Lab M has launched an enrichment broth to help reduce Listeria culture times and optimise samples for downstream testing.
The Listeria Express Enrichment (LEE) Broth is an enrichment medium that can be used prior to enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR) testing.
The firm said there is a trend in the food industry towards faster Listeria reporting to enable earlier product release.
The broth enhances expression of target antigens and adds to detection and isolation as it improves the growth rates of the pathogen.
Lisa Green, product manager at Lab M told FoodQualityNews.com that like for other pathogens, standardised protocols dictate Listeria isolation methods.
“Traditionally, Listeria is isolated by means of a two-stage selective enrichment, followed by plating out on selective media followed by a final confirmatory test. This is a time-consuming process and may take up to five days for a confirmed result.
“A proprietary mix of peptones and growth enhancers enable LEE Broth to stimulate high growth levels as well as enhancing the expression of antigenic material from relatively low numbers of organisms, within 24 hours.”
It is formulated to stimulate growth from low numbers of organisms in the original sample to achieve the required levels for further testing within a 24-hour incubation period.
The broth can be used for enrichment prior to plating on selective media such as Harlequin Listeria Chromogenic Agar and it is effective as a secondary selective enrichment broth following primary enrichment in Half Fraser Broth, said Lab M.
Green said that the broth offers a versatile solution that can maintain suppression of non-target organisms.
“It can be used as: an enrichment broth prior to plating on selective media; as a secondary selective enrichment medium following primary enrichment; or as the enrichment step of a rapid method e.g. ELISA, lateral flow device, PCR.
“Non-target organisms may yield false-positive results or weaken a positive signal and it’s therefore important to suppress their growth.”
Lab M for Listeria testing includes Harlequin Listeria Chromogenic Agar, available as dehydrated culture medium or as ready-to-use prepared plates; enrichment media for use in different protocols; Listeria Isolation Medium, Oxford (ISO) and Listeria Monocytogenes Blood Agar (LMBA).