ABSTRACT
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. vulniftcus (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.