A Sustainable Combined Approach to Control the Microbial Bioburden in the School Environment.

The indoor microbiome is a dynamic ecosystem including pathogens that can impact human health. In this regard, the school environment represents the main living space of humans for many years, and an unhealthy environment can significantly condition students' health. School rooms can suffer from insufficient ventilation and the use of building materials that may favor pathogen contamination, mostly sanitized by conventional chemical-based methods, which can impact pollution, have temporary effects, and induce the selection of antimicrobial resistance (AMR) in persistent microbes. In the search for sustainable and effective methods to improve the healthiness of the classroom environment, a pre-post case-control study was performed in an Italian high school. Over a year, different interventions were sequentially placed and evaluated for their impact on bioburden and air quality, including the introduction of plants, a mechanical ventilation system, and probiotic-based sanitation (PBS) in substitution for chemical sanitation. Through continuous microbial monitoring of the enrolled school rooms, via culture-dependent and -independent methods, a remarkable bioburden level was detected at baseline (around 12,000 and 20,000 CFU/m