World Kidney Day 2025

World Kidney Day is an annual event designed to shine a light on the importance of kidneys and the role they play in our overall health. To honour this special day, we’d like to acknowledge how the Whitley Anaerobic Workstation has been used to facilitate kidney research, particularly chronic kidney disease (CKD).

The composition of the oral microbiome is perturbed during CKD and following kidney transplantation, particularly due to increased urea concentrations in saliva. These bacteriological changes may affect health and recovery.

In a recent study by Campbell et al., increased salivary urea concentrations associated with kidney disease have been modelled in a constant-depth film fermenter (CDFF), in which biofilms of oral bacteria were established on removable polytetrafluoroethylene (PTFE) plugs following inoculation with saliva. Following biofilm establishment, various treatments (different urea concentrations) were applied and their effects on aerobic bacteria, anaerobic bacteria and Streptococcus species were determined by removing replicate PTFE plugs, recovering bacteria and performing viable counts.  

The sampled PTFE plugs were transferred to universal containers and vortexed with glass beads in phosphate-buffered saline (PBS). From these bacterial suspensions, further serial dilutions were prepared in PBS to target the production of plates containing 30 – 300 bacterial colonies. For total anaerobe counts, these dilutions were plated onto Wilkins Chalgren Agar and incubated in the Whitley Anaerobic Workstation for 4 days in an atmosphere of 10% H₂, 10% CO₂, and 80% N₂.

Viable bacterial counts demonstrate that biofilms in initial validation runs reached dynamic stability in the CDFF within 5 days. Following exposure to elevated urea concentrations, there were no obvious effects on viable counts. Similarly, DNA sequence data indicated minimal taxonomic variation over time and between low and high urea treatments. Sequencing data did reveal significant differences in bacterial diversity between low and high urea states, but not following reversion to a low urea environment.

This in vitro system modelled increased urea concentrations and subsequent reductions consistent with those occurring post-transplantation, and provided insight into the oral microbial shifts during different simulated clinical phases. Understanding these effects is crucial for understanding CKD-associated changes in the oral microbiome and their potential impact on patient wellbeing and recovery.

If you’d like to learn more about kidney research, please check out our Published Paper Database.

References

1. Campbell PM, Willmott T, Summers A, Knight CG, Humphreys GJ, Konkel JE, Augustine T, McBain AJ. Investigating oral microbiome dynamics in chronic kidney disease and post-transplantation in continuous culture. Microbiology spectrum. 2024 Nov 5;12(11):e00598-24.