What Are Superbugs, and How Are They Related to Antibiotic Resistance?

The Scottish researcher Alexander Fleming discovered penicillin in 1928. You’ve likely heard of penicillin, as it would go on to become a very common antibiotic. Shortly after his discovery, he issued this warning: Overusing antibiotics could result in them no longer being effective against bacteria. He was talking about antibiotic resistance. 

Antibiotics have saved millions of lives over the decades. But now, bacteria are fighting back more and more. Some strains are becoming “superbugs,” meaning they’re resistant to multiple antibiotics. These superbugs can be dangerous, but there are ways you can help keep them at bay.

What is antibiotic resistance?

When an antibiotic is no longer effective against bacteria it would normally treat, those bacteria are considered “antibiotic-resistant.” Antibiotic-resistant bacteria can be resistant to one specific antibiotic or to multiple antibiotics. The more antibiotics bacteria resist, the more dangerous and difficult they become to treat.

Antibiotic resistance is a big public health problem across the world. In 2024, the Global Research on Antimicrobial Resistance (GRAM) Project published a report on the extent of the problem. It shows that between 1990 and 2021, over 1 million people died each year as a result of antibiotic-resistant bacteria. The research group estimates that deaths from antibiotic resistance will continue to rise over the coming decades.

What causes antibiotic resistance?

When you take an antibiotic to treat an infection, the dose should be high enough, and the prescription course should be long enough, to stop all harmful bacteria. If not, the leftover bacteria can adapt, becoming resistant to the antibiotic and harder to kill. When it comes to bacteria, what doesn’t kill them literally makes them stronger!

Let’s review four ways that bacteria become resistant to antibiotics.

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Building walls 

Some bacteria have outer membranes (or walls) that make it harder for antibiotics to get inside of them. If antibiotics can’t get in, they can’t destroy the bacteria. Over time, species of bacteria that didn’t have these defenses before have developed restrictive walls, or biofilms, to block antibiotics. When this happens, the antibiotics can no longer stop these bacteria from multiplying and causing infections.

Changing their machinery

Some antibiotics work by targeting a bacteria’s internal machinery. By destroying these internal structures, the bacteria can no longer survive or multiply. (Think of it as taking out a car’s engine. The car is intact, but it can’t function.) Over time, some bacteria have been able to change their internal machinery so antibiotics no longer affect them. 

Neutralizing antibiotics

Some bacteria have developed ways to neutralize antibiotics. Similar to how the human immune system develops antibodies to stop infections, bacteria learn to stop invading antibiotics. They can do this by breaking down the antibiotic or by changing its chemical structure. Once this happens, the antibiotic can’t work properly. 

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Pumping out antibiotics

Your body has ways to get rid of toxins. And bacteria have mechanisms called efflux pumps that help remove foreign substances like antibiotics. These efflux pumps are genetically encoded in bacteria and can evolve over time, becoming more and more effective at removing antibiotics.

What is a superbug?

A superbug is a strain of bacteria that has become resistant to multiple antibiotics. These strains may even be resistant to newer antibiotics. When no effective antibiotic treatments are available, superbug infections can pose serious health risks. 

Why are superbugs so dangerous?

Before the discovery of antibiotics, common infections like pneumonia and tuberculosis were leading causes of death in the U.S. Now, imagine the impact if the antibiotics used to treat those infections suddenly stopped working. That’s why superbugs are so concerning. 

Types of superbugs

There’s a growing number of superbugs out there. The World Health Organization (WHO) has published a list of superbugs that urgently need new antibiotics to fight them. Here are four of the most common and dangerous ones. 

1. Methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) is a type of antibiotic-resistant bacteria that usually causes skin infections but can also cause fatal lung infections (pneumonia) and bloodstream infections (sepsis). MRSA is hard to treat because it doesn’t respond to many commonly used antibiotics, like penicillins.

2. Antibiotic-resistant Clostridium difficile

Antibiotic-resistant Clostridium difficile (C. diff) is a dangerous infection that causes severe inflammation, cramping, and diarrhea. Ironically, recent antibiotic use increases your risk of developing C. diff. Almost 30,000 people in the U.S. die of C. diff every year. This statistic is even more concerning since many C. diff infections are resistant to common antibiotics.

