Microbial Contamination and Food-Safety Relevance of Plate-Mill Surfaces Used for Food Grinding in Informal Markets in Yaoundé, Cameroon

Plate mills in informal food markets may harbour microorganisms and pose potential cross-contamination risks. This study assessed microbial contamination and potential contributing factors in seven markets in Yaoundé from October to December 2024. Forty swabbed funnels and 40 stirrers were analysed for aerobic colony counts (ACC), total coliform counts (TCC), faecal coliform counts (FCC), staphylococcal counts (SC) and fungal counts (FC). Bacterial isolates were characterized biochemically, including API 20E. Linear mixed-effects models identified significant market effects for ACC, FCC, SC and FC (p < 0.001), but not TCC (p = 0.052). Overall surface effects were not significant, while market-by-surface interactions were significant for SC (p = 0.022) and FC (p = 0.008). Of 204 bacterial isolates, 92 were Enterobacteriaceae (41 from funnels and 51 from stirrers). Proteus vulgaris was the predominant presumptively identified Enterobacteriaceae on both surfaces. Staphylococcus epidermidis comprised 90% of funnel and 80% of stirrer isolates. Method (3.85 ± 0.48) and Milieu (3.75 ± 0.74) had the highest 5M scores. Water alone was used for morning cleaning in 90.0% of mills, and cleaning was non-systematic in 90.0%. These findings support improved hygiene practices and microbiological monitoring. Further research should assess microbial transfer to food and evaluate sanitation interventions.