Isolation and Identification of Bacterial Contaminants in Selected Soup Thickeners: Achi (Brachystegia eurycoma) and Cocoyam Powder (Colocasia esculenta) from Markets in Enugu Metropolis, Nigeria

Abstract

Background: Traditional Nigerian soup thickeners Achi (Brachystegia eurycoma) and cocoyam powder (Colocasia esculenta) are widely consumed yet are often produced, processed, and marketed under conditions of limited hygiene control. Consumer complaints of gastrointestinal disturbances following their use and a lack of microbiological safety data on these commodities constitute a significant public health gap. Aims: The present study aimed to isolate, identify, and determine the antimicrobial susceptibility patterns of bacterial contaminants in Achi and cocoyam powder sold in selected markets in Enugu metropolis, Nigeria. Methodology: A laboratory-based cross-sectional study was conducted on 100 samples collected from open markets across the three local government areas of Enugu metropolis. Bacterial isolation was performed using peptone water enrichment followed by culture on nutrient agar, MacConkey agar, and blood agar. Identification of pure isolates used colonial morphology, Gram staining, and standard biochemical tests. Antimicrobial susceptibility testing was carried out by the Kirby–Bauer disc diffusion method and interpreted according to CLSI breakpoints. Data were analysed using SPSS version 26.0 with significance set at p < 0.05. Results: A total of 242 bacterial isolates representing 14 species were recovered. The overall distribution was statistically non-random (p = 0.008). Bacillus cereus was the most prevalent isolate (26.9%), followed by Staphylococcus aureus (20.7%) and Pseudomonas aeruginosa (16.5%). Proteus vulgaris distribution differed significantly between the two thickeners (p = 0.042). Widespread antimicrobial resistance was detected, including multidrug-resistant profiles, particularly among Gram-negative isolates. Conclusion: Achi and cocoyam powder sold in Enugu markets are contaminated with diverse pathogenic and multidrug-resistant bacteria, reflecting systemic hygiene deficiencies during processing and vending. Improved hygiene standards, routine microbiological surveillance, and strengthened food safety regulation are urgently required.