Evaluation of the relationship between quorum sensing system genes and antibiotic resistance in isolated Pseudomonas aeruginosa from cystic fibrosis patients

Background and Objectives: Pseudomonas aeruginosa is a Gram-negative bacterium that causes respiratory infections in individuals with cystic fibrosis. Its level of virulence is primarily controlled through Quorum Sensing (QS), a communication mechanism that utilizes small signaling molecules. This study investigates P. aeruginosa antibiotic resistance in CF patients in Imam Khomeini Hospital and examines the presence of QS genes in resistant strains. Materials and Methods: Sixty-five P. aeruginosa samples were identified in CF patients in Imam Khomeini Hospital in Tehran. Antibiotic resistance was assessed using the disk diffusion method, and QS genes (rhlI, rhlR, lasI, lasR) were eval- uated by applying PCR. Results: Approximately 61.5 % of P. aeruginosa strains were multiple-drug-resistant (MDR), with 30.7% classified as ex- tensively drug-resistant (XDR). The highest resistance was observed against amoxicillin, amikacin, and cefepime. The most common QS gene in MDR and XDR strains was rhlR. Additionally, 78.9% of XDR isolates carried rhlI, rhlR, lasI, and lasR genes. Conclusion: The study specified that more than half of the P. aeruginosa strains exhibited resistance to five antibiotic classes, and effective antibiotics against P. aeruginosa were colistin, meropenem, ciprofloxacin, piperacillin/tazobactam, and cefo- taxime. A noteworthy correlation was identified between MDR and XDR strains and the existence of QS genes in the strains.