COMPARATIVELY ASSESSED BIOLOGICAL MODELS FOR DETERMINING THE PATHOGENIC PROPERTIES OF CERTAIN PATHOGENS CAUSING COMMUNITY-ACQUIRED PNEUMONIA

Abstract

In recent years, it has been of interest to search for alternative, so-called surrogate models to investigate bacterial pathogenicity. The current work was aimed at comparing two biological models (using white mice and Galleria mellonella larvae) to evaluate the pathogenic potential of community-acquired pneumonia agents. All the studied strains were isolated from the sputum of patients at the Rostov-on-Don Anti–Plague Institute of Rospotrebnadzor and identified by time-of-flight mass spectrometry. The virulence of the pathogen strains was evaluated when white mice and G. mellonella larvae were experimentally infected by microbes at various doses (CFU/ml). It was found that the hypermucoid variant of Klebsiella pneumoniae caused death of white mice at a dose of <10³ CFU/mouse, whereas the classical morphotype was apathogenic even at a dose of 10⁶ CFU/mouse. At the same time, when the larvae were infected with two morphotypes, no difference in pathogenicity was observed. Other clinical isolates of the Enterobacteriacea family caused no disease in white mice even at an infection dose of 10⁶ CFU/mouse. However, E. coli and E. kobei caused the lethal process in (90%) in G. mellonella larvae. The exception was E. cloacae, which caused death in as few as 10% of individuals. In contrast to white mice, 100% of larvae died upon infection with Stenotrophomonas maltophilia, Chryseobacterium gleum, Rhizobium radiobacter, and Pantoea agglomerans. The virulence study of different staphylococcal species showed that S. aureus and S. haemolyticus had a high pathogenic potential for larvae, whereas S. epidermidis and S. saprophyticus were characterized by significantly lower potential to cause infection. In the surrogate model, clinical isolates of various fungal species: C. albicans, C. tropicalis, and G. capitatum – were most pathogenic for larvae, whereas C. glabrata and C. krusei, known as most invasive species, caused the delayed death of several individuals. Thus, the pathogenicity study of various microbial species requires to choose most appropriate biological model.