Mobile phones as fomites for potential pathogens in hospitals: microbiome analysis reveals hidden contaminants

Background: Smartphones used in clinical settings harbour potentially pathogenic bacteria, and this may pose an infection risk. Previous studies have relied on culture-based methods.

Aim: To characterize the quantity and diversity of microbial contamination of hospital staff smartphones using culture-dependent and culture-independent methods; to determine the prevalence of antibiotic-resistant potential pathogens; to compare microbial communities of hospital staff and control group phones.

Methods: Smartphones of 250 hospital staff and 191 control group participants were swabbed. The antibiotic resistance profile of Staphylococcus aureus and Enterococcus isolates was determined. Swabs were pooled into groups according to the hospital area staff worked in, and DNA was extracted. The microbial community of the phone was characterized using an Illumina MiSeq metabarcoding pipeline.

Findings: Almost all (99.2%) of hospital staff smartphones were contaminated with potential pathogens, and bacterial colony forming units (CFUs) were significantly higher on hospital phones than in the control group. Meticillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE) were only detected on hospital mobile phones. Metabarcoding revealed a far greater abundance of Gram-negative contaminants, and much greater diversity, than culture-based methods. Bacillus spp. were significantly more abundant in the hospital group.

Conclusion: This study reinforces the need to consider infection-control policies to mitigate the potential risks associated with the increased use of smartphones in clinical environments, and highlights the limitations of culture-based methods for environmental swabbing.