In Vitro antibiofilm activity of Salvadora persica hexane extract against selected multidrug-resistant gram-negative pathogens associated with ventilator-associated pneumonia

Aims Biofilm formation by multidrug-resistant (MDR) Gram-negative pathogens on endotracheal tubes is a major challenge in ventilator-associated pneumonia (VAP), necessitating novel antibiofilm agents. This study evaluated the activity of Salvadora persica hexane extract (SPHE) against clinical MDR isolates of Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii relevant to VAP. Methods and Results Biofilm-forming capacity was assessed using crystal violet (CV) assays. SPHE was evaluated at sub-inhibitory and MIC concentrations to assess biofilm inhibition and the reduction of preformed biofilm. Structural changes were analysed via scanning electron microscopy (SEM) with quantitative image analysis. Expression of adhesins FimH (K. pneumoniae) and OmpA (A. baumannii) was assessed by Western blot, while cytocompatibility was tested in WRL-68 hepatocytes and dental pulp stem cells (DPSCs) via MTT assays. SPHE demonstrated stage-dependent activity. At sub-inhibitory concentrations, early biofilm formation was inhibited by 88% in P. aeruginosa and 74% in K. pneumoniae. For mature biofilms, the greatest reduction (78% biomass) occurred in A. baumannii. SEM revealed significant architectural disruption, with surface coverage reduced by up to 56% (p = 0.002). Cell viability remained > 90% in both cell lines at all tested concentrations. Conclusions SPHE exhibits species- and developmental-stage-dependent antibiofilm activity against tested MDR Gram-negative pathogens associated with VAP and induces substantial disruption of biofilm architecture. Together with preliminary cytocompatibility findings within the tested concentration range, these results support further investigation of SPHE as a potential antibiofilm candidate to limit biofilm-associated colonisation in mechanically ventilated patients.