M. abscessus | Antibiotic regimen |
Clarithromycin-sensitive isolates or inducible macrolide-resistant isolates |
Initial phase: ≥1 month* intravenous amikacin 15 mg/kg daily or 3×per week† and intravenous tigecycline 50 mg twice daily and where tolerated intravenous imipenem 1 g twice daily and where tolerated oral clarithromycin 500 mg twice daily or oral azithromycin 250–500 mg daily Continuation phase: nebulised amikacin† and oral clarithromycin 500 mg twice daily or azithromycin 250–500 mg daily and 1–3 of the following antibiotics guided by drug susceptibility results and patient tolerance: oral clofazimine 50–100 mg daily‡ oral linezolid 600 mg daily or twice daily oral minocycline 100 mg twice daily oral moxifloxacin 400 mg daily oral cotrimoxazole 960 mg twice daily |
Constitutive macrolide-resistant isolates |
Initial phase: ≥1 month* intravenous amikacin 15 mg/kg daily or 3×per week† and intravenous tigecycline 50 mg twice daily and where tolerated intravenous imipenem 1 g twice daily Continuation phase: nebulised amikacin† and 2–4 of the following antibiotics guided by drug susceptibility results and patient tolerance: oral clofazimine 50–100 mg daily‡ oral linezolid 600 mg daily or twice daily oral minocycline 100 mg twice daily oral moxifloxacin 400 mg daily oral cotrimoxazole 960 mg twice daily |
*Due to the poorer response rates in patients with inducible or constitutive macrolide-resistant isolates and the greater efficacy of antibiotics administered through the intravenous route, -extending the duration of intravenous antibiotic therapy to 3–6 months in those that can tolerate it may be the most appropriate treatment strategy in this subgroup of patients.
†Substitute intravenous/nebulised amikacin with an alternative antibiotic if the M. abscessus is resistant to amikacin (ie, MIC >64 mg/L or known to have a 16S rRNA gene mutation conferring constitutive amikacin resistance).
‡Start clofazimine during the initial phase of treatment if tolerated as steady state serum concentrations may not be reached until ≥30 days of treatment.