Nocardiosis

Nocardia species are an aerobic filamentous soil bacterium that can cause pulmonary and systemic nocardiosis

Commonly identified nocardia species include members of the Nocardia asteroides complex and Nocardia brasiliensis

Bronchopulmonary abnormalities (eg, alveolar proteinosis) predispose to colonization, but infection is unusual unless the patient is also receiving systemic corticosteroids or is otherwise immunosuppressed

Central nervous system (CNS) involvement commonly accompanies pulmonary infection

Pulmonary involvement usually begins with malaise, loss of weight, fever, and night sweats

Cough and production of purulent sputum are the chief complaints

Pulmonary infiltrates may penetrate to the exterior through the chest wall, invading the ribs

Dissemination from pneumonia may involve any organ, especially CNS, skin, and bone, or there may be primary cutaneous disease

• Brain abscesses and subcutaneous nodules are most frequent

• Cutaneous lesions may mimic actinomycosis

• Dissemination is seen exclusively in immunocompromised patients

Suspect in setting of chronic lung disease or immunocompromised host

N asteroides is a branching, filamentous gram-positive bacterium that is weakly acid-fast

Identification is made by culture

Chest radiograph

• May show infiltrates accompanied by pleural effusion

• Lesions may penetrate through the chest wall and invade the ribs

Brain imaging should be considered even in absence of clinical symptoms and signs of CNS infection to rule out occult abscess

Trimethoprim-sulfamethoxazole (TMP-SMZ)

• For isolated primary cutaneous infections

  • 5–10 mg/kg/day (based on TMP) as an oral or intravenous formulation

• For disseminated or pulmonary infections: 15 mg/kg/day (based on TMP)

• Resistance to TMP-SMZ is increasing and initiating treatment with two drugs should be considered while awaiting antibiotic susceptibilities in cases of disseminated or severe localized disease

Alternative agents or drugs that can be given in combination with TMP-SMZ

• Imipenem, 500 mg intravenously every 6 hours

• Amikacin, 7.5 mg/kg intravenously every 12 hours

• Minocycline, 100–200 mg orally or intravenously twice daily

Surgical procedures such as drainage and resection may be needed as adjunctive therapy for isolated cutaneous disease

Response may be slow, and therapy should be continued for at least 6 mo

The prognosis in systemic nocardiosis is poor when therapy is delayed