Antibacterial Activity of Aqueous and Ethanoic Extracts of Garcinia kola on Enterobacter braakii and Citrobacter cloacae

Abstract

Citrobacter and Enterobacter infections are among diseases of public health concern. This study sought to evaluate the possible antimicrobial activity of aqueous and ethanolic extracts of Garcinia kola on the two test organisms. Collected plant materials were extracted and tested on the isolates following standard microbiological practices. Citrobacter clocae was inhibited more than E. braakii at all levels of the aqueous extracts. Similar effect was produced in ethanolic extracts except 20mg and 60mg where higher ZIs were recorded in E. braakii.  Generally, higher ZIs (>10mm) were observed on C. clocae in both aqueous and ethanolic extracts than on E. braakii.  Aqueous extract had more inhibitory effect on Citrobacter clocae than the ethanolic extracts.  Ciprofloxacin antibiotic gave higher inhibitory effect on C. cloaca than the bitter cola extracts. Bitter cola extracts showed inhibitory properties on the two test organisms under different extracts. Citrobacter cloaca was susceptible to both aqueous and ethanolic extracts of bitter cola at all levels of treatments. Enterobacter braakii tend to be more resistant to the plant extract than the other test organism due to the low zone of inhibition observed especially under aqueous extract of bitter cola. Comparatively, aqueous bitter cola extract had more inhibitory effect on Citrobacter clocae than the ethanolic extracts but ethanolic extracts had more inhibitory effect on Enterobacter braakii than the aqueous extract. Thus, when properly optimized in pharmacological research, bitter cola could be explored as a cheap source of antimicrobial agent in the treatment of bacterial infections.