Determination of Anti-Pseudomonal Activities of Cocoa (Theobroma cacao) Pod Husk using Time-Kill-Test and Agar-Well Diffusion Techniques

Aim: To determine the antimicrobial effectiveness of cocoa pod husk against P. aeruginosa.

Study Design: An experimental research

Place and Duration of Study: Department of Medical Microbiology, Olabisi Onabanjo University Teaching Hospital, Sagamu, Ogun State, Nigeria, between June 2015 and Sept. 2016.

Materials and Methods: Seventy-seven (77) isolates of P. aeruginosa obtained from three (3) teaching hospitals were involved in this study. Cocoa pod husk was processed into crude extract and its effectiveness against the isolates of P. aeruginosa were examined using agar well diffusion, time-kill test techniques and Anova.

Results: The percentage susceptibility of P. aeruginosa to Cocoa pod husk at 500 mg/mL and 250 mg/mL inhibited all the P. aeruginosa but only 14.29% were sensitive at a lower concentration of 31.25 mg/mL. Moreover, the comparison between the broth micro and macro dilution method of determining the MIC of cocoa pod husk against P. aeruginosa highlighted a significant decrease in the mean MIC value of the broth micro dilution method when compared with the broth macro dilution technique (T=13.519, P<0.05). The time kill test emphasized that P. aeruginosa was killed at a lower concentration of 62.5mg/ml at 150mins of introduction in to the Cocoa pod husk suspension.

Conclusion: This study revealed that the Cocoa pod husk possesses antibacterial properties. An increase in the concentration of cocoa pod husk increased its antibacterial activity against Pseudomonas aeruginosa. Moreover, the broth micro dilution technique is sensitive for determining the anti-pseudomonal activity.