Nocardiosis
Overview
Nocardiosis is an infection caused by bacteria (Nocardia) which live in the soil. If inhaled, the bacteria may cause pneumonia, which can lead to blood poisoning (sepsis) and the spread of nocardiosis to other organs of the body. This is called disseminated nocardiosis. People with compromised immune systems, such as people with cancer or those taking steroids or immunosuppressive medications, are at risk for disseminated nocardiosis. Nocardia may also infect the skin through a cut, puncture wound, or scratch that occurs while working outdoors or gardening. The skin infections, which may take different forms, are called cutaneous nocardiosis. Occupational exposure to soil, as in field work, landscaping, and farming, increases the risk of contracting cutaneous nocardiosis
Symptoms
Symptoms of nocardiosis depend on what type of infection has occurred. Disseminated nocardiosis * Most commonly starts as lung infection (pneumonia) * May spread to any organ of the body and cause illness in many body systems Cutaneous nocardiosis * Lymphocutaneous nocardiosis Injury to skin leads to lymph node infection * Other lymph nodes in the same group (chain) become infected * Most commonly occurs in arms * Mycetoma (also maduromycosis or Madura foot) Deep, destructive nocardiosis infection of skin and underlying tissues * Occurs most commonly on arms and legs, especially the feet * Walking barefoot in dirt increases risk of contracting mycetoma * Begins as a large, swollen area with redness and oozing * May cause destruction of muscle and bone, and deformity of foot * Skin infections May be pustules, abscesses, or cellulitis * May be mistaken for other more common skin infections * Often accompanied by fever Treatment
Causes
Pulmonary and disseminated nocardiosis are clearly associated with immunocompromising conditions, with approximately 60% of cases of nocardiosis other than mycetoma occurring in individuals with some compromise of host defense systems. Conditions associated with an increased risk of pulmonary and disseminated nocardiosis include the following: * Chronic pulmonary disease: Although pulmonary nocardiosis has been described in association with various chronic pulmonary diseases, patients with pulmonary alveolar proteinosis are at particular risk. * Alcoholism * Cirrhosis * Lymphoreticular malignancy * Solid-organ transplantation17 * Bone marrow or stem cell transplantation * Long-term corticosteroid use or Cushing syndrome * Systemic lupus erythematosus * Systemic vasculitis * Ulcerative colitis * Sarcoidosis * Renal failure * Whipple disease * Hypogammaglobulinemia * Treatment with anti–tumor necrosis factor antibody * HIV infection and AIDS: Nocardiosis in individuals with advanced HIV disease usually presents as a relentlessly progressive infiltrative pulmonary infection. The median CD4 count in patients infected with HIV who develop nocardiosis is approximately 50 cells/µL.13
Treatment
Individuals with nocardiosis, either disseminated or cutaneous, require long-term antibiotic treatment for the infection. Sulfamethoxazole-trimethoprim (Bactrim) is used most frequently, and can be taken in pill form. Skin lesions may need to be surgically drained or removed. Diseased tissue may need to be removed from mycetomas. With proper antibiotic treatment, full recovery from nocardiosis is likely. Individuals who are immune compromised, though, may have a more difficult time recovering.