Enhanced cleaning of sink drains alters the bacterial community in plumbing components but not on countertop surfaces

Hospital sink drainage systems serve as reservoirs for healthcare-associated pathogens, yet the ecological mechanisms of effective antimicrobial control remain poorly understood. We conducted a 35-week longitudinal study comparing sink microbiomes in 30 hospital rooms treated with hydrogen peroxide-based, acid-mixture versus untreated controls. Using 16S rRNA sequencing of 1,957 samples from tail pieces, P-traps, and countertops, we characterized treatment effects on community structure and pathogen abundance. Treatment reduced genus richness by 50% in plumbing components but had no effect on the countertop. Critically, genera that contain ESKAPEE pathogens (Klebsiella, Acinetobacter, and Enterobacter) were significantly enriched in untreated sinks, while treated communities were dominated by soil- and water-associated bacteria, with Bradyrhizobium showing the strongest effect. Treatment created a "controlled instability" signature with reduced temporal autocorrelation and directional drift, disrupting biofilm succession without chaotic fluctuations. Treatment effects were detectable from week 1 and sustained throughout the study. Differential abundance analysis revealed 85% of treatment-enriched genera were environmental bacteria, indicating ecological replacement rather than sterilization. Our findings demonstrate that effective antimicrobial treatment establishes alternative community states that resist pathogen colonization while maintaining environmental responsiveness, challenging traditional sterilization-based approaches to healthcare environment management.