Project description:Long term-catheterization leads inevitably to a catheter-associated bacteriuria caused by multispecies bacterial biofilms growing on and in the catheters. The overall goal of the presented study was (I) to unravel bacterial community structure and function of such an uropathogenic biofilm and (II) to elucidate the interplay between bacterial virulence and the human immune system within the urine. To this end, a metaproteomics approach combined with in vitro proteomics analyses was employed to investigate both, the pro- and eukaryotic protein inventory. Our proteome analyses demonstrated that the biofilm of the investigated catheter is dominated by three bacterial species, i.e. Pseudomonas aeruginosa, Morganella morganii and Bacteroides sp., and identified iron limitation as one of the major challenges in the bladder environment. In vitro proteome analysis of P. aeruginosa and M. morganii isolated from the biofilm revealed that those opportunistic pathogens are able to overcome iron restriction via the production of siderophores and high expression of corresponding receptors. Notably, a comparison of in vivo and in vitro protein profiles of P. aeruginosa and M. morganii also indicated that the bacteria employ different strategies to adapt to the urinary tract. Whilst P. aeruginosa seems to express secreted and surface-exposed proteases to escape the human innate immune system and metabolizes amino acids, M. morganii is able to take up sugars and to degrade urea. Most interestingly, a comparison of urine protein profiles of three long-term catheterized patients and three healthy control persons demonstrated the elevated level of proteins associated to neutrophils, macrophages and complement system in the patient urine, which might point to a specific activation of the innate immune system in response to biofilm-associated urinary tract infections. We thus hypothesize that the often asymptomatic nature of CAUTI´s might be based on a fine-tuned balance between the expression of bacterial virulence factors and the human immune system. Long term-catheterization leads inevitably to a catheter-associated bacteriuria caused by multispecies bacterial biofilms growing on and in the catheters. The overall goal of the presented study was (I) to unravel bacterial community structure and function of such an uropathogenic biofilm and (II) to elucidate the interplay between bacterial virulence and the human immune system within the urine. To this end, a metaproteomics approach combined with in vitro proteomics analyses was employed to investigate both, the pro- and eukaryotic protein inventory. Our proteome analyses demonstrated that the biofilm of the investigated catheter is dominated by three bacterial species, i.e. Pseudomonas aeruginosa, Morganella morganii and Bacteroides sp., and identified iron limitation as one of the major challenges in the bladder environment. In vitro proteome analysis of P. aeruginosa and M. morganii isolated from the biofilm revealed that those opportunistic pathogens are able to overcome iron restriction via the production of siderophores and high expression of corresponding receptors. Notably, a comparison of in vivo and in vitro protein profiles of P. aeruginosa and M. morganii also indicated that the bacteria employ different strategies to adapt to the urinary tract. Whilst P. aeruginosa seems to express secreted and surface-exposed proteases to escape the human innate immune system and metabolizes amino acids, M. morganii is able to take up sugars and to degrade urea. Most interestingly, a comparison of urine protein profiles of three long-term catheterized patients and three healthy control persons demonstrated the elevated level of proteins associated to neutrophils, macrophages and complement system in the patient urine, which might point to a specific activation of the innate immune system in response to biofilm-associated urinary tract infections. We thus hypothesize that the often asymptomatic nature of CAUTI´s might be based on a fine-tuned balance between the expression of bacterial virulence factors and the human immune system.
Project description:In Firmicutes, the nutrient-sensing regulators (p)ppGpp, the effector molecule of the stringent response, and CodY work in tandem to maintain bacterial fitness during infection. Here, we tested (p)ppGpp and codY mutant strains of Enterococcus faecalis in a catheter-associated urinary tract infections (CAUTI) mouse model and used global transcriptional analysis to investigate the (p)ppGpp and CodY relationship. Absence of (p)ppGpp or single inactivation of codY led to lower bacterial loads in catheterized bladders, and diminished biofilm formation on fibrinogen-coated surfaces under in vitro and in vivo conditions. Single inactivation of the bifunctional (p)ppGpp synthetase/hydrolase rel did not affect virulence supporting previous evidence that association of (p)ppGpp with enterococcal virulence is not dependent on activation of the stringent response. Inactivation of codY in the (p)ppGpp0 strain restored E. faecalis virulence in the CAUTI model as well as the ability to form biofilms in vitro. Transcriptome analysis revealed that inactivation of codY restores, for the most part, the dysregulated metabolism of (p)ppGpp0 cells. While a clear linkage between (p)ppGpp and CodY with expression of virulence factors could not be established, targeted transcriptional analysis indicate that a possible association between (p)ppGpp and c-di-AMP signaling pathways in response to the conditions found in the bladder may plays a role in enterococcal CAUTI. Collectively, this study identifies the (p)ppGpp-CodY network as an important contributor to enterococcal virulence in catheterized mouse bladder and supports that basal (p)ppGpp pools promote virulence through maintenance of a balanced metabolism during adverse conditions.
Project description:It was aimed to investigate the need for urinary retention and recatheterization in the postoperative period by removing the urinary catheter in patients undergoing low anterior resection, in the early or late period.