Bacteriological and Clinicopathological Studies of Corynebacterium pseudotuberculosis Isolated from Caseous Lymphadenitis in Sheep

Caseous lymphadenitis (CLA) is a chronic, contagious disease that affects sheep and is brought on by Corynebacterium pseudotuberculosis (C. pseudotuberculosis). The development of abscesses in the peripheral lymph nodes and widespread infections frequently characterizes it. The purpose of this study was to look into the prevalence of CLA in sheep, the virulence gene, drug resistance genes, and the effect of C. pseudotuberculosis on hematological and biochemical parameters, as well as the cellular immunity of diseased sheep. Pus and blood samples were collected aseptically from 100 sheep suffering from abscess formation. The C. pseudotuberculosis strain isolates were found in a percentage of 14%. Pseudotuberculosis antibiotic sensitivity revealed a higher resistance to β-lactam antibiotics, aminoglycosides, and lincosamides. Out of the 14 isolates of C. pseudotuberculosis, seven isolates were selected for investigation of the presence of C. pseudotuberculosis. All of the C. pseudotuberculosis isolates tested positive for 16S rRNA, RNA polymerase-subunit gene (rpoB) genes, β-lactam (bla), and integrons (int). Six isolates were positive for the phospholipase D (Pld) gene at a percentage of 85%. On the other hand, the aminoglycosides (aadA2) gene and the sigma factor E (sigE) gene were detected in percentages of 57% and 28.57%, respectively. Red blood cell count, hemoglobin (Hb), packed cell volume, mean corpuscular volume, mean corpuscular Hb concentration, white blood cell count, neutrophils, lymphocytes, monocytes, eosinophils, basophils, globulin, and total plasma proteins all showed significant changes. Similarly, the results of the biochemical analysis revealed significant changes in liver and kidney functions, as well as calcium concentration. However, there were no significant changes in potassium (K+). It concluded that C. pseudotuberculosis harms the sheep's health in general reflected by all the changes recorded in the hemogram, leukogram, and blood chemistry.