First order, then wash your hands: quantification and identification of bacteria on self-ordering touchscreens in fast food restaurants at times of high and low occupancy

Sampling with Violet Red Bile Agar plates indicated no contamination with Enterobacteriaceae. Sampling with Tryptic Soy Agar plates showed contamination for 28 out of 30 investigated screens, ranging from about 0.07 to 5.7 CFU/cm² (absolute minimum and maximum, respectively). For all restaurants, median bacterial contamination during high occupancy times was 2.8 to 7.5 times higher than during low occupancy. Across all samples, 126 isolates were identified at least on genus level. Samples were dominated by staphylococci and micrococci, indicating human skin microbiota as main source of contamination. The results underline the need for regular touchscreen cleaning and hand hygiene before the meal, in particular at times of high occupancy.