MOTILE AEROMONAS SPP IN RETAIL VEGETABLES FROM SAO-PAULO, BRAZIL

A total of 90 retail vegetable samples, including lettuce (30), water- cress (30) and escaroles (30), were examined for detection and enumera tion of motile Aeromonas spp. The isolation procedures employed were d irect plating onto starch-ampicillin agar (enumeration) and/or selecti ve enrichment in trypticase-soy broth containing ampicillin (establish ment of positive or negative samples), both involving a 24 h incubatio n period at 28 degrees C. Aeromonas species were detected in 43 sample s (47.8%) and their numbers varied from less than 10(2) to up to 2.0x1 0(6) CFU/g. Water-cress samples presented the highest numbers of Aerom onas spp. Sixteen (37.2%) of the 43 positive samples, 11 of which were water cress, gave counts of 10(4) CFU/g or higher. The number of wate r-cress positive samples (70.0%) was significantly higher (p<0,05) tha n that of lettuce (43.3%) and of escarole (30.0%). No significant diff erences were found between both methods of detection of Aeromonas spp. when lettuce and water-cress were analysed. For escarole samples, how ever, positivity was significantly greater after selective enrichment. Of the 143 strains isolated and identified as Aeromonas spp., 138 wer e A. caviae (96.5%), 4 were A. hydrophila (2.8%) and 1 (0.7%) was cons idered atypical due to its different biochemical profile. Results show that the vegetables examined might constitute a health hazard to cons umers due to the frequency of detection of motile Aeromonas spp. and t o the numbers present in positive samples.