Detection of inhibitors in milk by microbial tests A review

Abstract

The demands concerning microbial inhibitor tests were subjected to marked changes during the last decades: It started with the claim of being able to detect contaminated milk which might cause problems during fermentation processes ('technological safety'). Due to the present day attention drawn to toxic and allergic hazards for numerous antimicrobials Maximum Residue Limits (MRLs) or safe/tolerance levels are fixed ('toxicological safety'). This means a variety of demands underlying permanent changes with respect to the 'detection pattern' which cannot be fulfilled by a single test. Within an Integrated Detection System microbial inhibitor tests play an important role as screening methods for those antimicrobials which can be detected with satisfactory sensitivities. This paper deals with some features of microbial inhibitor tests such as detection limits, performance susceptibility for interference factors, qualitative determination and standardization.

Comparative Examination of the Analysis of β-Lactam Antibiotic Residues in Milk by Enzyme, Receptor–Enzyme, and Inhibition Procedures

“…Results can differ when milk samples are analyzed by different methods even if tests have very similar designs because the LOD could differ in 1, 2, or more ng/g (Suhren and Heeschen 1996). The test may also yield false-positive results.…”

“…Screening tests must satisfy the following requirements: they must detect antibiotics of interest such as β-lactams in the dairy products industry, detection limits must comply with the requirements (MRLs), they must be easy to perform and cost effective, the test results are to be obtained rapidly, and the tests must be standardized (low variability within and between batches/laboratories) (Suhren and Heeschen 1996).…”

Microbial screening methods for detection of antibiotic residues in slaughter animals

“…The presence of antimicrobial residues will prevent or delay bacterial growth, and thus is indicated by the absence or delay of the color change . This format is commonly applied in routine screening of milk [3, 4], but it is also increasingly used for analysis of other matrices [5–7]. A plate test consists of a layer of inoculated nutrient agar, with samples applied on top of the layer, or in wells in the agar.…”

Performance of a New Microbial Test for Quinolone Residues in Muscle

“…Most of these tests use Geobacillus stearothermophilus as an indicator strain. However, screening tests employing this microorganism are not able to detect quinolones at violative levels in foods because of their poor sensitivity to these antimicrobial compounds (Cullor 1992;Suhren and Heeschen 1996). Consequently, additional testing is required to ensure that the whole antibiotic spectrum is adequately covered.…”