Biofilm Associated Genotypes of Multidrug-Resistant Pseudomonas aeruginosa

Abstract

13Pseudomonas aeruginosa is a ubiquitous environmental microorganism that is also a 14 common cause of nosocomial infections that vary in severity from chronic wound infections 15 to pneumonia, bloodstream infections and sepsis. Its ability to survive in many different 16 environments and persistently colonize human tissue is linked to its presence within biofilms 17 that form on indwelling device surfaces such as plastics and stainless steel. Biofilm promotes 18 bacterial adhesion and survival on surfaces, reduces susceptibility to desiccation, and the 19 actions of antibiotics and disinfectants. Recent genome sequencing studies demonstrate 20 that P. aeruginosa is a highly diverse species with a very large pan-genome consistent with 21 its adaptability to differing environments. However, most MDR infections are caused by a 22 small number of "high-risk" clones or lineages that recently emerged and spread globally. 24In our 2017 study of the resistome of P. aeruginosa we confirmed the power of genome-25 wide association (GWAS) techniques to explore the genetic basis of several antibiotic 26 resistance phenotypes and discovered 46 novel putative resistance polymorphisms. In this 27 study we sought to examine genetic associations within a subset of these isolates with 28 simple biofilm phenotypes. We examined the genetic basis for biofilm production on 29 polystyrene at room temperature (22°C) and body temperature (37°C) within a total of 280 30 isolates. 69% of isolates (n=193) produced more biofilm mass at 22°C, whilst those 31 producing more biofilm at 37°C had reduced optical density 540 variation. We found 32 statistically significant associations with lpxO and other genes associated with arsenic 33 resistance to be significantly associated with this trait. lpxO which encodes a lipid A 34 hydroxylase and arsenic reduction genes have previously been found to be associated with 35 biofilm production in this species. We analyzed 260 ST111 and ST235 genomes and found 36 considerable genetic variation between isolates in their content of genes previously found 37 associated with biofilm production. This is indicative of a highly variable and flexible 38 population within these clades with frequent emergence of successful sub-lineages. Analysis 39 2 of 48 of these isolates' ability to form biofilm on stainless steel surfaces showed that a 40 'good' biofilm-forming phenotype had significant intra-clone variation, independent of core 41 genome phylogeny with pan-genome analysis, suggesting a possible association and 42 involvement of components of the type IV secretion system. However, GWAS and pan-43 GWAS analyses yielded weaker statistical significance. This study confirms GWAS and pan- 44GWAS trait associations can be performed for biofilm phenotype and produce data in 45 agreement with each other. This panel of 280 study isolates, matched to genomic data has 46 potential for the investigation of other phenotypes in P. aeruginosa perhaps as part of a 47 growing database / collection. A representative, curated, gen...

Genetic Basis and Physiological Effects of Lipid A Hydroxylation in Pseudomonas aeruginosa PAO1

“…Notably, lpxO1 was found to be slightly up-regulated (about two-fold) at 25 • C as compared to 37 • C by transcriptomic analysis [30], and a possible correlation between a specific single nucleotide polymorphism (SNP) in lpxO1 and biofilm formation at 22 • C has been recently proposed through genome-wide association analysis [31]. To investigate any possible temperature-dependent effects of LpxO enzymes, we performed growth, biofilm, and antibiotic resistance assays also at 22 and 30 • C. As shown in Figure S4, we did not observe any relevant differences between the wild type and lpxO mutants under both conditions.…”

Optimization of some environmental and nutritional conditions using microtiter plate for Pseudomonas aeruginosa biofilm formation

“…Biofilm of P. aeruginosa is formed from complex microbial communities correlated with matrices that help the bacterium resist desiccation and mechanical removal (Redfern et al 2019). The biofilm consists of matrices formed from complexes of polysaccharides, proteins, extracellular DNA, and lipids (Casciaro et al 2019;Ciofu and Tolker-Nielsen 2019).…”