The reestablishment of microbial communities after surface cleaning in schools

The goal of this study was to quantify the indoor microbiome dynamics of bacterial and fungal communities on school desk surfaces during a cleaning intervention.

Quantitative PCR and DNA sequenced-based approaches were employed to describe microbial community dynamics on ten desk surfaces, spread across three schools, located in the Northeast region of the United States. Six samples were taken from each desk, one precleaning, and five postcleaning at 30 min, 1, 3, 7 and 21 days. Cleaning of the desks physically removed c. 50% of bacteria, fungi, and human cells and a full recovery of the surface microbial concentrations occurred within 2-5 days. This recovery period is much shorter than the schools' once per semester cleaning schedule. The dominant source of bacteria and fungi on desks at all time points came from the human microbiome (skin, oral cavity, and gut). More than 50% fungi on desks were members of genera that contain known allergens.

Microbial communities on these school desks are primarily generated and maintained from the deposition of human-associated bacteria and fungi. Current school surface cleaning protocols and cycles may be ineffective at reducing student exposure to fungal allergens and microbes of human origin.

Multiple students often share desks in schools. Results on the removal and reestablishment of microbial communities on these surfaces are critical for setting cleaning schedules and practices that effectively interrupt exposure to surface-associated pathogens and allergens.