Why do antibiotics become resistant

An illustration showing how a population of bacteria can develop resistance to an antibiotic. Infectious diseases are caused by microorganisms such as viruses, bacteria, fungi or parasites and can spread between individuals. Staphylococcal infections are a group of infections caused by the bacterium Staphylococcus. Infection causes a range of symptoms, from skin conditions to food poisoning.

Streptococcal infections are any type of infection caused by the group of bacteria Streptococcus. Salmonella are a group of bacteria that cause a wide spectrum of diseases. They are able to cause significant morbidity, and in some case, mortality, in both humans and animals. Tuberculosis is a disease caused by a bacterium that mainly affects the lungs to cause a persistent and, occasionally bloody, cough.

This animation shows how bacteria exchange genes on small pieces of DNA called plasmids through a process called horizontal gene transfer. If you have any other comments or suggestions, please let us know at comment yourgenome. Can you spare minutes to tell us what you think of this website? Open survey. Antibiotic resistance happens when germs like bacteria and fungi develop the ability to defeat the drugs designed to kill them. That means the germs are not killed and continue to grow. Infections caused by antibiotic-resistant germs are difficult, and sometimes impossible, to treat.

In most cases, antibiotic-resistant infections require extended hospital stays, additional follow-up doctor visits, and costly and toxic alternatives. Antibiotic resistance does not mean the body is becoming resistant to antibiotics; it is that bacteria have become resistant to the antibiotics designed to kill them. Each year in the U. No one can completely avoid the risk of resistant infections, but some people are at greater risk than others for example, people with chronic illnesses.

Antibiotic resistant bacteria. Actions for this page Listen Print. Summary Read the full fact sheet. On this page. Bacteria resistant to antibiotics Ways to prevent antibiotic resistance Transmission of antibiotic resistant bacteria in hospitals Infection control in hospitals Additional precautions with antibiotic resistant bacteria Transmission of antibiotic resistant bacteria in the community Where to get help.

Bacteria resistant to antibiotics Some bacteria have developed resistance to antibiotics that were once commonly used to treat them. Important examples are: methicillin-resistant Staphylococcus aureus MRSA vancomycin-resistant Enterococcus VRE multi-drug-resistant Mycobacterium tuberculosis MDR-TB carbapenem-resistant Enterobacteriaceae CRE gut bacteria Ways to prevent antibiotic resistance The most important ways to prevent antibiotic resistance are: Minimise unnecessary prescribing and overprescribing of antibiotics.

This occurs when people expect doctors to prescribe antibiotics for a viral illness antibiotics do not work against viruses or when antibiotics are prescribed for conditions that do not require them. Complete the entire course of any prescribed antibiotic so that it can be fully effective and not breed resistance.

Practise good hygiene such as hand-washing and use appropriate infection control procedures. Transmission of antibiotic resistant bacteria in hospitals The common ways in which bacteria can be passed from person to person include: contact with contaminated hands of hospital staff contact with contaminated surfaces such as door handles, over-bed tables and call bells contact with contaminated equipment, such as stethoscopes and blood pressure cuffs.

Infection control in hospitals Standard precautions in hospitals are work practices that provide a basic level of infection control for the care of all people, regardless of their diagnosis or presumed infection status. These precautions should be followed in all hospitals and healthcare facilities and include: good personal hygiene, such as hand washing before and after patient contact and the appropriate use of alcohol-based hand rub solutions the use of barrier equipment such as gloves, gowns, masks and goggles appropriate handling and disposal of sharps for example, needles and clinical waste waste generated during patient care aseptic sterile techniques.

Additional precautions with antibiotic resistant bacteria Additional precautions are used when caring for people who are known or suspected to be infected or colonised with highly infectious pathogens micro-organisms that cause disease. Additional precautions may include: use of a single room with ensuite facilities or a dedicated toilet dedicated care equipment for that person restricted movement of the person and their healthcare workers.

Transmission of antibiotic resistant bacteria in the community Antibiotic resistant bacteria can also be passed from person to person within the community. Ways to prevent transmission of organisms, including antibiotic resistant bacteria, are: Wash hands before and after food handling, going to the toilet and changing nappies.

Cover your nose and mouth when coughing and sneezing. Mutations, rare spontaneous changes of the bacteria's genetic material, are thought to occur in about one in one million to one in ten million cells. Different genetic mutations yield different types of resistance.

Some mutations enable the bacteria to produce potent chemicals enzymes that inactivate antibiotics, while other mutations eliminate the cell target that the antibiotic attacks. Still others close up the entry ports that allow antibiotics into the cell, and others manufacture pumping mechanisms that export the antibiotic back outside so it never reaches its target. Bacteria can acquire antibiotic resistance genes from other bacteria in several ways.

By undergoing a simple mating process called "conjugation," bacteria can transfer genetic material, including genes encoding resistance to antibiotics found on plasmids and transposons from one bacterium to another. Viruses are another mechanism for passing resistance traits between bacteria. The resistance traits from one bacterium are packaged into the head portion of the virus. The virus then injects the resistance traits into any new bacteria it attacks.

Bacteria also have the ability to acquire naked, "free" DNA from their environment. Any bacteria that acquire resistance genes, whether by spontaneous mutation or genetic exchange with other bacteria, have the ability to resist one or more antibiotics. Because bacteria can collect multiple resistance traits over time, they can become resistant to many different families of antibiotics. How does antibiotic resistance spread?

Genetically, antibiotic resistance spreads through bacteria populations both "vertically," when new generations inherit antibiotic resistance genes, and "horizontally," when bacteria share or exchange sections of genetic material with other bacteria. Horizontal gene transfer can even occur between different bacterial species. Environmentally, antibiotic resistance spreads as bacteria themselves move from place to place; bacteria can travel via airplane, water and wind.

People can pass the resistant bacteria to others; for example, by coughing or contact with unwashed hands. Can bacteria lose their antibiotic resistance?