COMPARISON OF THE MICROBIAL QUALITY OF RAW SHRIMP FROM CHINA, ECUADOR, OR MEXICO AT BOTH WHOLESALE AND RETAIL LEVELS

Aerobic plate counts (APC), Listeria spp., and Vibrio spp. and antibiotic resistance patterns of Vibrio spp. were determined for imported shrimp from China, Ecuador, and Mexico obtained from wholesale/frozen and retail/previously frozen markets. Statistically significant differences in APC were observed among source countries and wholesale/frozen versus retail/previously frozen samples. Wholesale/frozen shrimp products were consistently excellent quality with respect to APC; higher contamination levels were observed in retail/previously frozen samples. Listeria spp. and L. monocytogenes were isolated from 16.7 and 6.7% of shrimp samples, respectively. Vibrio spp. were present in 63.3% of the samples, more often isolated from shrimp from Mexico or China than Ecuador. The majority of isolates were identified as V. parahaemolyticus (36.7%), V. alginolyticus (26.7%), or V. vulnificus (16.7%), and 53.7% were resistant to at least one antibiotic. These data reveal that important differences in microbial quality occur in raw shrimp products as a function of source and between retail and wholesale products.