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Detection of Mycoplasma hominis antigen by direct immunofluorescence method
Last reviewed: 05.07.2025
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Mycoplasma infection of the genitourinary system. Detection of Mycoplasma hominis antigen in the material by direct immunofluorescence
Mycoplasma infections of the genitourinary system currently occupy a leading place among sexually transmitted infections. They are often combined with gonococci, trichomonads and opportunistic microorganisms.
The diagnosis of urogenital mycoplasmosis is based on anamnesis, clinical examination and laboratory test results.
Mycoplasma hominiscauses acute and chronic inflammatory diseases of the urogenital tract, postpartum fever and sepsis, septic and spontaneous abortions. Mycoplasma hominis is detected by direct immunofluorescence in inflammatory diseases of the urogenital organs, according to various authors, in 15-90% of cases.
The obtained smear with the patient's material is processed with polyclonal antibodies to the cytoplasmic membrane of Mycoplasma hominis, labeled with FITC. When viewing the preparation in a fluorescent microscope, as a result of the antigen-antibody reaction, green fluorescence of mycoplasmas is determined. A positive assessment of the study results assumes the detection of at least 10 bright green granules in the preparation, clearly visible against the reddish background of the preparation. If a smaller number of luminous granules are obtained in the preparation and there are no epithelial cells in the preparation, the study is recommended to be repeated. If the number of epithelial cells in the preparation is sufficient, and the number of luminous granules is less than 10, the result is considered negative.
In men, mycoplasmas ( Mycoplasma hominis, Ureaplasma urealyticum ) most often cause urethritis, in women - endometritis and salpingitis, in newborns they can cause meningitis, respiratory infections, septicemia. However, mycoplasmas are opportunistic microorganisms that are part of the normal microflora of the mucous membranes of the urogenital tract, so their simple detection, especially in the absence of pronounced clinical manifestations, is very difficult to assess. Currently, it is believed that mycoplasmas are responsible for infection only if they are present in large quantities. Therefore, laboratory diagnostic methods that allow not only to identify mycoplasmas, but also to determine their concentration in the material being studied are diagnostically significant. For these purposes, diagnostic kits "Mycoplasma DUO" have been developed, allowing not only to identify mycoplasmas ( Mycoplasma hominis and/or Ureaplasma urealyticum ), but also to establish their titer. Urogenital mycoplasmoses are identified and differentiated by this test system based on their ability to metabolize arginine - for Mycoplasma hominis, urea - for Ureaplasma urealyticum. The titer of mycoplasmas is determined according to the classical dilution method, they are considered pathogenic if mycoplasmas ( Mycoplasma hominis or Ureaplasma urealyticum ) are detected in a titer of more than 10 4 CCU/ml (color-changing units in ml). The test results can be obtained within 24-48 hours.
Another problem for the clinician when detecting mycoplasmas in the test material in an increased titer is the correct choice of an antibacterial drug for effective treatment. Among mycoplasmas, strains resistant to various antibiotics are often encountered, so it is necessary to simultaneously determine the titer of mycoplasmas and establish their sensitivity to antibacterial drugs. For these purposes, diagnostic kits "SIR Mycoplasma" have been developed, allowing to determine the sensitivity of mycoplasmas to doxycycline, tetracycline, josamycin, erythromycin, clindamycin and ofloxacin. The results of the study can be obtained within 48 hours.
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