Executive Summary of State-of-the-Art Review: Modern Approach to Nocardiosis—Diagnosis, Management, and Uncertainties

WHAT IS THIS CLINICAL REVIEW ABOUT?

Nocardia is a genus of gram-positive, partially acid-fast bacilli that typically infect people with chronic lung disease or immunocompromised states. Nocardia most commonly affects the lungs or skin but has the potential to disseminate to essentially any anatomic site, such as the brain. Due to variability in presentation and complexities of the at-risk patient populations, successful management of nocardiosis requires a coordinated multidisciplinary approach, involving specialists in infectious diseases, pharmacy, microbiology, and pulmonology, as well as practitioners who manage immunosuppressive therapy.

WHAT ARE THE MAIN DIAGNOSTIC, MANAGEMENT, AND TREATMENT CHALLENGES OF NOCARDIOSIS?

There is a broad spectrum of Nocardia presentations, and it can resemble many other infectious and noninfectious disorders. The diagnosis of pulmonary nocardiosis can be challenging, as this often affects patients with chronic lung disease and Nocardia symptoms can be difficult to distinguish from underlying pulmonary disease. This is complicated by the possibility of Nocardia respiratory colonization. Patients are also at risk for dissemination and need assessment for potential sites of secondary infection. Once a diagnosis of nocardiosis is established, data on optimal treatment strategies are limited. Patients often receive empiric combination antibiotic therapy, which can be tailored based on Nocardia species identification and subsequent susceptibility testing. The duration of antibiotic treatment is understudied and based on few data. Pulmonary nocardiosis is commonly treated for 6 months, cutaneous disease for 3 months, and disseminated or central nervous system nocardiosis for 12 months. However, approximately 5% of patients with nocardiosis develop recurrence and should be closely monitored after completing initial treatment.

HOW DO YOU SET EXPECTATIONS AND ENGAGE IN SHARED DECISION MAKING IN NOCARDIOSIS?

There may be uncertainty regarding the diagnosis of pulmonary nocardiosis among patients with chronic lung disease, and the optimal duration of nocardiosis therapy is controversial. When the pathogenicity of a respiratory Nocardia isolate is uncertain, this should be discussed with patients and a plan for either a therapeutic trial or careful monitoring without treatment should be decided together. Adverse effects from common nocardiosis therapy are common, and patients should be educated on these possible reactions. When adverse effects occur, patients and their care teams should reassess the duration of therapy in the context of interval clinical and radiographic response. Treatment can be shortened from the traditional 6- to 12-month duration if the harmful effects of treatment begin to outweigh the potential benefits of continuing for more prolonged courses. These circumstances should prompt a discussion regarding the endpoint of treatment, and signs of recurrence should be monitored closely once therapy is stopped (Figure 1).

Figure 1.

Approach to nocardiosis. Abbreviations: CNS, central nervous system; MRI, magnetic resonance imaging; TMP-SMX, trimethoprim-sulfamethoxazole.

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