Presented by: Dirk Lange PhD
The Stone Centra at Vancouver General Hospital, Department of Urologic Sciences, University of British Columbia

Introduction

Murine models of sepsis, such as the cecal ligation and puncture (CLP) model, are typically polymicrobial and associated with a high mortality within hours after the specific intervention. To date, no models exist that follow the natural course of development from initial infection to sepsis, meaning that current models are not suitable to test the effiacy of interventions to prevent development to sepsis. To address this shortcoming, we developed a high-throughput, murine model that mimics a slow-paced, monomicrobial sepsis originating from the urinary tract. 

Materials

Twelve (12)-week-old male C57Bl/6 mice (n=23) underwent percutaneous insertion of a 4mm catheter piece into the urinary bladder. The following day mice were divided into three groups differing in the number of bacteria introduced into the bladder of animals: group 1 - 50 µl of a 1x10^8 CFU/ml solution (n=10), group 2 - 50 µl of a 1x10^7 CFU/ml solution (n=10), and group 3 (sham mice) - 50 µl of sterile saline (n=3). On day 4 mice were sacrificed. The number of bacteria in urine, colonizing bladder catheters, adherent to/invaded into the bladder tissue as well as a set of (32) sepsis-associated pro-/anti-inflammatory cytokines and chemokines were analyzed. 

Results

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All 23 mice survived the postinterventional period. Mean weight loss was 11% in group 1, 9% in group 2 and 2% in the control group. Mean urine CFU counts were highest in group 1 and all sham mice had negative urine cultures. All infected mice had high catheter-adhered bacterial counts. 18/20 infected mice had CFU counts in homogenized splenic tissue indicating septicemia. Cell-free DNA and D-Dimer was highest in group 1 and lowest in the control group. Serum levels of G-CSF were significantly increased in group 1 when compared to controls. Serum levels of IL-6, TNF-a, IFN-? and IL-1ß were all elevated (1.5 to 30-fold) compared to control mice. 

Conclusion

We present a monomicrobial murine model of urosepsis that follows the natural progression to sepsis from an initial urinary tract infection originating from an indwelling catheter. This model does not lead to rapid deterioration and death and can therefore be used as a model to test the efficacy of novel interventional strategies to prevent sepsis development. 

Funding

Roman Herout was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – 447437311. 

Lead Authors

Roman Herout, MD
The Stone Centra at Vancouver General Hospital, Department of Urologic Sciences, University of British Columbia

Co-Authors

Sreeparna Vappala, PHD
Department of Pathology and Laboratory Medicine and Centre for Blood Research, The University of British Columbia,

Sarah Hanstock,
The Stone Centra at Vancouver General Hospital, Department of Urologic Sciences, University of British Columbia

Igor Moskalev, MD
Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia

Ben Chew, MD
The Stone Centra at Vancouver General Hospital, Department of Urologic Sciences, University of British Columbia

Jayachandran Kizhakkedathu, PHD
Department of Pathology and Laboratory Medicine and Centre for Blood Research, The University of British Columbia,

Dirk Lange, PHD
The Stone Centra at Vancouver General Hospital, Department of Urologic Sciences, University of British Columbia