Diagnosis of salmonellosis
Last reviewed: 23.04.2024
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Typical forms of salmonellosis begin acutely with the increase in the severity of the general condition; fever relatively long, not typical. But prolonged "unmotivated" vomiting, soreness and rumbling in the right ileal region, densely lined tongue, phenomena of flatulence ("full belly"), enteric or enterocolitis chair of the "marsh mud" type with an unpleasant, fetid smell. With moderate and severe forms of hepatosplenomegaly, especially in young children, changes in the central nervous system in the form of lethargy, deafness, drowsiness, in the peripheral blood - pronounced leukocytosis, neutrophilia with a shift to the left (rod-nuclear shift), increased ESR.
Decisive in the establishment of the diagnosis - the results of bacteriological and serological research.
- The bacteriological method is of the greatest importance. Salmonella can be found in feces, vomit, stomach washings, urine, blood, cerebrospinal fluid. Material is collected and sowing is done on nutrient media in the same way as in shigellosis and other bacterial intestinal infections. Sowing feces, urine, bile is carried out on elective nutrient media (Ploskirev's medium, bismuth-sulfite agar, etc.) or on enrichment media (Müller's, Kaufman's, etc.). Sowing blood should be done throughout the feverish period. Take 5-8 ml of blood from the vein and inoculate 10-20% of bile broth or Rappaport medium. The percentage of positive results in bacteriological studies varies from 40 to 80%. The greatest number of positive results falls on the first week of the disease.
- Serological methods of investigation are aimed at detecting both specific antibodies in the patient's blood and antigen in the biomaterial. The presence of specific antibodies in the patient's blood and their titer is determined with the help of RA or RNGA with erythrocyte diagnosticums. Take 1-2 ml of blood from the vein or from the finger, the resulting blood serum is diluted with an isotopic sodium chloride solution, a diagnosticum containing O-antigens of Salmonella serogroups A, B, C, D is added. Diagnostic value is the presence of antibodies in a dilution of 1: 100 or an increase their titre in the dynamics of the disease in 2-4 times or more. At present, in practice, the most common is the RNGA as a more sensitive and specific reaction than RA. Negative results of serological examination are with the lightest, blurred forms of the disease, as well as in infants and newborns in severe forms of the disease.
To detect salmonella antigens in coprofiltrates, urine, a coagglutination reaction and ELISA are used, which allows to determine the antibody titer in the blood. This is a more effective and promising method, because with its help it is possible to separately identify specific antibodies of different classes (A, M, G). Specific immunoglobulins of class M always indicate an active infectious process.
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