Lucretia Petersen

Aminoglycoside: induced hearing loss in HIV-positive and HIV-negative multidrug-resistant tuberculosis patients

Background. Ototoxicity following aminoglycoside treatment for multidrug-resistant tuberculosis (MDR-TB) is a significant problem. This study documents the incidence of ototoxicity in HIV-positive and HIV-negative patients with MDR-TB and presents clinical guidelines relating to ototoxicity. Methods. A prospective cohort study of 153 MDR-TB patients with normal hearing and middle ear status at baseline controlling for 6 mitochondrial mutations associated with aminoglycoside-related ototoxicity, at Brooklyn Chest Hospital in Cape Town. Pure tone audiometry was performed monthly for 3 months to determine hearing loss. HIV status was recorded, as was the presence of 6 mutations in the MT-RNR1 gene. Results. Fifty-seven per cent developed high-frequency hearing loss. HIV-positive patients (70%) were more likely to develop hearing loss than HIV-negative patients (42%). Of 115 patients who were genetically screened, none had MT-RNR1 mutations. Conclusion. Ototoxic hearing loss is common in MDR-TB patients treated with aminoglycosides. HIV-positive patients are at increased risk of ototoxicity. Auditory monitoring and auditory rehabilitation should be an integral part of the package of care of MDR-TB patients.

Aminoglycoside-induced hearing loss : South Africans at risk

South Africa is currently experiencing a TB epidemic with an estimated incidence of 940 / 100 000 population / year, and the country has been ranked 4th among the 22 high-burden TB countries worldwide by the World Health Organization (WHO). A potentially devastating threat to TB control is the emergence of multidrug-resistant TB (MDR-TB) and, more recently, extensively drug-resistant TB (XDR-TB), mainly as a result of poor drug adherence by TB patients and incorrect management or treatment regimens by health providers ; however, direct transmission of drug-resistant strains also plays an important role. The MDR / XDR-TB strains necessitate prolonged chemotherapy for up to 2 years or more, and the use of more toxic second-line drugs including the aminoglycoside (streptomycin, kanamycin and amikacin) and polypeptide (capreomycin) antibiotics. In South Africa, in accordance with WHO guidelines, streptomycin is used for retreatment of TB while kanamycin, amikacin and capreomycin are used to treat MDR / XDR-TB.

Developing Human Rights competencies for South African health professional graduates

Human rights are social or material entitlements which are recognised universally in national and international law and that address fundamental human needs. They inhere in all people by virtue of their humanity, and represent a standard to which governments can be held accountable.

Aminoglycoside-induced balance deficits: a review of vestibulotoxicity

Abstract This article aims to inform clinicians about the current knowledge on aminoglycoside-induced vestibulotoxicity through a review of the literature. The effects of vestibulotoxicity are irreversible and may be profoundly disabling. It would appear that the sooner vestibular rehabilitation therapy is instituted, the more favourable the prognosis is. Thus, early referral and management are essential. Vestibulotoxicity is a commonly overlooked aetiology when assessing dizzy patients. This could be due to the difficulty that patients have in describing vestibular symptoms in general, as well as the absence of vertigo as a presenting complaint. Discussion includes the clinical presentation of vestibulotoxicity and its sequelae, as well as strategies to assess and monitor patients.

Screening for childhood hearing impairment in resource-constrained settings: Opportunities and possibilities.

Given the successful implementation of universal neonatal hearing screening and the value of such services in developed countries, we in developing countries should be asking ourselves ‘how’, and not ‘whether’, such services should be delivered in our contexts.

Aminoglycoside-induced hearing deficits – a review of cochlear ototoxicity

This article aims to inform the reader about current knowledge of the effects of aminoglycosides on hearing. The hearing loss caused by aminoglycosides is permanent and can negatively affect the individual’s quality of life. Although treatment with aminoglycosides cannot be avoided in some instances, timely intervention can minimise the impact of the hearing loss on the individual’s everyday life. The discussion includes the incidence of aminoglycoside-induced hearing loss and predisposing factors. In addition, monitoring and management of cochlear ototoxicity is described.

