An overview of risk factors, management and prevention of cochlear implant infections.

PURPOSE OF REVIEW: With cochlear implantation becoming increasingly performed worldwide, an understanding of the risk factors, preventive measures, and management of cochlear implant (CI) infection remains important given the significant morbidity and cost it conveys. RECENT FINDINGS: At the turn of the 21st century there was a decrease in rates of CI infection, particularly meningitis, following the discontinuation of positioner use for CI. However, in more recent years rates of CI infection have remained largely static. Recently, studies evaluating preventive measures such as pneumococcal vaccination, S. aureus decolonization and surgical antibiotic prophylaxis have emerged in the literature. SUMMARY: Prompt recognition of CI infection and appropriate investigation and management are key, however at present treatment is largely informed by cohort and case-control studies and expert opinion. Preventive measures including pneumococcal vaccination, S. aureus decolonization and preoperative antibiotic prophylaxis play a role in reducing rates of CI infection. However, there remains a need for well designed clinical trials to provide higher level evidence to better guide preventive measures for, and management decisions of, CI infections in the future.

The biofilm characteristics and management of skin flap infection following cochlear implantation.

Objective: This study aims to assess the frequency, bacteriology, biofilm characteristics and management of skin flap infection (SFI) following cochlear implantation (CI). Methods: The study enrolled 1,251 patients receiving CI in the First Affiliated Hospital of Fujian Medical University between August 2001 and March 2021. Scanning electron microscopy (SEM) was utilised to characterise the aetiology of infection. A proposed classification system was applied to optimise treatments for post-operative skin flap infection. Results: After CI, SFI was reported in 16 patients (1.28%) and occurred more frequently in patients under 6 years of age. Of all SFI cases Staphylococcus aureus was the most common pathogen for flap infection, with 8 cases (50%) and bacterial biofilm was evident within the jelly-like substance on the surface of implanted devices in SFI patients. A two-stage classification was proposed to optimise the treatment schemes. Conservative therapy was recommended for stage I cases and surgical treatment for stage II patients. Conclusions: Paediatric patients are more susceptible to SFI after CI, which may be attributed to the formation of bacterial biofilm. The proposed classification can facilitate the management of SFI.

Antibacterial Polysiloxane Polymers and Coatings for Cochlear Implants.

Within this study, new materials were synthesized and characterized based on polysiloxane modified with different ratios of N-acetyl-l-cysteine (NAC) and crosslinked via UV-assisted thiol-ene addition, in order to obtain efficient membranes able to resist bacterial adherence and biofilm formation. These membranes were subjected to in vitro testing for microbial adherence against S. pneumoniae using standardized tests. WISTAR rats were implanted for 4 weeks with crosslinked siloxane samples without and with NAC. A set of physical characterization methods was employed to assess the chemical structure and morphological aspects of the new synthetized materials before and after contact with the microbiological medium.

Use of negative pressure wound therapy to treat a cochlear implant infection around the auricle: a case report.

Although negative pressure wound therapy (NPWT) is widely used, its application to the head and neck region remains challenging due to anatomical complexities. This report presents the case of a female patient presenting with mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes, uncontrolled diabetes and severe bilateral sensorineural hearing loss. The patient had undergone cochlear implant surgery and five months later the wound was infected with methicillin-resistant Staphylococcus aureus (MRSA). NPWT was started shortly after removing the internal receiver and was stopped 11 days later. NPWT helped in controlling infection and led to a successful wound closure. In this case, NPWT was effective in treating infectious wounds around the auricle after cochlear implant surgery. Declaration of interest: The authors have no financial support for this article and no conflict of interest directly relevant to the content of this article.

Imaging studies of bacterial biofilms on cochlear implants-Bioactive glass (BAG) inhibits mature biofilm.

