The Effect of Moringa oleifera and Ocimum gratissimum Essential Oils and Extracts on Antimicrobial Resistant Enterobacteriaceae from Environmental Sources

Abstract

The continuous increase in resistance to antimicrobials amongst the Enterobacteriaceae constitutes a growing public health threat and thus has necessitated the need to continuously search for alternative antimicrobial chemotherapy. This study was aimed at evaluating the effects Moringa oleifera seed and Ocimum gratissimum plant extracts and essential oils on antimicrobial resistant Enterobacteriaceae isolated from aquatic sources. Two hundred isolates of Klebsiella pneumoniae and Escherichia coli were recovered from two different environmental sources. The susceptibility of the isolates to ten (10) different antimicrobials was examined by the Kirby-Bauer technique. The isolates were also tested for extended β-lactamase production (ESβL) by the modified double disc synergy test and the susceptibility of the isolates to essential oils and extracts from Moringa oleifera seeds and Ocimum gratissimum leaves was analysed using the agar - well diffusion assay. In addition, the phytochemical analysis of the extracts was carried out to determine their constituents. The river water isolates recorded high resistance rates for the following antibiotics: Ampicillin (99%), cefotaxime (83%), imipenem (77%) and low rates for levofloxacine (19%), while the aquaculture isolates expressed high resistance rates to ampicillin (95%) ceftazedime (86%), ertapenem (65%), and low rates to aztreonam (8%). Thirteen (37%) isolates out of 35 tested were positive for ESβL   production, four isolates from river water and nine from aquaculture. Antimicrobial analysis of the essential oils against the ESBL producers showed no inhibitory activity while the plant extracts produced zones of inhibition and minimum inhibitory concentrations of between 1.32 and 2.70 mg/ml for the two plant extracts tested. Phytochemical analysis showed the presence of alkaloids, saponins, tannins, flavonoids and glycosides in different quantities. This study has shown that crude extracts of Moringa oleifera seeds and Ocimum gratissimum leaf could become a potential alternative in the treatment of infections due to antimicrobial-resistant Enterobacteriaceae.