The clinical outcome and microbiological profile of bone-anchored hearing systems (BAHS) with different abutment topographies: a prospective pilot study

Purpose In this prospective clinical pilot study, abutments with different topologies (machined versus polished) were compared with respect to the clinical outcome and the microbiological profile. Furthermore, three different sampling methods (retrieval of abutment, collection of peri-abutment exudate using paper-points, and a small peri-abutment soft-tissue biopsy) were evaluated for the identification and quantification of colonising bacteria. Methods Twelve patients, seven with machined abutment and five with polished abutment, were included in the analysis. Three different sampling procedures were employed for the identification and quantification of colonising bacteria from baseline up to 12 months, using quantitative culturing. Clinical outcome measures (Holgers score, hygiene, pain, numbness and implant stability) were investigated. Results The clinical parameters, and total viable bacteria per abutment or in tissue biopsies did not differ significantly between the polished and machined abutments. The total CFU/mm2 abutment and CFU/peri-abutment fluid space of anaerobes, aerobes and staphylococci were significantly higher for the polished abutment. Anaerobic bacteria were detected in the tissue biopsies before BAHS implantation. Anaerobes and Staphylococcus spp. were detected in all three compartments after BAHS installation. For most patients (10/12), the same staphylococcal species were found in at least two of the three compartments at the same time-point. The common skin coloniser Staphylococcus epidermidis was identified in all patients but one (11/12), whereas the pathogen Staphylococcus aureus was isolated in five of the patients. Several associations between clinical and microbiological parameters were found. Conclusions There was no difference in the clinical outcome with the use of polished versus machined abutment at 3 and 12 months after implantation. The present pilot trial largely confirmed a suitable study design, sampling and analytical methodology to determine the effects of modified BAHS abutment properties. Level of evidence 2. Controlled prospective comparative study. Electronic supplementary material The online version of this article (10.1007/s00405-018-4946-z) contains supplementary material, which is available to authorized users.


Hearing deficiency
p. 5, Table 1______ All Tier 1 Vital state. Alive or deceased when biospecimens were obtained Alive p. 5______________

All
Tier 3 Disease state. Patient condition relative to disease and treatment, if known (eg, during-or post-therapy; acute, chronic, or terminal stage).

Chronic p. 5, Table 1_______
All Tier 3 Cause of death. For postmortem biospecimens, the cause of death and other diseases present at the time of death.

All
Tier 3 Agonal state. The patients' physical condition immediately preceding death (eg, prolonged degeneration or relatively healthy)

Not applicable _________________
All Tier 1 Diagnosis. Patient diagnoses pertinent to the study being conducted, using an accepted system of standards (eg, the Systemized Nomenclature of Medicine or the International Classification of Diseases). Please note that clinical and pathology diagnoses are not always the same.
Congenital conductive hearing loss, acquired conductive-mixed hearing loss, single sided deafness Table 1___ All Tier 1 Clinical. Patient clinical diagnoses (determined by medical history, physical examination, and analyses of a biospecimen) pertinent to the study being conducted.

Table 1___
All Tier 1 Pathology. Patient pathology diagnoses (determined by macro and/or microscopic evaluation of a biospecimen at the time of diagnosis and/or prior to research use) pertinent to the study being conducted.

All
Tier 2 Time between diagnosis and sampling. The time or range of time between disease diagnosis and sample acquisition.

Tier 3
Exposures. Neoadjuvant therapy, other current or past medical treatments or environmental factors that might influence the condition of the biospecimen (eg, chemo-and radiation therapy, blood thinner, smoking status).

Not applicable _________________
All Tier 2 Patient demographic information. Demographic information that might be relevant to the condition of the biospecimens (eg, age range, gender).

Table 1___________
All Tier 2 Accrual scheme. Whether the biospecimens were obtained for the study being conducted or for a generalized collection such as a population-based biospecimen resource (i.e. retrospective or prospective procurement); whether any standard operating procedures (SOPs) were employed and whether these SOPs are available to others upon request. Reference any clinical trials relevant to the accrual scheme.
Obtained for the study; sampling SOPs available p. 7__________

All
Tier 2 Nature of the biobanking institution(s). The biobanking context in which the biospecimens were obtained (eg, as part of an internal collection or a biospecimen-acquisition network); include name, location, and primary contact details such as email address or Web site and reference to any pertinent SOPs.

II. Acquisition
All Tier 1 Collection mechanism and parameters. How the biospecimens were obtained (eg, fine needle aspiration, pre-operative blood draw).

Tissue
Tier 3 Time from cessation of blood flow in vivo to biospecimen excision/acquisition. The time or range of times that the biospecimens were ischemic in the body. Tier 2 Time from biospecimen excision/acquisition to stabilization. The time or time-range between when the biospecimens were obtained (eg, blood drawn or tumor surgically removed) and when they were stabilized. For postmortem biospecimens, list the postmortem interval range (i.e. the time from death to stabilization of the biospecimen).

Immediately p. 7______________
All Tier 2 Temperature between biospecimen excision/acquisition and stabilization. The temperature or range thereof at which biospecimens were kept between when biospecimens were obtained (eg, blood drawn or tumor surgically removed) and when they were stabilized. For postmortem biospecimens, the temperature at which the cadaver was stored during the postmortem interval.
Room temperature p. 7______________

Fluid
Tier 2 Collection container. The kind of tube into which biospecimens were captured as they left the body.