The capability of Pseudomonas aeruginosa and Staphylococcus aureus to form biofilm on varying CI component materials differs in the presence and absence of bioactive glass (BAG). The application of BAG induces significant changes in biofilm morphology which can be visualized via scanning electron microscopy (SEM). Bacterial biofilm formation on medical devices, such as cochlear implants (CI), can lead to chronic infections. Interestingly, BAG of type S53P4 seems to be a promising tool for use in the reduction of biofilm development. Primarily, four bacterial species known to cause implant-related infections, P.aeruginosa (ATCC9027), S. aureus (ATCC6538), Staphylococcus epidermidis (ATCC12228) and Streptococcus pyogenes (ATCC19615) were analyzed regarding their capacity to form biofilm on CI components manufactured from three kinds of material: silicone, platinum and titanium. Subsequently, P. aeruginosa and S. aureus biofilms were visualized using scanning electron microscopy, comparing BAG-treated biofilm with non-treated biofilm. The four bacterial species presented biofilm-forming capabilities in a species and surface dependent manner. Metal CI components allowed for the greatest proliferation of biofilm. S. aureus and P. aeruginosa showed the highest rate of biofilm formation on polystyrene surfaces. For both species, SEM revealed altered biofilm morphology after treatment of S53P4 BAG. This study indicates that bacterial biofilm formation and structure on CI components is dependent on the surface composition, altering between metal and silicone surfaces. After application of BAG, changes in biofilm morphology on CI components were observed. These data highlight the impact of BAG on bacterial biofilm morphology.

Bioactive Glass Granules Inhibit Mature Bacterial Biofilms on the Surfaces of Cochlear Implants.

HYPOTHESIS: Biofilm formation on cochlear implant (CI) surfaces differs between bacterial species and can be reduced by the application of S53P4 bioactive glass. BACKGROUND: The formation of bacterial biofilms on medical devices, such as cochlear implants, can lead to chronic infections resulting in the need for implant removal. In this study, various surfaces of three CI implant kits from different manufacturers were examined for bacterial biofilm formation and reduction of a pre-existing biofilm by the application of bioactive glass. METHODS: Biofilm formations of 4 bacterial species causing implant-related infections were tested on 17 different surfaces: Pseudomonas aeruginosa (ATCC9027), Staphylococcus aureus (ATCC6538), Staphylococcus epidermidis (ATCC12228), and Streptococcus pyogenes (ATCC19615). For P. aeruginosa and S. aureus biofilm reduction after application of S53P4 bioactive glass was evaluated. RESULTS: All tested microbial species formed biofilms on the examined CI surfaces in a strain-dependent manner. For S. aureus, a significantly higher biofilm formation on metal components compared with silicone was found whereas the other strains did not show a material specific biofilm formation. Application of S53P4 bioactive glass resulted in a significant reduction of P. aeruginosa and S. aureus mature biofilm. CONCLUSION: The four bacteria species displayed biofilm formation on the CI surfaces in a species- and material-specific manner. The results show that bioactive glass can reduce biofilm formation on CI materials in vitro. Future studies are necessary to confirm the results in vivo.

Rates of Vaccination against Streptococcus Pneumoniae in Cochlear Implant Patients.

BACKGROUND Streptococcus pneumoniae can cause life-threatening illness, with invasive pneumococcal diseases (IPD) like meningitis, sepsis, bacteremic pneumonia, and bacteremia being major causes of morbidity and mortality. Studies have shown that patients who have had a cochlear implant, particularly children, have an increased risk of bacterial (pneumococcal) meningitis. Vaccination in patients with cochlear implants is important and recommended universally. The World Health Organization recommends the use of pneumococcal conjugate vaccines in all countries and considers their use to be a priority in all national immunization programs. The objective of this study was to assess rates of vaccination against Streptococcus pneumoniae in patients with cochlear implants who were implanted at the Institute of Physiology and Pathology of Hearing, Poland. MATERIAL AND METHODS We analyzed data from questionnaires administered to 2,628 patients who visited the Implants and Auditory Perception Department (IAPD) of the Institute of Physiology and Pathology of Hearing between January 2014 and March 2016. RESULTS The percentage of vaccinated patients in the study group was 28.2%, most of whom (90.7%) were children. Among the children, 49.3% were vaccinated against S. pneumoniae, but the corresponding rate for adults was only 5.5%. CONCLUSIONS The percentage of patients with cochlear implants who received vaccination against S. pneumoniae was low, both in children and adults, but especially in adults comparing to available reports.

