The influence of commonly used selective agents on the growth of Listeria monocytogenes

The effects, upon addition of various selective agents to a rich growth med ium (BHIEM) on the growth of Listeria monocytogenes and non-listeria were s tudied in microtitre wells. A combination of nalidixic acid (0.1 g/l), acri flavine (0.02 g/l) and fosfomycin (0.1 g/l) added to the medium (BHIEMNAF) was found to be the least inhibitory to Listeria while at the same time, ef fectively inhibitory to non-listeria organisms. Recovery of heat injured Li steria monocytogenes in BHIEM, BHIEMNAF and the two traditional Listeria-me dia, UVM I and II, was compared. Recovery in BHIEM was obtained within 24 h of incubation at 30 degrees C, whereas recovery in BHIEMNAF took up to 48 h. Growth and recovery in UVM I and II never reached the same level as in B HIEM or BHIEMNAF. (C) 1999 Elsevier Science B.V. All rights reserved.