Skip to main content Accessibility help
×
Home

Contents:

Information:

  • Access
  • Cited by 6

Actions:

      • Send article to Kindle

        To send this article to your Kindle, first ensure no-reply@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about sending to your Kindle. Find out more about sending to your Kindle.

        Note you can select to send to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

        Find out more about the Kindle Personal Document Service.

        Sampling Plans for Use of Rapid Adenosine Triphosphate (ATP) Monitoring Must Overcome Variability or Suffer Statistical Invalidity
        Available formats
        ×

        Send article to Dropbox

        To send this article to your Dropbox account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Dropbox.

        Sampling Plans for Use of Rapid Adenosine Triphosphate (ATP) Monitoring Must Overcome Variability or Suffer Statistical Invalidity
        Available formats
        ×

        Send article to Google Drive

        To send this article to your Google Drive account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Google Drive.

        Sampling Plans for Use of Rapid Adenosine Triphosphate (ATP) Monitoring Must Overcome Variability or Suffer Statistical Invalidity
        Available formats
        ×
Export citation

Reply to Visrodia

To the Editor—We write with respect to the article by Visrodia et al. 1 on using a commercial rapid adenosine triphosphate (ATP) device for validation of cleaning of flexible gastroendoscopes. The importance of timeliness in quality assurance testing in this device area is critical owing to the time pressures on the use of the gastroendoscopes by clinical staff involved in patient care. The work is a useful additional contribution to this growing field of use for ATP devices. 2

Nonetheless, we highlight concerns with 2 aspects of the method adopted within the work by Visrodia et al. 1 First, this work, like earlier references, utilizes only a single brand of rapid ATP device with acknowledged manufacturer support. The recommendations on “validated” relative light units (RLU) are entirely device specific and exclude other commercial devices. And, whilst the ATP/RLU readings in Visrodia et al. 1 may seem dramatic (some >100,000 RLU), the work lacks evaluation of microbial presence that could anchor the study against a quantitated standard. 3

Second, the work does not address any of the major published criticisms of the use of ATP systems as they are currently configured. Several authors have commented on the dangers of overstating the usefulness of these commercial ATP devices, the risks of alternative sources of ATP, the lack of correlation with specific pathogens of concern, the amount of ATP present within any particular cells or bacterial species, and the measurement variability that undermines statistical measures applied to the research. 4 7

In this regard, and of specific concern in terms of method in Visrodia et al., 1 is the way that ATP measurements and samples were obtained—for example, samples from the brush and flush sampling were divided into only 2 parts, with one part apparently used for a single ATP test and the other part tested for protein residues. The entire sample set of ATP testing appears to be without duplicates or preferably triplicate testing. Reliance by Visrodia et al. 1 upon the sample means of groups of singular ATP readings is undermined by the knowledge of variability where the standard deviation can be as high as 40% of the data mean for the individual brand of device used. 8 The authors themselves note the risk of singular testing in the body of the discussion: “to sample more than one… and to use more than 1 rapid indicator,” but we wonder how the statistical assumptions hold valid without multiple (replicate) samples taken for the ATP testing.

We also note 2 problems with the scaling of all commercial ATP devices. First, the scale of RLU is completely relative and cannot be used interoperatively between differently branded devices. 2 , 3 Second, the variability for each of the brands is so high that without a sampling approach that accounts for multiple samples at any one point, the ability of the scientists involved to meaningfully apply statistical methods renders the article subject to first principle flaws. 9 Reporting the RLU readings on a log scale is not the same as taking multiple samples, identifying the median value, and then log plotting the data. Perhaps this was done, but it remains unclear within the text.

We feel obliged to inform those who may be reliant upon the work to take care in not applying the work using one brand of ATP device to another brand of ATP device, as noted in the commentary by Petersen. 10 Likewise, we caution against relying on the statistical positioning in the field use of ATP without an appropriately constructed sampling plan to account for inherent variability. This overlay of concern will continue to apply until all ATP device manufacturers can agree to a commonly applicable scale that minimizes the impact of variability, no matter what the assignation given to the replacement reading scale.

Acknowledgments

Financial support. None reported.

Potential conflicts of interest. All authors report no conflicts of interest relevant to this article.

References

1. Visrodia, KH, Ofstead, CL, Yellin, HL, Wetzler, HP, Tosh, PK, Baron, TH. The use of rapid indicators for the detection of organic residues on clinically used gastrointestinal endoscopes with and without visually apparent debris. Infect Control Hosp Epidemiol 2014;35:987994.
2. Alfa, MJ, Fatima, I, Olson, N. The adenosine triphosphate test is a rapid and reliable audit tool to assess manual cleaning adequacy of flexible endoscope channels. Am J Infect Control 2013;41:249253.
3. Sciortino, CV, Giles, RA. Validation and comparison of three adenosine triphosphate luminometers for monitoring hospital surface sanitization: a Rosetta Stone for adenosine triphosphate testing. Am J Infect Control 2013;40:e233e239.
4. Malik, DJ, Shama, G. Estimating bacterial surface contamination by means of ATP determinations: 20 pence short of a pound. J Hosp Infect 2012;80:354356.
5. Shama, G, Malik, DJ. The uses and abuses of rapid bioluminescence-based ATP assays. Int J Hygiene Environ Health 2013;216:115125.
6. Mulvey, D, Redding, P, Robertson, C, Woodall, C, Kingsmore, P, Dancer, SJ. Finding a benchmark for monitoring hospital cleanliness. J Hosp Infect 2011;77:2530.
7. Whiteley, GS, Derry, C, Glasbey, T. The comparative performance of three brands of portable ATP-bioluminometer intended for use in hospital infection control. Healthcare Infect 2012;17:9197.
8. Whiteley, GS, Derry, C, Glasbey, T. Reliability testing for portable adenosine triphosphate bioluminometers. Infect Control Hosp Epidemiol 2013;34:538540.
9. Lautenback, E, Woeltje, KF, Malani, PN. Practical Healthcare Epidemiology, 3rd ed. Chicago, IL: University of Chicago Press; 2010.
10. Petersen, BT. Monitoring endoscope reprocessing: accumulating data but best practices remain undefined. Infect Control Hosp Epidemiol 2014;35:995997.