Phenotypical Comparison of Pseudomonas Aeruginosa Isolated from Human and Veterinary Samples; Impact of Host Adaptation on Infection Pathogenesis
Abstract Purpose: Determinants of virulence in Pseudomonas aeruginosa vary strongly depending on its habitat. In this study, we analyzed these alterations depending on the host organism in isolates cultured from canine ears and compared it to clinical extended-spectrum antibiotic-resistant Pseudomonas aeruginosa isolates (XDR), clinical antibiotic-sensitive (non-XDR) from humans and environmental isolates (EI) analyzed during our first study in 2017. Methods: A total of 22 veterinary isolates cultured from canine ears (VET) were examined for spontaneous biofilm formation, stress response in biofilm formation induced by meropenem, in vitro fitness, susceptibility to human serum and polymorphonuclear leukocytes and the genetically determined virulence factors toxA, exoS, exoT, exoU, exoY, nan1, cif, lasA and lasB.Results: We observed significantly elevated spontaneous biofilm formation and serum susceptibility in VET isolates compared to EI and non-XDR isolates as well as significantly decreased in vitro fitness compared to XDR isolates. The VET isolates resembled most the XDR subgroup of isolates previously cultured from blood. Within the environmental isolates, we observed an increase of spontaneous biofilm formation and exoU presence in isolates cultured from community water samples over hospital water samples to pool samples.Conclusions: Considering the distinct differences in some features of the examined VET isolates, a higher degree of phenotypical adaption can be assumed. Increased biofilm formation seems to be a common and characteristic event in isolates adapted to a specific habitat. Therefore amplification of potentially more virulent Pseudomonas aeruginosa strains in domestic animals may lead to elevated zoonotic risk for example for pet owners.