Main outcome measures
Patients with postoperative infection were treated immediately with ceftriaxone sodium and subsequently with pathogen-specific antibiotics on the basis of the culture results. The pus was drained when the formation was localized in the subcutaneous tissue.
Patients irresponsive to conservative treatment received revision surgery or re-implantation surgery if the revision surgery failed. The former consisted of cleaning up granulation tissue in the bone groove, rinsing equipment with 3% hydrogen peroxide, normal saline, and 1% iodophor repeatedly, finally reverting suitable temporal muscle covering the groove. The latter involved explanting equipment but saving the electrode in cochlear, and implanting a new cochlear in the opposite side. Both surgical treatments were followed by a 3-day administration of ceftriaxone sodium.
The jelly-like biofilm on the surface of receiver/stimulator was rinsed with phosphate buffered saline (PBS) 3 times (1 minute per time), soaked in 1% osmic acid solution at < 4℃ for 2 h. Then, the samples were sequentially dehydrated in 30%, 50%, 70%, 85%, 95%, and 100% ethanol for 15 minutes per time, respectively. After the CO2 critical dry point and correcting the position and orientation, samples were placed on the platform for sputter-coated with gold in a vacuum condition and examined in a high vacuum of 20kv under a scanning electron microscope (SEM; American FEI company, model Quanta 450). Multiple bacterial biofilm SEM areas of each specimen were observed with multiple magnifications (50~10000 times).
The formation of bacterial biofilms was diagnosed when the images met the three criteria: dense
accumulation of bacterial cells, the presence of a polysaccharide matrix around bacterial cells, and firm surface binding6.
All statistical tests were performed using SPSS software (version 26.0; SPSS Inc., Chicago, IL, USA). The differences of categorical variables were assessed using Fisher’s test as appropriate including sex, age, implant side, different regimens and outcomes. P -values of less than 0.05 indicated statistical significance. All statistical tests were two-sided.