|Classification and external resources|
|eMedicine||med/1644 derm/297 ped/1610|
Nocardiosis is an infectious disease affecting either the lungs (pulmonary nocardiosis) or the whole body (systemic nocardiosis). It is due to infection by bacterium of the genus Nocardia, most commonly Nocardia asteroides or Nocardia brasiliensis.
Normally found in soil, these organisms cause occasional sporadic disease in humans and animals throughout the world. Another well publicized find is that of Nocardia as an oral microflora. Nocardia spp. have been reported in the normal gingiva and periodontal pockets along with other species such as Actinomyces, Arthromyces and Streptomyces spp.
The usual mode of transmission is inhalation of organisms suspended in dust. Another very common method is that by traumatic introduction, especially in the jaw. This leads to the entrance of Nocardia into the blood stream and the propagation of its pathogenic effects. Transmission by direct inoculation through puncture wounds or abrasions is less common. Generally, nocardial infection requires some degree of immune suppression.
Signs and symptoms
- Produces a virulent form of pneumonia (progressive)
- night sweats, fever, cough, chest pain
- Pulmonary nocardiosis is subacute in onset and refractory to standard antibiotherapy
- symptoms are more severe in immunocompromised individuals
- radiologic studies show multiple pulmonary infiltrates with tendency to central necrosis
- Headache, lethargy, confusion, seizures, sudden onset of neurological deficit
- CT scan shows cerebral abscess
- Nocardial meningitis is difficult to diagnose
- Nocardia has been highly linked to endocarditis as a main manifestation
- In recorded cases, it has caused damage to heart valves whether natural or prosthetic
- Nocardial cellulitis is akin to erysipelas but is less acute
- Nodular lymphangeitis mimics sporotrichosis with multiple nodules alongside a lymphatic pathway
- Chronic subcutaneous infection is a rare complication and osteitis may ensue
- Very rarely nocardiae cause keratitis
- Generally there is a history of ocular trauma
- Dissemination occurs through the spreading enzymes possessed by the bacteria
- Disseminated infection can occur in very immunocompromised patients
- It generally involves both lungs and brain
- Fever, moderate or very high can be seen
- Multiple cavitating pulmonary infiltrates develop
- Cerebral abscesses arise later
- Cutaneous lesions are very rarely seen
- If untreated, the prognosis is poor for this form of disease
Diagnosis may be difficult. Nocardiae are gram positive weakly acid-fast branching rod-shaped bacteria and can be visualized by a modified Ziehl-Neelsen stain like Fite-Faraco method In the clinical laboratory, routine cultures may be held for insufficient time to grow nocardiae, and referral to a reference laboratory may be needed for species identification. Infiltration and pleural effusion are usually seen via x-ray.
Nocardiosis requires at least 6 months of treatment, preferably with trimethoprim/sulfamethoxazole or high doses of sulfonamides. In patients who do not respond to sulfonamide treatment, other drugs, such as ampicillin, erythromycin, or minocycline, may be added.
Treatment also includes surgical drainage of abscesses and excision of necrotic tissue. The acute phase requires complete bed rest; as the patient improves, activity can increase.
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- Lederman ER, Crum NF (September 2004). "A case series and focused review of nocardiosis: clinical and microbiologic aspects". Medicine (Baltimore). 83 (5): 300–13. doi:10.1097/01.md.0000141100.30871.39. PMID 15342974.
- Rapini, Ronald P.; Bolognia, Jean L.; Jorizzo, Joseph L. (2007). Dermatology: 2-Volume Set. St. Louis: Mosby. ISBN 1-4160-2999-0.
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- "Nocardia Endocarditis in a Native Mitral Valve Revista Espanola de Cardiologia Volume 57, Issue 8, August 2004, Pages 787-788".
- "Successful Antimicrobial Chemotherapy for Nocardia Asteroides Prosthetic Valve Endocarditis The American Journal of Medicine, Volume 115, Issue 4, Pages 330-332".
- "Nocardiosis: DBMD - WrongDiagnosis.com". Retrieved 2007-07-12.