ANTIBACTERIAL AND PHYTOCHEMICAL PROPERTIES OF SELECTED PLANT LEAF EXTRACT AGAINST PATHOGENIC ENTEROBACTERIACEAE ISOLATES

ABSTRACT

The problem of microbial resistance to drugs is continuously growing. Hence the use of existing antimicrobial drugs in future is still uncertain. Immediate action is therefore required to combat the problem by encouraging researchers to develop new medicines, more so of herbal origin, as synthetic drugs are known to cause side effects. The study was carried out to evaluate the antibacterial and phytochemical properties of selected plant leaf extract against pathogenic enterobacteriaceae isolates. Fresh leaves (waterleaf, bitter leaves and Moringa) were obtained and allowed to air dry before blending to powdered form. Four enteric bacterial pathogens were collected from Microbiology laboratory section of the University of Benin Teaching Hospital. The isolates were re-identified using cultural and biochemical characteristics before they were evaluated for their ability to express phenotypic virulence properties such as production of DNAse, Gelatinase, lipase and hemolysin. Aqueous, ethanol and n-hexane were used as extraction solvents for the plants. The obtained extracts were screened for microbial purity before antibacterial activity was carried out. The minimum inhibitory concentration of the extracts was evaluated using a logarithmic regression model and the minimum bactericidal concentration was assessed using standard procedure. Multiple antibiotic resistance index was evaluated for the isolates. The results revealed that the four (04) bacterial isolates obtained from UBTH were identified to be Escherichia coli, Enterobacter aerogenes, Klebsiella pneumoniae and Salmonella enterica. The isolates were found to be positive for at least one of the four phenotypic virulence properties evaluated in the study. There was no significant antibacterial activity (0.00±0.00 mm) from waterleaf and bitter leaf against the confirmed pathogens as all extraction solvents (except ethanol for Enterobacter aerogenes) were not active. Only Moringa leaf extracts (ethanol and n-hexane) showed significant antibacterial activity against all pathogenic bacteria evaluated in the study. The phytochemical components of the plant extracts were tannins, saponins, alkaloids, flavonoids, and glycosides amongst others. The bacterial isolates were found to be of public health significance because they all had multiple antibiotic resistance index greater than the permissible level of 0.2. Overall, the findings underscore the potential of Moringa leaf extracts as a valuable source of antimicrobial agents and support the need for further research to harness the therapeutic properties of these natural compounds in combating pathogenic bacteria.