Antimicrobial and synergistic potential of Ocimum gratissimum leaves and Petiveria alliacea bark against some selected microorganisms

Background: This study was carried out to investigate the antimicrobial and synergistic potential of the leaves of Ocimum gratissimum and bark of Petiveria alliacea against some tested bacterial and fungal isolates. Fresh and matured leaves of Ocimum gratissimum and bark of Petiveria alliacea were collected from the Institute of Agriculture, Research and Training, Ibadan, Nigeria. The specimens were identified at the Herbarium unit of the Department of Botany, Obafemi Awolowo University, Ile-Ife, Nigeria. The pathogenic organisms used include bacteria namely, Providencia stuartii, Bacillus cereus, Staphylococcus aureus, Corynebacterium Pyogenes, Streptococcus faecalis, Klebsiella oxytoca, Klebsiella pneumonia, Escherichia coli, Pseudomonas fluorescence, Serratia rubidae, Proteus mirabilis, Salmonella pullorum; and fungi namely, Trychophyton tonsurans, Candidia albicans, Trychophyton rubrum, Penicillium expansium, Alternaria sp, Fusarium sp, Aspergillus niger, Aspergillus fumigatus, Aspergillus flavus, and Penicillium camenberti. Methods: Pure isolates of the tested microorganisms were obtained from the department of microbiology, University of Ibadan, Ibadan, Nigeria. The bacterial isolates were maintained on nutrient agar slant and the fungal isolates were on Sabouraud Dextrose Agar (SDA). Antimicrobial sensitivity test (AST) followed by Clinical and Laboratory Standard Institute. Minimal bactericidal and fungicidal concentrations were determined following established protocols. Results: Fungal isolates of Aspergillus flavus, Penicillium expansiumm, Trychophyton rubrum, and bacterial isolates Klebsiella oxytoca, Klebsiella pneumonia, Escherichia coli, Proteus mirabilis, and Salmonella pullorum were all resistant to the plant extract. Findings from this study opined that ethanolic extract of Ocimum gratissimum leaves is more potent than the methanolic and aqueous extracts of Petiveria alliacea. Conclusion: The plant extracts showed greater antimicrobial activity against bacterial- with respect to fungal isolates suggesting a broader spectrum of activity with ethanolic extract on the gram-positive and the gram-negative bacteria.