Inhibitory Effect of Newbouldia laevis and Stereospermum acuminatissimum on Multi-Resistant Bacteria Isolates

Abstract

Aim: Multi-drug-resistant bacteria is a growing concern worldwide. Plants have emerged as a promising avenue due to their bioactive compounds. Newbouldia laevis and Stereospermum acuminatissimumare two plants with a long history of use in traditional medicine. This study aimed at exploring the antimicrobial activity of their extracts against multi-drug-resistant bacteria.Materials and Methods: Extracts were prepared by maceration of pulverized leaves or stem barks (250 g) in 2L dichloromethane/methanol (30/70) filtered and the filtrate was dried using a rotary evaporator. The crude extracts were then tested against five pathogenic multi-resistant bacterial strains and Minimum Inhibition Concentration (MIC) was determined using the broth dilution method. The combinations of extracts and reference drug ceftriaxone was carried out following the checkerboard technique.Results: The overall results showed that Newbouldia laevis and Stereospermum acuminatissimumcrude extracts contain various phytochemicals such as alkaloids, flavonoids, terpenoids, and polyphenols, which were found to be associated with strong anti-bacterial effects against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Klebsiella pneumonia, exhibiting MICs values ranging from 100 μg/ mL to 400 μg/mL. The combinatorial analysis showed a combination and strains dependent-out, including synergism, additivity, and antagonism.Conclusion: These findings suggest that Newbouldia laevisandStereospermum acuminatissimumcould be used as alternative sources of antimicrobial agents for treating bacterial infections.

Keywords: Antibacterial; Combination; Multi-resistance; Newbouldia laevis; Stereospermum acuminatissimum