Larsen, Lone Heimann

Schønheyder, Henrik Carl

Thomsen, Trine Rolighed

Xu, Yijuan

English

IntroductionStaphylococcus aureus is a major human pathogen. It has the ability to adapt to a biofilm mode of growth in response to the host environment, and this is crucial for its leading role in device-related infections and chronic infections. However, little is known about stepwise changes in virulence expression and metabolism from inception of infection to establishment of chronic biofilm infections.AimTo identify and compare the in vivo transcriptional changes of a clinical S. aureus strain (SAU060112) during infection development in vitro, in a guinea pig biofilm model and in a patient with an infected prosthetic joint. ResultsPrincipal component analysis showed  In vivo gene expression profiles were distinctly different from in vitrocultures of S. aureus. The guinea pig data grouped together with a patient case of prosthetic joint infection.Reference: Xu et al. (2016). In vivo gene expression in a Staphylococcus aureus prosthetic joint infection characterized by RNA sequencing and metabolomics: a pilot study. BMC Microbiology, 16(1), 80. Function of Staphylococcus aureus biofilm - studied in vitro, in guinea pigs and in a patientLone Heimann Larsen1, Yijuan Xu2,3, Henrik C. Schønheyder1,4 andTrine Rolighed Thomsen2,31. Department of Clinical Microbiology, Aalborg University Hospital, Aalborg, Denmark2. Biotech, Danish Technological Institute, Aarhus, Denmark3. Department of Chemistry and Bioscience, Aalborg University4. Department of Clinical Medicine, Aalborg University, Aalborg, DenmarkMethodsTotal RNA extraction (PowerLyser® Ultraclean® Tissue & Cells RNA Isolations Kit)Removal of human RNA (MICROBEnrichTM)Sequencing library prep (Illumina® TruSeq® Stranded mRNA Library Prep )Sequencing on IlluminaRemoval of bacterial rRNA(RiboZero rRNA Removal Kit (Bacteria) )Bioinformatics analysis on CLC genomic workbench  Conclusions In vivo S. aureus gene expression profiles are distinct from in vitro profiles. S. aureus adjusts its virulence expression and adapts to hypoxic and acidic environment during infection development.  During prosthetic joint infection in the patient S. aureus sustained on a versatile human-cell-based diet consisting of amino acids, glycans and nucleosides in the hypoxic joint fluid. Many, but not all, of the known virulence factor genes were upregulated in vivo compared with in vitro. The applied guinea pig model is suitable for studying S. aureus pathogenesis.  Contact: Trine Rolighed Thomsentrt@dti.dk+45 72201828Differential gene expression in the guinea pig model showed  Virulence genes: 16 were upregulated at infection day 3 compared to  infection day 7 and 9.  Metabolic pathways: the arginine deiminase pathway and the urea degradation pathway were upregulated at day 7 and 9 compared to day 3 and Treat14.  This indicated decreased virulence expression and a response to the acidic environment during infection development.Poster # 65Synovial fluid from patientIsolate SAU060112NMR measurementMaterial aspirated from subcutaneous tissue cagesFigure 2 All enzymes in the pathway for amino acid degradation are highly expressed in the patient sampleFigure 3 Free amino acids were abundant in the infected joint fluid from the patientAcknowledgement: This study was prepared within the framework of the ‘Prosthetic-Related Infection and Pain’ (PRIS) - Innovation project.  http://www.joint-prosthesis-infection-pain.dk   The  study was supported by a grant for the PRIS Innovation Consortium from The Danish Council for Technology and Innovation (no. 09–052174). The research protocol was approved by the Danish Animal Ethics Council (2015-15-0201-00620).In vitroMOX 14Treat14 INFDay 3PatientIn vitro, SAU060112INF Day 7INFDay 9Figure 1 Principal component analysis of all transcriptome profilesA controlled study of infection development in guinea pig model:

Function of Staphylococcus aureus biofilm - studied in vitro, in guinea pigs and in a patient

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Function of Staphylococcus aureus biofilm - studied in vitro, in guinea pigs and in a patient

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