Sensitivity of microbial inhibition assay for screening antibiotic residues in retailed meats collected from the public market of Kabacan, Cotabato, Philippines

The threat of antibiotic residues imposes a great concern in public health and at the same time in food safety. This study was conducted to screen antibiotic residues in retailed meats and evaluate the antibiotic sensitivity of indicator test organisms (Bacillus subtilis & Staphylococcus aureus). A total of 125 samples from three different types of meats (beef, chicken, and pork) were collected from the Public Market of Kabacan, Cotabato. Microbial Inhibition Assay utilizing B. subtilis and S. aureus was used for screening antibiotic residues. The total percentage of positive samples was 14.4%. The highest percentage was detected in chicken (22%) followed by beef (16%) and pork (6%), respectively. In evaluating the antibiotic sensitivity of test organisms, Bacillus subtilis detects Amoxicillin, Enrofloxacin, Tetracycline, and Oxytetracycline up to its maximum residual limits. There was no significant difference in beef (p > 0.05) and pork samples (p > 0.05) for the detection of antibiotics by the indicator organisms, while in chicken, the analysis revealed that the antibiotic sensitivity of test organisms was significantly different (p = 0.021). Hence, B. subtilis was ideal test organism than S. aureus (p<0.05). The binomial Logistic regression model also further suggests that B. subtilis was likely to be sensitive in detecting antibiotic residues in all meat types (B = -1.23, OR = 0.29, p = 0.013).