No hearing loss after repeated courses of tobramycin in cystic fibrosis patients

[Assessment of the risk of hearing loss in children with cystic fibrosis]

BACKGROUND

Cystic fibrosis (CF) is a severe hereditary disease with a multisystem lesion. Manifestations of CF include severe infectious purulent lesions of all parts of the respiratory tract, including purulent rhinosinusitis with nasal polyps. The involvement of the sinonasal region and the need for systemic use of ototoxic drugs (primarily aminoglycosides to treat resistant bacterial infection) potentially create a risk of both conductive and sensorineural hearing loss (SNHL). The available data on the epidemiology of hearing disorders in CF is contradictory. Currently, genetic determinants of the development of aminoglycoside SNHL have been identified.

MATERIAL AND METHODS

For 136 CF patients (75 girls, 61 boys) aged 3 to 17 (9.4±3.9) years were performed audiological examination: tympanometry, transient-evoked otoacoustic emission and the pure tone threshold audiometry (standard frequency range) (n=126). History of systemic therapy with aminoglycosides was evaluated for each patient. Sequencing of c.35delG mutations in the GJB2 gene (nuclear DNA) and A1555G in the 12S rRNA gene (mitochondrial DNA) was performed in 215 patients with cystic fibrosis (the group partially overlaps with the audiological group), and as a control - 106 children with bronchial asthma and 103 healthy children, their age ranged from 3 to 17 (8.8±3.8) years.

RESULTS

Audiological examination of CF children reveled a prevalence of conductive hearing loss comparable to the general population (2.4%). The frequency of SNHL was 1.6%, wich exceeds that of non-CF children. A genetic study revealed one case of heterozygous carriage of the c.35delG mutation in the GJB2 gene in a patient with bronchial asthma. In the group of patients with CF (n=215), mutations in the connexin 26 gene were not detected. No A1555G mutation was detected either in the group of patients with CF or in the control groups.

CONCLUSIONS

Children with CF are at risk for the development of sensorineural, but not conductive hearing loss. Routine total screening for A1555G and c.35delG mutations probably seems not to be recommended.

Clinical Considerations for Routine Auditory and Vestibular Monitoring in Patients With Cystic Fibrosis

Purpose Specific classes of antibiotics, such as aminoglycosides, have well-established adverse events producing permanent hearing loss, tinnitus, and balance and/or vestibular problems (i.e., ototoxicity). Although these antibiotics are frequently used to treat pseudomonas and other bacterial infections in patients with cystic fibrosis (CF), there are no formalized recommendations describing approaches to implementation of guideline adherent ototoxicity monitoring as part of CF clinical care. Method This consensus statement was developed by the International Ototoxicity Management Working Group (IOMG) Ad Hoc Committee on Aminoglycoside Antibiotics to address the clinical need for ototoxicity management in CF patients treated with known ototoxic medications. These clinical protocol considerations were created using consensus opinion from a community of international experts and available evidence specific to patients with CF, as well as published national and international guidelines on ototoxicity monitoring. Results The IOMG advocates four clinical recommendations for implementing routine and guideline adherent ototoxicity management in patients with CF. These are (a) including questions about hearing, tinnitus, and balance/vestibular problems as part of the routine CF case history for all patients; (b) utilizing timely point-of-care measures; (c) establishing a baseline and conducting posttreatment evaluations for each course of intravenous ototoxic drug treatment; and (d) repeating annual hearing and vestibular evaluations for all patients with a history of ototoxic antibiotic exposure. Conclusion Increased efforts for implementation of an ototoxicity management program in the CF care team model will improve identification of ototoxicity signs and symptoms, allow for timely therapeutic follow-up, and provide the clinician and patient an opportunity to make an informed decision about potential treatment modifications to minimize adverse events. Supplemental Material https://doi.org/10.23641/asha.16624366.

