Assessment of bacterial contamination and antibiotic resistance in traditional yogurt marketed in Xai-Xai and Chokwe districts of Gaza province

Abstract

Antimicrobial resistance (AMR) is a profound threat to worldwide health and development. This crisis is driven by the overuse of antibiotics in livestock to boost growth and prevent disease. This misuse creates resistant bacteria that can transfer to humans, making infections difficult or impossible to treat. The objectives of this research was to assess the bacterial contamination and antibiotic resistance profiling of locally fermented yogurts. Bacterial contamination and AMR prevalence was assessed through 41 samples collected from the informal market in Xai-Xai and Chókwè districts of Gaza provinces of Mozambique. Yogurt samples were examined regard to lactic acid bacteria and microorganisms of food safety concern (Staphylococcus aureus and Echerichia coli) using selective media. The purified isolates were identified and confirmed by gram-staining and biochemical assay. Antimicrobial susceptibility was evaluated using the Kirby-Bauer disk diffusion method following CLSI guidelines. Statistical analysis was performed using STATA version 15. Statistical analysis was performed using descriptive statistics, chi-square test. The findings showed that a total of 60 isolates were obtained. Lactic acid bacteria were detected in all yogurt samples (100%), with mean log count of 3.8 and 3.7 in natural and sweet yogurt, respectively. Pathogenic bacteria were also detected, with Staphylococcus aureus present in 39% (16/41) of samples and Escherichia coli in 7.3% (3/41). Chókwè district showed the highest prevalence of contamination, with 42.8% of samples positive for S. aureus and 14.3% positive for E. coli. Antibiotic susceptibility assay revealed high resistance among LAB isolates above 90% in tested antibiotics. All E. coli isolates were resistance to penicillin 3/3 (100%) and susceptible to both ampicillin and ciprofloxacin (100%). Notably, 66.7% of the isolate demonstrated intermediate susceptibility to tetracycline. S. aureus isolates indicated the highest resistance to penicillin (68.8%), while most remained susceptible to ampicillin, gentamicin, and tetracycline (75%). In Chókwè, resistance was presented in 66.7% of isolates for penicillin & tetracycline, 50.0% of isolates for lest of tested antibiotics. In Xai-Xai, penicillin resistance was observed in 70.0% of isolates, whereas resistance to rest tested antibiotics was 10.0%. The mean Multiple Antibiotic Resistance (MAR) index was highest in LAB (0.8), followed by S. aureus (0.40) and E. coli (0.27). It was concluded that in general LAB count was low, pathogenic bacteria was present and high prevalence of resistance profile was obtained in these products which pose a significant public health concern.