Investigation the Role of Quorum Sensing Genes in Biofilm Formation and Antibiotic Resistance Among Clinical Isolates of Pseudomonas Aeruginosa

Background: Biofilm development in P. aeruginosa is a complicated mechanism controlled by several genetic factors, among which quorum sensing (QS) plays a pivotal role.     Objectives: Investigating the Impact of Quorum-sensing Systems genes (rhlI, rhlR, lasI, and lasR) on biofilm-mediated antibiotic resistance in Pseudomonas aeruginosa. Patients and Methods: A total of 30 Pseudomonas aeruginosa isolates were collected from four major referral hospitals in Baghdad, including Al-Imamian Al-Kadhimiyain Medical City and the Iraq Medical City complex (comprising Baghdad Teaching Hospital, Burns Hospital, and Ghazy Al-Hariri Hospital for Surgical Specialties). Antibiotic susceptibility testing and minimum inhibitory concentration (MIC) determination were evaluated. Quantitative microtiter plate assays were used to study the biofilm formation ability. Conventional PCR was used to detect quorum-sensing genes using specific primer pairs after DNA extraction.  Results: Of the 30 Pseudomonas aeruginosa isolates,43% were identified as extensively drug-resistant (XDR), while 17% were classified as multidrug-resistant (MDR). The highest level of antibiotic resistance was observed against levofloxacin (60%). Formation of Biofilms was detected in 93.33% of the isolates, with varying strength. The occurrence of quorum-sensing genes among the isolates was as follows: lasI (96.67%), lasR (76.67%), rhlI (93.33%), and rhlR (63.33%). Conclusion: The quorum-sensing genes lasI and rhlI were consistently noticed in all isolates that formed moderate to strong biofilms. Additionally, a correlation was observed between the existence of lasR and rhlR genes and resistance to fluoroquinolones and aminoglycosides.  Keywords: Pseudomonas aeruginosa, Quorum-sensing genes, Biofilm, rhlI, lasI.