Acquisition of Antibiotic Resistance in Escherichia coli Exposed To a Locally Produced Herbal Drug

Background: Antimicrobial resistance poses great threats to the treatment and eradication of pathogenic microbes. An increasing number of infectious diseases are now becoming difficult to treat in the developing world, but the root of the problems is vaguely known.

Aims: This study aimed at determining the phenotypic properties of Escherichia coli isolates exposed to a locally prepared drug, usually called Goko Alcoholic Bitters (GAB), a commonly consumed herbal medication in Nigeria.

Methods: In order to determine GAB-induced resistance the antimicrobial efficacy of GAB against E. coli isolates was first determined using the disc diffusion method and was compared to a control (Ampicillin). A growth response assay was performed to monitor the response of E. coli exposed to GAB and analyzed by bacterial count on nutrient agar as well as using a spectrophotometer to measure optical density. Finally, GAB-treated E. coli was investigated for drug resistance acquisition using antibiotic discs.

Results: Different concentrations of GAB did not show considerable zones of inhibition compared to the Ampicillin (30 µg) control. The effects of GAB on growth of E. coli showed that the highest concentration (neat concentration = 0.036 g/ml) of GAB inhibited growth of E. coli, but did not completely eliminate bacteria (bacteriostatic). Antimicrobial susceptibility testing of surviving E. coli isolates previously exposed to different concentrations of GAB showed significantly reduced sensitivity (P-value=0.01) to Ampicillin compared to untreated E. coli. This implies that resistance has been induced in bacteria by GAB.

Conclusion: This study suggests the possibility of GAB conferring resistance of some Gram-negative such as E. coli against some antibiotics like Ampicillin.