Study on synergistic and antimicrobial activity of certain Bifidobacterium bifidum strains and plant extracts against clinical isolates

To evaluate the synergistic and antimicrobial activity of certain Bifidobacterium bifidum strains and methanolic extracts of Withania somnifera (Aswagandha) and Aloe vera plant extracts against clinical isolates from veterinary hospitals by using well diffusion method. The results obtained from the combined testing of Bifidobacterium adolescentis 236 strain and methanolic plant extracts of Withania somnifera showed significantly higher antibacterial/synergistic activity against isolates of E.coli and Staphylococcus aureus with an average zone of inhibition of 19.0 mm and 20.0 mm respectively, whereas against Klebsiella pneumoniae and Salmonella typhimurium showed resistance/lower zone of inhibition with an average zone of inhibition 13.0 mm and 14.0 mm, respectively. Further, it was also observed that the Bifidobacterium bifidum strains and Withania somnifera and Aloe vera plants methanolic extracts exhibited excellent antibiotic activity when they were tested alone against the clinical pathogens. However, Bifidobacterium bifidum strains 229 and 232 tested in combination with methanolic extracts of Withania somnifera and Aloe vera plant extracts exhibited significantly low antibacterial activity/zone of inhibition against clinically isolated pathogens. The present study specifies that the Bifidobacterium adolescentis 236 strain and methanolic extract of Withania somnifera extracts exhibited good antibacterial activity when they are used in combination, such combinations can be further tested as an alternative to antibiotics for effective prophylactic measures and also for treatment of contagious diseases caused by pathogenic microorganisms.