2.1. Material

The research material included 6000 swabs taken from the surface of pork, beef, and poultry in 2016–2018. Every year, 2000 samples were taken, respectively: (1) 610 from poultry, 685 from pork, and 705 from beef in 2016; (2) 650 from poultry, 715 from pork, and 635 from beef in 2017; and (3) 690 from poultry, 684 from pork, and 626 from beef in 2018. All samples of a given meat-type were collected from the same meat plant.

Samples for testing were collected by wet swab method with the use of a sterile, flexible template limiting the swabbed area to 100 cm². Samples were taken for the part of the carcass currently processed in the plant (one sample per carcass part). A new sterile template was used for each part of the carcass. A sterile 50 cm² cellulose sponge (Environscreen, Technical Service Consultants Ltd., Heywood, UK) soaked in 10 mL 0.9% NaCl sterile packed in a reinforced zip-bag was used for sampling.