About Antibiotic Resistance
Frequently Asked Questions
What is antimicrobial resistance?
Antimicrobial resistance is one of our most serious health threats. Infections from resistant bacteria are now too common, and some pathogens have even become resistant to multiple types or classes of antibiotics (antimicrobials used to treat bacterial infections). Antibiotic-resistant infections can also come from the food we eat.
The germs that contaminate food can be resistant because of the use of antibiotics in people and in food animals. We can prevent many of these infections by:
- Using antibiotics carefully,
- Keeping Salmonella and other bacteria out of the food we eat, and
- Following food safety guidelines.
What is an antibiotic?
An antibiotic is a type of drug that kills or stops the growth of bacteria. Examples include penicillin and ciprofloxacin, and there are many others.
What does "susceptible" mean when it comes to antibiotics?
The term "susceptible" means that the antibiotic can kill the bacteria or stop its growth. For example, when we say that a type of bacteria is susceptible to the antibiotic penicillin, it means that penicillin kills or stops the growth of that bacteria.
Antibiotics in the Home
To learn more about when when to take antibiotics and when not to, visit CDCs Get Smart: Know When Antibiotics Work.
What is antibiotic resistance?
Antibiotic resistance is the ability of bacteria to resist the effects of an antibiotic—that is, the bacteria are not killed, and their growth is not stopped.
Resistant bacteria survive exposure to the antibiotic and continue to multiply in the body, potentially causing more harm and spreading to other animals or people.
Antibiotics and food safety
How do resistant bacteria in food animals end up in our food?
All animals carry bacteria in their intestines. Giving antibiotics to animals will kill most bacteria, but resistant bacteria can survive and multiply.
- When food animals are slaughtered and processed, these bacteria can contaminate the meat or other animal products.
- These bacteria can also get into the environment when an animal poops and may spread to produce that is irrigated with contaminated water.
Food can get contaminated whether the bacteria are resistant to antibiotics or not.
How do people get infections with resistant bacteria from animals?
People can get exposed to resistant bacteria from animals when they:
- Handle or eat meat or produce contaminated with resistant bacteria; or
- Come into contact with the animals’ poop (either directly or when it’s on a surface).
What effects do resistant infections have on people?
Some resistant infections cause severe illness.
People with these infections:
Antibiotic Use and Healthcare
Did you know nearly 50% of antibiotic use in hospitals is unnecessary or inappropriate?
Visit CDC’s Get Smart for Healthcare website to learn how improving antibiotic use in hospitals can reduce rates of infection and antibiotic resistance, as well as individual patient outcomes, all while saving hundreds of thousands of dollars in healthcare costs.
- May require increased recovery time;
- Tend to incur increased medical expenses; and/or
- May die from infection.
What are some other consequences of antibiotic resistance?
Sometimes the bacteria that cause infections are resistant to the drug of choice and this drug doesn’t work. Physicians must then recommend second- or third-choice drugs for treatment, but these drugs might be less effective, more toxic, and more expensive. Preserving the effectiveness of antibiotics is vital to protecting human and animal health.
Antibiotics and food-producing animals
Is antibiotic resistance in food animals an important problem for human health?
Yes, antibiotic resistance is an important problem for human health. Antibiotic use in any setting may lead to development of resistance. There is strong evidence that some antibiotic resistance in bacteria is caused by antibiotic use in food animals.
What causes antibiotic resistance in food animals?
Any use of antibiotics can lead to resistance. However, when animals are given antibiotics for growth promotion or increased feed efficiency, bacteria are exposed to low doses of these drugs over a long period of time. This long-term, low-level exposure to antibiotics may lead to the survival and growth of resistant bacteria.
- Antibiotics used in high concentrations for a short time for treating infections in individual animals is less risky.
- Resistant bacteria can pass on resistance to their offspring and can also pass some resistance traits to other kinds of bacteria.
What uses are antibiotics approved for in food animals?
In food animals, FDA has approved the use of antibiotics for:
- Disease treatment for animals that are sick;
- Disease control for a group of animals when some of the animals are sick;
- Disease prevention for a group of healthy animals that are at risk of becoming sick; and
- Growth promotion or increased feed efficiency in a herd or flock of animals to promote weight gain.
How commonly are antibiotics used in food animals?
Antibiotics are used quite commonly in food animals. This use may contribute to the development of antibiotic-resistant bacteria. However, there is currently no system to track the precise amount of antibiotics used in food animals in the United States.
How do we know that antibiotic use in food animals is linked to resistant infections in humans?
Scientists around the world have provided strong evidence that antibiotic use in food animals can lead to resistant infections in humans. Studies have shown that:
- Antibiotic use in food animals allows antibiotic-resistant bacteria to thrive while susceptible bacteria die;
- Resistant bacteria can be transmitted from food animals to humans through contaminated food;
- Resistant bacteria in food can cause infections in humans; and
- Infections with resistant bacteria can cause illnesses that are more severe and more likely to result in death as well as higher health care costs.
Can we stop using antibiotics in food animals?
No, we cannot stop all antibiotic use in food animals. Antibiotics are valuable tools for reducing animal disease and suffering. But decisions about what antibiotics to use and how to use them must be made with consideration of their potential impact on human health.
