Biofilm-forming ability and infection potential of Pseudomonas aeruginosa strains isolated from animals and humans

Abstract

Pseudomonas aeruginosa has been amongst the top 10 'superbugs' worldwide and is causing infections with poor outcomes in both humans and animals. From 202 P. aeruginosa isolates (n = 121 animal and n = 81 human), 40 were selected on the basis of biofilm-forming ability and were comparatively characterized in terms of virulence determinants to the type strain P. aeruginosa PAO1. Biofilm formation, pyocyanin and hemolysin production, and bacterial motility patterns were compared with the ability to kill human cell line A549 in vitro. On average, there was no significant difference between levels of animal and human cytotoxicity, while human isolates produced higher amounts of pyocyanin, hemolysins and showed increased swimming ability. Non-parametric statistical analysis identified the highest positive correlation between hemolysis and the swarming ability. For the first time an ensemble machine learning approach used on the in vitro virulence data determined the highest relative predictive importance of the submerged biofilm formation for the cytotoxicity, as an indicator of the infection ability. The findings from the in vitro study were validated in vivo using zebrafish (Danio rerio) embryos. This study highlighted no major differences between P. aeruginosa species isolated from animal and human infections and the importance of pyocyanin production in cytotoxicity and infection ability.

Groundwater, soil and compost, as possible sources of virulent and antibiotic-resistant Pseudomonas aeruginosa

“…Regarding biofilm-forming ability, the detected rate of strong biofilm producer environmental isolates (22.7%) is closer to the previously reported rate for human isolates (23.5%) than for strains isolated from animals (9%) (Milivojevic et al 2018). The fact that 34.8% of the positive microtiter-plate results were not structured biofilms emphasize the importance of visual techniques in biofilm detection (Van Duuren et al 2017).…”

Potentially pathogenic bacteria isolated from diverse habitats in Spitsbergen, Svalbard

“…Finally, to the best of our knowledge, the closest neighbors to isolates An34, S32, S58, N2, N36a, N39, N42, N60, N61, N71, N83, and N106, which are, respectively, Leifsonia kafniensis, Tessaracoccus flavescens, Salinibacterium amurskyense, Exiguobacterium undae, Pedobacter nyackensis, Carnobacterium funditum, Streptomyces fulvissimus, Pseudomonas helmanticensis, Psychrobacter nivimaris, Pseudomonas lurida, Bacillus idriensis, and Salinibacterium xinjiangense, had not been previously assessed for hemolytic activity but some reports exist of these species or other members of their genera with pathogenic phenotypes (Ostroff et al 1990;Ko et al 2006;Ülbegi-mohyla et al 2009;Leisner et al 2012;Tayabali et al 2015;Chen et al 2017;Milivojevic et al 2018).…”

Antibiofilm potential of purified environmental bacteriophage preparations against early stage Pseudomonas aeruginosa biofilms

“…; Milivojevic et al . ), and the results may therefore suggest that a reduction in pathogenicity enhances the lytic activity of the aforementioned bacteriophages. This observation is, however, limited to three bacterial strains, and the hypothesis needs to be further assessed using several wild‐type and quorum sensing‐deficient strains and/or by combining these bacteriophages with a compound that reduces pathogenicity such as a quorum sensing inhibitor.…”

“…None of the bacteriophages were able to produce clear plaques or demonstrate any signs of lytic activity against pyocyaninproficient strains (PS 118, PS 119 and PS 1123). Pyocyanin production is a terminal signal of quorum sensing, and a potent virulence factor of P. aeruginosa (Dietrich et al 2006;Milivojevic et al 2018), and the results may therefore suggest that a reduction in pathogenicity enhances the lytic activity of the aforementioned bacteriophages. This observation is, however, limited to three bacterial strains, and the hypothesis needs to be further assessed using several wild-type and quorum sensing-deficient strains and/or by combining these bacteriophages with a compound that reduces pathogenicity such as a quorum sensing inhibitor.…”

“…The persistence of P. aeruginosa in up to 80% of all infections is attributed to its ability to form complex biofilms. In one study, Milivojevic et al (2018) showed that the infection ability of 40 P. aeruginosa can be predicted based on different virulence factors, where a positive correlation between cytotoxicity (an indicator of infection) and biofilm formation was found. Bacteria in a biofilm display many different features from their planktonic counterparts.…”