In-Vitro and In-Vivo Antimicrobial Activity of Five Medicinal Plants against Virulent Escherichia coli O157:H7 Strain Harboring Shiga Toxin Gene

Abstract

This study aimed to determine the anti-bacterial efficacy of 5 different medicinal plant extracts against Shiga toxin (E. coli O157:H7) based on the in-vitro and in-vivo trial. A total of twenty-one (n=21) PCR-confirmed isolates were selected for detection of virulent genes in-vitro trial (zone of inhibition). For in-vivo trial, forty-two (n=42) day-old chicks were divided into seven equal groups randomly (n=6 birds/ group), and were classified as: G1 (Azadirachta indica @ 18.25 mg/ml), G2 (Melia azedarach @ 15.75 mg/ml), G3 (Withania coagulans @ 25 mg/ml), G4 (Nigela sativa @ 30 mg/ml), and G5 (Calotropis procera @ 10 mg/ml) were taken as treatment groups, while G6 as a negative control, and G7 as a positive control. The results showed that 47.6% serovars were positive for the virulent gene (Stx-1). Moreover, the highest zone of inhibition was observed in G5 (17.1 ± 0.60 mm, P<0.05) as compared to other groups, which indicated high anti-bacterial efficacy on in-vitro basis. The survival rate and weight gain of chicks were significantly higher (P<0.05) in G5 compared with all other groups. However, none of the medicinal plant extracts affect liver function and blood parameters. Finally, in conclusion, C. procera was found to be highly effective to protect birds against E. coli O157:H7 infection.