Evaluation of Methods for Determining Cleaning Performance in Pig Stables

All-in-all-out production systems are well established for pig fatting, but without proper cleaning and disinfection carry over of microorganisms cannot be avoided. Thus, advantages of an all-in-all out system are made void and diseases can be easily transmitted to new arriving pigs. To our knowledge, reliable methods for determination of the cleaning and disinfection performance in pig stable beside visual control are lacking. Aim of this study was to identify critical control points in pig pens and compare five different methods that are routinely applied for cleaning control in food processing or hospitals. Samples were collected in a randomly chosen cleaned pen of six different fattening farms with swabs or agar contact plates at 15 defined locations (entrance door, side wall, back wall, ceiling, slatted floor, dumping area, floor in front of the feeder, feeder outside, feeder inside, windowsill, two toys, two nipple drinkers, pipe). All farms differ in cleaning and disinfection procedure. Swabs samples were used for measurement of protein- and atp-content as well as for the microbiologically parameters total aerobic count, MRSA and ESBL. Three different contact plates were applied (violet red bile dextrose agar (VRBD) for Enterobacteriaceae, Plate Count (PC) agar for total aerobic count and Dey Engley (DE) Agar for aerobic count on surfaces with disinfectant residues). Additionally, visually cleanliness (VC) of the sampled area was recorded using a 4-score grading scheme. Contact plates were only applicable to 12 of the 15 locations, whereby VRBD showed good performances to control cleanliness in pig stables. DE and PC showed a very high bacterial load that was not quantifiable. We found high spearman rank correlations within protein content, atp value, total aerobic count and ESBL (0.38 ≥ r ≥ 0.82; P < 0.003, respectively). Based on additional criteria like time between sampling and result as well as handling, protein swabs seem very useful as a semi quantitative method for rapid detection of cleaning performance and ATP analysis for rapid identification of hygienic problems. Additionally, comparison between sampling locations in pens showed that highest bacterial load was found on nipple drinkers independent of farm and previous cleaning and disinfection process. This can cause serious problems if bacterial load contains pathogens which are than transmitted to new arriving pigs.