A microbial inhibition assay in microplates using Bacillus licheniformis for detection of enrofloxacin and sulfamethazine in chicken spiked kidney, liver and muscle tissues.

BACKGROUND:The presence of antimicrobial drugs residues in animal products at levels higher than the maximum residue level (MRL) may have adverse effects on consumer health such as allergic reactions and resistance development. Therefore, it is necessary to monitor animal products for the presence of antimicrobial residues. OBJECTIVES:The aim of this study was to evaluate the detection limit of microbial inhibition assay (MIA) in microplate by using of Bacillus licheniformis as indicator microorganism for two antibiotics, enrofloxacin (ENR) and sulfamethazine (SMT), in broiler chicken's kidney, liver and muscle tissue samples. METHODS:Spiked tissues samples for the two antibiotics were analysed separately by this method. The results of the assay were evaluated by the determination of the absorbance after mean 3.47 h of incubation at 45°C. RESULTS:Results showed that the detection limits of MIA for ENR and SMT in kidney (124.03 and 23.21 μg/kg, respectively) and liver (90.02 and 62.03 μg/kg, respectively) as well as SMT in muscle (46.95 μg/kg) were lower than EU (European Union) - MRL, whereas the detection limit for ENR in muscle was slightly higher than MRL (136.3 μg/kg compared to 100 μg/kg MRL). Furthermore, the MIA in the current study was found to be more sensitive to SMT than ENR (92% and 88% sensitivity rate, respectively). No false-positive was observed in the assay. CONCLUSIONS:Based on the results, the MIA investigated in this study had the potential to detect ENR and SMT residues in broiler chicken kidney, liver and muscle tissues at levels below or close to EU - MRL but offered lower capability for the detection of ENR compared with SMT in kidney and muscle tissue samples.