INTRODUCTION AND OBJECTIVE:
Sacral neuromodulation is an effective treatment for refractory overactive bladder. Based on standard culture, about 25% of explanted stimulators have been shown to be colonized by bacteria, but there is only about a 2% risk of infection requiring explantation. In order to understand the changes associated with device-associated infection, we sought to determine the resident microbial composition of explanted sacral nerve stimulators after explantation using next-generation sequencing. We hypothesized that, with our highly-sensitive assay, we would consistently detect bacteria even in the absence of clinical symptoms.
We identified urological patients scheduled to undergo removal or revision of sacral nerve stimulator devices for noninfectious reasons. Patients were consented per our IRB-approved protocol, and the first accessed portions of the devices were swabbed intraoperatively, while avoiding contamination from the remainder of the surgical field. The swab samples, alongside controls from the operative field, were then subjected to next-generation sequencing to determine their composition.
6 devices were explanted due to clinical need for MRI or device malfunction/end of device life. By 16s rRNA sequencing, all of the devices harbored a detectable microbiota. The genera of greatest abundance were Acinetobacter (22%), Faecalibaculum (6%), and Pseudomonas (6%), followed by Sphingobium, Renibacterium, Corynebacterium, Staphylococcus, Sphingomonas, and Escherichia/Shigella (Figure).
All explanted devices harbored detectable microbiota, which, in the absence of clinical symptoms, is a novel finding. Some of the most commonly detected microbes in our study have been implicated in stimulator-associated infections in other investigations (Staphylococcus 48% of infections, Pseudomonas 10%, Corynebactrium 5%). Our results open new avenues for investigations that interrogate the microbial and metabolic changes that occur during the transition from asymptomatic device colonization to clinical infection, and identify preventive strategies. Future studies will utilize a larger sample size, characterize microbes to the species level, and compare sacral nerve stimulators explanted due to infection to those removed for other reasons to understand this pathophysiology.
Source of Funding: