The antibiotic, also known as the Antimicrobial Sensitivity Test (ASD), is a test that aims to determine the sensitivity and resistance profile of bacteria and fungi to antibiotics. With the result of the antibiotic, your doctor can indicate which antibiotic is best suited to treat the person’s infection, thus avoiding the use of unnecessary antibiotics that do not fight the infection, as well as preventing the onset of resistance.
The antibiotic is usually done after the identification of microorganisms in large amounts in blood, urine, stool and tissues. Thus, depending on the identified microorganism and sensitivity profile, your doctor may indicate the most appropriate treatment.
- To perform the antibiotic.
- Your doctor will order the collection of biological material such as blood.
- Urine.
- Saliva.
- Snot.
- Stool.
- Or organ cells contaminated with microorganisms.
- These samples are then sent to a microbiology laboratory for analysis and cultivation in a culture medium that promotes the growth of bacteria or fungi.
After growth, the microorganism is isolated and subjected to identification tests to conclude the microorganism responsible for the infection. After isolation, the antibiotic is also performed in order to know the sensitivity and resistance profile of the identified microorganism, which can be done in two ways:
Currently in laboratories, the antibiotic is carried out by equipment that tests resistance and sensitivity. The report published by the team indicates which antibiotics the infectious agent was resistant to and which were effective in controlling the microorganism and at what concentration.
Urinary tract infection is one of the most common infections in women, mainly, and in men. Therefore, it is common for doctors to order in addition to the type 1 urine test, SAA and a uroculture accompanied by an antibiotic. This way, your doctor can check for a change in your urine that indicates kidney problems, through SAA, and the presence of fungi or bacteria in your urinary tract that may indicate infection, by urine culture.
If bacteria are checked for urine, the antibiotic is given so your doctor can know which antibiotic is best for treatment. However, for urinary tract infections, antibiotic treatment is only recommended when the person has symptoms to prevent the development of microbial resistance.
Understand how urine culture is done
The result of the antibiotic can take 3 to 5 days and is obtained by analyzing the effect of antibiotics on the growth of microorganisms. The antibiotic that inhibits microbial growth is indicated to treat the infection, but if there is growth it indicates that the microorganism in question is not sensitive to this antibiotic, i.e. resistant.
The result of the antibiotic should be interpreted by the doctor, who observes the values of the minimum inhibitory concentration, also called WCC or MIC, and/or the diameter of the inhibition halo, according to the test performed. BMI is the minimum concentration of antibiotics capable of inhibiting microbial growth and complies with the Institute of Clinical and Laboratory Standards, CLSI, and may vary depending on the antibiotic to be tested and the identified microorganism.
In the case of the agar spreading antibiotic, where papers containing certain concentrations of antibiotic are placed in the culture medium with the microorganism, after an incubation period of approximately 18 hours, it is possible to perceive the presence or not of inhibition halos. From the size of the diameter of the halos can be checked whether the microorganism is insensitive, sensitive, intermediate or resistant to antibiotics.
The result should also be interpreted on the basis of the CLSI determination, which determines that for the Test of sensitivity of Escherichia coli to ampicillin, for example, the inhibition zone of 13 mm or less indicates that the bacteria is resistant to antibiotics and a halo equal to or more than 17 mm indicates that the bacteria is susceptible. Learn more about the result of urine growth with antibiotics.
Therefore, depending on the outcome of the antibiotic, your doctor may indicate the most effective antibiotic to fight the infection.
The use of uns adapted and effective antibiotics for a microorganism delays the recovery of the person, partially treats the infection and promotes the development of mechanisms of microbial resistance, making it difficult to treat the infection.
For the same reason, it is very important not to use antibiotics without the doctor’s advice and unnecessarily, as this may end up selecting more antibiotic-resistant microorganisms, reducing drug options to fight infections.