Moringa Oleifera Leaf Extract and Its Promising Synergistic Antimicrobial Effect with Typhoid Fever Vaccine in Immunized Mice

Typhoid fever, a systemic infection caused by Salmonella typhi has maintained a high morbidity and mortality profile around the globe especially in developing countries. Though currently licensed vaccines are efficacious in prevention of the infection, their potency is ephemeral; hence, they require a boost by employing adjuvants that are safe and instrumental in achieving a better prolonged protective immune defense outfit. In this work, Moringa oleifera ethyl acetate leaf extract was evaluated for its possible adjuvant property to a heat-killed ST vaccine. Mice were vaccinated with typhoid vaccine and subsequently, daily weight of mice was measured. Also, post-vaccination microbial colony counts were enumerated after challenging the mice with Salmonella typhi cells. From the blood culture results, MO extract demonstrated an excellent synergistic antimicrobial effect as the mice group administered our formulated vaccine-MO extract combination had the lowest microbial load (12.25 ± 4.86) colony forming units following microbial challenge, when compared to the mice groups administered the vaccine alone (37.25 ± 4.5) and the MO extract alone (31.25 ± 9.43). Furthermore, assessment of the mice body weight of treated groups showed a growth pattern that did not deviate significantly from those of the control group. In conclusion, MO extract demonstrated a promising synergistic antimicrobial effect on coadministration with the typhoid fever vaccine against S. typhi and did not lead to adverse side effects in mice.