Bacteria on smartphone touchscreens in a German university setting and evaluation of two popular cleaning methods using commercially available cleaning products
Smartphone touchscreens are known as pathogen carriers in clinical environments. However, despite a rapidly growing number of smartphone users worldwide, little is known about bacterial contamination of smartphone touchscreens in non-clinical settings. Such data are needed to better understand the hygienic relevance of these increasingly popular items. Here, 60 touchscreens of smartphones provided by randomly chosen students of a German university were sampled by directly touching them with contact agar plates. The average bacterial load of uncleaned touchscreens was 1.37 ± 0.33 CFU/cm2. Touchscreens wiped with commercially available microfiber cloths or alcohol-impregnated lens wipes contained significantly less bacteria than uncleaned touchscreens, i.e., 0.22 ± 0.10 CFU/cm2 and 0.06 ± 0.02 CFU/cm2, respectively. Bacteria isolated from cleaned and uncleaned touchscreens were identified by means of MALDI Biotyping. Out of 111 bacterial isolates, 56 isolates (50 %) were identified to genus level and 27 (24 %) to species level. The vast majority of the identified bacteria were typical human skin, mouth, lung, and intestinal commensals, mostly affiliated with the genera Staphylococcus and Micrococcus. Five out of 10 identified species were opportunistic pathogens. In conclusion, the touchscreens investigated here showed low bacterial loads and a species spectrum that is typical for frequently touched surfaces in domestic and public environments, the general health risk of which is still under debate.
KeywordsHealthcare Worker Bacterial Load Colony Count Cleaning Method Heterotrophic Plate Count
The authors wish to thank all students who participated in the study and provided their smartphones for microbiological analyses as well as Dr. Wayne Young (AgResearch, Palmerston North, NZ) for English suggestions.
Conflict of interest
- Akinyemi KO, Atapu AD, Adetona OO, Coker AO (2009) The potential role of mobile phones in the spread of bacterial infections. J Infect Dev Ctries 15:628–632Google Scholar
- BAuA - German Federal Institute for Occupational Safety and Health (2010) Technical rule for biological agents #466 - Classification of prokaryotes (bacteria and archaea) into risk groups. Edition: December 2010Google Scholar
- Bloomfield SF, Exner M, Carlo Signorelli C, Nath KJ, Scott EA (2012) The chain of infection transmission in the home and everyday life settings, and the role of hygiene in reducing the risk of infection. http://www.ifh-homehygiene.org/IntegratedCRD.nsf/111e68ea0824afe1802575070003f039/9df1597d905889868025729700617093?OpenDocument
- El-Bouri K, Johnston S, Rees E, Thomas I, Bome-Mannathoko N, Jones C, Reid M, Ben-Ismaeil B, Davies AR, Harris LG, Mack D (2012) Comparison of bacterial identification by MALDI-TOF mass spectrometry and conventional diagnostic microbiology methods: agreement, speed and cost implications. Br J Biomed Sci 69:47–55PubMedGoogle Scholar
- Holm S (1979) A simple sequentially rejective multiple test procedure. Scand J Stat 6:65–70Google Scholar
- Mellmann A, Cloud J, Maier T, Keckevoet U, Ramminger I, Iwen P, Dunn J, Hall G, Wilson D, Lasala P, Kostrzewa M, Harmsen D (2008) Evaluation of matrix-assisted laser desorption ionization-time-of-flight mass spectrometry in comparison to 16S rRNA gene sequencing for species identification of nonfermenting bacteria. J Clin Microbiol 46:1946–1954CrossRefPubMedCentralPubMedGoogle Scholar
- R Core Team (2013) R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. URL http://www.R-project.org/
- Strategy Analytics (2013) Global smartphone user base forecast by OS for 88 countries: 2007–2017, June 2013Google Scholar
- Walia SS, Manchanda A, Narang RS, AN, Singh B, Kahlon SS (2014) Cellular telephone as reservoir of bacterial contamination: myth or fact. J Clin Diagn Res 8:50–53Google Scholar
- Wilson M (2008) Bacteriology of humans—an ecological perspective. Blackwell Publishing, MaldenGoogle Scholar