserve” group consists of last-resort treatments for when other antibiotics have failed to work.

The CDC has a similar effort with its hospital-based antibiotic stewardship programs.

Developing strategies to fight antibiotic resistance is slow work, and in fact there hasn’t been a discovery of a new class of antibiotics since 1987. “There’s not a lot of incentive for drug companies to make these new antibiotics,” says Shah. Drug companies aren’t investing in the research since there’s little chance to make money. Meanwhile, the problem continues to grow.

Medically reviewed in January 2019.

More On

C. Diff: Can You Get Infected at Your Doctor’s Office?


C. Diff: Can You Get Infected at Your Doctor’s Office?
A recent study from the Centers for Disease Control and Prevention (CDC) revealed that Clostridium difficile, or C. diff—once mainly found in hospital...
Have Antibiotics Reached Their Expiration Date?


Have Antibiotics Reached Their Expiration Date?
In many ways, antibiotics have been one of the great success stories of modern medicine. Numerous illnesses that would have led to death hundreds of y...