Sponge and Skin Excision Sampling for Recovery of Inoculated Salmonella and Campylobacter from Defeathered Broiler Carcasses

Introduction: Salmonella and Campylobacter contamination of broiler carcass skin increases during feather removal.  There are several methods for sampling carcasses including sponging or swabbing of skin surface and skin excision.  It is unclear whether sponge sampling is adequate to remove bacteria from the skin or if subsequent skin excision would greatly enhance the likelihood of recovery.

Purpose: The purpose of this study was to test sponge sampling followed by skin excision to recover inoculated Salmonella and Campylobacter from the breast skin of defeathered broiler carcasses.

Methods: On each of three replicate days, five freshly defeathered broiler carcasses were obtained from a commercial processor.  The skin of each breast (2 per carcass) was inoculated with approximately 10⁶ cells of an antimicrobial resistant Salmonella and Campylobacter.  Inocula were allowed 60 s contact time before using three passes with a sterile sponge to sample the skin.  Subsequently, the breast skin was aseptically excised.  Skin and sponge samples were cultured for enumeration of both inoculated organisms.  Numbers recovered were compared by Student’s T test. 

Results: Mean Salmonella inoculum was 6.48 log CFU per breast.  Sponge sampling recovered a mean of 5.12 log CFU representing 5 % of the inoculum; subsequent skin excision recovered an additional 0.8% of the inoculum resulting in a total of  5.20 log CFU per breast. Campylobacter results were similar with a mean inoculum of 6.65 log CFU, recovery by sponge of 5.58 log CFU (10% of the inoculum); additional Campylobacter recovered by skin excision resulted in a total of 5.62 log CFU recovered per breast. 

Significance: Sampling broiler skin by sponge wipe allows recovery of 5 to 10% of inoculated bacteria, subsequent skin excision does not significantly (P > 0.05) increase recovery beyond what is possible by sponge sampling.