Phenotypic and Genotypic Characteristics of Clinical Pseudomonas aeruginosa Isolates

Abstract

Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen associated with human nosocomial infections. It causes chronic infections in pulmonary passages, as in cystic fibrosis patients, urinary tract infections, and sepsis. It is a ubiquitous bacterium found in animals, plants, and soil. Multi-drug resistant P. aeruginosa is recognized by the World Health Organization (WHO) as an important public health concern. In this study, whole genome sequencing (WGS) based analysis of nine P. aeruginosa, one Pseudomonas stutzeri, and one Pseudomonas putida isolates was performed to understand their molecular epidemiology. Genome comparison, multi- locus sequence typing (MLST), and whole genome SNP- based phylogenetic analysis (wgSNP) were used to determine the relatedness of the isolates. In silico typing was used to determine the antimicrobial resistance, virulence determinants, and plasmids. PCR was used to detect exoS and exoU genes, and biofilm assays were performed to identify biofilm formers. Nine distinct MLST allelic profiles were identified. Antimicrobial susceptibility tests showed that all the isolates were susceptible to kanamycin, while six isolates were resistant to piperacillin-tazobactam. Genomic analysis revealed the presence of several β-lactamases (blaPAO, blaOXA-50, blaPAU-1, and blaVIM-2) and aminoglycoside resistance encoding determinants (aph(3’)-IIb, aac(6’)-29a, and aac(2’)-Ia). exoU and exoS toxin encoding genes were detected in 54% and 45% of the isolates, respectively, and 63% of the isolates were biofilm formers. Six different plasmids were detected, and a number of virulence factors related to toxins, kinases, and pigments that contribute to the ability of the bacterium to adapt to environmental changes. Our study revealed the diversity among P. aeruginosa in Lebanese hospitals. The emergence and spread of MDR P. aeruginosa emphasize on the importance of integrating whole-genome sequencing into infection control and outbreak detection.