Identifying a context-effective school hearing screening test: An emic/etic framework

Abstract Objective: To identify a context-effective hearing screening test for primary schools in the Western Cape, South Africa using an emic-etic framework for test selection. Design: A sequential mixed methods design was used to: (1) Identify test properties needed to successfully screen hearing in primary school children in the Western Cape, (2) select the hearing screening test most likely to succeed in this context, and (3) assess the use of the test in context. Study sample: Three nurses, two nursing assistants, two paediatric audiologists, and 100 grade-one children participated. Results: Distortion product otoacoustic emissions (DPOAEs) were identified as the test most likely to succeed as a hearing screening test in primary school children in the Western Cape. While school nurses were able to successfully apply OAE testing in this context, its sensitivity to hearing loss in these children was 57.14%. Conclusions: The sensitivity would need to be improved before OAE testing could be used as a context-effective screening test for primary school children in the Western Cape. The study demonstrated the value of collaborative program planning using an emic-etic framework to ensure that screening tests are contextually appropriate.

A systematic review of stimulus parameters for eliciting distortion product otoacoustic emissions from adult humans

Abstract Objective: The objective of this study is to review the scientific literature to determine if a set of stimulus parameters can be described to elicit distortion product otoacoustic emissions (DPOAEs) of higher absolute level and/or greater reliability in healthy adult humans and higher sensitivity and specificity in adults with cochlear lesions. Design: Systematic review. Study sample: Searches of four electronic databases yielded 47 studies that had used different parameters to elicit DPOAEs from within or between-groups of adult humans. Results: The wide range of stimulus parameters used in the reviewed studies saw a wide range of reported values for DPOAE level, reliability, and sensitivity and specificity to cochlear lesions. Conclusion: The most commonly used stimulus parameters for eliciting DPOAEs from adult humans have included frequency ratios for the two primary tones (f2/f1) of between 1.04 and 1.4 and levels (L1/L2) of 65/55 dB SPL. The most commonly used parameters for eliciting DPOAEs of higher level in healthy adults appear to be linked to f2/f1 values between 1.20 and 1.22 and L1/L2 levels of 75/75 dB SPL. The stimulus parameters for eliciting DPOAEs of greater reliability in healthy adults and higher sensitivity and specificity in adults with cochlear lesions have yet to be clearly determined.

The occurrence of auditory dysfunction in children with TB receiving ototoxic medication at a TB hospital in South Africa

OBJECTIVES to describe the auditory dysfunction of children with tuberculosis receiving ototoxic medication at a residential TB hospital in the Cape Town metropolitan area. METHODS A descriptive survey research design was adopted. The auditory status of participants was evaluated by otoscopy, immittance, audiometry or OAE and AABR (depending on the age). STUDY SAMPLE 29 in-patients (7 months to 16.6 years). RESULTS Fifty five percent of participants presented with middle ear abnormalities (n=16) and 48% (n=12) had sensorineural or mixed hearing loss. The degree of hearing loss ranged from mild to profound in 16% of the ears. The conventional pure-tone average of .5, 1, & 2 kHz did not allow for the determination of the degree of hearing loss in the remaining 18% which had high frequency hearing loss. CONCLUSIONS The high occurrence of hearing loss necessitates the implementation of monitoring program for children receiving ototoxic medication. Consideration should be given to using the average of hearing thresholds at 4, 6 and 8 kHz to determine the classification of degree of hearing loss in cases of ototoxicity.

Towards the preferred stimulus parameters for distortion product otoacoustic emissions in adults: A preliminary study

Background Although distortion product otoacoustic emissions (DPOAEs) are useful in evaluating cochlear outer hair cell function, determining the optimal stimulus parameters could result in a more reliable, sensitive and specific diagnostic tool across the range of DPOAE applications. Objectives To identify which stimulus parameters warrant further investigation for eliciting the largest and most reliable DPOAEs in adult humans. Method A single group, repeated measures design involving a convenience sample of 20 normal-hearing participants between 19 and 24 years of age. Results Descriptive statistics and mixed model analyses suggested L1/L2 intensity levels of 65/65 dB sound pressure level (SPL) and 65/55 dB SPL, and f2/f1 ratios of 1.18, 1.20 and 1.22 elicited larger and more reliable DPOAEs in both ears. Conclusion Further investigation of the 65/65 dB SPL and 65/55 dB SPL intensity levels and the 1.18, 1.20 and 1.22 f2/f1 ratios is warranted to determine the stimulus parameters for eliciting the largest and most reliable DPOAEs in adult humans across the range of DPOAE applications.