The paper discusses the issues of morphofunctional variability of causative agents of sapronoses under stressful environmental conditions. In the current century, sapronoses infections attract more and more attention. Under unfavorable habitat conditions, their pathogens use a strategy for the formation of resting (stable) states: viable but non-cultured cell forms and the persistence of bacteria, which are characterized by reduced metabolism, changes in the morphology and physiology of microorganisms, and termination of their replication. With the formation of resistant forms of bacteria, the possibility of survival of sapronoses causative agents in the interepidemic period, the formation of their antibiotic resistance, which plays an important role in the chronicity of infections, is associated. The literature widely discusses the mechanisms and conditions for the formation of resistant states of pathogenic bacteria, their pathogenetic significance in infectious pathology, whereas the ultrastructural organization and morphological variability of resistant cellular forms, as well as their differentiation, causing the heterogeneity of the pathogens population, are not yet well covered. The emergence of molecular cell biology methods and the discovery of genetic modules of toxin-antitoxin systems revealed a single mechanism for regulating the formation of resistant cellular forms of bacteria. This served as the basis for the development of fundamentally new technologies for the study of the mechanisms for the conservation of the pathogenic potential of resistant cellular forms of pathogens of natural focal sapronosis in interepidemic periods. Based on the analysis of current data, as well as their own experience, the authors assess the role of morphofunctional changes in resistant cellular forms of bacteria and their significance in the adaptation strategies of causative agents of sapronoses (on the example of Yersinia pseudotuberculosis). The study of the manifestations of heteromorphism of causative agents of sapronoses forms the paradigm of the need to improve methods for detecting resistant forms of these bacteria in human and animal biomaterial in order to diagnose chronic recurrent and persistent infections, create effective strategies for monitoring and monitoring the environment.
Keywords: L-transformation; Yersinia pseudotuberculosis; morphology; persister-cells; sapronoses; ultrastructure and adaptive changes of pathogens; viable, but noncultivated (VBNC-forms) cells.