Nocardiosis

Nocardiosis
Other names: Lung nocardiosis
Top:This individual had contracted a nocardiosis infection of his right upper arm Bottom:Nocardia keratitis
Specialty	Infectious disease
Symptoms	Presentation depend on the site of infection
Complications	Brain abscess,meningitis,osteomyelitis
Causes	Nocardia asteroides or Nocardia brasiliensis
Risk factors	Alcoholism,chronic lung disease,solid-organ transplant,use of corticosteroids
Diagnostic method	Bacterial cultures
Differential diagnosis	Bacterial pneumonia,community-acquired pneumonia, Glioblastoma multiforme,Kaposi sarcoma
Treatment	Amikacin, imipenem, meropenem

Nocardiosis is an infectious disease affecting either the lungs (pulmonary nocardiosis) or the whole body (systemic nocardiosis). It is due to infection by a bacterium of the genus Nocardia, most commonly Nocardia asteroides or Nocardia brasiliensis.

It is most common in adult males, especially those with a weakened immune system. In individuals with brain nocardia infection, mortality exceeds 80%; in other forms, mortality is 50%, even with appropriate therapy. It is one of several conditions that have been called "the great imitator". Cutaneous nocardiosis commonly occurs in immunocompetent hosts.

Signs and symptoms

Pulmonary infection

• Produces a virulent form of pneumonia (progressive)
• Night sweats, fever, cough, chest pain
• Pulmonary nocardiosis is subacute in onset and refractory to treatment with standard antibiotics
• Symptoms are more severe in immunocompromised individuals
• Radiologic studies show multiple pulmonary infiltrates

Neurological infection

• Headache, lethargy, confusion, seizures, sudden onset of neurological deficit
• CT scan shows cerebral abscess
• Nocardial meningitis may be difficult to diagnose

Cardiac conditions

• 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

Lymphocutaneous disease

• 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
• Cultures must incubate more than 48 hours to guarantee an accurate test

Ocular disease

• Very rarely, nocardiae cause keratitis
• Generally there is a history of ocular trauma

Disseminated nocardiosis

• 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

Causes

Nocardia asteroides

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 part of the oral microflora. Nocardia spp. have been reported in the normal gingivae 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 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.

A weakened immune system is a general indicator of a person who is more susceptible to nocardiosis, such as someone who already has a disease that weakens their immune system. Additionally, those with low T-cell counts or other complications involving T-cells can expect to have a higher chance of becoming infected. Besides those with weak immune systems, a local traumatic inoculation can cause nocardiosis, specifically the cutaneous, lymphocutaneous, and subcutaneous forms of the disease.

Risk factors

In terms of risk factors that are associated with Nocardiosis we find the following:

• HIV
• Solid-organ transplant
• Hematological malignancy
• Alcoholism
• Whipple disease

Diagnosis

Chest CT showed consolidation in the right middle lung

Diagnosis of nocardiosis can be made by a doctor using various techniques. These techniques include, but are not limited to: a chest x-ray to analyze the lungs, a bronchoscopy, a brain/lung/skin biopsy, or a sputum culture.

However, 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 such as the 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.

Pulmonary infiltration and pleural effusion are usually detected via x-ray.

Differential diagnosis

Fungal pneumonia

In terms of the DDx we find the following should considered:

• Fungal pneumonia

• Glioblastoma multiforme

• Histoplasmosis

• Kaposi sarcoma

• Lung abscess

• Mycobacterium avium complex

• Community-acquired pneumonia

Treatment

Sulfonamide functional group

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 may be added( ampicillin, erythromycin, or minocycline).

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.

A new combination drug therapy (sulfonamide, ceftriaxone, and amikacin) has also shown promise.

Prognosis

The prognosis of nocardiosis is highly variable. The state of the host's health, site, duration, and severity of the infection all play parts in determining the prognosis. Currently, skin and soft tissue infections have a 100% cure rate, and pleuropulmonary infections have a 90% cure rate with appropriate therapy. The cure rate falls to 63% with those infected with disseminated nocardiosis. Additionally, 23% of people who are infected in the central nervous system (CNS) die. There are no preventative treatments for nocardiosis. The only recommendation is to protect open wounds to limit entrance of the bacterium.

Epidemiology

Individuals diagnosed with nocardiosis in China 2009 - 2021

Although there are no international data available on worldwide infection rates per year, there are roughly 500–1000 documented cases of nocardiosis per year in the US. Most of these cases occur in men, as there is a 3:1 ratio of male to female cases annually; however, this difference may be due to exposure frequency rather than susceptibility differences. From an age perspective, it is not highly more prevalent in one age group than another.

Cutaneous nocardiosis is slightly more common in middle aged men, but as a whole, all age groups are susceptible.

A 2022 article by Wang, et al indicates the geographical locations and distribution of Nocardia spp. from individuals diagnosed with nocardiosis in 21 cities/provinces in China between the years 2009 and 2021 recovering 441 nocardiosis strains

History

In terms of history we find that Nocardial infections were first explained by Edmond Nocard (1850-1903), who was a French veterinarian, as well as a microbiologist.

External links

Webmd article on Nocardiosis Archived 2021-03-01 at the Wayback Machine

Classification	ICD-10: A43 ICD-9-CM: 039.9 MeSH: D009617 DiseasesDB: 9058 SNOMED CT: 29227009
External resources	eMedicine: med/1644 derm/297 ped/1610 Orphanet: 31204