Surface charge modification decreases Pseudomonas aeruginosa adherence in vitro and bacterial persistence in an in vivo implant model.

OBJECTIVE: Chronic, persistent infections complicate otologic procedures utilizing implantable devices such as cochlear implants or tympanostomy tubes. These infections are thought to be due to the establishment of microbial biofilms on implant surfaces. To address this issue, we hypothesized that surface charge modification may inhibit the formation of Pseudomonas aeruginosa biofilms on implant surfaces in vitro and in vivo. STUDY DESIGN: We evaluated the effect of surface charge modification on bacterial biofilm formation by assessing the effect of the surface charge on bacterial adhesion in vitro and bacterial persistence in vivo. METHODS: To study the effect of surface charge in vitro, the surface wells in culture plates were modified using a layer-by-layer polyelectrolyte assembly method. Bacterial adherence was measured at 30-, 60-, and 120-minute intervals. To study the effect of surface charge modification in vivo, the surface of titanium microscrews was similarly modified and then surgically implanted into the dorsal calvaria of adult rats and inoculated with bacteria. Two weeks after implantation and inoculation, the number of bacteria remaining in vivo was evaluated. RESULTS: Surface charge modification results in a significant decrease in adherence of bacteria in vitro. Surface charge modification of titanium microscrew implants also resulted in a significant decrease in P. aeruginosa recovered 2 weeks after surgical implantation. CONCLUSION: Charge modification decreases the number of bacteria adherent to a surface in vitro and decreases the risk and severity of implant infection in an in vivo rat infection model. These results have promising biomedical applications. LEVEL OF EVIDENCE: NA. Laryngoscope, 127:1655-1661, 2017.

Microflora of Retained Intracochlear Electrodes from Infected Cochlear Implants.

Objectives Cochlear implant infections may be refractory to medical management and require device removal with subsequent reimplantation. During device removal, the intracochlear electrode array is commonly left in place to prevent obliteration of the cochlear lumen. If the electrode is colonized with pathogens, this risks contaminating the replacement implant. In this study, we compare the microorganisms detected on infected cochlear implants against those on the retained electrode using culture and microbial gene-sequencing techniques. Study Design Prospective single-cohort study. Setting Tertiary medical center. Subjects and Methods Six patients with refractory cochlear implant infections had the receiver-stimulator and extracochlear electrode removed to facilitate treatment of the infection. The intracochlear electrode was removed at (delayed) reimplantation. Implant specimens were analyzed by microbial culture and 16S DNA gene sequencing. Results Staphylococcus aureus was the organism most commonly identified. None of the 6 patients' intracochlear electrodes yielded microbes by culture. Two intracochlear electrodes revealed bacterial species, and 1 revealed fungal species by gene sequencing. There was no correlation between the microbes on the infected extracochlear implants and the retained intracochlear electrodes. All subjects underwent reimplantation after resolution of their infections. One of 6 subjects developed a second infection after reimplantation, with S aureus in the primary and secondary infections. Conclusions The intracochlear electrodes of infected cochlear implants carry a low microbial burden. Preserving intracochlear electrodes upon removal of infected cochlear implants appears to carry a low risk of contaminating a replacement cochlear implant.

Recurrent cochlear implant infection treated with exteriorization and partial mastoid obliteration.

