An improved selective isolation medium for the recovery of Listeria monocytogenes from smoked fish

摘要

Aims: The aim of this study was to improve the selective isolation of Listeriamonocytogenes from smoked haddock fillets.Methods and Results: Listeria selective agar (LSA) - Oxford formulation wassupplemented with 25 lg ml)1 of colistin sulphate and 30 lg ml)1 of nalidixicacid. Inocula from four smoked haddock fillets produced colonies (approx. 2-13bacteria g)1), identified as L. monocytogenes, on LSA supplemented withantimicrobial compounds (MLSA). Moreover, there was only negligible evidence ofbacteria which were not L. monocytogenes on MLSA. In contrast, LSA supporteddense bacterial growth, which was not equated with L. monocytogenes.Significance and Impact of the Study: The modified medium permitted the recoveryof L. monocytogenes from smoked haddock fillets and reduced the growth ofcontaminating bacteria.