Variation in detection limits between bacterial growth phases and precision of an ATP bioluminescence system. (16th December 2013)

• Record Type: Journal Article
• Authors: Vogel, S.J.; Tank, M.; Goodyear, N.
• Is Part Of: Letters in applied microbiology. Volume 58:Number 4(2014:Apr.)
• Page Start: 370
• Page End: 375
• Publication Date: 2013-12-16
• Subjects: Microbiology -- Periodicals; 660.62
• DOI: 10.1111/lam.12199
• Languages: English
• ISSNs: 0266-8254

Abstract

<abstract abstract-type="main" id="lam12199-abs-0001"> <title>Abstract</title> <sec id="lam12199-sec-0102" sec-type="section"> <p>To determine the detection limits of the SystemSure Plus, <italic>Escherichia coli</italic> and <italic>Staphylococcus aureus</italic> growth curve samples were taken in lag (1 h), log (6 h), stationary (12 h) and death phases (<italic>E. coli</italic> 144 h, <italic>Staph. aureus</italic> 72 h). At each time point, the log<sub>10</sub> CFU ml<sup>−1</sup> was determined for the dilution where the SystemSure read 0 relative light units (RLU). Average detection limits were <italic>E. coli</italic>: lag 6·27, log 5·88, stationary 7·45 and death 6·88; <italic>Staph. aureus</italic>: lag 4·37, log 5·15, stationary 7·88 and death 7·57. Between‐run precision was determined with positive control; within‐run precision with positive control, lag and log growth for each bacteria. Within‐run precision mean RLU (CV): positive control 274 (12%), <italic>E. coli</italic> lag 1 (63%), log 2173 RLU (19%), <italic>Staph. aureus</italic> lag 2 (58%) and log 5535 (18%). Between‐run precision was 232 (16%). The precision is adequate with most values within the 95% confidence interval. The detection limit varied by 3·51 log<sub>10</sub> for <italic>Staph. aureus</italic> and 1·47 log<sub>10</sub> for <italic>E. coli</italic>. The lowest detection limits were during <italic>E. coli</italic> log and <italic>Staph. aureus</italic> lag phases; the highest was during stationary phase. These results suggest that organism identification and growth phase both impact ATP RLU readings.</p> </sec> <sec id="lam12199-sec-0112" sec-type="section"> <title>Significance and Impact of the Study</title> <p>Surface hygiene is a critical component of food safety and infection control; increasingly, ATP detection by bioluminescence is used to evaluate surface hygiene and effective cleaning. This is the first study to show that the number of living and potentially infectious bacteria remaining when the device reads zero varies between the different bacterial life cycle phases: lag, log, stationary and death. ATP device users need to be aware of this information to use the devices appropriately.</p> </sec> </abstract>