Efficient Nondestructive Sampler for Carcasses and Other Surfaces

Two versions of an electrically powered device (Rotorinser) to sample carcasses or other surfaces in situ for microbiological analysis and several different sampling protocols were evaluated against excision plus stomaching for ability to remove bacteria from pig skin and beef carcass tissue. Both devices sampled circular areas of approximately 14 cm². Ten tissue samples were used for each set of conditions. Rotorinser bacterial removal efficiency was calculated as R/(R + S), where R is the Rotorinser count (CFU cm^-2) and S is the count on stomached excised tissue after rotorinsing. Stomacher efficiencies were calculated as S1/(S1 + S2), where S1 is the first stomacher count of excised tissue and S2 is the count from a second stomaching. Both Rotorinsers were much better than traditional swabs. Rotorinser 1 gave removal efficiencies of 0.79 to 0.88 for beef, and 0.79 to 0.95 for pork. Prewetting surfaces for 5 min improved removal, but mixtures of enzymes did not. Rotorinser 2 applied with NaCl or NaCl-Tween 80 diluent for either 30 or 60 s was significantly better (0.93 and 0.98) than the stomacher (0.86) at removing aerobic mesophilic bacteria from pork skin. The Rotorinser causes negligible tissue damage and can be used on surfaces at any angle.