gms | German Medical Science

Objective: The development of bacterial biofilm on the surface of any implanted device may be associated with infection close to the implants necessitating device removal. This study aimed to identify specifically the DNA of bacterial biofilm on neurostimulation systems using polymerase chain reaction (PCR).

Method: Forty-five pacemakers were aseptically removed during routine surgery for battery replacement in 36 patients with implanted neurostimulation systems. The devices were stored immediately at -80°C under sterile conditions. To determine the presence of bacteria, the pacemakers were processed and DNA was extracted. 500-bp fragments of purified DNA were amplified using universal primers which target hypervariable regions within the bacterial 16S rRNA gene. In the following Single Strain Conformation Polymorphism (SSCP) analysis, genetic information of different bacterial species were separated from each other, isolated, re-amplified, and finally identified using sequencing methods.

Results: Following the initial implantation, antibiotics had been administered in all patients (cefazolin). PCR detected DNA of gram-positive bacteria on the surface of 3 pacemakers (deep brain stimulation, n=2; occipital nerve stimulation, n=1), which were collected from 3 patients (mean age, 42 years). The specimens were derived from staphylococcus epidermidis (n=1), lactobacillus iners et crispatus (n=1), and bacillus sp. (n=1). The mean interval between implantation and removal had been 14.0 ± 8.1 months. During follow-up, there had been no infection or wound healing impairment in these three patients.

Conclusions: Our preliminary data suggest that biofilm formation with possibly pathogenic bacteria may occur on neurostimulation systems even in patients with well-healed wounds and no signs of clinical infection.