Abstract

The emergence of bacterial resistance to antibiotics is a serious draw back in the management of infections. In this study, the antibacterial activity of the methanol fruit and leaf extracts of Myrisctica fragrans Houtt. (Myristicaceae) against typed strains of Staphylococcu saureus, Bacillus suibtilis, Enterococcus faecalis, Proteus vulgaris, Escherichia coli, Salmonella typhi and Pseudomonas aeruginosa were determined using a modified Kirby-Bauer agar well diffusion method. Their influence on the minimum inhibitory concentration of ciprofloxacin, tetracycline, erythromycin and amoxicillin against the test organisms were also determined using themicro-dilution method. The extracts exhibited antibacterial activity against all the test organisms. In the presence of sub-inhibitory concentrations of the leaf and fruit extracts (1.0 and 2.0 mg/mL respectively), the antibacterial activity of amoxicillin against all the organisms was nullified. The antibacterial activity of ciprofloxacin against all the organisms was also cancelled by the fruit extract while the leaf extract acted similarly against all the test organisms except E. faecalis and S. typhiboth of which saw four-fold reduction in susceptibility. The antibacterial activity of erythromycin against all the test organisms were nullified by both extracts except S. aureus and B. subtilis where the leaf extract caused an 8-fold reduction in activity. In the presence of the leaf extract, tetracycline lost activity against S. aureus, P. aeruginosa and P. vulgaris, its activity was reduced 16-fold against B. subtilis and E. faecalis and 32-fold against E. coli. The fruit extract caused a complete loss of activity of tetracycline against S. aureus, P. aeruginosa, B. subtilis and E. faecalis; there was 16-fold, 8-fold and 32-fold reduction in activity against P. vulgaris, S. typhi and E. coli respectively. The extracts of M. fragrans enhanced the resistance of these organisms to all the antibiotics used.

Key words: Antibiotic resistance, antibacterial, resistance enhancing, minimum inhibitory concentration, Myristica fragrans.