PCR products of the amplified mefA, aad6, tetM and ampC genes in L.monocytogenes were electrophoresed on an agarose gel.(a)amplified prodcut of mefA gene at 348bp, lane1: Gel Pilot 100 bp ladder, lane 2:postive control, lane3: negative control, lane:5,6 and9 postive isolates. (b) amplified prodcut of aad6 gene at 978bp,lane1: Gel Pilot 100 bp ladder, lane2:postive control, lane(3-10)postive isolates, lane11:negative control. (c) amplified prodcut of tetM gene at 405bp, lane1: Gel Pilot 100 bp ladder, lane2: postive control, lane3: negative control, lane: 4-11postive isolates.(d) amplified prodcut of ampC gene at 550bp,lane1: Gel Pilot 100 bp ladder, lane2: postive control,lane3: negative control, lane:4-11postive isolates