What is the role of medications in the treatment of nocardiosis?

Updated: Jul 24, 2018
  • Author: George Kurdgelashvili, MD; Chief Editor: Michael Stuart Bronze, MD  more...
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General treatment guidelines for nocardiosis are hindered by (1) lack of controlled clinical trials of therapy; (2) difficult, and, in the past, poorly standardized in vitro susceptibility testing leading to widely disparate reports of in vitro antimicrobial susceptibility [23, 24] ; (3) lack of firm data on correlation of in vitro susceptibility with in vivo therapeutic efficacy; and (4) the changing taxonomy of Nocardia species. Therapy should likely be guided by in vitro susceptibility testing at a specialized laboratory experienced at testing Nocardia strains.

Sulfonamides have long been the first-line antimicrobial therapy for nocardiosis. Among the sulfonamides, sulfadiazine is generally preferred because of its CNS and CSF penetration. Although not convincingly demonstrated superior, trimethoprim-sulfamethoxazole (TMP-SMZ) is considered the therapy of choice by most authorities. Divided doses of 5-10 mg/kg/d of the trimethoprim component should be administered to produce sulfonamide levels of 100-150 mcg/mL; such levels should possibly be confirmed in individuals with severe disease.

Additional or alternative parenteral therapies include carbapenems (imipenem or meropenem, but not ertapenem), third-generation cephalosporins (cefotaxime or ceftriaxone), and amikacin, alone or in combination. Imipenem plus amikacin may be the preferred regimen in sulfonamide-allergic individuals. Linezolid in vitro activity and in vivo efficacy has been reported. [25] Tigecycline also has reported activity in vitro. [1]

For most serious Nocardia infections, combination therapy has been recommended. [1] Combination therapy should be continued until clinical improvement occurs and confirmation of in vitro drug susceptibility has been acquired.

Alternative oral therapies include minocycline and amoxicillin/clavulanate, in addition to linezolid. These may be used initially in mild-to-moderately severe disease or as sequential therapy after an induction course of parenteral therapy. Modern fluoroquinolones often have demonstrable in vitro activity against Nocardia species but have failed therapeutically.

Duration of treatment is generally prolonged to minimize risk of disease relapse. Immunocompetent patients with non-CNS nocardiosis may be successfully treated with 6-12 months of antimicrobial therapy. Immunosuppressed patients and those with CNS disease should receive 12 months of therapy or longer if escalation of immunosuppression takes place (such as graft or organ rejections). In For patients on chronic steroid or cytotoxic therapy, prolonged maintenance of anti-nocardial therapy may be indicated. Appropriate clinical monitoring should be conducted during protracted antimicrobial therapy. [1]

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