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Diagnosis of pneumococcal infection
Last reviewed: 23.04.2024
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Precisely diagnose pneumococcal infection can only be after the excretion of the pathogen from the lesion or blood. For examination, sputum is taken for croupous pneumonia, blood for suspected sepsis, purulent discharge or inflammatory exudate in other diseases. Pathological material is subjected to microscopy. The detection of gram-positive diplococci lanceolate form, surrounded by a capsule, is the basis for the preliminary diagnosis of pneumococcal infection. To establish the attribution of isolated diplococci to pneumococci use combined type-specific sera containing antibodies in high titers to all serotypes of pneumococcus. In the first days of pneumococcal meningitis, the causative agent can be found in the cerebrospinal fluid, where it is located both outside and intracellularly.
In order to isolate a pure culture, the test material is sown to blood, serum or ascitic agar. On nutrient media, pneumococcus gives rise to small, transparent colonies. A biological sample can be used to isolate a pure culture. To this end, white mice are infected intraperitoneally with the test material. If pathogenic pneumococci are present in the mouse material, they die after 24-48 hours. For the detection of pneumococcal antigens, the method of solid-phase immuno-electrophoresis and PCR can be used.
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