Evaluation of immunomagnetic separation by Dynabeads anti-Listeria as a tool to reduce the detection time of Listeria spp. in cheese

An immunomagnetic separation (IMS) method was evaluated, for the detection of Listeria spp. in cheese, by comparison to the reference method ISO 11 29 0-1. The IMS-involving method took three days, compared to 5 days of the re ference method, and it is based on the immunomagnetic separation by Dynabea ds anti-Listeria. When artificially contaminated samples of cottage cheese, parenica and bryndza (with decimal dilutions of a Listeria monocytogenes c ulture or with a reference material containing on average 5 ufc of L. monoc ytogenes) were analysed, controversial results for the IMS method were obta ined. Such results have been obtained also from the analyses of naturally-c ontaminated samples of raw ewe's cheese, bryndza and Olomoucke tvaruzky. Th e presented results indicate that the IMS method is inferior to the referen ce one for the detection of Listeria spp. in certain types of cheese.