Alternative methods for sampling from surfaces

Detection of attached microorganisms and biofilms on surfaces is essential in assessing process hygiene. Alternative methods to assess surface hygiene were studied. As a sampling method, ultrasonication was found to be more effective than swabbing. Swabbing can, however, be improved using wetting agents. The wetting agent breaks the biofilm and reveals the bacteria in it without affecting the survival rate of the bacteria. These agents can be applied either by spraying directly onto the surface or by moistening the swabs before sampling. The viability of surface-bound microorganisms and/or the quantity of biofilm was estimated by ATP bioluminescence, by protein residue detection, by impedimetry and by epifluorescence microscopy. The ATP method and detection of protein are easily applicable for industrial use, whereas impedimetry and epifluorescence microscopy are indispensable research tools. These techniques offer many benefits compared to conventional methods, although some limitations were also noticed.