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.