Antibiotic resistance

Antimicrobials - resistance; Antimicrobial agents - resistance; Drug-resistant bacteria

Using antibiotics incorrectly can cause some bacteria to change or permit resistant bacteria to grow. These changes make bacteria stronger, so most or all antibiotic medicines no longer work to kill them. This is called antibiotic resistance. Resistant bacteria continue to grow and multiply, making infections harder to treat.

Images

Information

Antibiotics work by killing bacteria or keeping them from growing. Resistant bacteria keep growing, even when antibiotics are used. This problem is seen most often in hospitals and nursing homes.

New antibiotics are created to work against some resistant bacteria. But there are now bacteria that no known antibiotic can kill. Infections with such bacteria are dangerous. Because of this, antibiotic resistance has become a major health concern.

Causes of Antibiotic Resistance

Antibiotic overuse is a major cause of antibiotic resistance. This occurs in both humans and animals. Certain practices increase the risk of resistant bacteria:

Using antibiotics when not needed. Most colds, sore throats, and ear and sinus infections are caused by viruses. Antibiotics don't work against viruses. Many people don't understand this and sometimes ask for antibiotics when they are not helpful or needed. This leads to an overuse of antibiotics. The Centers for Disease Control and Prevention (CDC) estimates that 1 in 3 antibiotic prescriptions are not needed.
Not taking antibiotics as prescribed. This includes not taking all of your antibiotics, missing doses, or using leftover antibiotics. Doing so helps the bacteria learn how to grow in spite of the antibiotic. As a result, the infection may not fully respond to treatment the next time the antibiotic is used.
Misuse of antibiotics. You should never buy antibiotics online without a prescription or take someone else's antibiotics.
Exposure to food sources. Antibiotics are widely used in agriculture. This can lead to resistant bacteria in the food supply.

Why Antibiotic Resistance Is a Concern

Antibiotic resistance causes a number of problems:

The need for stronger antibiotics with possibly severe side effects
Fewer choices of antibiotics to treat antibiotic-resistant bacteria
More expensive treatment
Harder-to-treat illness can spread from person to person
More hospitalizations and longer hospital stays
Serious health problems, and even death

How Antibiotic Resistant Bacteria Spread

Antibiotic resistance can spread from person to person or from animals to humans.

In people, it may spread from:

One patient to other patients or staff in a nursing home, urgent care center, or hospital
Health care staff to other staff or to patients
Patients to other people who come in contact with the patient

Antibiotic-resistant bacteria may spread from animals to humans through:

Food sprayed with water that contains antibiotic-resistant bacteria from animal feces

Help Prevent Antibiotic Resistance

To prevent antibiotic resistance from spreading:

Antibiotics should only be used as directed and when prescribed by your health care provider.
Unused antibiotics should be discarded safely.
Antibiotics should not be prescribed or used for viral infections.

References

Centers for Disease Control and Prevention website. About antimicrobial resistance. www.cdc.gov/antimicrobial-resistance/about/index.html. Updated April 22, 2024. Accessed June 17, 2024.

Centers for Disease Control and Prevention website. Antibiotic prescribing and use. www.cdc.gov/antibiotic-use/data-research/facts-stats/index.html#. Updated April 22, 2024. Accessed June 17, 2024.

Opal SM, Pop-Vicas A. Molecular mechanisms of antibiotic resistance in bacteria. In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 18.

Review Date: 5/23/2024

Reviewed By: Jatin M. Vyas, MD, PhD, Roy and Diana Vagelos Professor in Medicine, Columbia University Vagelos College of Physicians and Surgeons, Division of Infectious Diseases, Department of Medicine, New York, NY. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

Health Content Provider

06/01/2028

A.D.A.M., Inc. is certified by URAC, for Health Content Provider (www.urac.org). URAC's certification program is an independent audit to verify that A.D.A.M. follows rigorous standards of quality and accountability. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial policy, editorial process and privacy policy.

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. No warranty of any kind, either expressed or implied, is made as to the accuracy, reliability, timeliness, or correctness of any translations made by a third-party service of the information provided herein into any other language.

© 1997- 2026 A.D.A.M., a business unit of Ebix, Inc. Any duplication or distribution of the information contained herein is strictly prohibited.

All content on this site including text, images, graphics, audio, video, data, metadata, and compilations is protected by copyright and other intellectual property laws. You may view the content for personal, noncommercial use. Any other use requires prior written consent from Ebix. You may not copy, reproduce, distribute, transmit, display, publish, reverse-engineer, adapt, modify, store beyond ordinary browser caching, index, mine, scrape, or create derivative works from this content. You may not use automated tools to access or extract content, including to create embeddings, vectors, datasets, or indexes for retrieval systems. Use of any content for training, fine-tuning, calibrating, testing, evaluating, or improving AI systems of any kind is prohibited without express written consent. This includes large language models, machine learning models, neural networks, generative systems, retrieval-augmented systems, and any software that ingests content to produce outputs. Any unauthorized use of the content including AI-related use is a violation of our rights and may result in legal action, damages, and statutory penalties to the fullest extent permitted by law. Ebix reserves the right to enforce its rights through legal, technological, and contractual measures.