OBJECTIVE AND IMPORTANCE: Preoperative chronic otitis media (COM) is a risk factor for postoperative infection after cochlear implantation (CI), but its management varies by surgeon. Our case highlights a strategy for implant preservation in a patient with a history of recurrent cochlear implant infection. CLINICAL PRESENTATION: A 70-year-old woman with a history of chronic lymphocytic leukemia presented in 2005 with bilateral COM and sensorineural hearing loss meeting CI candidacy. Four months after left mastoid obliteration with abdominal fat graft and external auditory canal closure, a left CI was placed. Subsequent postauricular cellulitis resolved with oral antibiotics. A similar two-stage CI was performed on the right without complication. During the following year, numerous left-sided infections and fluid collections developed but were treated unsuccessfully with intravenous (IV) antibiotics and operative debridement. With concern for biofilm colonization, the implant was explanted and the electrode left in the cochlea. After reimplantation in 2010, infections resumed despite long-term IV antibiotics and incision and drainage. Intervention and technique In 2012, the left mastoid cavity was exteriorized and converted to standard canal wall-down anatomy. Bone pâté was placed over the electrode, followed by cadaveric acellular dermis and a split-thickness skin graft. After more than 2 years, her better-performing CI remains infection-free. CONCLUSION: After 6 years of postoperative infections unresponsive to aggressive medical management, surgical interventions, and period of device removal, our patient's infections resolved after mastoid exteriorization and multilayered protection of the electrode. This strategy may enable implant preservation in patients with recurrent post-CI infection in an obliterated cavity.

Infected cochlear implant after large-volume nasal irrigation.

OBJECTIVE: A patient with a well-healed, functional cochlear implant (CI) experienced a CI and mastoid infection shortly after initiating large-volume nasal irrigations after sinus surgery. The goal of this report is to bring attention to a rare complication and to question if large-volume nasal irrigation is safe in CI recipients. PATIENTS: Single patient at a tertiary care hospital. INTERVENTIONS: A CI recipient began using large-volume nasal irrigations with saline and budesonide after undergoing sinus surgery. MAIN OUTCOME MEASURES: CI infection and mastoiditis. RESULTS: Two weeks after starting nasal irrigations, the patient presented with mastoiditis and CI infection. Mastoid and intranasal middle meatal cultures both grew Group A streptococcus. CONCLUSION: Large-volume nasal irrigations may be related to our patient's CI infection, ultimately leading to explantation. Though a causal relationship cannot be definitively proven, awareness of this potential safety issue should be disseminated.

Preliminary results of a novel quorum sensing inhibitor against pneumococcal infection and biofilm formation with special interest to otitis media and cochlear implantation.

The purpose of the study is to assess the effect of a novel quorum sensing inhibitor (QSI), coded as 'yd 47', against otitis media and biofilm formation on Cochlear implants (CIs). Small pieces cut from cochlear implant were implanted under the skin in the retroauricular area on both sides of four guinea pigs. The implant pieces in the study and control sides were implanted in Streptococcus pneumoniae strain solution and saline, respectively. The right and left middle ears were also instilled with a solution containing pneumococci and saline, respectively. The animals were only given an intraperitoneal 'yd 47' twice daily for three months to be assessed later with electron microscopy. Clinical examination with palpation, inspection and otoscopy did not reveal any sign of implant infection or otitis media. In the study and control implant materials, soft tissues around the implant and tympanic membranes, there was no biofilm formation by pneumococci. Contamination by various cells and some rod-shaped bacteria (not diplococcic) were seen in some of the materials. In conclusion, the novel QSI seems promising in the prevention of otitis media and biofilm formation on CIs by pneumococci.

Biofilm prevention on cochlear implants.

OBJECTIVES: To examine the efficiency of a bacteria-resistant coating for the polydimethylsiloxane (PDMS) casing of cochlear implants. METHODS: The coatings are based on thin titania films that are made by liquid phase deposition or atomic layer deposition. The antibacterial activity of the coating was tested by two different detection assays: BCA protein and confocal microscopy. RESULTS: Coating the PDMS with thin films (10-40 nm) of titania significantly reduces the accumulation of bacteria. DISCUSSION: Thin oxide films made under conditions that do not undermine the integrity of polymeric materials can be used as anti-microbial coatings for soft polymers such as the PDMS that is used as a casing for cochlear implants or other medical devices.

The management of acute mastoiditis in children with cochlear implants: saving the device.

