The occurrence of antibiotic-resistant bacteria in foods of animal origin is a potential health threat because resistance can be transferred among bacteria, and antibiotic-resistant pathogens may not respond to antibiotic treatments. Thirteen brands of ready-to-eat shrimp representing four countries of origin were obtained from local grocery stores. Total heterotrophic plate counts were determined, and antibiotic-resistant bacteria were isolated. Total heterotrophic colony counts ranged from 3.3 to 5.6 log CFU/g, which was within approved quality limits. A total of 1,564 isolates representing 162 bacterial species were recovered during screening of resistance to 10 antibiotics: ampicillin, ceftriaxone, chloramphenicol, clindamycin, erythromycin, nalidixic acid, streptomycin, tetracycline, trimethoprim, and vancomycin. Six hundred fifty-seven (42%) of the isolates and 131 (81%) of the species had acquired resistance to antibiotics. Numerous resistant human pathogens were isolated, including Escherichia coli, Enterococcus spp., Salmonella, Shigella flexneri, Staphylococcus spp., and Vibrio spp. Nonresistant Yersinia spp. also were isolated. Ready-to-eat shrimp is sold with instructions to thaw the product before serving, which may result in consumer exposure to antibiotic-resistant bacteria. Widespread trade of this product provides an avenue for international dissemination of antibiotic-resistant pathogens.

Chlorine, iodophor, and quaternary ammonium solutions of various concentrations were assayed with rapid test kits and with three Bactometer impedimetric test codes (the impedance, conductance, and capacitance test codes). An initial study was conducted to determine which test code was most suitable for each sanitizer. Impedance was shown to be the best for sodium hypochlorite solutions, conductance for iodophor solutions, and capacitance for quaternary ammonium solutions. When Bactometer results were compared with test kit results, linear regression revealed strong correlations for all three sanitizer solutions. For sodium hypochlorite concentrations of 0 to 100 ppm and 100 to 1,000 ppm, R2 values of 0.87 and 0.99, respectively, were obtained. For iodophor concentrations between 25 to 150 ppm, an R2 value of 0.95 was obtained. For quaternary ammonium compound concentrations of 100 to 1,000 ppm, an R2 value of 0.94 was obtained. The impedimetric methods proved to be simple and rapid (6 min) alternatives for measuring concentrations of the sanitizer solutions with a high level of certainty (P < 0.0002). The Bactometer will save time when multiple samples are tested.