Optimization of microbiological plastic film test plate conditions for rapid detection of antibiotics in milk

Food safety and quality are issues of great concern to food producers and consumers. Key challenges towards achieving these include availability of rapid, user-friendly, economic and reliable techniques to detect problems such as antibiotic residues. Therefore, the present study was conducted to evaluate performance of plastic film test plate (PFTP) as influenced by antibiotic type, test bacterium, inoculum volume and concentration. Comparison was made to the microtiter test plate (MTP) and the National Standard method (SN/T 3979-2014). For this, antibiotic susceptibility testing was conducted on four bacterial types ( Micrococcus luteus , Streptococcus thermophillus suspensions, Staphylococcus aureus and Coliform bacteria ) against three antibiotics (penicillin G, sulfadiazine and tetracycline). Results showed high susceptibility of Micrococcus luteus to penicillin G with minimum inhibitory concentration of 3 µg L −1 and 1 µg L −1 via PFTP and MTP respectively. Optimum performance was realized at bacterial concentration of 10 4 CFU ml −1 with detection limit of 1 µg L −1 , sensitivity and predictive positive value (PPV) of 81–83% and 97–100% respectively. Detection time was recorded as 6 and 9 h for MTP and PFTP respectively compared to the 18–24 h of the National Standard method (SN/T 3979–2014). The microbiological plastic film test plate under optimized bacterial culture conditions demonstrated tremendous potential for rapid and reliable detection of antibiotics in milk.