Antibiotic Resistance (Drug Resistance, Antimicrobial Resistance)

Antibiotics are medications used to kill or slow the growth of bacteria and some fungi. Antibiotics are not effective in treating infections caused by viruses.

The definition of antibiotic resistance is the adaptive change in bacteria (mutation) that allows them to grow in the presence of a drug (an antibiotic) that would normally slow their growth or kill them. These antibiotic resistant bacteria and fungi become harder to treat, causing increased morbidity.

CDC (Centers for Disease Control and Prevention) statistics show there are approximately 2 million antibiotic resistant infections each year in the United States. According to the WHO (World Health Organization), antibiotic resistant infections can lead to longer hospital stays, higher treatment costs, and more deaths.

• Methicillin-resistant Staphylococcus aureus (MRSA) bacteria: commonly seen in hospitals and healthcare settings (hospital acquired or HA-MRSA), but also in among people in close contact such as athletes (community associated or CA-MRSA).
• Vancomycin-resistant Enterococci (VRE) bacteria are resistant to vancomycin, an antibiotic often used as a last resort
• Certain microbes are becoming increasingly resistant to antibiotics:
  • Food-borne bacteria responsible for food poisoning such as E. coli, Salmonella, and Campylobacter
  • Sexually transmitted bacteria that cause gonorrhea
  • Penicillin-resistant Streptococci that cause pneumonia
  • Tuberculosis
  • Influenza
  • Human Immunodeficiency Virus (HIV)
  • Malaria

Bacteria, viruses are living organisms that can change over time. They reproduce and spread quickly and efficiently, and can adapt to their environments and change in ways to ensure their survival. When confronted with an antibiotic that may hinder their ability to reproduce, genetic changes (mutations) can occur that enable the microbe to survive. This evolution can happen in a number of ways:

• Selective Pressure: In the presence of an antibiotic, microbes that carry resistance genes can survive and replicate.
• Mutation: Most microbes reproduce by dividing every few hours and mutations may occur that can help microbes survive exposure to antibiotics.
• Gene Transfer: Microbes can get genes from each other that make the microbe drug resistant.
• Societal Pressures: The widespread use of antibiotics in different spheres of society, sometimes when they're unnecessary, creates selective pressure that allows resistant organisms to be produced.
  • Inappropriate Use: Inappropriate use of antibiotics can occur, such as when a healthcare provider will prescribe an antibiotic because an insistent patient has demanded it, even without a diagnosis.
  • Inadequate Diagnostics: Sometimes broad-spectrum antibiotics are used even when a specific antibiotic might be better because there is incomplete or imperfect information to diagnose an infection. This contributes to selective pressure.
  • Hospital Use: Critically ill patients are more susceptible to infections and they frequently need antibiotics, but this increased use along with close contact among sick patients creates an environment where antimicrobial-resistant germs can spread easily.
  • Agricultural Use: Adding antibiotics to agricultural feed can promote drug resistance.

Tests may be used to determine which microbe is causing an infection and to which antibiotics the microbe might be resistant (called a “culture and sensitivity”). But often, diagnostic tests can take days to weeks to get results because many of tests require the microbe to grow over a period of time before it can be identified.

Samples may be taken of blood, urine, stool, sputum, tissue, cerebrospinal fluid (CSF), or mucus from the nose, throat, or genitals. Samples may then be stained and examined under a microscope, cultured (allowed to grow), or tested for antibodies, antigens, or genetic material (such as DNA or RNA) from the microorganism to determine the organism responsible for the infection.

In many cases treatment decisions are needed before test results are known and healthcare providers may prescribe broad-spectrum antibiotics when a more specific treatment might be better.

A doctor will decide when to use antibiotics, and what drugs should be used. Antibiotics are used to fight bacterial infections and sometimes, fungal infections. Antibiotics are not intended for use against viral infections. They are ineffective and may contribute to the development antibiotic-resistant bacteria.

If you have a bacterial infection that is resistant to a particular antibiotic, a doctor can prescribe a different, more appropriate, antibiotic that is more effective against that organism.

To prevent antibiotic resistance, follow all instructions from your doctor on taking prescription medications. Complete the entire course of the antibiotics as directed, even if you feel better before you finish them. Never share your medications with others or take medicine prescribed for another person.

The less often you get sick, the less often you might need to take antibiotics. The less often you take antibiotics, the less likely your infections are to develop antibiotic resistance. Maintaining a healthy lifestyle including proper nutrition, regular exercise, and getting adequate sleep can help your immune system stay healthy.

In addition, practice good hygiene such as washing hands frequently to prevent the spread of illness.