The perennial problem of variability in adenosine triphosphate (ATP) tests for hygiene monitoring within healthcare settings.
OBJECTIVE
To investigate the reliability of commercial ATP bioluminometers and to document precision and variability measurements using known and quantitated standard materials.


METHODS
Four commercially branded ATP bioluminometers and their consumables were subjected to a series of controlled studies with quantitated materials in multiple repetitions of dilution series. The individual dilutions were applied directly to ATP swabs. To assess precision and reproducibility, each dilution step was tested in triplicate or quadruplicate and the RLU reading from each test point was recorded. Results across the multiple dilution series were normalized using the coefficient of variation.


RESULTS
The results for pure ATP and bacterial ATP from suspensions of Staphylococcus epidermidis and Pseudomonas aeruginosa are presented graphically. The data indicate that precision and reproducibility are poor across all brands tested. Standard deviation was as high as 50% of the mean for all brands, and in the field users are not provided any indication of this level of imprecision.


CONCLUSIONS
The variability of commercial ATP bioluminometers and their consumables is unacceptably high with the current technical configuration. The advantage of speed of response is undermined by instrument imprecision expressed in the numerical scale of relative light units (RLU).
1University of Western Sydney,School of Science and Health,Richmond,NSW,Australia.
Greg S
GS
Whiteley
1University of Western Sydney,School of Science and Health,Richmond,NSW,Australia.
Chris
C
Derry
2Whiteley Corporation,North Sydney,NSW,Australia.
Trevor
T
Glasbey
1University of Western Sydney,School of Science and Health,Richmond,NSW,Australia.
Paul
P
Fahey
D000255:Adenosine Triphosphate / Q000032:analysis / Q000378:metabolism; D003428:Cross Infection / Q000517:prevention & control*; D004784:Environmental Monitoring / Q000379:methods; D006801:Humans; D006920:Hygiene / Q000592:standards; D008163:Luminescent Measurements / Q000295:instrumentation / Q000379:methods; D011550:Pseudomonas aeruginosa / Q000302:isolation & purification* / Q000378:metabolism; D015203:Reproducibility of Results; D013212:Staphylococcus epidermidis / Q000302:isolation & purification* / Q000378:metabolism
D000255:Adenosine Triphosphate