III. Stabilization/Preservation
All Tier 1 Mechanism of stabilization. The initial process by which biospecimens were stabilized during collection [eg, snap or controlled-rate freezing, fixation, additive (heparin, citrate, or EDTA), none].
Total immersion in liquid Amies medium p. 7______________

All
Tier 1 Type of long-term preservation. The process by which the biospecimens were sustained after collection (eg, freezing and at which temperature; formalin fixation, paraffin embedding; additive; none). Please note, this might or might not differ from the mechanism of stabilization.
Total immersion in liquid Amies medium p. 7_____________

All
Tier 1 Constitution and concentration of fixative/preservation solution.
The make-up of any formulation employed to maintain the biospecimens in a non-reactive state (eg, 10 percent neutral-buffered formalin or 10 USP Heparin Units/mL).

Tissue
Tier 2 Time in fixative/preservation solution. The time or range thereof that biospecimens were exposed to the preservation medium.

Tissue
Tier 2 Temperature during time in preservation solution. The temperature of the medium during the preservation process.

Fluid
Tier 2 Aliquot volume. The amount in each liquid biospecimen sample. p. 7______________

Tissue
Tier 2 Specimen size. The approximate size or weight of solid biospecimen samples processed (eg, cubes approximately 0.5 cm on a side, 0.5 gram).
at 4 o C and room temperature Absorbed in 2 Roeko size 45 paper-points p. 7__________

IV. Storage/Transport
Storage parameters. The conditions under which the biospecimens were maintained until analysis.

All
Tier 1 Storage temperature. The temperature or range thereof at which the biospecimens were maintained until distribution or analysis.

All
Tier 1 Storage duration. The time or range thereof between biospecimen acquisition and distribution or analysis.

All
Tier 2 Storage details. Other conditions under which specimens were maintained during storage (eg, to minimize oxidation).
Samples completely submerged p. 7______________

Tier 3
Type of storage container. The vessel in which biospecimens were kept.

Plastic Tube
All Tier 3 Type of slide. The microscope slides to which biospecimens were affixed. Not applicable p. 7_____________ ________________ Shipping parameters. The conditions to which biospecimens were exposed during each shipment or inventory management.

Tier 1
Shipping temperature(s). The temperature or range thereof at which biospecimens were maintained during each shipment or relocation.

All
Tier 2 Shipping duration. The time, estimate, or range thereof that the biospecimens spent in shipment each time they were transported.

Tier 3
Type of transport container. The type of vessel (eg, pre-manufactured shipping container, polystyrene box) and the packing material in which the biospecimens were transported.

Carton box p. 7_____________
All Tier 3 Shipping parameters. Other conditions under which the biospecimens were transported (eg, vacuum sealing, desiccant, packing material). Please note any deviations from standard operating procedures that might influence the condition of the biospecimens (eg, shipping anomalies that exposed paraffin blocks to high temperatures).
Carton box with an upright position of the tubes p. 7_________________ Freeze-thaw parameters. The conditions to which biospecimens were subjected during any thaw events.

Online Resource 1. (Continued)
Apply to Tier # Item Description Item # Location Fluid Tier 2 Number of freeze-thaw cycles. The number, estimate, or range thereof of thaw-refreeze events to which biospecimens were subjected prior to analysis.

Fluid
Tier 3 Duration of thaw events. The amount of time or range thereof the biospecimens spent thawed prior to the final thaw before processing.

Fluid
Tier 3 Time from last thaw to processing. The time or range of times between unfreezing and analysis.

All
Tier 3 Temperature between last thaw and processing. The temperature at which biospecimens were kept between unfreezing and analysis.
Not applicable _________________

V. Quality Assurance Measures Relevant to the Extracted Product and Processing Prior to Analyte Extraction and Evaluation
All Tier 1 Composition assessment and selection. Any parameters that were used to evaluate and/or choose biospecimens for inclusion in the study.
Visual inspection p. 8______________

All
Tier 2 Gross and microscopic review. The anatomical characteristics of the biospecimens in the study and the relevant qualifications of the individual performing the review (eg, anatomist, pathologist, hematologist, microbiologist, or researcher).

Tissue
Tier 2 Proximity to primary pathology of interest. Whether the biospecimen was taken from a region adjacent to or distal from another region of interest, such as a tumor or area of necrosis. Give approximate distances if known.
All specimens taken from the immediate site of interest. Soft tissue biopsy (3 m, 12 m) obtained 5 mm from abutment p. 7_____________

All
Tier 2 Method of enrichment for relevant component(s). The method by which pertinent portions of the biospecimen were separated from the rest of the biospecimen (eg, laser-capture microdissection of tissue, block selection for region of lesion, centrifugation of blood).

All
Tier 2 Details of enrichment for relevant component(s). The parameters used to separate pertinent portions of the biospecimen from the rest of the biospecimen, if applicable (eg, centrifugation speed and temperature).

All
Tier 2 Quality assurance measures. Any methods used to assess the quality of the biospecimens relevant to the biomolecular analyte, when these methods were employed (eg, prior to long-term storage or immediately before experimental analysis), and the results (eg, RNA integrity number, hemolysis assessment).

Not applicable
Testing of selective media with relevant control strains