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The purpose of our research was detection and identification by laboratory-based methods of bacterial pathogens Cl. perfringens and Cl. difficile in cattle within the territory of the Ural region. In the period from 2020 to 2021, 80 biological samples from cows and calves were examined from 10 agricultural organizations of the Ural region. The studies were carried out by PCR and culture methods, followed by identification of microorganisms using mass spectrometric analysis. PCR studies showed that in 80 biological samples from animals, clostridial genomes were found in 36.2% of samples. DNA of Cl. difficile was identified in 31.2% of samples, Cl. perfringens – 20.0%, Cl. difficile+Cl. perfringens simultaneously – 25.0%. Identified Cl. difficile exhibited toxicogenity in 48.0% of cases. Binary toxin (CDT) was detected in 41.0% of clostridia, toxin type B in 6.0% of pathogens. At the same time, the samples contained A/B/CDT types of toxins (6.0%), and singularly contained combination of toxins – A/B, A/ CDT, B/CDT. PCR diagnostics and mass spectrometry showed the presence of Cl. perfringens and Cl. difficile B in the material from the dead calves, which confirmed the diagnosis – necrotic enteritis. In material from dead cows, classical microbiology using mass spectrometry revealed abundant growth of E. coli and Salmonella enterica spp. enterica sergr C (0:9, 2) and multiple antibiotic resistance (penicillin/novobiocin, tetracycline). PCR diagnostics revealed DNA of Cl. perfringens and Cl. difficile CDT, which confirmed the diagnosis of acute intestinal infection. The DNA of Cl. difficile, Cl. perfringens and opportunistic cocci microflora were detected in milk samples from cows with signs of an inflammatory process of the mammary gland. Laboratory studies have shown a high detectability of clostridia in biomaterial from animals, as well as a high virulence and resistance of these bacteria to antibiotics.

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The assessment of the intoxication degree and the state of general organism resistance was carried by identifying “hematological indices” showing the connections between various cell classes of leukocyte formula. Comparison of integral indices of intoxication has recorded “slight degree of intoxication of the organism” in sick calves in 47.6% of cases. In the case of “moderate severity of organism intoxication”, the tension in the hemopoiesis system was recorded in 85.7% of cases, and the imbalance in the reactions of the cellular and humoral link of immunity – in 48.1% cases. For animals with a “severe degree of organism intoxication” imbalance in the links of immunity was determined in 90.9% of cases. According to the results of the determination of LII, LSI and LI, 31.6% calves were identified as having a risk of gastrointestinal complications development, whereas according to the results of CBC only 9.5% animals were classified as a “risk group”.