OBJECTIVE: Early treatment of profound bilateral sensorineural hearing loss with cochlear implantation has become routine, resulting in an increased proportion of children implanted at younger ages. These children are at a relatively high risk for acute otitis media (AOM), and are more likely to develop mastoiditis in the implanted ear. Despite the significant risks associated with mastoiditis, including compromise of the implant, there are no specific guidelines on the management of this population. We propose a treatment algorithm emphasizing early but conservative operative intervention. METHODS: A retrospective chart review included eight patients, who experienced mastoiditis, in the context of cochlear implantation at our center from August 2005 to November 2012. During this period 806 implant surgeries were completed. RESULTS: The median age at which mastoiditis occurred was 37 months, and the mean time from implantation to mastoiditis was 9.56 months. All patients underwent drainage of the middle ear in conjunction with intravenous antibiotics, and two additionally underwent post-auricular incision and drainage. DISCUSSION: Recent mastoidectomy may be a risk factor for the development of a post-auricular abscess in children, who develop AOM following cochlear implantation. A treatment algorithm was developed, which emphasizes early operative drainage in conjunction with aggressive antibiotic therapy. Conclusions A consistent approach to the management of mastoiditis in children with cochlear implants has not been established. Rapid initiation of aggressive antibiotic therapy and a low threshold for conservative operative intervention results in effective resolution of infection while allowing preservation of the implant.

Microbial flora of cochlear implants by gene pyrosequencing.

OBJECTIVE: To describe the microbial flora associated with cochlear implants (CIs) removed for infectious and noninfectious indications. STUDY DESIGN: Prospective, controlled. SETTING: Academic, tertiary medical center. PATIENTS: All patients undergoing CI removal. INTERVENTION: CIs were removed with aseptic technique and processed for microbial identification. MAIN OUTCOME MEASURE: CI microbes were identified with routine culture and speciation and 16s deoxyribonucleic acid 454-pyrosequencing. RESULTS: All CIs had evidence of microbes. Propionibacterium acnes and Acidovorax facilis were more common on noninfected CIs (p = 0.005, 0.031). Staphylococcus aureus was more common on infected CIs (p = 0.003). The microbial profiles associated with CI infection were different from, but overlapped with those of noninfected CIs. Microbial culture with selective media identified pathogens not identified on pyrosequencing. CONCLUSION: Bacteria are present on all CIs, both with and without evidence of clinical infection, but species differ with clinical status. Empiric therapy for CI infections should include coverage for S. aureus. Gene pyrosequencing and selective culture techniques may yield complementary results that may impact the management of CI infections.

Bacterial growth on cochlear implants as a potential origin of complications.

OBJECTIVE: To investigate the presence and spectrum of bacterial colonization in relation to cochlear implant infections by introducing molecular biologic methods. METHOD: In a pilot test, a virgin device served as a control to validate the subsequent sampling and analysis process via PCR and SSCP. Subsequently, analysis was performed on specimens of 15 cochlear implants explanted from 15 patients because of device failures, infections, or malinsertions. RESULTS: Positive SSCP results could be verified on 8 of the 15 explanted CI, in detail, 3 of 4 infected cochlear implants and 5 of 9 cochlear implants explanted because of device failure. The germ spectrum shows common germs such as Staphylococcus aureus, Pseudomonas aeruginosa, and Haemophilus influenzae, as well as germs from the dental cavity, with a peak of P. aeruginosa in infections. CONCLUSION: Detection and identification of microbial colonization on cochlear implants can be successfully conducted using the proposed approach of smear test subsequent genetic analysis. The prevalence of P. aeruginosa and germs from the dental cavity may demand an adaption of antibiosis with respect to these germs. Further investigations of the path of infection are needed, and patients might require a prevention by preoperative dental treatment.

