Pathogenic properties of enterobacteria isolated from calves in the Far Eastern Federal District

Abstract

Methods of modern control of infectious animal diseases have led to a change in the etiological structure of infectious agents. Irrational use of antibiotic therapy may be the cause of bacterial variability and involvement in the infectious process of opportunistic bacteria that are present in the normal microflora of the animal body. Opportunistic bacteria are the cause of many animal diseases. Infections caused by them have a prolonged character, the pathogenetic basis of which is the persistence of the pathogen in the host body. Bacterial exotoxins damage the plasma membrane of cells. Pore-forming toxins and enzymes disrupt the selective entry and exit of ions through the plasma membrane. This group of toxins includes cytolysins, hemolysins of gram-negative opportunistic enterobacteria, leukotoxins, metalloproteases, and lipases. When pores are formed under the action of hemolysin, secondary processes are triggered that cause the development of pathological consequences. The vaccines and serums produced by biofactories lag behind the practical needs in terms of antigenicity and do not provide protection for newborn calves in the system of anti-epizootic measures. Of particular importance in the etiopathogenesis of acute intestinal disorders is a decrease in colonization resistance of the gastrointestinal mucosa, resulting in an expansion of the spectrum of pathogenic and opportunistic microorganisms that lead to the development of diarrhea.