High Incidence of MDR and XDR Pseudomonas aeruginosa Isolates Harboring blaGES, blaVEB, and blaPER Extended-Spectrum Beta-Lactamase Genes in Iran

Abstract

Backgrounds:The ever-increasing incidence of multidrug resistance in ESBL-producing Pseudomonas aeruginosa is one of the most serious public health threats. This study aimed to investigate the antibiotic resistance profile and molecular characteristics of ESBL-producing P. aeruginosa isolates. Materials & Methods: Antimicrobial susceptibility testing was performed for 120 P. aeruginosa clinical isolates using the Kirby-Bauer disk diffusion and broth microdilution assays. Combined disk test (CDT) was applied to screen for ESBL production among P. aeruginosa isolates. PCR assays determined the presence of bla GES , bla PER , and bla VEB genes in all isolates. Findings: The clinical isolates of P. aeruginosa showed the highest resistance to cefotaxime (86.7%) and gentamicin (65.8%). Of 120 P. aeruginosa isolates, 60.8% were MDR, and 53.3% were XDR. The prevalence of these strains was significantly higher in hospitalized patients than in out-patients (p<.001). Also, 58 P. aeruginosa strains (48.3%) were considered as phenotypic ESBL producers. Furthermore, 15, 35, and 24.2% of P. aeruginosa isolates harbored bla GES , bla VEB , and bla PER , respectively. The incidence of MDR (71.4% vs. 41.9%, p= .001) and XDR (63.6% vs. 34.9%, p= .002) was significantly higher in ESBL-producing P. aeruginosa isolates compared to non-ESBL producers. The highest incidence rate of MDR was reported in bla VEB gene-positive P. aeruginosa isolates (95.2%), followed by isolates harboring bla PER (79.3%) and bla GES (55.6%) genes. Conclusion:This study findings show a high prevalence of MDR ESBL-producing P. aeruginosa isolates, indicating the importance of correct identification of these superbugs and judicious use of various antibiotics to prevent their spread.