Characterization of bacterial isolates, antibiogram profile and pro-inflammatory cytokines in subclinical mastitis in cross-bred dairy cows

الملخص EN

Subclinical mastitis (SCM) is a major problem in the dairy industry creating a great loss both in quantity and quality of milk.

The aim of this study was to characterize bacteria, antibiogram profile, evaluation of immune cells and proinflammatory cytokines (IL-2, IL-6, TNF-α) associated with the inflammatory response in SCM.

Out of total twenty six (26) milking cows, microbial and biochemical tests revealed that fifteen (15) cows (57.68%) having a total of 18 bacterial isolates of which the prevalence of coagulase negative Staphylococci spp., Staphylococcus aureus, Streptococci spp., E.

coli, and Corynebacterium spp.

were revealed as 38.89%, 16.67%, 22.22%, 16.67%, and 5.56%, respectively.

On antibiogram profile, it was found effective against isolated organisms in ranking order as chlortetracycline, bacitracin, chloramphenicol, amoxicillin, nalidixic acid, penicillin, ampicillin, etc.

although resistant isolates to penicillin, bacitracin, ampicillin, and chloramphenicol were detected.

Blood and milk samples taken from those SCM+ cows further underwent for characterizing the pro-inflammatory cytokines IL-2, IL-6, and TNF-α, where both IL-2 and IL-6 revealed significant differences(P < 0.05); and then justified with the SCC, differential leucocytes differentiations.

SCM+ milk and blood samples revealed a significantly higher (P < 0.05) level of total leukocytes and a marked neutrophilia prevailed in SCM+ cows than those of healthy ones.

However, there were no significant differences found in aspect of macrophages, eosinophils, and lymphocytes population.

Blood and milk albumin, but not globulin, showed significant differences (P < 0.05) in SCM cow blood and milk compared to control cows.

Therefore, our findings suggest that microbes related with SCM cases result in increase pattern of neutrophilic inflammation and subsequent induction of pro-inflammatory cytokines.