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

• Published in: Letters in applied microbiology Vol. 36; no. 4; pp. 230 - 233
• Main Authors: Neamatallah, A.A.N., Dewar, S.J., Austin, B.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01.01.2003; Blackwell Science
• Subjects: Animals; Bacteriological Techniques; Biological and medical sciences; Colony Count, Microbial; Culture Media; Fish and seafood industries; Fishes - microbiology; Food industries; Food Microbiology; Food Technology - methods; Fundamental and applied biological sciences. Psychology; Humans; Listeria monocytogenes; Listeria monocytogenes - isolation & purification; Listeria monocytogenes - pathogenicity; Listeriosis - etiology; selective isolation; smoked haddock; Selective medium; Smoked fish; Microbiological testing; Listeria monocytogenes; Bacteria; Haddock; Isolation; Biological contamination
• ISSN: 0266-8254; 1472-765X
• DOI: 10.1046/j.1472-765X.2003.01298.x

Aims: The aim of this study was to improve the selective isolation of Listeria monocytogenes from smoked haddock fillets. Methods and Results: Listeria selective agar (LSA) – Oxford formulation was supplemented with 25 μg ml−1 of colistin sulphate and 30 μg ml−1 of nalidixic acid. Inocula from four smoked haddock fillets produced colonies (approx. 2–13 bacteria g−1), identified as L. monocytogenes, on LSA supplemented with antimicrobial compounds (MLSA). Moreover, there was only negligible evidence of bacteria which were not L. monocytogenes on MLSA. In contrast, LSA supported dense bacterial growth, which was not equated with L. monocytogenes. Significance and Impact of the Study: The modified medium permitted the recovery of L. monocytogenes from smoked haddock fillets and reduced the growth of contaminating bacteria.