Evaluation of two novel biofilm-specific antibiotic resistance genes in clinical Pseudomonas aeruginosa isolates

Background: The ability of Pseudomonas aeruginosa to form biofilm plays a significant role on its pathogenesis in susceptible hosts. One of the best known clinically relevant consequences of biofilm-specific properties is the wide range of drug-resistance. Several mechanisms account for antibiotic resistance in biofilms. Objective: The present study aimed to evaluate the role of two novel genetic loci, PA2070 and PA5033 genes, on biofilm-specific antibiotic resistance of P. aeruginosa. Methods: One hundred clinical isolates of P. aeruginosa were obtained from two educational hospitals and identified by conventional microbiological methods. Biofilm formation was assessed by 96-well flat-bottomed microtiter plate assay. Biofilm-producer isolates were further investigated by polymerase chain reaction (PCR) to assess the presence of PA2070 and PA5033 genes. RNA extraction and complementary DNA synthesis were performed for both biofilm and planktonic P. aeruginosa. Target genes were quantified by real-time PCR assay using specific primers. SPSS version 21.0 and Chi-square were used to analyze the results. Results: The expression analysis revealed overexpression of PA2070 and PA5033 genes in biofilm mode in comparison to planktonic cells by a mean factor of 4.330 for PA2070 and 4.733 for PA5033 gene. Moreover, statistical analysis revealed the correlation between overexpression of mentioned genes in biofilm cultures (p < 0.05). However, no statistically significant association was found between PA2070/PA5033 genes and planktonic isolates. Conclusions: Our results indicate that these genes have participation in biofilm-specific antibiotic resistance of P. aeruginosa. As these genes encode yet-uncharacterized hypothetical proteins, understanding of mechanisms by which confer resistance can provide insights for the development of approaches aimed at controlling biofilm-associated infection.