Biofilm associated genotypes of multiple antibiotic resistant Pseudomonas aeruginosa

James Redfern,Mark Charles Enright,Alex Van Belkum,Joanna Verran,Peter Kelly,Elliot Whittard,Roobinidevi Ragupathy,Magali Jaillard,Janine Wallace

doi:10.1186/s12864-021-07818-5

James Redfern, Mark Charles Enright + Show 7 more

Open Access

https://doi.org/10.1186/s12864-021-07818-5

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Abstract

BackgroundPseudomonas aeruginosa is a ubiquitous environmental microorganism and also a common cause of infection. Its ability to survive in many different environments and persistently colonize humans is linked to its presence in biofilms formed on indwelling device surfaces. Biofilm promotes adhesion to, and survival on surfaces, protects from desiccation and the actions of antibiotics and disinfectants.ResultsWe examined the genetic basis for biofilm production on polystyrene at room (22 °C) and body temperature (37 °C) within 280 P. aeruginosa. 193 isolates (69 %) produced more biofilm at 22 °C than at 37 °C. Using GWAS and pan-GWAS, we found a number of accessory genes significantly associated with greater biofilm production at 22 °C. Many of these are present on a 165 kb region containing genes for heavy metal resistance (arsenic, copper, mercury and cadmium), transcriptional regulators and methytransferases. We also discovered multiple core genome SNPs in the A-type flagellin gene and Type II secretion system gene xpsD. Analysis of biofilm production of isolates of the MDR ST111 and ST235 lineages on stainless-steel revealed several accessory genes associated with enhanced biofilm production. These include a putative translocase with homology to a Helicobacter pylori type IV secretion system protein, a TA system II toxin gene and the alginate biosynthesis gene algA, several transcriptional regulators and methytransferases as well as core SNPs in genes involved in quorum sensing and protein translocation.ConclusionsUsing genetic association approaches we discovered a number of accessory genes and core-genome SNPs that were associated with enhanced early biofilm formation at 22 °C compared to 37 °C. These included a 165 kb genomic island containing multiple heavy metal resistance genes, transcriptional regulators and methyltransferases. We hypothesize that this genomic island may be associated with overall genotypes that are environmentally adapted to survive at lower temperatures. Further work to examine their importance in, for example gene-knockout studies, are required to confirm their relevance. GWAS and pan-GWAS approaches have great potential as a first step in examining the genetic basis of novel bacterial phenotypes.

Highlights

Pseudomonas aeruginosa is a ubiquitous environmental microorganism and a common cause of infection
Flagellar motility is wellknown as a requirement for biofilm production in P. aeruginosa[30] and suppression of fliC has been linked to increasing temperature in P. syringae[31], with similar temperature-association of flagellar being reported in Listeria monocytogenes and Proteus vulgaris[32, 33]
Lrt-pvalue 1.14E-05 1.08E-04 3.45E-04 3.45E-04 3.45E-04 3.52E-04 3.52E-04 4.58E-04 4.58E-04 5.38E-04 5.38E-04 5.38E-04 6.85E-04 1.17E-03 1.17E-03 1.17E-03 1.17E-03 1.17E-03 2.21E-03 2.92E-03 beta 1.95E+00 2.18E+00 2.33E+00 2.33E+00 2.33E+00 2.15E+00 2.15E+00 -2.91E+00 -2.91E+00 1.68E+00 1.68E+00 1.68E+00 1.82E+00 2.64E+00 2.64E+00 2.64E+00 2.64E+00 2.64E+00 1.55E+00 1.74E+00. This resulted in our discovery of a genetic region containing many heavy metal resistance genes that we found associated with increased biofilm production at 22 °C compared to 37 °C and core genome Single nucleotide polymorphism (SNP) in biofilm associated genes such as algA, algX, type II secretion system protein D gene xpsD and response regulator genes such as pleD and quiP that are significantly associated with this phenotype and have previously been shown to have roles in biofilm biosynthesis and quorum sensing

Summary

Introduction

Pseudomonas aeruginosa is a ubiquitous environmental microorganism and a common cause of infection. Multidrug resistant (MDR) isolates of lineages associated with outbreaks of infection belonging to MLST Sequence Types (STs) 111 and ST235 are two such ‘high risk’ clones that have global distributions and numerous and transferable antibiotic resistances [11]. Isolates of these lineages contain a large number of horizontally transferred β-lactamase genes [8] and are highly virulent in comparison to a third, less significant lineage - ST175 [12]

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