Abstract:

Bacterial mastitis is a significant welfare and financial problem in sheep flocks in Egypt. The purpose of the study was to diagnose subclinical mastitis; investigate some virulence factors of Pseudomonas aeruginosa in ewes’ mastitis cases and antibiotic resistance profile as well as evaluate hematological, biochemical parameters and the role of oxidative stress/ antioxidant enzymes activity from mastitic milk of ewe. One hundred ewes’ milk samples (20 from clinical mastitic and 80 from apparently healthy ewe) and blood samples were collected from different sheep farms. Milk samples from apparently healthy ewes were subjected to MCT (California mastitis test) and SCC (somatic cell count). All milk samples were bacteriologically examined with special reference to Pseudomonas aeruginosa organisms. Blood samples subjected to hematological, biochemical and determined the level of oxidative stress and antioxidant enzyme activity. The bacteriological results showed that the prevalence of P. aeruginosa was 30.77% while others were: S. aureus (50.77%), E.coli (44.61%), Coagulase negative staphylococcus (33.85%) and Proteus vulgaris (20%) from all mastitic ewes. Antibiotic resistance profile of P. aeruginosa isolates showed 100% resistance against most tested antibiotics; however, gentamycine (65%) and ciprofloxacin (55%) recorded the highest sensitivity rates. PCR evaluation of some virulent genes of P. aeruginosa isolates detected the presence of (Las I, Tox A, and opr L) genes in 71.43% of the isolates for each. In addition, genotypic profile of antibiotic resistance genes (TetA and Sul1) detected their presence in 100% in all examined P. aeruginosa isolates.

The hematological analysis revealed a significant decrease in RBCs count; hemoglobin concentration, and packed cell volume (PCV) as well as leucocytosis, neutrophilia, lymphopenia and eosinophilia were observed in mastitic ewes. The biochemical analysis showed a significant increase in AST, ALT, ALP, LDH, BUN, creatinine and calcium. Hypoproteinemia, hypoalbuminemia and hyperglobulinemia were detected in both mastitic samples. A significant increased level of alpha and beta globulins in clinical mastitic ewes however, in subclinical cases, the increased level of alpha and gamma globulins were recorded. Also, there was a significant decrease in the antioxidant enzyme (TAC, and CAT) as well as a significant increase in the activity of antioxidant enzyme (GSH and SOD) and oxidative stress (MDA and NO). In conclusion, the virulent strains of P. aeruginosa caused for a great proportion of mastitis in ewes milk and were adversely affected on blood analysis and oxidative/ antioxidant enzymes activity.