REVIEW OF STREPTOMYCIN-ASSOCIATED OTOTOXICITY IN BRUCELLOSIS CASES

Abstract

Brucellosis is a zoonotic infectious disease with a worldwide distribution and one of the challenges with its treatment is the risk of ototoxicity associated with aminoglycoside-containing regimens.  In this study we aimed to review streptomycin-containing brucellosis treatment cases in order to determine the incidence of streptomycin-induced ototoxicity in the study population in order to inform treatment efforts.  We conducted a single-center retrospective cohort study.  Study subject inclusion criteria were being aged ≥18 years, having been diagnosed with brucellosis at the study institution during 10 January 2023-31 March 2024, having normal tympanic membranes on otoscopy, receiving a treatment regimen containing streptomycin and having undergone pure tone audiometry assessing air conduction at 500, 1000, 2000 and 4000 Hz.  Hearing loss was classified as mild (26-40 dB), moderate (41-55 dB), moderately severe (56-70 dB), severe (71-90 dB) and profound (≥91 dB).  Study subject exclusion criteria were pregnancy or lactation, chronic renal failure, receiving ongoing chemotherapy for a malignancy, use of known ototoxic medications (excluding nonsteroidal anti-inflammatory drugs) within the previous 3 months, having the presence of severe hearing loss at baseline prior to treatment and having missing data.  A total of 70 subjects were included in our study, 60% (n = 42) females.  The mean (±standard deviation (SD)) age of study subjects was 43 (±14) (range: 19-70) years.  At baseline the number of subjects with hearing loss was 9 (13%); during treatment 7 (10%); 5 (71%), 1 (14%), 0 (0%), 1 (14%) and 0 (0%) had mild, moderate, moderately severe, severe and profound hearing loss, respectively; at completion 0 subjects (0%) had hearing loss.  The mean (±SD) age of subjects who developed temporary high-frequency hearing loss during treatment was 57 (±4) years, significantly higher (p-value = 0.030) than the age of subjects without hearing loss, which was 43 (±2) years.  In summary, among our study subjects, streptomycin-associated ototoxicity during standard brucellosis treatment was uncommon and reversible.  However, older subjects were at greater risk of developing temporary but reversible ototoxicity.  We conclude streptomycin is safe to use in brucellosis-treatment regimens in the study population.  However, caution should be used in older adults and may warrant audiological testing during and at the end of treatment among older patients.  Further testing is needed to determine at what age such testing may be considered.