INCIDENCE OF LISTERIA SPECIES IN RAW AND PASTEURIZED MILK PRODUCED INSAO-PAULO, BRAZIL

The present study evaluated the incidence of Listeria spp. in Taw and pasteurized milk from a Brazilian dairy plant. Ten samples of each typ e of milk (raw types B and C and pasteurized types B and C) were colle cted monthly from October 1989 to September 1990 (except in December), comprising 440 samples (110 samples of each type of milk). The recove ry of Listeria spp. was carried out using LPM (lithium chloride phenyl ethanol moxalactam) and MOX (modified Oxford) agars, after a two-step enrichment procedure in Listeria enrichment broth (LEB) and Fraser bro th. Overall, 12.7% of raw milk samples, 0.9% of pasteurized milk sampl es and 6.8% of total of milk samples were positive for Listeria spp., while 9.5% of raw milk samples, none of the pasteurized milk samples a nd 4.8% of total milk samples, were positive for Listeria monocytogene s. Raw milk also contained L. innocua (9.5%), L. welshimeri (0.9%) and L. grayi (0.4%). Pasteurized milk contained only L. innocua (0.9%).