Detection of antimicrobial residues in camel milk - suitability of various commercial microbial inhibitor tests as screening tests

摘要

The applicability of six commercially available inhibitor tests for camel milk was determined in a comparative study. 259 milk samples collected from untreated camels were tested using the Delvotest SP and various versions of the brilliant black reduction test (BR-Test "AS Special", BR-Test "AS Brilliant", BRT-lnhibitor Test, BRT-lnhibitor Test with prediffusion and BRT MRL-Screening Test). The occurrence of unspecific reactions (specificity) and the sensitivity against common antimicrobial compoundswere assessed. According to German Official Methods of Analysis L 01.00-11 and L 01.00-51-EG the BRT-lnhibitor Test with prediffusion indicated negative results for all samples when the control milk turned yellow, the BR-Test "AS Special" resulted in anearlier colour change. Four test systems (BR-Test "AS Brilliant", BRT-lnhibitor Test, BRT MRL-Screening Test and Delvotest SP) indicated positive - unspecific - results when the tests were evaluated, at the same time the negative control sample showed acomplete colour change. However, extension of the incubation period led to negative results for 100 % (BRT-lnhibitor Test and Delvotest SP), 95 % (BR-Test "AS Brilliant") and 89 % (BRT MRL-Screening Test) of the samples, respectively. The sensitivitiesagainst most of the antimicrobials tested in camel milk did not significantly differ from those determined in cow milk.