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An antibiogram is a microbiological test that is performed prior to treatment with an antibiotic. Antibiogram allows you to determine what is the right antibiotic, the so-called targeted therapy, in the treatment of a particular strain of bacteria that is responsible for the clinical problem. This is particularly important due to the emergence of bacterial strains resistant to a given antibiotic – then you need to apply a therapy with a different specificity, suitable for combating a specific type of microorganisms.
Indications for performing an antibiogram
Antibiogram it is usually performed in the case of severe or repeated bacterial infections. Primary indication is to find out what specific strains of bacteria have attacked the body and to determine whether they are resistant to treatment with a given antibiotic. If it turns out that the bacteria have developed resistance to a given drug, another, effective antibiotic is selected. It is definitely more beneficial for the patient to use targeted therapy to destroy a specific strain of bacteria than to use more antibiotics, in the hope that one of them will help. Such action weakens the patient’s immune system and makes the therapy, instead of having beneficial effects, additionally harmful. Antibiogram It is also performed when it is known that a strain that is not very sensitive to antibiotics is responsible for the bacterial infection – then the test will help to choose the optimal drug in a given situation.
What does an antibiogram take?
Antibiogram is performed on the basis of a urine or blood sample. In the case of a bacterial infection of the mouth, you can do it antibiogram download oral swab patient.
In order to comply antibiogram a sample taken from the patient is placed on a special bacteriological medium, that is, it is inoculated on a nutrient medium. A dozen or so hours after the inoculation, bacteria grow on the medium, if they were present in the patient’s sample. On the basis of the culture, it is possible to determine which specific bacterial strain we are dealing with.
Then, the laboratory tests the reaction of bacteria grown on the medium to a given antibiotic. For this purpose, cotton discs impregnated with different antibiotics (each on a separate plate) are placed on the substrate. After approximately 24 hours, it can be determined which antibiotic is most effective in limiting the growth of the bacteria of a given strain. This allows the appropriate selection of the antibiotic to the type of bacteria that caused the infection, which increases the effectiveness of treatment and speeds up the pace of therapy.
How to prepare for an antibiogram?
Antibiogram requires reporting for blood donation on an empty stomach. If you are taking a throat swab, you should refrain from using topical medications for a few days before the test, as they may change the test result.
Interpretation of the results of the antibiogram
Results antibiogram are most often developed and annotated by a computer system – antibiogram in most cases it is done automatically. Special automatic devices apply the bacterial sample to plates containing different types of antibiotics or one type of antibiotic at different concentrations, and then automatically interpret the results. If study was carried out using the disc method (the diameter of the circle of inhibition of bacterial growth on the plate with the use of a given antibiotic is examined), it allows to determine whether the bacterial strain is sensitive, medium-sensitive or resistant to antibiotic therapy.
In the case of susceptible strains it is recommended to administer the antibiotic in a standard dose.
In the case of medium-sensitive strains the dose of the antibiotic should be increased.
Resistant strains they do not respond to treatment with known antibiotics, regardless of the dose – their administration could only further weaken the patient’s body.
How effective is the antibiogram?
Performing an antibiogram it is not always XNUMX% certain which type of antibiotic should be used to control the bacterial strain responsible for a given infection. Interpreting the results is especially difficult antibiogram based on a throat swab. Bacteria in the mouth are sensitive to skin care products (mouthwashes) and topical medications (sprays, lozenges), so it is sometimes difficult to cultivate them from culture. In this case, the culture may be sterile (bacteria will not appear on the medium), although the infection in the oral cavity continues.