Assessment of human health risk associated with pyaemia in Danish finisher pigs when conducting visual-only inspection of the lungs

Abstract

The most important lesion to be overlooked when performing visual-only inspection of the lungs is embolic pneumonia. The aim of the present study was to assess the additional human health risk represented by overlooking cases of pyaemia represented by embolic pneumonia in finisher pigs, when conducting visual-only compared to palpation of the lungs, as is the traditional meat inspection procedure.An examination of bacteria isolated from 19 finisher pigs identified with embolic pneumonia at traditional meat inspection was undertaken. From each pig samples were taken from various organs (lungs, spleen, heart, liver and kidney), from the carpal joints (A. carpi) and flexor muscle (M. flexor digitorum superficialis) on the right foreleg. These data were included in a risk assessment following OIE guidelines.Bacteria were isolated from 78 out of 127 tissue and swap samples taken (61% positive samples). Staphylococcus aureus (N=37) was the most frequently isolated bacterium. The predominant site of S. aureus was the lung. S. aureus was detected although less frequently in low numbers in some organs (<100CFU/sample) and muscle samples (<10CFU/sample). Only one MRSA isolate was found.Staphylococcus warneri (N=24) was the second most commonly found bacterium. There was no predominant site and the number of S. warneri was less than 50CFU per sample.The risk of a food-borne intoxication from S. aureus in relation to pyaemia in pigs was considered very low due to the low quantitative numbers of S. aureus in muscle tissue samples. Implementing visual-only inspection will reduce the exposure of S. aureus due to less cross-contamination and handling of the plucks by the meat inspectors. The human health risk associated with S. warneri was considered very low, due to the limited zoonotic potential of this bacterium. In conclusion, the additional human health risk in relation to possibly overlooking pyaemia in Danish finisher pigs was considered negligible when conducting visual-only compared to traditional meat inspection.