HYGIENE MONITORING

Abstract: A hygiene monitoring method comprises the collection of a sample from a locus, and the determination of the presence of glucose in the sample.

Description: HYGIENE MONITORING Field of the Invention This invention relates to hygiene monitoring, and in particular to an assay for the presence of food residues and/or microorganisms. Background of the Invention Hygiene monitoring procedures typically involve swabbing a surface, and analysing the sample taken up in the swab, for the presence of food residues and/or microorganisms. By way of example only, a typical hygiene monitoring device is disclosed in WO-A-98/27196. The ability to detect the presence of food residues and/or microorganisms in the sample that has been taken up by swabbing relies on the presence of ADP/ATP, and the ability to amplify the amount of ADP/ATP, and convert it to a detectable signal, also as disclosed in WO-A-94/25619. The preferred amplification reaction involves, inter alia, the amplification of ATP and then the conversion of glucose-6-phosphate to glucose, and the conversion of glucose, via a sequence of enzymatic reactions, to a coloured end point. Summary of the Invention It has now been found that, in certain circumstances, glucose itself may be a sufficient indicator, for the purposes of an assay used in hygiene monitoring. According to the present invention, therefore, such an assay comprises the collection of a sample from a locus, and the determination of the presence of glucose in the sample. The reagents disclosed in WO-A-94/25619 include those sufficient to convert glucose to a detectable signal; if desired, the reagents used in this invention may exclude those that convert ATP, but the signal generated in the presence of glucose appears relatively rapidly, and can thus be distinguished, in addition to the advantage of providing a rapid response. The amplification of ATP needed to generate the signal is relatively slow. Description of the Invention In use of the invention, it may desirable to ensure that the sample is collected from an environment that originally was, or has subsequently been tested and shown to be, free of sugar. It may also be desirable that the locus to be tested is also assayed for the substantial absence of materials that may interfere in the novel assay, e.g. by inhibiting or by giving false positives, such as peroxide or reducing agents that may be incorporated in materials used to sanitise the locus. The present invention can be practised utilising the same reagents as are disclosed in WO-A-94/25619, especially in so far as that relates to the conversion of glucose to a detectable signal. If desired, the reagents may exclude one or more of the components that are disclosed there for the conversion of ATP to glucose. A suitable device that can be used for the purposes of swabbing and detection is disclosed in WO-A-98/27196 and WO-A-99/31218. The following -Examples illustrate the utility of the present invention. All used the same amplification system, with a colour end-point, as disclosed in Example 1 of WO-A-94/25619. Example 1 Swabs were taken from a variety of locations, and tested. In addition to determining the total viable count (TVC) and Enterobacteria (Enteros), contact plates were used alongside two devices. systemSURE ("sSURE") is a portable hygiene monitoring system (available from Becton Dickinson) that uses bioluminescence as an endpoint. The "Pen Swab" is generally as disclosed in WO-A-99/31218. Results are shown in Table 1. Table 1 ND = no data Inst = "Instant" colour change Threshold - 500 RLU The data show that, in samples 1 and 4, the colour reagents produced an instant positive signal which, when compared to the bioluminescence results, is an indication of the present of glucose and not ATP. Sample 2 also gave a high total viable count (over enumeration limit) and 75 counts for Enteros, while giving 625 RLU for systemSURE and an immediate colour change for the pen. This again indicates the presence of glucose leading to contamination. Example 2 The colour reagents were used to determine the level at which glucose was detectable. The reagents were activated in the presence of different concentrations of glucose. The absorbance values for a complete colour change were obtained within 120 seconds. Results are shown in Table 2. Table 2 Swabs were taken from a variety of locations in a store, at different times of day and tested. Results are shown, for two different days, in Tables 3A and 3B. A large proportion of the data shows a rapid colour change (in seconds), characteristic of glucose detection. The corresponding RLU values do not show the presence of gross amounts of ATP, which is consistent with the detection of glucose. Table 3A Table 3B on

Claims: CLAIMS 1. A hygiene monitoring method which comprises the collection of a sample from a locus, and the determination of the presence of glucose in the sample. 2. A method according to claim 1 , which comprises adding to the sample reagents that convert glucose to give a signal. 3. A method according to claim 2, wherein the reagents also convert ATP to give the signal, and the signal is generated more quickly in the presence of glucose than in the presence of ATP.

Inventors: GRANT PETER LEONARD, PIRZAD RAMIN, GRANT, PETER, LEONARD, PIRZAD, RAMIN
Applicants: CELSIS INT PLC, GRANT PETER LEONARD, PIRZAD RAMIN, CELSIS INTERNATIONAL PLC, GRANT, PETER, LEONARD, PIRZAD, RAMIN
Application year: 1999
Main classification: C12Q1
IPC codes: C12Q1, G01N33