What is antibiotic sensitivity?

Antibiotic sensitivity is the level of susceptibility that a bacterium has to a particular type of antibiotic. Antibiotics work in different ways on bacterial cells, and many bacteria are more susceptible to certain antibiotics than others. By using laboratory tests to determine antibiotic sensitivity, a doctor can find the most appropriate antibiotic to treat a patient and reduce the development of antibiotic resistance in a strain of bacteria by using only one type of antibiotic in treatment, instead of several different drugs

To perform this test, a sample is taken from a patient and then cultured to grow the bacteria in the laboratory. An agar plate is prepared with small tablets of various antibiotics, or strips impregnated with varying concentrations of antibiotics, and the cultured bacteria are placed on the plate. If the bacteria are susceptible, small rings will appear around the antibiotic samples, indicating that the bacteria cannot grow there. Often the bacteria will have trouble growing around multiple samples, allowing the doctor a variety of treatment options.

When a patient needs to be treated immediately, antibiotics are often given before an antibiotic susceptibility test is done, as it can be critical to start fighting bacteria. The test will determine whether or not those medications are appropriate, and the patient's treatment may be changed in response to the test results. For common or routine infections, clinicians may choose to skip the susceptibility testing phase, assuming a standard treatment is effective.

It can be expensive to perform antibiotic susceptibility testing and to obtain antibiotics that turn out to be suitable for use in the tests. For this reason, the test is usually only used when clearly needed. Testing in the laboratory is generally preferable to trying different courses of antibiotics on the patient, for a number of reasons, including concerns about finding the most effective treatment, avoiding the development of antibiotic resistance, and keeping treatment costs affordable for patients. the patient or the medical clinic.

Some bacteria are infamous for developing resistance to antibiotics or being very difficult to treat. In cases where patients are infected with these bacteria, a doctor often recommends testing for antibiotic sensitivity to ensure proper treatment is provided. The tests can also be used to learn more about a specific infection and to collect data on emerging outbreaks that can reveal the ways the bacteria spreads.

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