Unexpected induction of resistant Pseudomonas aeruginosa biofilm to fluoroquinolones by diltiazem: A new perspective of microbiological drug–drug interaction

SummaryThe increase of multi-drug resistant Pseudomonas aeruginosa infections is a worldwide dilemma. At the heart of the problem is the inability to treat established P. aeruginosa biofilms with standard antibiotic therapy, including fluoroquinolones. We address a previously unstudied question as to the effect of a commonly prescribed calcium channel blocker (CCB) diltiazem on the biofilm growth. Real-time monitoring of the overall growth and killing of P. aeruginosa biofilm during fluoroquinolones therapy in the presence and absence of diltiazem was performed. In this study, we demonstrate that for P. aeruginosa biofilms, resistance to the first-line fluoroquinolones may be induced by the commonly prescribed calcium channel blocker diltiazem.