Antibiotic complications during the treatment of Mycobacterium ulcerans disease in Australian patients

Background: Antibiotics are the recommended first-line treatment for Mycobacterium ulcerans disease. Antibiotic toxicity is common in Australian patients, yet antibiotic complication rates and their risk factors have not been determined. Aim: To determine the incidence rate and risk factors for antibiotic toxicity in Australian patients treated for M. ulcerans disease. Methods: An analysis of severe antibiotic complications was performed using data from a prospective cohort of M. ulcerans cases managed at Barwon Health from 1 January 1998 to 30 June 2016. A severe antibiotic complication was defined as an antibiotic adverse event that required its cessation. Antibiotic complication rates and their associations were assessed using a Poisson regression model. Results: A total of 337 patients was included; 184 (54.6%) males and median age 57 years (interquartile range (IQR) 36-73 years). Median antibiotic treatment duration was 56 days (IQR 49-76 days). Seventy-five (22.2%) patients experienced severe antibiotic complications after a median 28 days (IQR 17-45 days) at a rate of 141.53 per 100 person- years (95% confidence interval (CI) 112.86-177.47). Eleven (14.7%) patients required hospitalisation. Compared with rifampicin/clarithromycin combinations, severe complication rates were not increased for rifampicin/ciprofloxacin (rate ratio (RR) 1.49, 95% CI 0.89-2.50, P = 0.13) or rifampicin/moxifloxacin (RR 2.54, 95% CI 0.76-8.50, P = 0.13) combinations, but were significantly increased for 'other' combinations (RR 2.53, 95% CI 1.13-5.68, P = 0.03). In a multivariable analysis, severe complication rates were significantly increased with reduced estimated glomerular filtration rates (EGFR) (adjusted rate ratio (aRR) 2.65, 95% CI 1.24-5.65 for EGFR 60-89 mL/min and aRR 1.31, 95% CI 0.49-3.53 for EGFR 0-59 mL/min compared with EGFR = 90 mL/min, P <0.01) and female gender (aRR 2.15, 95% CI 1.38-3.30, P <0.01). Conclusions: Severe antibiotic complications during M. ulcerans treatment are high with increased rates independently associated with reduced renal function and female gender.