Nocardiosis | |
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Specialty | Infectious diseases |
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 immunocompromised males. In patients with brain involvement, mortality exceeds 80%; in other forms, mortality is about 50%, even with appropriate therapy. [1]
It is one of several conditions that have been called "the great imitator". [2] Cutaneous nocardiosis commonly occurs in immunocompetent hosts and is caused in 80% of cases by Nocardia brasiliensis. [3] [4]
Pulmonary infection
Neurological infection
Cardiac conditions
Lymphocutaneous disease
Ocular disease
Disseminated nocardiosis
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 [ clarification needed ] and Streptomyces spp. [8]
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. [1] Generally, nocardial infection requires some degree of immune suppression.[ citation needed ]
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. [9] [10] There is no racial pattern in the risk of becoming infected with Nocardiosis.[ citation needed ]
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. [11] Pulmonary infiltration and pleural effusion are usually detected via x-ray.[ citation needed ]
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.[ citation needed ]
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 (trimethoprim/sulfamethoxazole, ceftriaxone, and amikacin) has also shown promise. [11]
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, with only half of patients surviving infections that cause brain abscess. Additionally, 44% of people who are infected in the central nervous system (CNS) die, increasing to 85% if that person has an already weakened immune system. There are no preventative treatments for nocardiosis. The only recommendation is to protect open wounds to limit entrance of the bacterium.[ citation needed ]
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 of 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. [9] Cutaneous nocardiosis is slightly more common in middle aged men, but as a whole, all age groups are susceptible. [12] There is no racial pattern in the risk of becoming infected with nocardiosis.[ citation needed ]
An abscess is a collection of pus that has built up within the tissue of the body. Signs and symptoms of abscesses include redness, pain, warmth, and swelling. The swelling may feel fluid-filled when pressed. The area of redness often extends beyond the swelling. Carbuncles and boils are types of abscess that often involve hair follicles, with carbuncles being larger. A cyst is related to an abscess, but it contains a material other than pus, and a cyst has a clearly defined wall.
Brain abscess is an abscess within the brain tissue caused by inflammation and collection of infected material coming from local or remote infectious sources. The infection may also be introduced through a skull fracture following a head trauma or surgical procedures. Brain abscess is usually associated with congenital heart disease in young children. It may occur at any age but is most frequent in the third decade of life.
Histoplasmosis is a fungal infection caused by Histoplasma capsulatum. Symptoms of this infection vary greatly, but the disease affects primarily the lungs. Occasionally, other organs are affected; called disseminated histoplasmosis, it can be fatal if left untreated.
Cellulitis is usually a bacterial infection involving the inner layers of the skin. It specifically affects the dermis and subcutaneous fat. Signs and symptoms include an area of redness which increases in size over a few days. The borders of the area of redness are generally not sharp and the skin may be swollen. While the redness often turns white when pressure is applied, this is not always the case. The area of infection is usually painful. Lymphatic vessels may occasionally be involved, and the person may have a fever and feel tired.
Cryptococcosis is a potentially fatal fungal infection of mainly the lungs, presenting as a pneumonia, and brain, where it appears as a meningitis. Cough, difficulty breathing, chest pain and fever are seen when the lungs are infected. When the brain is infected, symptoms include headache, fever, neck pain, nausea and vomiting, light sensitivity and confusion or changes in behavior. It can also affect other parts of the body including skin, where it may appear as several fluid-filled nodules with dead tissue.
Zygomycosis is the broadest term to refer to infections caused by bread mold fungi of the zygomycota phylum. However, because zygomycota has been identified as polyphyletic, and is not included in modern fungal classification systems, the diseases that zygomycosis can refer to are better called by their specific names: mucormycosis, phycomycosis and basidiobolomycosis. These rare yet serious and potentially life-threatening fungal infections usually affect the face or oropharyngeal cavity. Zygomycosis type infections are most often caused by common fungi found in soil and decaying vegetation. While most individuals are exposed to the fungi on a regular basis, those with immune disorders (immunocompromised) are more prone to fungal infection. These types of infections are also common after natural disasters, such as tornadoes or earthquakes, where people have open wounds that have become filled with soil or vegetative matter.
Miliary tuberculosis is a form of tuberculosis that is characterized by a wide dissemination into the human body and by the tiny size of the lesions (1–5 mm). Its name comes from a distinctive pattern seen on a chest radiograph of many tiny spots distributed throughout the lung fields with the appearance similar to millet seeds—thus the term "miliary" tuberculosis. Miliary TB may infect any number of organs, including the lungs, liver, and spleen. Miliary tuberculosis is present in about 2% of all reported cases of tuberculosis and accounts for up to 20% of all extra-pulmonary tuberculosis cases.
