Antibodies to salmonella in serum

Diagnostic AT titer for salmonella in the serum at RPGA - 1: 200( 1: 100 in children under 1 year) and above;during the agglutination reaction( Vidal's reaction) - 1:40( 1:20 in children under 1 year) and above.

Currently, the most widely used for the detection of antituberculosis to salmonella( to O-Ar) are RPGA and ELISA, they are more sensitive compared to the Vidal's response and give positive results from the 5th day of the disease( Vidal's reaction to the 7-8thday).AT in patients with typhoid fever, paratyphoid or other serological types of salmonella appear in the blood by the fourth day of the disease and increase dramatically by the 8th-10th day. Their number is even more increased at the 2-3 th week of the disease. In adults and older children, the RPHA provides confirmation of the diagnosis of salmonellosis

in 80-95% of cases at the end of the first week of the disease. In children of the first year of life( especially up to 6 months), RPGA with salmonella diagnosis is negative throughout the disease. In the first months after recovery, the study of AT to salmonella can serve for the purposes of retrospective diagnosis. However, it is necessary to take into account individual deviations from the normal cycle of immunogenesis and the described dynamics of AT titer change. In an attenuated organism with reduced reactivity, AT is weakly and slowly synthesized. Inter-curative diseases can also delay their formation. Early treatment with chloramphenicol or ampicillin may lead to a decrease in the titer of AT or their absence. Therefore, the AT titer of less than 1: 200 does not allow eliminating the disease, it is extremely important to investigate the AT titer in dynamics - at the onset of the disease and 10-14 days later. Increasing the titer AT at 10-14 days not less than 4 times with the study of paired sera indicates an infectious process.

When using the Vidal's reaction, a titer of & gt;1: 40 to & gt;1: 160 depending on the geographical area and the laboratory. When using the 1: 160 separation point for the diagnosis of infection, the sensitivity of the method is 46%, the specificity is 98%;1:80 gives a sensitivity of 66%, specificity is 94%;at 1:40 the sensitivity is 90%, the specificity is 85% [Rose N. R. et al.1997].