Anti-Salmonella activity of metabolites from African soldier termites, Macrotermes bellicosus

Abstract

Background: The global emergence and rapid dissemination of multidrug resistant Salmonella strains necessitate research to find new antimicrobials that will effectively be used against these pathogens. In the present study, anti-Salmonella activity of metabolites from African Soldier Termites, Macrotermes bellicosus was demonstrated and subsequently compared with a potent antibiotic, ciprofloxacin.

Materials and Methods: N-hexane, ethylacetate, methanol and aqueous extracts of metabolites from the M. bellicosus were assayed for anti-Salmonella activity using the agar dilution method in the determination of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The inhibitory activities of the extracts were compared to ciprofloxacin (256μg/ml). Also, the bioactive components of the extracts were determined using standard techniques.

Results: At 4000 μg/ml, N-hexane extract inhibited the growth of Salmonella Typhi, S. Paratyphi A, B and C while ethylacetate extract was able to inhibit S. Paratyphi A and C. Methanolic and aqueous extracts at the same concentration were unable to inhibit these strains of Salmonella. Furthermore, our findings revealed that the MIC of ethylacetate extract was 2000μg/ml for S. Paratyphi A and B, 250μg/ml for S. Typhi, and 125μg/ml for S. Paratyphi C. Also, the MIC of hexane extract was 4000μg/ml for S. Paratyphi B, 2000 μg/ml for S. Paratyphi C, 500μg/ml for S. Typhi and 250μg/ml for S. Paratyphi A respectively. The screening of bioactive components revealed the presence of cardiac glycosides and alkaloids.

Conclusion: Our results provide evidence of anti-Salmonella action of metabolites from African Soldier Termites, M. bellicosus. N-hexane and ethylacetate extracts of M. bellicosus may be explored as novel antimicrobials for the treatment of typhoid and paratyphoid fevers thereby reducing the pressure exerted on available antibiotics.

Keywords: Salmonella, antimicrobials, insects, extracts