Background and Aim : :
Pseudomonas aeruginosa is gram negative, motile and aerobic bacteriathat pauses as a major cause of nosocomial infections and infections in immunosuppressed andburn patients worldwide. In this study, we aimed to determine the presence and prevalence of pelA,
pslA ,
QacE and QacEΔ۱ genes and the MIC for
Chlorhexidine in Pseudomonas aeruginosaisolates obtained from clinical samples from Shahid Faghihi and Namazi Hospitals in Shiraz.Methods : In this study, ۱۲۰
Pseudomonas aeruginosa isolates were collected from inpatientssamples (urine, blood, trachea, wound, and body fluids) from October ۲۰۲۰ to July ۲۰۲۱. Afterconfirming the isolates, their antibiotic resistance was checked by disc diffusion method. Then theminimum inhibitory concentration (MIC) was determined for chlorhexidine. DNA was thenextracted by boiling. Finally, prevalence of pelA ,
pslA ,
QacE and QacEΔ۱ genes determined byPCR .Results : Out of the ۱۲۰ studied isolates, ۶۶ were positive for pelA or
pslA genes and ۵۵ (۵۴.۲%)had
QacE and QacEΔ۱. The average MIC (n=۱۲۰) for
Chlorhexidine was ۰.۲۲۳% (۲.۲۳mg/mL)while the MIC for pelA/pslA positive isolates was ۰.۳۴۶۶% (۳.۴۶۶mg/mL) and the MIC forpelA/pslA negative isolates was ۰.۰۷۱۲% (۰.۷۱۲mg/mL). Cephalosporins showed the lowestoverall efficacy with ceftazidime having a sensitivity of only ۱۷.۵%. Amikacin was the only testedantibiotic to show a more than ۷۰% effectiveness, with a total sensitivity of ۷۳.۳۳% followed byofloxacin with a total sensitivity of ۶۷.۵%. In addition, the sensitivity of all the tested antibioticsexcept for Amikacin showed a meaningful correlation with the presence of pelA/pslA genes (pvalue<۰.۰۵) which further implies the role of biofilm formation in antibiotics resistance.Furthermore, ۳۱.۸% of pelA/pslA positive samples were identified as MDR in comparison to۷.۴۱% among pelA/pslA negative ones with an average of ۲۶.۸%.Conclusion : The nearly ۵-fold increase in the MIC for chlorhexidine alongside the significantlyhigher prevalence of MDR strains and antibiotics resistances in pelA/pslA positive samplesfurthermore implies the critical role of these genes in biofilm formation and antimicrobialresistance.