were conducted on 10 types of fresh produce from two Minneapolis area supermarkets to detect Listeria spp. The produce included broccoli, cabbage, carrots, cauliflower, cucumbers, lettuce, mushrooms, potatoes, radishes, and tomatoes. The vegetables were tested by the Food and Drug Administration method for isolation of Listeria spp., with the addition of LiClphenylethanol-moxalactam agar in the last 280 tests; 8.6 and 11.4% of these tests were positive by modified McBride and LiCl-phenylethanol-moxalactam agars, respectively. Listeria monocytogenes was isolated from cabbage, cucumbers, potatoes, and radishes; L. innocua was isolated from cucumbers, lettuce, mushrooms, potatoes, and radishes; L. seeligeri was isolated from cabbage and radishes; and L. welshimeri was isolated from cucumbers, potatoes, and radishes. The isolates were of various serotypes; however, the L. monocytogenes isolates were predominantly serotype 1 (82%). Only potatoes (25.8% positive) and radishes (30.3% positive) showed significant amounts of L. monocytogenes contamination.

METHODS & MATERIALSThe fluorogenic 4-methylumbelliferone glucuronide (MUG) test for identifying and enumerating Escherichia coli was compared with the standard most probable number method described in the Official Methods of Analysis of the Association of Official Analytical Chemists. Pecan nutmeats, frozen headless shrimp, and chicken pot pies were seeded with high, medium, and low numbers of viable E. coli organisms ranging from 15 to 500 CFU/g. Twelve replicate units of each food at each seeding level were analyzed by both methods. A statistical evaluation indicated that the MUG method yielded significantly (a = 0.05) higher recovery in three of nine comparisons. The MUG method ranged from 22% lower to 92% higher than the AOAC geometric mean. The MUG method has the potential for reducing analytical time, labor, and media usage.