Tracking, reporting, and preventing resistant infections
The federal government established the National Antimicrobial Resistance Monitoring System for Enteric Bacteria (NARMS) in 1996 as a national public health surveillance system.
It tracks antibiotic resistance among bacteria from three sources:
NARMS is a result of a partnership between CDC, FDA, USDA, and state and local public health departments.
What is CDC doing to prevent foodborne infections caused by antibiotic-resistant bacteria?
Preventing foodborne and other enteric (intestinal) infections reduces both antibiotic-susceptible and antibiotic-resistant infections. CDC activities that help prevent these infections include:
- Tracking resistance infections;
- Estimating how many antibiotic-resistant infections occur;
- Collaborating with international partners to monitor resistance and improve detection capacities;
- Studying how resistance emerges and spreads;
Identify Sources of Infection
- Determining the sources of antibiotic-resistant infections that are commonly spread through food;
- Investigating antibiotic-resistant infections to solve outbreaks and improve prevention;
- Developing better tools to rapidly and accurately find sources of food contamination;
Improve Food Safety
- Strengthening the capacity of state and local health departments to detect, respond to, and report antibiotic-resistant infections;
- Educating consumers and food workers about safe food handling and proper hand-washing practices;
- Identifying groups at high risk for infection and educating them about how to reduce their risk; and
- Promoting the judicious use of antibiotics in animals as well as humans.
Why is it important to use antibiotics judiciously?
Antibiotics must be used judiciously in both humans and animals because both uses contribute to the emergence, persistence, and spread of resistant bacteria.
Visit FDA's Strategy on Antimicrobial Resistance to learn more about their guidance on judicious use of antibiotics in agriculture
How do I decrease my risk of infection with resistant bacteria from foods?
You can decrease your risk of getting a resistant bacterial infection by following some easy recommendations for safe food handling and preparation. These steps can help prevent foodborne illness caused by both resistant and susceptible bacteria in food.
- Follow Foodsafety.gov’s Clean, separate, cook, and chill guidelines.
- Thoroughly cook your meat, poultry, and eggs.
- Prevent cross-contamination from animal products by washing your hands and kitchen surfaces during meal preparation.
- Don’t drink raw milk.
- Wash your hands after contact with poop, animals, or animal environments.
- Review CDC’s Traveler’s Health recommendations when preparing to travel to a foreign country.
Antibiotic Use in Food Animals and Antibiotic Resistance in Humans
- Angulo FJ, Nargund VN, & Chiller TC. Evidence of an Association Between Use of Anti-microbial Agents in Food Animals and Anti-microbial Resistance Among Bacteria Isolated from Humans and the Human Health Consequences of Such Resistance. J. Vet. Med. B Infect. Dis. Vet. Public Health. 2004; 51: 374–379.
- FDA. Evaluating the Safety of Antimicrobial New Animal Drugs with Regard to Their Microbiological Effects on Bacteria of Human Health Concern [PDF - 36 pages]. Guidance for Industry #152. 2003. Retrieved from FDA website (January 15, 2014).
- FDA. The Judicious Use of Medically Important Antimicrobial Drugs in Food-Producing Animals [PDF - 26 pages]. Guidance #209. 2012. Retrieved from FDA website (January 15, 2014):
- WHO. Tackling antibiotic resistance from a food safety perspective in Europe. (2011). Retrieved from World Health Organization website (January 15, 2014).
Mechanisms and Public Health Impact of Antibiotic Resistance
- Glynn MK, Bopp C, Dewitt W, Dabney P, Mokhtar M, Angulo FJl. Emergence of Multi-drug Resistant Salmonella enterica Serotype Typhimurium DT104 Infections in the United States. N Engl J Med. 1998; 338: 1333–1339.
- Nelson JM, Smith KE, Vugia DJ, Rabatsky-Her T, Segler SD, Kassenberg HD, et al. Prolonged Diarrhea Due to Ciprofloxacin-Resistant Campylobacter Infection. J Infect Dis. 2004; 190(6): 1150–1157.
- Sjolund-Karlsson M, Howie RL, Blickenstaff K, Boerlin P, Ball T, Chalmers G, Duval B, Haro J, Rickert R, Zhao S, Fedorka-Cray PJ, Whichard JM. Occurrence of beta-lactamase genes among non-Typhi Salmonella enterica isolated from humans, food animals, and retail meats in the United States and Canada. Microbial drug resistance. 2013;19(3):191-7.
- Varma JK, Greene KD, Ovitt J, Barrett TJ, Medalla F, Angulo FJ. Hospitalization and Antimicrobial Resistance in Salmonella Outbreaks, 1984-2002. Emerg Infect Dis. 2005;11(6): 943–53.
- Varma JK, Mølbak K, Barrett TJ, Beebe JL, Jones TF, Rabatsky-Her T, et al. Antimicrobial-resistant nontyphoidal Salmonella is associated with excess bloodstream infections and hospitalizations. J Infect Dis. 2005;191:554–61.
- Page last reviewed: September 9, 2014
- Page last updated: September 15, 2015
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