DEVELOPMENT OF ESSENTIAL OIL AND MEDIUM CHAIN FATTY ACID BASED FORMULATION TO MITIGATE MASTITIS IN DAIRY ANIMALS
Loading...
Date
2022
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ICAR-NDRI, KARNAL
Abstract
Bovine mastitis is of significant economic importance to dairy industry. Poor milk quality and emergence of antimicrobial resistance due to mastitis infection has necessitated to develop alternative therapy to antibiotics for treatment of mastitis. Essential oils (EOs) and medium-chain fatty acids (MCFAs) are well known natural antimicrobials, however, their combined effect has yet to be investigated. The current investigation was aimed to evaluate antimicrobial potentials of eight EOs and three MCFAs alone and in combination against antibiotic-sensitive (Staphylococcus aureus ATCC 29213; Escherichia coli ATCC 25922; Klebsiella pneumoniae ATCC 27736 and Streptococcus agalactiae ATCC 27956) and antibiotic-resistant strains (S. aureus ATCC 700698, K. pneumoniae ATCC 700603 and ESBL E. coli FcW5). To select best combination for the development of cream based bio-formulation as topical application for prevention of subclinical mastitis towards improving animal and consumer health as well as to minimize economic losses. Three EOs viz; trans-cinnamaldehyde (TC), carvacrol (CAR) and thymol (TM) exhibited broad-spectrum antimicrobial potential with minimum inhibitory concentrations (0.38-1.3 mg/mL) and minimum bactericidal concentration (0.66-2.64 mg/mL). However, selected MCFAs showed potential only against Gram-positive bacteria with MIC (0.2-1.9 mg/mL) and MBC (0.5-2.7 mg/mL). Combinational results of EOs and MCFAs showed most pronounced significant additive effect against maximum pathogens: CAR+OA, CAR+DA and TH+OA with FICI = 0.56-2.5. The combination (CAR+OA) killed bacterial (~106 CFU/mL) strains within 1 min. Observations on antimicrobial mechanism revealed that combined action of CAR+OA resulted severe morphological changes with significant release of cellular constituents and reduction in membrane potential. Also, fourier transformed infrared spectrophotometery analysis revealed possible structural alteration at cellular surface protein and carbohydrate region. Efficacy of developed bio-formulation was assessed by topical application on udder and teats for seven days w.r.t lowering SCC, pH and microbial load of milk. A cream based bio-formulation containing carvacrol (7.6 mg/mL) and octanoic acid (14.3 mg/mL) showed a broad-spectrum antimicrobial activity with zone of inhibition (12.5- 27.0 mm) against all selected pathogens. Ex vivo application of cream based bio-formulation showed significant reduction in SCC from day 4 onward, i.e. from 515 x 103 to 252 x 103 cells/mL. Further, microbial load of predominant bacterial species also showed reduction: Staphylococcus spp. (from 2.68 to 0.69 log CFU/mL), Streptococcus spp. (1.62 to 0.69 log CFU/mL). Significant reduction of Gram-negative bacteria (E. coli and Klebsiella spp.) was recorded from 0.97 to 0.28 log CFU/mL at the end of study period. Antimicrobial sensitivity test of isolated bacterial species from mastitis infected milk showed resistance to one or more antibiotics. Therefore, developed bio-formulation could be used as an alternative approach to antibiotic therapy and that will indirectly leads to elimination/minimize antibiotic residues in milk and milk products thereby safeguarding animal and human health. Further, use of such natural antibacterials would go a long way to improve food safety and shelflife.