Microbial Contamination, Antimicrobial Activities of Dissotis rotundifolia Leaf: A Common Ethnomedicine for Ocular Diseases

Abstract

Backgroud: Direct leaf extracts of Dissotis rotundifolia are commonly used in rural settings including Abakaliki, Ebonyi State, Nigeria as  traditional medicine for the treatment of eye injury and related diseases with limited information on the scientific basis of the  microbiological quality/safety of the extract.

Objective: This study investigated the microbial quality, antimicrobial effects of D. rotundifolia direct leaf extract.

Materials and Methods: The extracts were evaluated for microbial contamination and stored for 5 days with daily screening for  microbial quality. Antimicrobial test was assessed by agar diffusion at various concentrations against five clinical isolates namely;   Staphylococcus aureus, Streptococcus pneumoniae, Pseudomonas aeruginosa, Citrobacter freundii and Candida species. Minimum inhibitory  concentration (MIC) and minimum bactericidal concentration (MBC) were also determined.

Results: The findings of the study showed  that D. rotundifolia fresh direct extract was not contaminated by any pathogenic bacteria or fungi until after 2 days of storage. The fresh  extract was significantly (p < 0.05) more contaminated with Aspergillus flavus (20%) and Aspergillus niger (80%) whereas Aspergillus niger  was the only contaminant in the dry extract up to 5 days of storage. The extract significantly (< 0.05) inhibited the growth of all test  organisms with zone of inhibition varying between 4mm (S. Pneumoniae) to 15mm (Candida species). MIC for Candida species was  observed at 500mg/ml and 200mg/ml for other test organisms while MBC was 500mg/ml for other test organisms.

Conclusions: The  findings of this study are supportive of the use of D. rotundifolia extract in the treatment of bacterial-related ocular diseases and  inflammation.