Impact of elastase overproduction on antibiotic resistance and biofilm formation in Pseudomonas aeruginosa

Background: Pseudomonas aeruginosa is a gram-negative pathogen found in a wide range of habitats. Approximately 10-20% of hospital-acquired diseases are estimated to be caused by infections attributed to Pseudomonas. The presence of biofilm-associated lifecycle and multidrug resistance (MDR) in P. aeruginosa contributes to its high pathogenicity. Objectives: To detect the effect of elastase overproduction in P. aeruginosa on antibiotic resistance and biofilm formation. Methods: Twenty-five clinical isolates of P. aeruginosa were obtained from a private center in Baghdad, Iraq and re-identified by Vitek-2 system. The Kirby-Bauer disc diffusion method was used for antibiotic susceptibility testing. The microtiter plate assay was used to quantify biofilm production. Transformation of pMGB vector into one strong biofilm producer (P13) to produce P13(pMGB) isolate was performed by electroporation method. Results: Out of 25 isolates, 18 (72%) were strong and 7 (28%) were moderate biofilm producers. P13(pMGB) was susceptible to amoxicillin-clavulanate and ampicillin, unlike P13, which was resistant. Furthermore, P13(pMGB) showed a notable reduction in resistance to gentamicin and a substantial increase in sensitivity to piperacillin-tazobactam. Nevertheless, no changes in susceptibility to ciprofloxacin, erythromycin, imipenem, levofloxacin, and tetracycline were found in comparison to P13. Biofilm formation in P13(pMGB) was significantly reduced compared to P13. Conclusion: The current study showed that overproduction of elastase has significant effect on antibiotic resistance and biofilm formation in P. aeruginosa.