Antimicrobial Resistance and Virulence Profiles of Staphylococcus aureus and Escherichia coli Strains Isolated from Tchakpalo: A Traditional Beninese Beer

Abstract

Background and Aim: Tchakpalo is an emblematic traditional beer within Benin's brewing heritage, and its artisanal production processes may favour contamination by potentially pathogenic and spoilage bacteria. This study evaluated the antibiotic resistance profiles and selected virulence factors of S. aureus (n = 50) and E. coli (n = 40) strains isolated from Tchakpalo. Study Design and Methodology: Antibiotic susceptibility was evaluated using the Kirby-Bauer disc diffusion method according to CA-SFM and CLSI recommendations. Virulence factors, including biofilm-forming capacity, haemolytic activity and extended-spectrum beta-lactamase (ESBL) production, were determined using standardised phenotypic methods. Results: Both bacterial species exhibited resistance to several antibiotics. S. aureus strains showed high resistance (≥70%) to ampicillin, erythromycin, clindamycin and kanamycin. In contrast, low resistance (≤30%) was observed for linezolid, quinupristin-dalfopristin, vancomycin, ciprofloxacin and rifampicin. All E. coli strains were resistant to ampicillin, ertapenem and fosfomycin. Resistance to amoxicillin-clavulanic acid and aztreonam was 90% and 75%, respectively, whereas resistance to gentamicin was 17.5%. Strong biofilm-forming capacity was observed in 74% of S. aureus and 47.5% of E. coli strains. The β-haemolytic phenotype predominated in both species, occurring in 62% of S. aureus and 55% of E. coli strains. Furthermore, 37.5% of E. coli strains produced ESBLs. Conclusion: Tchakpalo may harbour antimicrobial-resistant bacteria with phenotypic characteristics associated with persistence and virulence. These findings support the need to strengthen hygiene practices throughout production and to implement appropriate surveillance to improve consumer food safety.