Detection of bacterial DNA on neurostimulation systems in patients without overt infection

Hardware-related infection remains a major problem in patients with neurostimulation systems. The role of bacterial colonization and the formation of biofilm on the surface of implanted devices remain unclear. Here, we analysed the incidence of bacterial DNA on the surface of implantable pulse generators (IPGs) using 16S rRNA gene sequencing in a consecutive series of patients who underwent routine IPG replacement without clinical signs of infection.

We included 36 patients who underwent scheduled replacement surgery of 44 IPGs. The removed IPGs were processed and whole genomic DNA was extracted. The detection of bacterial DNA was carried out by Polymerase Chain Reaction (PCR) using universal bacterial primers targeting the 16S rRNA gene. The DNA strands were analysed by single-strand conformation polymorphism (SSCP) analysis.

Indications for chronic neurostimulation were Parkinson disease, tremor, dystonia, neuropathic pain and peripheral artery occlusion disease. Mean age of patients at the time of implantation was 48 ± 17.6 years. The mean interval between implantation and replacement of the IPG was 24.8 months. PCR/SSCP detected bacterial DNA of various species in 5/36 patients (13.9%) and in 5/44 pacemakers (11.4%), respectively. There was no evidence of clinical infection or wound healing impairment during follow-up time of 45.6 ± 19.6 months.

Bacterial DNA can be detected on the surface of IPGs of neurostimulation systems in patients without clinical signs of infection by using PCR techniques. It remains unclear, similar to other permanently implanted devices, which mechanisms and processes promote progression to the point of overt infection.