OPTIMIZATION OF HEMOLYSIS IN ENHANCED HEMOLYSIS AGAR (EHA) - A SELECTIVE MEDIUM FOR THE ISOLATION OF LISTERIA-MONOCYTOGENES

The presence of Listeria monocytogenes in enrichment media can be mask ed by faster growth of other Listeria spp. Therefore, enhanced haemoly sis agar (EHA) is a good alternative for another isolation media, beca use the presence of a few L. monocytogenes colonies can be detected in a majority of colonies of other listeriae on the basis of haemolysis. In this study the haemolysis reaction in EHA was optimized. In a coll aborative study using reference samples, no significant differences in counts on EHA, Palcam and Oxford agar were shown.