Nocardia is a genus of weakly staining Gram-positive, catalase-positive, rod-shaped bacteria. It forms partially acid-fast beaded branching filaments. It contains a total of 85 species. Some species are nonpathogenic, while others are responsible for nocardiosis. Nocardia species are found worldwide in soil rich in organic matter. In addition, they are oral microflora found in healthy human gingiva, as well as periodontal pockets. Most Nocardia infections are acquired by inhalation of the bacteria or through traumatic introduction through openings in epithelial barriers.
Lung abscess is a type of liquefactive necrosis of the lung tissue and formation of cavities containing necrotic debris or fluid caused by microbial infection.
An aspergilloma is a clump of mold which exists in a body cavity such as a paranasal sinus or an organ such as the lung. By definition, it is caused by fungi of the genus Aspergillus.
Sporotrichosis, also known as rose handler's disease, is a fungal infection that may be localised to skin, lungs, bone and joint, or become systemic. It presents with firm painless nodules that later ulcerate. Following initial exposure to Sporothrix schenckii, the disease typically progresses over a period of a week to several months. Serious complications may develop in people who have a weakened immune system.
Bacillary angiomatosis (BA) is a form of angiomatosis associated with bacteria of the genus Bartonella.
Pneumocystis pneumonia (PCP), also known as Pneumocystis jirovecii pneumonia (PJP), is a form of pneumonia that is caused by the yeast-like fungus Pneumocystis jirovecii.
Sporothrix schenckii, a fungus that can be found worldwide in the environment, is named for medical student Benjamin Schenck, who in 1896 was the first to isolate it from a human specimen. The species is present in soil as well as in and on living and decomposing plant material such as peat moss. It can infect humans as well as animals and is the causative agent of sporotrichosis, commonly known as "rose handler's disease." The most common route of infection is the introduction of spores to the body through a cut or puncture wound in the skin. Infection commonly occurs in otherwise healthy individuals but is rarely life-threatening and can be treated with antifungals. In the environment it is found growing as filamentous hyphae. In host tissue it is found as a yeast. The transition between the hyphal and yeast forms is temperature dependent making S. schenckii a thermally dimorphic fungus.
Mucormycosis, also known as black fungus, is a serious fungal infection that comes under fulminant fungal sinusitis, usually in people who are immunocompromised. It is curable only when diagnosed early. Symptoms depend on where in the body the infection occurs. It most commonly infects the nose, sinuses, eyes and brain resulting in a runny nose, one-sided facial swelling and pain, headache, fever, blurred vision, bulging or displacement of the eye (proptosis), and tissue death. Other forms of disease may infect the lungs, stomach and intestines, and skin. The fatality rate is about 54%.
Alezzandrini syndrome is a very rare syndrome characterized by a unilateral degenerative retinitis, followed after several months by ipsilateral vitiligo on the face and ipsilateral poliosis. Deafness may also be present.
Aquarium granuloma is a rare skin condition caused by a non-tubercular mycobacterium known as Mycobacterium marinum. Skin infections with M. marinum in humans are relatively uncommon, and are usually acquired from contact with contaminated swimming pools, aquariums or infected fish.
Majocchi's granuloma is a skin condition characterized by deep, pustular plaques, and is a form of tinea corporis. It is a localized form of fungal folliculitis. Lesions often have a pink and scaly central component with pustules or folliculocentric papules at the periphery. The name comes from Domenico Majocchi, who discovered the disorder in 1883. Majocchi was a professor of dermatology at the University of Parma and later the University of Bologna. This disease is most commonly caused by filamentous fungi in the genus Trichophyton.
Nocardia farcinica is a species of bacteria, once thought to be associated with farcy, and a member of the genus Nocardia. This species is very similar in phenotype to Nocardia asteroides, to the degree that some isolates of N. asteroides were later found to be Nocardia farcinica.
A lung cavity or pulmonary cavity is an abnormal, thick-walled, air-filled space within the lung. Cavities in the lung can be caused by infections, cancer, autoimmune conditions, trauma, congenital defects, or pulmonary embolism. The most common cause of a single lung cavity is lung cancer. Bacterial, mycobacterial, and fungal infections are common causes of lung cavities. Globally, tuberculosis is likely the most common infectious cause of lung cavities. Less commonly, parasitic infections can cause cavities. Viral infections almost never cause cavities. The terms cavity and cyst are frequently used interchangeably; however, a cavity is thick walled, while a cyst is thin walled. The distinction is important because cystic lesions are unlikely to be cancer, while cavitary lesions are often caused by cancer.