In hy­gien­i­cal­ly de­mand­ing areas (e.g. food in­dus­try, phar­ma­ceu­tics, cos­met­ics and health sec­tor) rou­tine clean­ing and sur­face dis­in­fec­tions have to be per­formed in order to meet the high hy­giene stan­dards. The per­for­mance and fre­quen­cy of these pro­ce­dures are de­fined in hy­giene and dis­in­fec­tion plans which are in­te­grat­ed con­stituents of qual­i­ty man­age­ment (QM) and qual­i­ty as­sur­ance sys­tems (QA). The basis for these sys­tems is a manda­to­ry hy­giene con­trol, a suit­able doc­u­men­ta­tion and the use of val­i­dat­ed dis­in­fec­tion pro­ce­dures. Cur­rent­ly the only pos­si­bil­i­ty to eval­u­ate the hy­giene of a sur­face after dis­in­fec­tion is a ran­dom end prod­uct con­trol. These con­trols are gen­er­al­ly per­formed via Repli­cate Or­gan­ism De­tec­tion and Count­ing (RODAC)-plates. The re­sults, how­ev­er, are avail­able after a min­i­mum of two days. Be­cause of this delay, an in­suf­fi­cient dis­in­fec­tion (caused e.g. by an in­ad­e­quate dosage, pro­tein- or soap-mis­take) is rec­og­nized late.

The wfk-In­sti­tute has de­vel­oped a rapid test for a sim­ple and se­cure pro­cess con­trol for sur­face dis­in­fec­tion so that an in-house self-mon­i­tor­ing is pos­si­ble. This pro­cess con­trol can be per­formed by clean­ing and hy­giene ser­vice providers with­out mi­cro­bi­o­log­i­cal pro­fes­sion­als and a lab­o­ra­to­ry.

In order to ver­i­fy a suc­cess­ful dis­in­fec­tion pro­ce­dure, vi­su­al­ly de­tectable colour re­ac­tions were anal­ysed. Such colour re­ac­tions have to be sen­si­tive, fast, re­pro­ducible, clear­ly vis­i­ble and sta­ble for a cer­tain pe­ri­od of time. There­fore dye re­leas­ing en­zyme-sub­strate-re­ac­tions are suit­able. The more ac­tive en­zymes are avail­able, the high­er the re­leased dye con­cen­tra­tion is. It was proven that the re­ac­tion of pro­teas­es with a flu­o­res­cent sub­strate is a very sen­si­tive de­tec­tion method. The basis for the de­vel­op­ment of a rapid test were di­verse in­ac­ti­va­tion ki­net­ics of pathogenic and non pathogenic mi­croor­gan­isms due to dis­in­fec­tants. To be suit­able, the de­crease of en­zyme ac­tiv­i­ty due to the ef­fect of dis­in­fec­tant has to cor­re­late with in­ac­ti­va­tion ki­net­ics of the dif­fer­ent mi­croor­gan­isms.

With­in the pro­ject, car­ri­ers con­sist­ing of a polyvinyl al­co­hol were de­vel­oped which can be fixed re­versibly on dif­fer­ent sur­faces (e.g. syn­thet­ics, stain­less steel, glass) with a pres­sure sen­si­tive ad­he­sive de­vel­oped by wfk-in­sti­tute. Pro­teas­es were im­mo­bilised on the sur­face of the car­ri­er in order to avoid spread­ing of en­zymes by wip­ing dur­ing dis­in­fec­tion. After the dis­in­fec­tion step this func­tion­al mod­els of a biomon­i­tor can be re­moved from the sur­face. After the ap­pro­pri­ate res­i­dence time a sub­strate so­lu­tion has to be ap­plied to the biomon­i­tors. The biomon­i­tors can be eval­u­at­ed vi­su­al­ly after a few min­utes. By means of a colour scale it is pos­si­ble to mon­i­tor the suc­cess or fail­ure of the dis­in­fec­tion pro­cess.

Thus a rapid method is avail­able for im­me­di­ate eval­u­a­tion of the sur­face dis­in­fec­tion with­out the help of ex­ter­nal pro­fes­sion­als. This method en­ables the clean­ing ser­vice providers to in­crease the safe­ty of the sur­face dis­in­fec­tion and to de­crease the hy­giene risk.

The IGF-pro­ject 16490 N of the re­search as­so­ci­a­tion Europäische Forschungs­ge­mein­schaft Reini­gungs- und Hy­gien­etech­nolo­gie e.V., Cam­pus Ficht­en­hain 11, D-47807 Krefeld, was sup­port­ed via the AiF with­in the fund­ing pro­gramme „In­dus­trielle Gemein­schafts­forschung und –en­twick­lung (IGF)“ by the Fed­er­al Min­istry of Eco­nom­ic Af­fairs and Tech­nol­o­gy (BMWi) due to a de­ci­sion of the Ger­man Par­lia­ment.

The re­search re­port is avail­able on re­quest from FRT.