3. Antibiotic-resistant gonorrhea

Gonorrhea is one of the most common sexually transmitted infections (STIs) in the U.S. It typically affects teens and people in their early 20s. If untreated, it can cause sterility and miscarriage.

Gonorrhea used to be easily treated with azithromycin (Zithromax) or ceftriaxone (Rocephin). But antibiotic-resistant gonorrhea — sometimes called “super gonorrhea” — has become more common over time. The bacteria has grown resistant to almost every medication used to treat it. 

4. Multidrug-resistant tuberculosis (MDR-TB)

Tuberculosis (TB) is an infection that attacks your lungs and can cause severe coughing, chest pain, fatigue, and weight loss. The WHO declared multidrug-resistant tuberculosis (MDR-TB) a global emergency. It doesn’t respond to isoniazid or rifampin (Rifadin), two of the first-choice antibiotics to treat TB. 

Extensively drug-resistant tuberculosis (XDR-TB) is another type of TB that’s even more resistant to antibiotics. XDR-TB won’t respond to at least four of the core antibiotics used to treat TB.

One of the major concerns with TB is how easily it spreads. The bacteria can be transmitted through the air when someone with TB coughs, sings, sneezes, or speaks. In 2023, 10.8 million people across the world had TB. Part of the problem is that people can carry the bacteria for years without knowing. This is why TB testing is so important.

Can you treat an antibiotic-resistant infection?

Treatment options are limited when it comes to antibiotic-resistant infections. And developing new antibiotics can take decades.

To treat antibiotic-resistant infections, healthcare professionals will try to work around treatment barriers. (Though these workarounds sometimes aren’t effective.) 

Strategies include: 

• Prescribing another antibiotic that’s less effective: A healthcare professional can usually prescribe an alternative to the first-choice antibiotic. But it may not be as effective.

• Prescribing older antibiotics with higher risks of side effects: Sometimes the only option is to use an older antibiotic that the bacteria isn’t resistant to. But these older medications often come with a high risk of side effects — or more severe side effects — compared to newer antibiotics.

• Providing supportive care: In a worst-case scenario, there isn’t an effective alternative antibiotic. Your care team will provide supportive care to try and keep you stable. The hope is that the infection will eventually go away on its own.

There are still treatment options for most infections, even if those options are very limited. But as the battle against superbugs continues, this may not always be the case.

How to prevent antibiotic resistance and superbugs

The fight against superbugs is global. Organizations like the WHO, CDC, and FDA are working together with healthcare professionals and communities to address the issue.

Here are some ways you can help in the effort against superbugs:

• Avoid asking your prescriber for antibiotics if you have a cold or the flu. Colds and the flu are caused by viruses, and antibiotics only work against bacteria.

• Don’t share antibiotics or take leftover antibiotics from past infections. Always confirm with a healthcare professional that your infection is caused by bacteria before taking antibiotics.

• Take the full round of antibiotics, even if you start feeling better. Stopping early could leave room for leftover bacteria to become stronger and more resistant to the antibiotics you’re taking.

• Stay up to date on your vaccines. Getting vaccinated can help protect you from getting infected in the first place. The WHO estimates that improving vaccine use could lower how many antibiotics are used a year by 22%. 

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Written by:

Jennifer Clements, MD, MSEd, NBHWC

Jennifer Clements, MD, MSEd, NBHWC, is a board-certified physician and health coach who is passionate about achieving optimal health through healthy lifestyles. Clements is a diplomate of the American Board of Obesity Medicine and the American Board of Integrative Medicine.

Edited by:

Alex Eastman, PhD, RN

Alex Eastman, PhD, RN, is a California-based registered nurse and staff medical editor at GoodRx, where he focuses on clinical updates and Latino health.

Reviewed by:

Farzon A. Nahvi, MD

Dr. Nahvi is an emergency medicine physician and author of “Code Gray: Death, Life, and Uncertainty in the ER.” He works clinically at Concord Hospital in Concord, New Hampshire, and is a clinical assistant professor of emergency medicine at the Geisel School of Medicine at Dartmouth. Prior to this, he worked as an ER physician and clinical assistant professor of emergency medicine at the Mount Sinai Health System, NYU Langone Health, NYC Health + Hospitals/Bellevue, and the Manhattan VA. He is a graduate of Cornell University and NYU School of Medicine.

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