Functional Impacts of Aminoglycoside Treatment on Speech Perception and Extended High-Frequency Hearing Loss in a Pediatric Cystic Fibrosis Cohort

Purpose The purpose of this study is to better understand the prevalence of ototoxicity-related hearing loss and its functional impact on communication in a pediatric and young adult cohort with cystic fibrosis (CF) and individuals without CF (controls). Method We did an observational, cross-sectional investigation of hearing function in children, teens, and young adults with CF (n = 57, M = 15.0 years) who received intravenous aminoglycoside antibiotics and age- and gender-matched controls (n = 61, M = 14.6 years). Participants completed standard and extended high-frequency audiometry, middle ear measures, speech perception tests, and a hearing and balance questionnaire. Results Individuals with CF were 3-4 times more likely to report issues with hearing, balance, and tinnitus and performed significantly poorer on speech perception tasks compared to controls. A higher prevalence of hearing loss was observed in individuals with CF (57%) compared to controls (37%). CF and control groups had similar proportions of slight and mild hearing losses; however, individuals with CF were 7.6 times more likely to have moderate and greater degrees of hearing loss. Older participants displayed higher average extended high-frequency thresholds, with no effect of age on average standard frequency thresholds. Although middle ear dysfunction has not previously been reported to be more prevalent in CF, this study showed that 16% had conductive or mixed hearing loss and higher rates of previous otitis media and pressure equalization tube surgeries compared to controls. Conclusions Individuals with CF have a higher prevalence of conductive, mixed, and sensorineural hearing loss; poorer speech-in-noise performance; and higher rates of multiple symptoms associated with otologic disorders (tinnitus, hearing difficulty, dizziness, imbalance, and otitis media) compared to controls. Accordingly, children with CF should be asked about these symptoms and receive baseline hearing assessment(s) prior to treatment with potentially ototoxic medications and at regular intervals thereafter in order to provide otologic and audiologic treatment for hearing- and ear-related problems to improve communication functioning.

Pharmacokinetic and Pharmacodynamic Optimization of Antibiotic Therapy in Cystic Fibrosis Patients: Current Evidences, Gaps in Knowledge and Future Directions

Antibiotic therapy is one of the main treatments for cystic fibrosis (CF). It aims to eradicate bacteria during early infection, calms down the inflammatory process, and leads to symptom resolution of pulmonary exacerbations. CF can modify both the pharmacokinetic (PK) and pharmacodynamic (PD) profiles of antibiotics, therefore specific PK/PD endpoints should be determined in the context of CF. Currently available data suggest that optimal PK/PD targets cannot be attained in sputum with intravenous aminoglycosides. Continuous infusion appears preferable for β-lactam antibiotics, but optimal concentrations in sputum are unlikely to be reached, with some possible exceptions such as meropenem and ceftolozane. Usual doses are likely suboptimal for fluoroquinolones and linezolid, whereas daily doses of 45-60 mg/kg and 200 mg could be convenient for vancomycin and doxycycline, respectively. Weekly azithromycin doses of 22-30 mg/kg could also be appropriate for its anti-inflammatory effect. The difficulty with achieving optimal concentrations supports the use of combined treatments and the inhaled administration route, as very high local concentrations, concomitantly with low systemic exposure, can be obtained with the inhaled route for aminoglycosides, colistin, and fluoroquinolones, thus minimizing the risk of toxicity.

Ototoxicity in cystic fibrosis patients receiving intravenous tobramycin for acute pulmonary exacerbation: Ototoxicity following tobramycin treatment

Aminoglycosides are commonly used to treat infections in CF patients and are highly ototoxic. The incidence of tobramycin-induced hearing loss, tinnitus, vertigo or dizziness (ototoxicity) varies widely from 0 to 56% secondary to variation in patient enrollment, dosing, audiometry, and ototoxic criteria. The aim of this study is to determine the incidence of ototoxicity after one course of once-daily IV tobramycin in CF patients. Adult CF patients with acute pulmonary exacerbations were enrolled on IV tobramycin (10 mg/kg/d, ≥10 days). Pure-tone audiometry was performed for standard and extended high frequencies in the sensitive range for ototoxicity (SRO). American-Speech-Language-Hearing-Association cochleotoxicity criteria were applied. Distortion product otoacoustic emissions (DPOAE) and the words-in-noise-test (WINT) were assessed. Tinnitus Functional Index (TFI) and Vertigo Symptoms Scale (VSS) were used. Eighteen CF patients, mean age 31.1 (18-59), were enrolled. The incidence of cochleotoxic change from baseline at 2 and 4 weeks post-treatment was 89% and 93%. For DPOAE, a measure of outer hair-cell function, the incidence of ≥5 dB decrease was 82% and 80%. For WINT, a measure of word recognition, the incidence of ≥10% decrease was 17% and 40%. For TFI, the incidence of ≥10pt increase was 12% and 8%, and for VSS, the incidence of ≥6pt increase was 0% and 8%. One course of IV tobramycin was sufficient to cause hearing loss and other ototoxic symptoms four weeks after treatment ended. Audiometric measures were more sensitive to ototoxic change than TFI & VSS. Age and duration of tobramycin treatment were not obvious factors for predicting ototoxicity.

