Microbiological screening method for detection of aminoglycosides,ß-lactames,macrolides,tetracyclines and quinolones in meat samples

Antibiotics are natural products of a micro-organism, identical synthetic products or similar semi synthetic products that inhibit the growth of or destroy microorganisms. In veterinary medicine antibiotics are used for therapeutic, prophylactic, metaphylactic and nutritive purposes. The presence of antibiotics or their metabolites in food is potentially hazardous to health as it may cause allergic reactions in people and antibiotic resistance in pathogenic microorganisms. In addition antibiotics may influence starter cultures in food industry and lead to economic damage. The methods used to detect antibiotic residues in food of animal origin are microbiological, immuno-enzymatic and chemical. Microbiological methods are used as screening methods whose results direct the choice for more expensive and time consuming chemical confirmation methods. To serve this purpose the sensitivity of a microbiological method must be at or below the prescribed maximum residue level (MRL) for specific antibiotic group. The purpose of our study was to develop a microbiological method for detection of macrolide, aminoglicoside, β-lactame, quinolone and tetracycline antibiotic families in meat by identifying the most appropriate set of bacterial test strains and to establish the limit of detection for each antibiotic group. Micrococcus luteus ATCC 9341 was selected as the most appropriate sensitive strain for detection of macrolides and β-lactams, Bacillus subtilis BGA for aminoglicosides, Bacillus cereus ATCC 11778 for tetracyclines and E. coli ATCC 10536 for quinolones. In addition magnesium sulphate was used to inactivate aminoglicosides beta-lactamase to differentiate between macrolides and beta-lactames. For all antibiotic groups the level of detection was below the MRL.