Polymicrobial biofilms of Staphylococcus aureus and Pseudomonas aeruginosa pose serious clinical challenges due to their persistence, metabolic adaptability, and antibiotic tolerance. The present study investigated the ability of these two bacteria to co-exist and form mixed-species biofilms and evaluated the antibiofilm potential of piperine, a plant-derived alkaloid from Piper nigrum. Co-existence of S. aureus and P. aeruginosa was confirmed by enumeration of colony-forming units, growth kinetics, cross-streaking, metabolic fingerprinting, Gini coefficient analysis, and antibiotic susceptibility. Sub-minimum inhibitory concentrations of piperine significantly inhibited mixed-species biofilm formation, as demonstrated by biochemical, microbiological and microscopic analysis. Piperine treatment led to noticeable reductions in biofilm biomass, exopolysaccharide content, total protein content, metabolic activity and extracellular DNA. Mechanistic investigations revealed that piperine impaired biofilm-forming determinants by reducing cellular co-aggregation and cell surface hydrophobicity, inducing intracellular reactive oxygen species (ROS) accumulation, and increasing membrane permeability. Significantly, piperine effectively disrupted pre-established mixed-species biofilms, and its antibiofilm efficacy was further validated in a catheter model, highlighting its relevance against device-associated infections. Collectively, these findings demonstrate that piperine inhibits and disintegrates S. aureus-P. aeruginosa biofilms through diverse mechanisms, positioning it as a promising phytochemical for managing biofilm-associated infections.
Das et al. (Fri,) studied this question.