Chirp-Evoked Otoacoustic Emissions and Middle Ear Absorbance for Monitoring Ototoxicity in Cystic Fibrosis Patients

OBJECTIVES

The goal of this study was to investigate the use of transient-evoked otoacoustic emissions (TEOAEs) and middle ear absorbance measurements to monitor auditory function in patients with cystic fibrosis (CF) receiving ototoxic medications. TEOAEs were elicited with a chirp stimulus using an extended bandwidth (0.71 to 8 kHz) to measure cochlear function at higher frequencies than traditional TEOAEs. Absorbance over a wide bandwidth (0.25 to 8 kHz) provides information on middle ear function. The combination of these time-efficient measurements has the potential to identify early signs of ototoxic hearing loss.

DESIGN

A longitudinal study design was used to monitor the hearing of 91 patients with CF (median age = 25 years; age range = 15 to 63 years) who received known ototoxic medications (e.g., tobramycin) to prevent or treat bacterial lung infections. Results were compared to 37 normally hearing young adults (median age = 32.5 years; age range = 18 to 65 years) without a history of CF or similar treatments. Clinical testing included 226-Hz tympanometry, pure-tone air-conduction threshold testing from 0.25 to 16 kHz and bone conduction from 0.25 to 4 kHz. Experimental testing included wideband absorbance at ambient and tympanometric peak pressure and TEOAEs in three stimulus conditions: at ambient pressure and at tympanometric peak pressure using a chirp stimulus with constant incident pressure level across frequency and at ambient pressure using a chirp stimulus with constant absorbed sound power across frequency.

RESULTS

At the initial visit, behavioral audiometric results indicated that 76 of the 157 ears (48%) from patients with CF had normal hearing, whereas 81 of these ears (52%) had sensorineural hearing loss for at least one frequency. Seven ears from four patients had a confirmed behavioral change in hearing threshold for ≥3 visits during study participation. Receiver operating characteristic curve analyses demonstrated that all three TEOAE conditions were useful for distinguishing CF ears with normal hearing from ears with sensorineural hearing loss, with an area under the receiver operating characteristic curve values ranging from 0.78 to 0.92 across methods for frequency bands from 2.8 to 8 kHz. Case studies are presented to illustrate the relationship between changes in audiometric thresholds, TEOAEs, and absorbance across study visits. Absorbance measures permitted identification of potential middle ear dysfunction at 5.7 kHz in an ear that exhibited a temporary hearing loss.

CONCLUSIONS

The joint use of TEOAEs and absorbance has the potential to explain fluctuations in audiometric thresholds due to changes in cochlear function, middle ear function, or both. These findings are encouraging for the joint use of TEOAE and wideband absorbance objective tests for monitoring ototoxicity, particularly, in patients who may be too ill for behavioral hearing tests. Additional longitudinal studies are needed in a larger number of CF patients receiving ototoxic drugs to further evaluate the clinical utility of these measures in an ototoxic monitoring program.

Progressive Hearing Loss among Patients with Cystic Fibrosis and Parenteral Aminoglycoside Treatment

OBJECTIVE

Hearing loss is a significant and growing problem as patients with cystic fibrosis (CF) live longer and experience frequent courses of intravenous aminoglycoside antibiotics (hereafter, "IVs"). This study seeks to document that risk in a large adult population with CF, accounting for age and aminoglycoside exposure.

STUDY DESIGN

Retrospective case review of patients with CF who had multiple audiograms over years.

SETTING

Tertiary care cystic fibrosis setting.

SUBJECT AND METHODS

The first and last audiograms recorded over a 10-year period were compared for 165 adult patients with CF. Patients were divided into 3 study groups: 34 patients with no intervening aminoglycoside IVs (0 IVs), 103 patients with 1 to 9 IVs, and 28 patients with ≥10 IVs. Threshold shift (TS) between the audiograms were examined for the 3 groups before and after age/sex adjustments. Two new hearing loss metrics were tested.

