[Biological properties of salmonellae and local immunity in Salmonella infection]

The comparative study of the biological properties of S. enteritidis and S. typhimuruim, isolated from patients and convalescent carriers, was carried out. Factors inactivating the components of the local immunity of the intestine (lysozyme, complement, lactoferrin, IgG, IgM and IgA) were detected in the causative agents of Salmonella infections. The spread and expression degree of properties of a causative agent were serovar-depended: high penetration characteristics and the expression of anti-lactoferrin and anti-immunoglobulin activity were characteristic of S. typhimurium. S. enteritidis strains isolated from patients with carrier state formed in the convalescence period were found to have higher persistence level. In co-profiltrates obtained from carriers at the peak of the disease and during convalescence lower levels of IgM, IgG, sIgA, complement and lactoferrin were determined in comparison with those in coprofiltrates obtained from patients in whom no subsequent carrier state was formed. These results indicate that an increase in the persistence of salmonellae, occurring simultaneously with the local immunodeficiency, contributes to the prolonged survival of bacteria in the intestine.