Mycobacterium avium complex | |
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Species complex: | Mycobacterium avium complex |
Binomial name | |
Mycobacterium intracellulare Runyon 1965, [1] ATCC 13950 | |
Mycobacterium avium Chester 1901 emend. Thorel et al. 1990 |
Mycobacterium avium complex is a group of mycobacteria comprising Mycobacterium intracellulare and Mycobacterium avium that are commonly grouped because they infect humans together; this group, in turn, is part of the group of nontuberculous mycobacteria. These bacteria cause Mycobacterium avium-intracellulare infections or Mycobacterium avium complex infections in humans. [2] These bacteria are common and are found in fresh and salt water, in household dust and in soil. [3] MAC bacteria usually cause infection in those who are immunocompromised or those with severe lung disease.
In the Runyon classification, both bacteria are nonchromogens. They can be differentiated from M. tuberculosis and each other by commercially available DNA probes. [4] : 245
They are characterized as Gram-positive, nonmotile, acid-fast, short to long rods.[ citation needed ]
Colony characteristics
Physiology
Differential characteristics
MAC bacteria enter most people's body when inhaled into the lungs or swallowed, but only cause infection in those who are immunocompromised or who have severe lung disease such as those with cystic fibrosis or chronic obstructive lung disease (COPD). [3] MAC infection can cause COPD and lymphadenitis, and can cause disseminated disease, especially in people with immunodeficiency. [4] : 245 During the last decade Mycobacterium chimaera (see below) infections following cardiothoracic surgery, especially open-heart surgery, have been increasingly reported worldwide. [8] Infections usually involve the respiratory system. Mycobacterium chimaera is acquired during cardiopulmonary bypass via bioaerosols emitted from contaminated heater-cooler units water systems. Due to nonspecific symptoms and long latency, postoperative Mycobacterium chimaera infections may not be promptly diagnosed and treated, and may become life-threatening.
In 2004, Tortoli et al. proposed the name M. chimaera for strains that a reverse hybridization–based line probe assay suggested belonged to MAIS (M. avium–M. intracellulare–M. scrofulaceum group), but were different from M. avium, M. intracellulare, or M. scrofulaceum. The new species name comes from the Chimera, a mythological being made up of parts of three different animals. [9] [10]
Mycobacterium is a genus of over 190 species in the phylum Actinomycetota, assigned its own family, Mycobacteriaceae. This genus includes pathogens known to cause serious diseases in mammals, including tuberculosis and leprosy in humans. The Greek prefix myco- means 'fungus', alluding to this genus' mold-like colony surfaces. Since this genus has cell walls with a waxy lipid-rich outer layer that contains high concentrations of mycolic acid, acid-fast staining is used to emphasize their resistance to acids, compared to other cell types.
Nontuberculous mycobacteria (NTM), also known as environmental mycobacteria, atypical mycobacteria and mycobacteria other than tuberculosis (MOTT), are mycobacteria which do not cause tuberculosis or leprosy/Hansen's disease. NTM are able to cause pulmonary diseases that resemble tuberculosis. Mycobacteriosis is any of these illnesses, usually meant to exclude tuberculosis. They occur in many animals, including humans and are commonly found in soil and water.
Mycobacterium avium subspecies paratuberculosis (MAP) is an obligate pathogenic bacterium in the genus Mycobacterium. It is often abbreviated M. paratuberculosis or M. avium ssp. paratuberculosis. It is the causative agent of Johne's disease, which affects ruminants such as cattle, and suspected causative agent in human Crohn's disease and rheumatoid arthritis. The type strain is ATCC 19698.
Mycobacterium avium-intracellulare infection (MAI) is an atypical mycobacterial infection, i.e. one with nontuberculous mycobacteria or NTM, caused by Mycobacterium avium complex (MAC), which is made of two Mycobacterium species, M. avium and M. intracellulare. This infection causes respiratory illness in birds, pigs, and humans, especially in immunocompromised people. In the later stages of AIDS, it can be very severe. It usually first presents as a persistent cough. It is typically treated with a series of three antibiotics for a period of at least six months.
Mycobacteroides abscessus is a species of rapidly growing, multidrug-resistant, nontuberculous mycobacteria (NTM) that is a common soil and water contaminant. Although M. abscessus most commonly causes chronic lung infection and skin and soft tissue infection (SSTI), it can also cause infection in almost all human organs, mostly in patients with suppressed immune systems. Amongst NTM species responsible for disease, infection caused by M. abscessus complex are more difficult to treat due to antimicrobial drug resistance.
Mycobacterium avium is a species of the phylum Actinomycetota, belonging to the genus Mycobacterium.
Mycobacterium boenickei is a member of the Mycobacterium fortuitum third biovariant complex. They are rapidly growing ubiquitous environmental organisms that normally inhabit soil, dust and water. These organisms frequently are human pathogens that cause a wide spectrum of clinically significant disease. It is important for practitioners to be aware of these organisms as possible etiological agents, as they are resistant to most first-line anti-tuberculous agents.
Mycobacterium celatum is a species of the phylum Actinomycetota, belonging to the genus Mycobacterium.
Mycobacterium diernhoferi is a species of the phylum Actinomycetota, belonging to the genus Mycobacterium.
Mycobacterium florentinum is a strain of bacteria found in humans that can cause infections and other disease conditions, and prolong sickness. It presents a high resistance to antimycobacterial drugs. It is characterized by: slow growth and a short helix 18 in the 16S rDNA.
Mycobacterium fortuitum is a nontuberculous species of the phylum Actinomycetota, belonging to the genus Mycobacterium.
Mycobacterium genavense is a slow-growing species of the phylum Actinomycetota, belonging to the genus Mycobacterium.
Mycobacterium gordonae is a species of Mycobacterium named for Ruth E. Gordon. It is a species of the phylum Actinomycetota, belonging to the genus Mycobacterium.
Mycobacterium hassiacum is a rapid-growing thermophilic mycobacterium that was isolated in human urine in 1997 by researchers at the German University of Regensburg. It's a species of the phylum Actinomycetota, belonging to the genus Mycobacterium.
Mycobacterium kansasii is a bacterium in the Mycobacterium genus. It is an environmental bacteria that causes opportunistic infections in humans, and is one of the leading mycobacterial causes of human disease after tuberculosis and leprosy.
Mycobacterium lentiflavum
Etymology: Lentus from Latin for slow, flavus, Latin for yellow.
Mycobacterium wolinskyi is a rapidly growing mycobacterium most commonly seen in post-traumatic wound infections, especially those following open fractures and with associated osteomyelitis. Mycobacterium wolinskyi is clearly clinically significant, and occurs in the same settings as Mycobacterium smegmatis and members of the Mycobacterium fortuitum complex; they differ from members of the Mycobacterium fortuitum complex in the type of chronic lung disease they produce, with essentially all cases occurring in the setting of chronic lipoid pneumonia, either secondary to chronic oil ingestion or chronic aspiration. Etymology: Wolinsky, named after Emanuel Wolinsky in honour of, and in recognition for, significant contributions to the study of the non-tuberculous mycobacteria.
Mycobacteria that form colonies clearly visible to the naked eye in more than 7 days on subculture are termed slow growers.
Mycobacterium scrofulaceum is a species of Mycobacterium.
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.
Citing public domain text from the CDC.