RESULTS

At first examination, 48% of patients (average age, 30.0 years) already had hearing loss. At last examination (average, 4.4 years later), 64% of the patients had hearing loss even with age/sex adjustment. Use of the age/sex hearing threshold adjustment eliminated the TS in the 0 IVs group. Two new metrics calculated for each patient demonstrated that 48% of patients who had 1 to 9 IVs had ototoxic scores, while almost 80% of the ≥10 IV group had ototoxic scores.

CONCLUSION

The majority of adult patients with CF are (often repeatedly) exposed to parenteral aminoglycosides and lose hearing at a rate that far exceeds that predicted from aging alone.

Current practice of ototoxicity management across the United Kingdom (UK)

OBJECTIVE

Effective management of patients diagnosed with ototoxicity is needed to reduce hearing and balance damage which affects communication and life quality. Despite widespread recommendations to monitor and manage ototoxicity in an early and effective manner, there is limited evidence to support the actual implementation of these recommendations for affected patient groups in healthcare services across the UK with limited publications available. In this study, an online questionnaire analysed the current practice of ototoxicity management and patient pathways across the UK once the diagnosis of ototoxicity was confirmed, targeting Audiologists, ENTs/AVPs and GPs.

DESIGN

Qualitative Survey Study.

STUDY SAMPLE

A randomised sample of hearing services in the UK, including audiology departments; GP practices and local health settings were targeted with a total of 134 completed surveys.

RESULTS

About 72% reported the absence of ototoxicity management protocols within their centre. Results depicted great inconsistency and variation across the UK in ototoxicity management services provided, treatment modification, monitoring and referral pathways.

CONCLUSION

Developing and advocating national guidelines are intended not only to inform clinical decision making but to provide minimum standards of care in ototoxicity management and offer greater awareness and education to improve patients' quality of life.

The cumulative effects of intravenous antibiotic treatments on hearing in patients with cystic fibrosis

BACKGROUND

Aminoglycosides (AGs) and glycopeptides are antibiotics essential for treating life-threatening respiratory infections in patients with cystic fibrosis (CF). The goal of this study was to examine the effects of cumulative intravenous (IV)-AG (amikacin and/or tobramycin) and/or glycopeptide (vancomycin) dosing on hearing status in patients with CF.

METHODS

Hearing thresholds were measured from 0.25 to 16.0kHz, in 81 participants with CF. Participants were categorized into two groups: normal hearing in both ears (≤25dB HL for all frequency bands) or hearing loss (>25dB HL for any frequency band in either ear). Participants were also characterized into quartiles by their cumulative IV-AG (with or without vancomycin) exposure. Dosing was calculated using two strategies: (i) total number of lifetime doses, and (ii) total number of lifetime doses while accounting for the total doses per day. This was referred to as the "weighted" method.

RESULTS

Participants in the hearing loss group were significantly older than those in the normal-hearing group. After adjusting for gender and age at the time of hearing test, participants in the two highest-quartile exposure groups were almost 5 X more likely to have permanent sensorineural hearing loss than those in the two lowest-quartile exposure groups. There was a small group of CF patients who had normal hearing despite high exposure to IV-antibiotics.

CONCLUSIONS

Cumulative IV-antibiotic dosing has a significant negative effect on hearing sensitivity in patients with CF, when controlling for age and gender effects. A trend for increasing odds of hearing loss was associated with increasing cumulative IV-antibiotic dosing.

d-Methionine reduces tobramycin-induced ototoxicity without antimicrobial interference in animal models

BACKGROUND

Tobramycin is a critical cystic fibrosis treatment however it causes ototoxicity. This study tested d-methionine protection from tobramycin-induced ototoxicity and potential antimicrobial interference.

METHODS

Auditory brainstem responses (ABRs) and outer hair cell (OHC) quantifications measured protection in guinea pigs treated with tobramycin and a range of d-methionine doses. In vitro antimicrobial interference studies tested inhibition and post antibiotic effect assays. In vivo antimicrobial interference studies tested normal and neutropenic Escherichia coli murine survival and intraperitoneal lavage bacterial counts.

RESULTS

d-Methionine conferred significant ABR threshold shift reductions. OHC protection was less robust but significant at 20kHz in the 420mg/kg/day group. In vitro studies did not detect d-methionine-induced antimicrobial interference. In vivo studies did not detect d-methionine-induced interference in normal or neutropenic mice.

CONCLUSIONS

d-Methionine protects from tobramycin-induced ototoxicity without antimicrobial interference. The study results suggest d-met as a potential otoprotectant from clinical tobramycin use in cystic fibrosis patients.