Abstract
Different agar diffusion methods were compared in order to find a sensitive method for the detection of various antimicrobial residues in milk. A total of 588 producer milk samples were analyzed using subsets of the most sensitive methods.
With the IDF method, 2 positive cases (0.34 %) appeared among the producer milk samples, with the Thermocult method 13 positive cases (2.21 %) and with the Test agar pH 8 method with trimethoprim and glucose 4 positive cases (0.68 %). A combination of the IDF method and the Test agar pH 8 method resulted in 6 positive cases (1.02 %) and a combination of the Thermocult method and the Test agar pH 8 method in 17 positive cases (2.89 %). With penicillinase 41 % of the positive cases were identified as β-lactam antibiotics and with p-aminobenzoic acid 18 % of the positive cases were identified as sulphonamides. 41 % of the positive cases remained unexplained.
The best combination for the detection of antimicrobial agents in milk seems to be that of the Thermocult method and the Test agar pH 8 method with trimethoprim and glucose.
Sammanfattning
I undersökningen jämfördes olika agar-diffusions metoder för att firma en sensitiv metod för att upptäcka olika antimikrobiella rester i mjölk. 588 prover av producentmjölk analyserades med de mest sensitiva metoderna.
I proverna på producentmjölk upptäcktes 2 positiva fall (0.34 %) med IDF-metoden, 13 positiva fall (2.21 %) med Thermocult-metoden och 4 positiva fall (0.68 %) med Test agar pH 8-metoden med trimetoprim- och glucos-tillsatser. En kombination av IDF-metoden och Test agar pH 8-metoden resulterade i 6 positiva fall (1.02 %) och en annan kombination av Thermocult-metoden och Test agar pH 8-metoden resulterade i 17 positiva fall (2.89 %). Med penicillinas blev 41 % av de positiva fallen identifierade som β-lactam antibioter och med paminobenzoicsyra kunde 18 % av de positiva fallen påvisas vara sulfonamider. 41 % av de positiva fallen förblev oidentifierade.
Den bästa kombinationen för att upptäcka antimikrobiella rester i mjölk värkade vara en kombination av Thermocult-metoden och Test agar pH 8-metoden med trimetoprim- och glukos tillsatser.
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Footnotes
This work was partly supported by the Walter Ehrström Foundation, Helsinki, Finland.
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