Assessment of the sanitary quality of food preparation surfaces

Microbiological counts were determined for 27 tables used routinely for food preparation to assess their sanitary status. Each table was monitored at 10 surface locations by taking 5 successive rodac plates or 3 successive swabs at each location. The efficiency for estimating normal bioburden for the 2 sampling methods was compared, and, from this, the minimum number of locations needed for testing to reliably characterize sanitation quality was determined. The swab method appeared to recover a higher percentage of the bioburden, but microbial counts by the plate method were higher, probably due to partial retention of microorganisms by the swab cotton fibers. An acceptable low incidence of false positives or negatives is obtained if the maximum count of 2 randomly-obtained rodac plates or swabs per surface does not exceed 150 colony-forming units per 25.8 square centimeters. (wz)