Experimental Evaluation of Performance of Sampling Techniques for Microbiological Quantification on Carcass Surfaces

Microbiological quantification methods are applied in European abattoirs for evaluating carcass hygiene. Sampling may influence the results and the aim of this study was to evaluate sampling methods for microbiological quantification of slaughter hygiene. Based on these results, a sampling technique in a subsequent Europe-wide baseline study would be selected. To ensure comparable results, a laboratory carcass model was developed from lamb flanks contaminated with a pre-defined inoculum. The SimPlate method for Enterobacteriaceae and Escherichia coli was used. The study consisted of three sections: pilot study (n = 36), two inocula, three sampling times (2 h, 12 h, and 24 h post-inoculation); main and confirmatory study: one inoculum level (n = 96); main study: four swabbing techniques (100 cm2), two sampling times (2 h and 24 h), compared with a destructive sampling method (5 cm2). The recovery of Enterobacteriaceae and E. coli was in the order: destructive > gauze cloth swab ≥ spongestick ≥ sponge swab > wet-dry double-swab. Although the destructive excision method resulted in the highest recovery of Enterobacteriaceae and E. coli in this study, other factors must also be considered for selecting a method for routine carcass sampling. Thus, gauze cloth swabbing was judged to be the most appropriate technique.