Shine like a diamond: Rapid ATP measurements to evaluate the efficacy of different cleaning methods for worn spectacles.

Spectacles can harbor various types of microorganisms, predominantly bacteria, which pose potential health risks to spectacle wearers as well as to persons regularly working with worn spectacles, such as opticians [1-3]. ATP measurement represents a rapid and widely used method in hygiene to analyses the organic contamination of surfaces. However, clear correlations with microbial contents on the investigated surfaces are not always provable. Here, we examined the suitability of rapid ATP measurements to assess the efficacy of different cleaning methods for spectacle surfaces. Moreover, we explored the potential correlation with microbial germ counts. To do so, we swab-sampled worn spectacles at our university laboratory, and subsequent ATP bioluminescence assays with a handheld device were used to assess the level of contamination.

Six popular cleaning methods were evaluated for their ability to reduce the level of contamination using ten worn spectacles, respectively. Microfiber cloths were the most effective, reducing ATP levels by 93.2%. Alcohol-free wipes followed closely, with a 92.0% decrease. In addition, we investigated the correlation between germ counts and ATP content, which revealed no significant correlation for aerobic cultivation (p = 0.36), but a statistically significant correlation for anaerobic conditions (p = 0.025). Higher CFU values correlated positively with higher ATP levels, suggesting that ATP measurements can rapidly indicate microbial contamination. Our previous studies have shown that spectacles and similar surfaces are indeed colonized by significant shares of (aerotolerant) anaerobic bacteria [2,3]. In summary, ATP measurements are a suitable method to rapidly measure the contamination of spectacles and demonstrate the efficacy of cleaning measures under non-laboratory conditions, such as eyewear stores.

[1] Fritz, B. et al. (2018). PLoS ONE 13(11): e0207238. doi.org/10.1371/journal.pone.0207238

[2] Fritz B. et al. (2020). Sci Rep. 10(1): 5577. doi.org/10.1038/s41598-020-62186-6.

[3] Fritz, B. et al. (2020). J. Clin. Med. 9(5): 1572. doi.org/10.3390/jcm9051572