Nocardiosis is caused by gram-positive bacilli that are aerobic soil saprophytes. Typical infections are pneumonia, slowly destructive lesions of skin and subcutaneous tissues, and brain abscesses. Organisms are inoculated into the skin or inhaled from water, decaying plants, and soil.
CASES/YEAR
1,200 (US); 24,000 (Global)
OTHER NAMES
Nocardia infection;
INCUBATION
Estimated a few days to a few weeks; [CCDM, p. 426]
INITIAL SYMPTOMS
Invasive pulmonary disease, disseminated disease, or brain abscess (80% of cases); Cellulitis (20% of cases); [CDC website--2013] Most commonly causes subacute pneumonia (often misdiagnosed as TB), but also CNS and skin disease; [Cecil, p. 2032]
PRECAUTIONS
Standard; "Not transmitted from person to person." [CDC 2007 Guideline for Isolation Precautions]
COMMENTS
Main Types: 1.) Immunocompetent Pulmonary/Systemic; 2.) Immunocompromised Pulmonary/Systemic; 3.) CNS disease; 4.) Cellulitis/Lymphocutaneous Syndrome (resembles sporotrichosis); 5.) Osteomyelitis/Arthritis/Laryngitis/Sinusitis; 6.) Actinomycetoma (Madura foot, tropics); 7.) Keratitis; [Harrisons, p. 499, 500t] More than 60% of patients are immunocompromised. In one survey, CNS involvement was identified in more than 44% of cases with systemic nocardiosis. Inhalation is the primary route of exposure, and pulmonary disease predominates. Pulmonary disease includes pneumonia, lung abscesses, irregular nodules, and pleural effusions. [PPID, p. 3063] Rupture of a brain abscess can lead to meningitis. [PPID, p. 1224] After a soil contaminated wound, Nocardia brasiliensis is usually the cause of the skin infections. Immunocompetent patients with pulmonary nocardiosis have a 15% mortality rate. [Cecil, p. 2033, 2034]] Patients with pulmonary infection have cough, fever, chest pain, weakness and weight loss. [Merck Manual, p. 1616] In 1050 cases of systemic nocardiosis, 44% of patients had cerebral infections (headaches, seizures, focal deficits, or asymptomatic). Patients with pulmonary infection typically have productive cough and dyspnea. [Cohen, p. 1551] Among cases of extrapulmonary disease, endocarditis is rare, and meningitis is uncommon. Percutaneous inoculation leads to cellulitis, lymphocutaneous syndrome, or actinomycetoma. [Harrison ID, p. 590-1] Bone is rarely involved. Skin disease results from inoculation or dissemination. Up to 55% of patients with disseminated disease have CNS infection. [ID, p. 1855]
DIAGNOSTIC
Examine sputum & pus for Gram +, branching filaments that are beaded; Partially acid fast; Notify lab of suspected dx. [ABX Guide] Rarely isolated in blood cultures; [ID]
SCOPE
Global; Actinomycetoma (chronic skin and subcutaneous disease with nodules & draining sinuses) occurs in tropical and subtropical regions; [Harrison ID, p. 589]
SIGNS & SYMPTOMS
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>fatigue, weakness
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>fever
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H lymphadenopathy
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N headache
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N muscle weakness
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N seizure
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R chest pain
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R cough
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R dyspnea
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R hemoptysis
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R sputum production
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S cellulitis or rash, circinate
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S entry wound with lymph nodes
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S lymphadenitis, acute
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S lymphangitis
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S nodular lymphangitis
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S papules or plaques
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S pustule
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S skin or subcutaneous nodule
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S ulcer of skin
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X cystic or cavitary lesions
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X lung infiltrates
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X pleural effusions
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*arthritis
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*brain abscess or lesion
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*endocarditis
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*mediastinitis
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*meningitis
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*osteomyelitis
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*pericarditis
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*pneumonia
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*weight loss
ENTRY
Inhalation, Skin or Mucous Membranes (Includes Conjunctiva)
SOURCE
Soil or Dust (Ingesting or Inhaling)
RISK FACTORS
- AIDS patients
- Cancer patients
REFERENCES FOR CASES/YEAR
1. (US) About 1000 cases/year diagnosed in US; [Gorbach, p. 288] Estimated at 0.4 cases per 100,000 per year; [Cecil, p. 2032] Calculate US rate =: 0.4 X 3000 = 1200;
2. (Global) Global cases/yr estimated at 20 X US cases/yr;