Vol. 11, Special Issue 1 (2022)

Author(s):
Lakshmi Kavitha K, Rajesh K and Sambasiva Rao K

Abstract:
Proteus vulgaris accounts for 4.5% of environmental mastitis in bovines. The organism exhibits intrinsic high antibiotic resistance and becomes refractory to treatment. In the present study 185, lytic bacteriophages were screened and based on plaque morphology five were selected as therapeutic agents. The five lytic bacteriophages named ɸPV1, ɸPV2, ɸPV3, ɸPV4 and ɸPV5. These were characterized for host range on the reference strain of Proteus vulgaris and on strains isolated from the cases of mastitis and observed 80 to 92.5%. Biophysical characterization of phages was done to ascertain their stability in hostile environments and observed stability at pH 4, 7, 9 and temperature 16 °C, 37 °C and 42 °C. The morphology of the phage PV3 belonged to order Caudovirales and the family Siphoviridae. Molecular characterization showed DNA as nucleic acid and phage PV3 was about 28.9Kbp and showed digestion with a restriction endonuclease. Therapeutic activity of phage mixture was evaluated in lactating Swiss albino mice that were divided into control, infected and treatment groups. At the multiplicity of infection 10, lytic bacteriophage mixture eliminated infection (milk bacterial load) and observed a reduction in swelling of the mammary gland.