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Diagnostic Tests 2023

Bacterioscopy: what é and what is it for

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Bacterioscopy: what é and what is it for
Bacterioscopy: what é and what is it for

Bacteroscopy is a diagnostic technique that allows you to quickly and simply identify the occurrence of infections, because through specific staining techniques, it is possible to visualize bacterial structures under the microscope.

This exam can be performed with any biological material, and the doctor must indicate which material to collect and analyze, and the result indicates whether or not the presence of bacteria has been verified, as well as their quantity and characteristics visualized.

What is it for

Bacteroscopy is a diagnostic test that can be performed with any biological material and that can be used to quickly identify bacterial infections:

  1. Sexually transmitted diseases, such as gonorrhea and chlamydia, for example, with penile or vaginal secretions being used for this purpose. The collection is performed using a sterile swab and it is contraindicated to perform the hygiene of the genital region 2 hours before the exam and not to have sexual intercourse in the 24 hours before the collection;
  2. Tonsillitis, because through the collection of throat secretion it is possible to identify gram-positive bacteria responsible for inflammation in the tonsil, usually streptococcus-type bacteria;
  3. Infections in the urinary system, which is done by analyzing the urine of the first stream;
  4. Tuberculosis, in which sputum is analyzed;
  5. Infections in surgical wounds, as it is common for infections to occur after operations due to a decrease in the person's immune system. Thus, the collection of wound secretion with a sterile swab may be indicated to check the possible presence of bacteria at the site;
  6. Skin or nail lesions, which consists of collecting a superficial sample, and it is recommended not to use creams and nail polishes for at least 5 days before the exam. Although bacterioscopy can be performed, fungi are usually observed when analyzing the nail sample, for example.

In addition, bacterioscopy can be used to aid in the diagnosis of bacterial meningitis, respiratory and gastrointestinal tract diseases, and can be performed through biopsy or material from the anal region.

Thus, bacterioscopy is a laboratory technique that can be used in clinical practice to diagnose diseases caused by bacteria, indicating the characteristics of the disease-causing agent and, thus, allowing the doctor to start treatment even before identification in the laboratory, which can take about 1 week.

Microscopic visualization of bacteria stained by the Gram method

Microscopic view of bacteria stained by Gram method

How it's made

The bacterioscopy exam is performed in the laboratory and the material collected from the patient is analyzed under a microscope to investigate the absence or presence of bacteria, in addition to their characteristics.

Preparing to take the exam depends on the material that will be collected and analyzed. In the case of vaginal material, it is not recommended that the woman performs hygiene 2 hours before the exam and does not have sexual intercourse in the last 24 hours, while in the case of collection of material from the nail or skin, for example, it is recommended not to nail polish, creams or substances on the skin before the exam.

In the case of a vaginal secretion sample, for example, the swab that was used to make the collection is passed in circular movements on a slide, which must be identified with the patient's initials, and then must be stained with Gram stain.In the case of a sputum sample, for example, which is the material collected mainly to verify the presence of the bacteria responsible for tuberculosis, the stain used in bacterioscopy is the Ziehl-neelsen stain, which is more specific for this type of microorganism.

Usually when the presence of bacteria is verified, the laboratory performs the identification of the microorganism and the antibiogram, giving a more complete result.

How is Gram staining done

Gram staining is a simple and fast staining technique that allows the differentiation of bacteria according to their characteristics, allowing the differentiation of positive or negative bacteria according to their staining, allowing their visualization in the microscope.

This staining method uses two main dyes, one blue and one pink, which may or may not stain the bacteria. Bacteria stained in blue are called gram-positive, while those in pink are called gram-negative.From this classification, it is possible for the doctor to initiate preventive treatment, even before having the identification of the microorganism. Understand how it's made and what gram coloring is for.

What does the result mean

The bacterioscopy result is intended to indicate whether there is presence or absence of microorganisms, characteristics and quantity, in addition to the material that was analyzed.

The result is said to be negative when microorganisms are not observed and positive when microorganisms are visualized. The result is usually indicated in crosses (+), where 1 + indicates that 1 to 10 bacteria were seen in 100 fields, which could be indicative of an initial infection, for example, and 6 + represents the presence of more than 1000 bacteria per field observed, representing a more chronic infection or bacterial resistance, for example, indicating that the treatment is not being effective.

In addition, the coloring that was used is informed in the report, which may be Gram or Ziehl-neelsen, for example, in addition to the characteristics of the microorganism, such as shape and disposition, whether in bunches or in a chain, for example.

Usually, when the result is positive, the laboratory identifies the microorganism and antibiogram, indicating which antibiotic is most recommended to treat the infection by a particular bacterium.

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