preparationof suchinocula mightbe questionablefor practicaltests,particularlyfor
surfacetests. Microorganismsassociated withsurfaces are often foundas a biofilm
communityrather than singlecells.Thisis particularlyimportant sincebiofilmsare
often moreresistant than theirplanktoniccounterpartsto antimicrobials(Allisonet
al., 2000). The use of biofilms as the inoculumshouldadd morestringencyto the
test, and simulatebetter situationsin the field(Fineet al., 2001; Cappelliet al.,
2003 ). As for other practical tests,the standardisationof the `biofilminoculum'
would be critical for the reproducibilityof results.Thereare several methodologies
to produce biofilms(e.g. sedimentation; chemostats andconstant-depthfilm
fermentor).Ceriet al.(2001) discussedthe differentmethodologiesto produce
biofilmsand theirpotential application for antimicrobialtesting.Otherparameters
directlyrelevantto biofilmsneedto be controlled,suchas microorganismtype,and
biofilmage, depthand structure.The developmentand standardisationof biofilm
testing protocols wouldbe highlyrelevantfor the foodand healthcare industries,
although it wouldadd morestringencyto test protocols and mightresultin the
recommendationfor the use of higher disinfectantconcentrations.
As mentioned in Section38.3.2,the developmentof rapid,sensitiveand
reliable detection methods to palliate the drawbacks of using agar-based
protocolsto enumerate survivingmicrorganismsoffersan attractiveoption.
These methodsare particularly attractive for those microrganisms thatare
particularlyslowgrowing, suchas mycobacteria, for whichsurvivalis difficult
to assess (e.g.viruses,prions).
Standardisation of antimicrobial test protocolsis beneficialif it allowssome
flexibility in the parameters and test conditions,especiallywithpracticaltests.
The establishment of CEN/TC216has beenimportantin developinga rangeof
tests adaptedto specific end users(Holah, 2003).While a numberof standard
protocolshavealreadybeenpublished, a numberare still at a development
stage. Meanwhile,a varietyof test protocols are stillbeing used thatare
contributingto possible discrepanciesin efficacyclaimsfor a givendisinfectant/
sanitiser.Here,regulatoryauthoritieshaveto play a role in the development and
commercialisationof newbiocidal products (Kappesand Rasmussen,2003;
Sobanskaet al., 2003).The purpose of antimicrobialtests is to ensure that a
product meetsits antimicrobial claimand to provide confidence aboutlabel
claims for the end users(Favero, 2002).
38.7 Sourcesof furtherinformation and advice
There is a wealth of informationon testing protocols, factors influencing
biocidal activity in the literatureand some useful informationhas alreadybeen
referredto in this chapter. However, Reybrouck (1999), Lambert (2004),
Cremieuxand colleagues(2001)and Graband Bennett(2001)provide detailed
and usefulinformationon testing protocols whilebiofilmtest methodologies are
describedfurtherby Ceriet al.(2001).Readerswill find usefulinformationon
TDEsin the chapterwrittenby Taylor (2004).
664 Handbookof hygiene controlin the foodindustry