Cochlear implants and bacterial meningitis: A speech recognition study in paired samples

Introduction: Cochlear implants may guarantee sound perception and the ability to detect speech at a close-to-normal hearing intensity; however, differences have been observed among implantees in terms of performance on discrimination tests and speech recognition. Objective: To identify whether patients with post-meningitis deafness perform similarly to patients with hearing loss due to other causes. Method: A retrospective clinical study involving post-lingual patients who had been using Nucleus-22 or Nucleus-24 cochlear implants for at least 1 year. These patients were matched with respect to age (± 2 years), time since the onset of deafness (± 1 year), and the duration of implant use with implant users who had hearing loss due to other causes. Speech perception was assessed using the Portuguese version of the Latin-American Protocol for the Evaluation of Cochlear Implants. Results: The sample consisted of 52 individuals (26 in each of the 2 groups). The post-meningitic group had a median of 18.5 active electrodes. The group with hearing loss due to other causes had a median of 21, but no significant statistical difference was observed (p = 0.07). The results of closed- and open-set speech recognition tests showed great variability in speech recognition between the studied groups. These differences were more pronounced for the most difficult listening tasks, such as the medial consonant task (in the vowel-consonant-vowel format). Conclusion: Cochlear implant recipients with hearing loss due to bacterial meningitis, who had been using the device for 1 year performed more poorly on closed- and open-set speech recognition tests than did implant recipients with hearing loss due to other causes...

Case report - biofilm infection of a cochlear implant.

One of the most dreaded complications after cochlear implantation is infection. These infections are a challenge due to lack of any data regarding optimal methods of investigation and management. More often than not, these patients have to undergo explantation and revision surgery. This paper presents a case report and literature review which focuses on the role of antibiotics and the need for early explantation in most biofilm-related infections of cochlear implants.

Staphylococcus aureus biofilm formation on an explanted cochlear implant demonstrated using an ultrasonication technique.

RELEVANCE: Biofilm forming microorganisms are responsible for the infection of a number of different indwelling medical devices including cochlear implants. The current definitive technique for proving biofilm infection is the use of scanning electron microscopy that is expensive and of limited availability. CLINICAL PRESENTATION: A persistently infected cochlear implant was explanted. At operation it was surrounded by a fibrous capsule containing a glue-like substance, characteristic of biofilm formation that yielded Staphylococcus aureus after ultrasonication of the device. TECHNIQUE: The explanted cochlear implant was placed in a nutrient broth in an ultrasonic water bath. The implant was ultrasonicated for 5 minutes and the broth cultured on blood agar, incubated aerobically and anaerobically for 48 hours, and then incubated in air on Maconkey agar for 24 hours. This produced a heavy, confluent growth of S. aureus, in contrast to previous aspirates from a blister that lay over the infected implant that grew a coliform organism and Pseudomonas sp. CONCLUSION: Ultrasonication is a widely available and relatively inexpensive technique that can be used to improve the recovery of biofilm-associated organisms from explanted cochlear implants.

Eradicating chronic ear, nose, and throat infections: a systematically conducted literature review of advances in biofilm treatment.

OBJECTIVE: Bacteria can grow as individual, planktonic organisms or as complex biofilm communities that are more resistant to treatment. This review was designed to systematically search to identify recent laboratory studies on eradication of biofilms in otolaryngologic infections to highlight promising advances in biofilm treatment. DATA SOURCES: A systematic electronic literature search of Medline/PubMed, CINHAL, and Web of Science was conducted for articles describing the treatment of biofilm infections in ear, nose, and throat (ENT) diseases through March 2010. English-language articles and articles with an English abstract that focused on biofilm treatment were considered for review. REVIEW METHODS: Each included article was reviewed by one of the authors for study design, treatment intervention, and outcome. Data from in vitro and animal studies were considered separately from human studies. RESULTS: A total of 30 articles were identified for this review, including 5 studies that included a human treatment component. In general, antibiotics were relatively ineffective for eradicating biofilm infections. Markedly higher antibiotic dosages were required to reduce biofilm presence compared with doses that were effective in eradicating planktonic bacteria. Mupirocin irrigation, gentian violet, and thiamphenicol glycinate acetylcysteine effectively eradicated biofilms. Physical disruption, surfactants, and probiotics were also shown to be beneficial in both nonhuman and human studies. CONCLUSION: Eradicating ENT biofilms is difficult when treating single-organism or mixed flora biofilms. Antibiotic therapy is often ineffective against biofilms, and clinical treatment may need to focus on nonantibiotic therapies that reduce, disrupt, or eradicate ENT biofilms.