Biofilm disruption and gene expression alteration by phages against multidrug-resistant Pseudomonas aeruginosa

Pseudomonas aeruginosa is a major opportunistic pathogen responsible for severe human infections and is increasingly associated with multidrug resistance and limited treatment options. In this study, we isolated and characterized bacteriophages targeting drug-resistant P. aeruginosa strains and evaluated their capacity to disrupt biofilms and modulate biofilm-associated gene expression. Phages recovered from sewage showed broad lytic activity against P. aeruginosa and were classified morphologically into the families Podoviridae and Myoviridae. Two phages, A2 and A4, exhibited the highest lytic activity against the resistant strains examined. Both phages significantly degraded preformed biofilms, with phage A4 showing comparatively stronger antibiofilm activity. In addition, phage exposure altered the expression of several biofilm-associated genes, including pelA, htpB, bifA, psl, fimW, and wspA. A notable finding was the reversal of bifA expression from downregulation at 12 h to upregulation at 24 h following treatment with phage A4. Collectively, these results demonstrate that phages A2 and A4 possess strong lytic and antibiofilm activities and are capable of modulating biofilm-associated transcriptional responses in drug-resistant P. aeruginosa. The findings support the potential application of bacteriophages as alternative therapeutic agents against drug-resistant biofilm-associated infections.