Nocardiosis
| Nocardiosis | |
| ICD-10 | A43 |
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| ICD-9 | 039.9 |
| DiseasesDB | 9058 |
| MeSH | D009617 |
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Synonyms and keywords: Infections, Nocardia
Overview
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.
It is most common in men, especially those with a compromised immune system. In patients with brain infection, mortality exceeds 80%; in other forms, mortality is 50%, even with appropriate therapy.[1]
Causes
The majority of cases are caused by the Nocardia asteroides complex (at least 50% of invasive infections). The N. asteroides complex is comprised of N. abscessus, N. cyriacigeorgica, N. farcinica, and N. nova. Other known pathogenic species of Nocardia include N. transvalensis complex, N. brasiliensis, and N. pseudobrasiliensis.
Pulmonary, disseminated and CNS infections are acquired through inhalation; primary cutaneous disease is acquired through inoculation of the skin. Rarely, nosocomial postsurgical transmission occurs.
Normally found in soil, these organisms cause occasional sporadic disease in humans and animals throughout the world. The usual mode of transmission is inhalation of organisms suspended in dust. Transmission by direct inoculation through puncture wounds or abrasions is less common.[1] Generally, nocardial infection requires some degree of immune suppression.
Epidemiology and Demographics
In the United States, it has been estimated that 500-1,000 new cases of Nocardia infection occur annually. Approximately 60% of nocardiosis cases are associated with pre-existing immune compromise. Although incidence data are extremely limited, the number of cases is likely rising as a result of the increase in the number of severely immunocompromised persons.
Risk Factors
Severely immunocompromised persons are at greatest risk for nocardiosis. These include persons with connective tissue disorders, malignancy, HIV infection, pulmonary alveolar proteinosis, alcoholism, or high-dose corticosteroid use.
Natural History, Complications and Prognosis
Approximately 10% of cases with uncomplicated pneumonia are fatal. The case-fatality rate increases with overwhelming infection, disseminated disease, or brain abscess. Surgical drainage may be indicated and may improve patient outcome.
Diagnosis
History and Symptoms
Overall, 80% of nocardiosis cases present as invasive pulmonary infection, disseminated infection, or brain abscess; 20% present as cellulitis. Pulmonary infection commonly presents with fever, cough, or chest pain. Central nervous system (CNS) symptoms include headache, lethargy, confusion, seizures, or sudden onset of neurologic deficit. Pulmonary Infection
- 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
Neurological Infection
- Headache, lethargy, confusion, seizures, sudden onset of neurological deficit
- CT scan shows cerebral abscess
- Nocardial meningitis is very rare and difficult to diagnose
Lymphocutaneous disease
- Nocardial cellulitis is akin of erysipela but is more subacute
- Nodular lymphangeitis mimics sporotrichosis with multiple nodules alongside a lymphatic pathway
- Mycetoma is a rare complication and osteitis may ensue .
Ocular disease
- Very rarely nocardiae cause keratitis
- Gennerally there is a history of ocular trauma
Disseminated nocardiosis
- 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 grim for this form of disease
Laboratory Findings
Diagnosis may be difficult. Nocardiae are weakly acid-fast organisms and can be visualized by modified Ziehl Neelsen stains 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.[2] Infiltration and pleural effusion are usually seen via x-ray.
Treatment
Nocardiosis requires at least 6 months of treatment, preferably with co-trimoxazole or high doses of sulfonamides. In patients who don’t 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.[1] A new combination drug therapy (sulfonamide, ceftriaxone, and amikacin) has also shown promise.[2]
Future or Investigational Therapies
Although incidence data are extremely limited, the number of cases is likely rising as a result of the increase in the number of severely immunocompromised persons.
Sources
http://www.cdc.gov/nczved/divisions/dfbmd/diseases/nocardiosis/technical.html#eight
References
- ↑ 1.0 1.1 1.2 "Nocardiosis (Professional Guide to Diseases (Eighth Edition)) - WrongDiagnosis.com". Retrieved 2007-07-12.
- ↑ 2.0 2.1 "Nocardiosis: DBMD - WrongDiagnosis.com". Retrieved 2007-07-12.