# 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

## TL;DR

This study found that self-ordering touchscreens in fast food restaurants are contaminated with bacteria, especially when busy, and recommends cleaning and hand hygiene.

## Contribution

Quantified bacterial contamination on fast food touchscreen surfaces during varying occupancy levels and identified dominant bacterial types.

## Key findings

- 28 out of 30 touchscreens showed bacterial contamination ranging from 0.07 to 5.7 CFU/cm².
- Bacterial contamination was 2.8 to 7.5 times higher during high occupancy compared to low occupancy.
- Staphylococci and micrococci were the dominant bacteria, likely from human skin.

## Abstract

Frequently touched public surfaces represent fomites. Interestingly, little is known about the microbial contamination of self-ordering touchscreens in fast food restaurants, despite the fact that food is usually consumed with hands shortly after ordering. To bridge this gap, we investigated the bacterial load of self-ordering touchscreens by surface sampling and subsequent identification of dominant morphotypes using MALDI-biotyping. We repeatedly (n = 5) sampled touchscreens in three different restaurants in the greater area of Villingen-Schwenningen, Germany, at times of low (≤ 5 guests) and high occupancy (≥ 20 guests), respectively.

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.