Zoopathogenic role of Moraxellaceae and Corynebacteriaceae bacteria in mastitis in ruminants

Background. The article examines the incidence and pathogenic significance of Moraxella and Corynebacteria in mastitis of ruminants using the example of large and small cattle in various farms in the regions of the Russian Federation. As a result of the conducted studies, the sporadic presence of Moraxella microorganisms in the microbiota of mastitis milk among opportunistic pathogens in cows was established. No Moraxella was found in goats. Several cases were identified at once in which Acinetobacter spp., belonging to the Moraxellaceae family, was isolated in associations. The incidence of pathogenic corynebacteria as the leading representative of the clinical microbiota was noted at the level of 60% in the goats of LLC « Pikaev » in the Republic of Morodovia and 26.7% in cows from various farms in the Moscow region, the Republic of Morodovia and Bashkortostan.

Purpose. The purpose of this work is to study the incidence and pathogenic significance of bacteria Moraxella and Corynebacterium in mastitis in cattle and small cattle.

Materials and methods. The research was carried out at livestock enterprises in the Moscow region, the Republic of Mordovia, and the Republic of Bashkortostan. In the period from March to August 2024, clinical trials were conducted in the field and in production conditions for mastitis of large and small cattle with sampling of pathological material. The clinical (pathological) material was milk, which was collected in sterile containers. Screening bacteriological studies for indication of microorganisms (20 studies) and identification of bacteria were conducted. The samples were seeded onto Petri dishes with 10% blood and chocolate agar content. Petri dishes were incubated at 37 °C for 48 hours. Putative colonies of Moraxella, identified by their smooth, rounded and grayish-white appearance with a hemolysis zone, were subjected to Gram staining and biochemical tests, then positive colonies were further confirmed using MALDI–TOF, other bacterial pathogens were also identified using biochemical tests and mass spectrometry. For this purpose, after sampling, a well-isolated colony was removed using a sterile loop, then re-suspended in 300 µl of distilled water, then the suspension was centrifuged for 10 minutes at 10,000 rpm, after which 2 µl of a reactogenic solution was added to the precipitate, transferred to a MALDI plate and loaded into an ionization chamber.

Results. The following types of microorganisms have been detected and identified in cattle with a clinical picture of serous, catarrhal mastitis: Streptococcus uberis, Staphylococcus capitis, Trueperella pyogenes, Bacillus pumilus, Brevibacterium celere, Corynebacterium xerosis, Bacillus licheniformis, Acinetobacter junii, Escherichia coli, Paraclostridium bifermentans, Psychrobacter immobilis, Enterococcus faecium, Serratia liquefaciens, Citrobacter freundii, Pseudomonas spp., Corynebacterium spp., Enterococcus faecalis, Psychrobacter phenylpyruvicus, Raoultella ornithinolytica, Moraxella catarrhalis (1 isolate). The following types of microorganisms were found in goats with a clinical picture of serous catarrhal mastitis: Aerococcus viridians, Corynebacterium stationis, Staphylococcus haemolyticus, Staphylococcus chromogenes, Corynebacterium xerosis, Corynebacterium stationis, and Staphylococcus epidermidis. The results are presented in table 1. No growth was detected from samples of biological material from mastitis milk of sheep and goats, during screening bacteriological studies on blood agar. To determine the pathogenic properties of the isolated cultures, a coagulase test for staphylococci and a bioassay on white mongrel mice were used. The inoculum diluted to the desired concentration (10⁸ CFU/ml), OD = 600 nm = 1, obtained from a pure culture of Moraxella bovis and Moraxella bovoculi, was administered subcutaneously to mice at a dose of 100 µl.

Conclusion. The nosological role of moraxella microorganisms in mastitis in cows and goats has not been confirmed at this stage of research. Cases of indication of Moraxella catarrhalis and Acinetobacter spp. have been noted among the clinical microbiota, which does not exclude the nosological role of microorganisms of the Moraxellaceae family in these pathologies, as early studies occasionally noted.