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Microbial contamination in the hospital environment is a major concern for public health, since it significantly contributes to the onset of healthcare-associated infections (HAIs), which are further complicated by the alarming level of antimicrobial resistance (AMR) of HAI-associated pathogens. Chemical disinfection to control bioburden has a temporary effect and can favor the selection of resistant pathogens, as observed during the COVID-19 pandemic. Instead, probiotic-based sanitation (probiotic cleaning hygiene system, PCHS) was reported to stably abate pathogens, AMR, and HAIs. PCHS action is not rapid nor specific, being based on competitive exclusion, but the addition of lytic bacteriophages that quickly and specifically kill selected bacteria was shown to improve PCHS effectiveness. This study aimed to investigate the effect of such combined probiotic-phage sanitation (PCHSφ) in two Italian hospitals, targeting staphylococcal contamination. The results showed that PCHSφ could provide a significantly higher removal of staphylococci, including resistant strains, compared with disinfectants (-76%, p < 0.05) and PCHS alone (-50%, p < 0.05). Extraordinary sporadic chlorine disinfection appeared compatible with PCHSφ, while frequent routine chlorine usage inactivated the probiotic/phage components, preventing PCHSφ action. The collected data highlight the potential of a biological sanitation for better control of the infectious risk in healthcare facilities, without worsening pollution and AMR concerns.

Background: The COVID-19 pandemic has highlighted the extent to which the public transportation environment, such as in subways, may be important for the transmission of potential pathogenic microbes among humans, with the possibility of rapidly impacting large numbers of people. For these reasons, sanitation procedures, including massive use of chemical disinfection, were mandatorily introduced during the emergency and remain in place. However, most chemical disinfectants have temporary action and a high environmental impact, potentially enhancing antimicrobial resistance (AMR) of the treated microbes. By contrast, a biological and eco-sustainable probiotic-based sanitation (PBS) procedure was recently shown to stably shape the microbiome of treated environments, providing effective and long-term control of pathogens and AMR spread in addition to activity against SARS-CoV-2, the causative agent of COVID-19. Our study aims to assess the applicability and impact of PBS compared with chemical disinfectants based on their effects on the surface microbiome of a subway environment., Results: The train microbiome was characterized by both culture-based and culture-independent molecular methods, including 16S rRNA NGS and real-time qPCR microarray, for profiling the train bacteriome and its resistome and to identify and quantify specific human pathogens. SARS-CoV-2 presence was also assessed in parallel using digital droplet PCR. The results showed a clear and significant decrease in bacterial and fungal pathogens (p < 0.001) as well as of SARS-CoV-2 presence (p < 0.01), in the PBS-treated train compared with the chemically disinfected control train. In addition, NGS profiling evidenced diverse clusters in the population of air vs. surface while demonstrating the specific action of PBS against pathogens rather than the entire train bacteriome., Conclusions: The data presented here provide the first direct assessment of the impact of different sanitation procedures on the subway microbiome, allowing a better understanding of its composition and dynamics and showing that a biological sanitation approach may be highly effective in counteracting pathogens and AMR spread in our increasingly urbanized and interconnected environment. Video Abstract., (© 2023. The Author(s).)

Background: Antimicrobial resistance (AMR) represents a major threat to public health, especially in the hospital environment, and the massive use of disinfectants to prevent COVID-19 transmission might intensify this risk, possibly leading to future AMR pandemics. However, the control of microbial contamination is crucial in hospitals, since hospital microbiomes can cause healthcare-associated infections (HAIs), which are particularly frequent and severe in pediatric wards due to children having high susceptibility. Aim: We have previously reported that probiotic-based sanitation (PCHS) could stably decrease pathogens and their AMR in the hospital environment, reduce associated HAIs in adult hospitals, and inactivate enveloped viruses. Here, we aimed to test the effect of PCHS in the emergency room (ER) of a children's hospital during the COVID-19 pandemic. Methods: Conventional chemical disinfection was replaced by PCHS for 2 months during routine ER sanitation; the level of environmental bioburden was characterized before and at 2, 4, and 9 weeks after the introduction of PCHS. Microbial contamination was monitored simultaneously by conventional culture-based CFU count and molecular assays, including 16S rRNA NGS for bacteriome characterization and microarrays for the assessment of the resistome of the contaminating population. The presence of SARS-CoV-2 was also monitored by PCR. Results and conclusions: PCHS usage was associated with a stable 80% decrease in surface pathogens compared to levels detected for chemical disinfection (P < 0.01), accompanied by an up to 2 log decrease in resistance genes (Pc < 0.01). The effects were reversed when reintroducing chemical disinfection, which counteracted the action of the PCHS. SARS-CoV-2 was not detectable in both the pre-PCHS and PCHS periods. As the control of microbial contamination is a major issue, especially during pandemic emergencies, collected data suggest that PCHS may be successfully used to control virus spread without simultaneous worsening of the AMR concern. [ABSTRACT FROM AUTHOR]