Characterization of clinical extensively drug resistant Pseudomonas aeruginosa from a Chinese teaching hospital

Abstract

Introduction: Pseudomonas aeruginosa, an important opportunistic pathogen, carries multiple virulence factors which contribute to its adaptation and pathogenicity. The goal of this study was to characterize the virulence factors among extensively drug-resistant P. aeruginosa.

Methodology: In this study, 63 non-duplicated extensively drug-resistant P. aeruginosa clinical isolates were collected from December 2013 to July 2015. Polymerase chain reaction (PCR) was used to analyze the homogeneity and the type III secretion system. Microtiter plate method was performed to evaluate the ability to form biofilms associated to twitching and swimming motilities.

Results: High percentage (96.8%) of isolates was sensitive to polymyxin B, while the resistance rate to other antibiotics (amikacin, aztreonam, ceftazidime, ciprofloxacin, gentamicin, imipenem, levofloxacin, meropenem, piperacillin-tazobactam) ranged from 80.9% to 100%. Enterobacterial repetitive intergenic consensus-PCR detected seven major groups with minimal genetic variation. All the isolates carried exoT gene, 96.8% carried exoY, 69.8% carried exoS, and 31.7% carried exoU gene. Biofilm formation was confirmed in all strains, out of which 41.3% formed strong biofilm. Motilities analysis showed heterogeneous diameters ranging from 6.02 to 26.09 mm for swimming and from 7.60 to 23.34 mm for twitching motilities.

Conclusions: Our findings revealed that the clinical P. aeruginosa isolates tested are the major invasive types in nature and multiple virulence factors were commonly carried in the extensively drug-resistant strains.

Keywords: Pseudomonas aeruginosa; extensively drug-resistant; molecular epidemiology.