Comparison of detection sensitivity of five microbial inhibition tests for the screening of aminoglycoside residues in fortified milk

The assessment of detection sensitivity of five microbial inhibition tests (MITs), STAR (screening test for antibiotic residues) with the test strain Bacillus subtilis BGA, Delvotest® S P-NT, Total Antibiotics, Kalidos TB, and Kalidos MP with the test strain Bacillus stearothermophilus var. calidolactis to five aminoglycosides (AMGs), gentamicin, neomycin, streptomycin, kanamycin, and spectinomycin in fortified milk samples were studied. The sensitivity of MITs to AMGs was evaluated on the basis of experimental determination of detection limits (LODs) of MITs for AMGs. The LODs of these tests were compared with the maximum residue limits (MRLs) established for milk by the Commission Regulation (EU) No. 37/2010. LODs of STAR for AMGs in fortified milk samples were at the levels of MRL for neomycin (1.50 µg/g), gentamicin (0.10 µg/g), streptomycin (0.20 µg/g) and kanamycin (0.15 µg/g). Spectinomycin (0.20 µg/g) was not detected at the level of MRL. The LODs determined by Delvotest® SP-NT, Total Antibiotics and Kalidos MP were comparable, but only gentamicin and neomycin were reliably detected at the levels of MRL. Kalidos TB was more sensitive to AMGs than Delvotest® SP-NT, Total Antibiotics and Kalidos MP. Gentamicin, neomycin and streptomycin were detected at the levels of MRL.