Evaluation of six sampling methods for recovery of bacteria from beef carcass surfaces

Abstract

Six bacterial sampling methods that might be used for rapid sampling of beef carcasses were evaluated in two separate studies. In Study 1, bacterial recovery from uninoculated beef rounds was 2.6, 2.3, 2.1 and 1.3 log10 cfu cm-2, respectively for excision (EX), and swabbing with cheesecloth (CC), sponge (SP) and cotton-tipped wooden swabs (CS). For Study 2, beef tissue was inoculated with bovine faeces at different levels and the mean recovery was 3.7, 3.0, 3.1 and 3.1 log10 cfu cm-2, respectively for EX, and swabbing with SP, griddle screen (GS) and 3M mesh (M). For both studies EX was determined to be the most consistently effective method while the initial study determined swabbing with CS was the least effective of the methods used. In both studies the most abrasive materials approached the effectiveness of EX even at low inoculation levels. As the inoculation levels increased, the additional effect of abrasiveness was lessened. When the carcasses were contaminated with bovine faeces, the bacterial populations that were rapidly recoverable from beef tissue using SP, GS or M were not significantly lower than those recovered using EX. Consequently SP, GS or M are an adequate method of beef carcass sampling for rapid, in-plant process monitoring to detect faecal contamination.