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A urine culture with antibiogram is a laboratory test requested by the doctor that aims to identify the microorganism that causes urinary tract infection and its sensitivity and resistance profile to antibiotics normally used to treat the infection. Thus, based on the results of the exam, the doctor can indicate the most appropriate antimicrobial for the person.
Performing this test is usually indicated when the person has signs and symptoms of urinary infection, however it can also be requested when, after a type I urine test, the EAS, bacteria and numerous leukocytes are identified in the urine, This is because these changes are indicative of urinary tract infection, and it is important to identify the responsible microorganism.
What is the use of urine culture with antibiogram
The urine culture test with antibiogram is used to identify the microorganism responsible for the urinary alteration and which antimicrobial can be used more effectively to combat it.
This test is mainly indicated in case of urinary infection, and may be requested after the result of the type 1 urine test, the EAS, or when the person has signs and symptoms of urinary infection, such as pain and burning when urinating and frequent urge to pee.
This test is used to identify the presence and antimicrobial susceptibility profile of some microorganisms, the main ones being:
- Escherichia coli;
- Klebsiella pneumoniae;
- Candida sp.;
- Proteus mirabilis;
- Pseudomonas spp.;
- Staphylococcus saprophyticus;
- Streptococcus agalactiae;
- Enterococcus faecalis;
- Serratia marcenses;
- Morganella morganii;
- Acinetobacter baumannii.
The identification of other microorganisms that may also be related to urinary tract infection, such as Chlamydia trachomatis, Neisseria gonorrhoeae, Mycoplasma spp. and Gardnerella vaginalis, for example, most of the time it is not done by means of urine culture, and in these cases it is usually requested to perform a collection of vaginal or penile secretion for the identification of the microorganism and the antibiogram, or analysis of the urine through of molecular methods.
How it's made
The urine culture test is a simple test that is performed using a urine sample, which must be collected and stored in a suitable container provided by the laboratory.To perform the collection, it is first necessary to clean the intimate region with soap and water and collect the first urine of the day. The person should discard the first stream of urine and collect the intermediate stream.
It is important that the sample is taken to the laboratory within 2 hours so that it is viable for performing the urine culture and antibiogram. In the laboratory, the sample is placed in a culture medium that favors the growth of microorganisms normally present in the urine. After 24 to 48 hours, it is possible to verify the growth of microorganisms and, thus, it is possible to carry out the microbial identification tests.
Furthermore, from the moment the growth of microorganisms is observed in the culture medium, it is possible to verify the amount of microorganisms, and it can be indicated that it is a case of colonization or infection, in addition to being possible to perform the antibiogram, in which the microorganism is tested for different antibiotics, being verified to which antibiotics it is sensitive or resistant.Understand more about the antibiogram.
How to understand the result
The result of the urine culture with antibiogram is given in the form of a report, in which it is indicated whether the test is negative or positive and, in these cases, which microorganism was identified, its quantity in the urine and the antibiotics to which it was sensitive and resistant.
The result is considered negative when only the growth in normal amounts of microorganisms that are naturally part of the urinary system is verified. On the other hand, the result is positive when there is an increase in the amount of any of the microorganisms that are part of the normal microbiota or when the presence of an unusual microorganism is verified.
In relation to the antibiogram, in addition to informing whether the microorganism is sensitive or resistant to the antibiotic, it also indicates the Minimum Inhibitory Concentration, also called MIC or MIC, which corresponds to the minimum concentration of the antibiotic that is capable of inhibiting the microbial growth, and this information is very important for the doctor to indicate the most appropriate treatment.
Uroculture with antibiogram for Escherichia coli
Escherichia coli, also known as E. coli, is the bacterium most often associated with urinary tract infections. When the urine culture is positive for the bacteria, the report indicates the amount in which it is in the urine and which antibiotics it is sensitive to, usually Phosphomycin, Nitrofurantoin, Amoxicillin with Clavulanate, Norfloxacin or Ciprofloxacin.
In addition, the MIC is indicated, which in the case of Escherichia coli, for example, it is determined that the MIC for Ampicillin less than or equal to 8 µg/mL is indicative of susceptibility to the antibiotic, and its recommended use for treatment, while values equal to or greater than 32 µg/mL indicate that the bacterium is resistant.
Thus, according to the results obtained by the urine culture and the antibiogram, the doctor can indicate the best treatment for the infection.