PHYTOCHEMICAL ASSAY AND ANTIBACTERIAL APPRAISAL OF METHANOLIC LEAF EXTRACTS OF BORRERIA VERTICILLATA AND AGERATUM CONYZOIDES AGAINST MDR NOSOCOMIAL PATHOGENS

Abstract

In a bid to find solution to the global menace of antibiotic resistance, the current work attempts to explore the phytochemical composition and validate the antibacterial potential of methanolic leaf extracts of B. verticillata and A. conyzoides against nosocomial pathogens. The test organisms namely Klebsiella pneumoniae, Acinetobacter baumannii and Enterococcus faecalis were collected from Microbiology laboratory, Nigerian Navy Reference Hospital, Calabar, Nigeria. The bacteria were authenticated by standard microbiological methods. Multi-drug resistance attribute of the organisms was determined by Kirby Bauer disc diffusion technique. Methanol was used as solvent for plants’ extraction by the aid of Soxhlet apparatus. Phytochemical evaluation was carried out using standard protocol and subjected to GC-MS analysis. The in vitro antibacterial potentials of the plants’ extracts were investigated against the bacterial isolates using agar well diffusion technique. Results revealed the presence of saponins, alkaloids, cardiac glycosides, flavonoids, steroids, tannins, phenols and volatile oils in the methanolic leaf extract of B. verticillata. Also, extract of A. conyzoides indicated the presence of alkaloids, cardiac glycosides, saponins, flavonoids, phenols, volatile oils and tannins. GC-MS investigation showed the detection of hexadecenoic acid, methyl ester, 11-0ctadecanoic acid, methyl stearate, 9-octadecanamide, 1,2-benzenedicarboxylic acid and butyl-2-ethylhexyl ester in A. conyzoides. The major components detected in B. verticillata leaf extract were 1.2-15,16-dieoxyhexadecane, 1,2-benzenedicarboxylic acid, butyl 2-ethyhexyl ester, hexadecenoic acid, 2,3-bis (trimethyl islyl) oxyl propyl ester, 9-octadecenamide, 2-ethylbutyric acid and eicosyl ester, 3-tetradecanol. It was observed that K. pneumoniae was resistant to amoxicillin, ofloxacin and clindamycin with a percentage drug resistance rate of 3(21.43%). A. baumannii was resistant to eight (8) antibiotics including vancomycin, amoxicillin+clavulanic acid and had percentage drug resistance rate of 8(53.43%). E. faecalis was resistant to five (5) antibiotics including vancomycin, amoxillicin and ciprofloxacin while the percentage drug resistance rate was 5(35.71%). The results established the fact that the bacterial isolates exhibited multidrug-resistance. B. verticillata leaf extract inhibited bacterial growth producing zone sizes ranging from 7.7 to 17.4mm. Antibacterial activity of A. conyzoides against the organisms revealed lesser zone sizes (9.6 to 14.1mm) with A. baumannii having the least zone size (12.6mm) at 100% concentration. Therefore, it can be concluded that B. verticillata and A. conyzoides present remarkable potential of producing significant plant-derived pharmaceuticals against multidrug-resistant nosocomial pathogens.