Piscine tuberculosis (piscine mycobacteriosis or fish tuberculosis) is a chronic infectious disease that afflicts many species of fish. This disease is caused by members of the Mycobacterium genus and can afflict marine, brackish, and freshwater fish. [1] Piscine mycobacteriosis has been known to affect over 200 species of fish [2] and is a major cause of mortality in ornamental and farmed fish.
Piscine mycobacteriosis is caused by acid-fast bacilli colloquially referred to as nontuberculous mycobacteria (NTM). These are pleomorphic Gram-positive bacteria found ubiquitously in the environment. The most common causes of piscine mycobacteriosis are M. marinum , M. chelonae , and M. fortuitum . [3]
Piscine tuberculosis is a common disease in fish and has been reported in aquaria, laboratories, commercial fish farms, and wild populations. It is considered to be a major cause of morbidity and mortality in fish.
Piscine mycobacteriosis often presents as a chronic disease, with affected fish surviving for several weeks to years. [4] Signs are variable and nonspecific; they can include emaciation, ascites, skin ulceration, hemorrhages, paleness, and skeletal deformities. [3] Granulomatous inflammation may be found throughout internal organs and muscles and all tissues of the fish may be involved. [2]
Fish can acquire mycobacteria through the ingestion of contaminated feed or of infected dead fish. [4] Transmission can also occur through contact with affected lesions or through the gills.
A presumptive diagnosis can be made upon the visualization of acid-fast bacilli within granulomatous material from lesions. [5] Sensitivity for acid-fast staining is low, granulomas containing no visible acid-fast bacilli are reported in many experimentally infected species of fish. [6]
A definitive diagnosis requires the isolation and identification of the bacteria. Culture involves inoculating tissue samples onto Middlebrook 7H10, Lowenstein-Jensen, or another form of laboratory media. [7] Culture-based detection of Mycobacterium spp. is complicated by the presence of bacterial flora that compete with Mycobacterium on standard laboratory media. The isolation of Mycobacterium from feces, external surfaces, and whole viscera is questionable. [7]
There is currently no widely accepted treatment for mycobacteriosis in fish. [5] Treatment is infrequently attempted as it appears ineffective at eliminating Mycobacterium from affected colonies and is not practical in fish intended as food. [4] Treating the fish with antibiotics has been reported to fail even when in vitro susceptibility is confirmed. [8] Control of piscine mycobacteriosis may necessitate the destruction of all affected stocks and disinfection of tanks and plumbing.
The Ag85A DNA vaccine was shown to provide short term immunity in striped bass against M. marinum , but it was unsuccessful at achieving long-term immunity. [9]
Bacillus Calmette–Guérin (BCG) vaccine is a vaccine primarily used against tuberculosis (TB). It is named after its inventors Albert Calmette and Camille Guérin. In countries where tuberculosis or leprosy is common, one dose is recommended in healthy babies as soon after birth as possible. In areas where tuberculosis is not common, only children at high risk are typically immunized, while suspected cases of tuberculosis are individually tested for and treated. Adults who do not have tuberculosis and have not been previously immunized, but are frequently exposed, may be immunized, as well. BCG also has some effectiveness against Buruli ulcer infection and other nontuberculous mycobacterial infections. Additionally, it is sometimes used as part of the treatment of bladder cancer.
Tuberculosis (TB), also known colloquially as the "white death", or historically as consumption, is an infectious disease usually caused by Mycobacterium tuberculosis (MTB) bacteria. Tuberculosis generally affects the lungs, but it can also affect other parts of the body. Most infections show no symptoms, in which case it is known as latent tuberculosis. Around 10% of latent infections progress to active disease which, if left untreated, kill about half of those affected. Typical symptoms of active TB are chronic cough with blood-containing mucus, fever, night sweats, and weight loss. Infection of other organs can cause a wide range of symptoms.
The disease mycobacterial cervical lymphadenitis, also known as scrofula and historically as king's evil, involves a lymphadenitis of the cervical lymph nodes associated with tuberculosis as well as nontuberculous (atypical) mycobacteria.
Mycobacterium tuberculosis, also known as Koch's bacillus, is a species of pathogenic bacteria in the family Mycobacteriaceae and the causative agent of tuberculosis. First discovered in 1882 by Robert Koch, M. tuberculosis has an unusual, waxy coating on its cell surface primarily due to the presence of mycolic acid. This coating makes the cells impervious to Gram staining, and as a result, M. tuberculosis can appear weakly Gram-positive. Acid-fast stains such as Ziehl–Neelsen, or fluorescent stains such as auramine are used instead to identify M. tuberculosis with a microscope. The physiology of M. tuberculosis is highly aerobic and requires high levels of oxygen. Primarily a pathogen of the mammalian respiratory system, it infects the lungs. The most frequently used diagnostic methods for tuberculosis are the tuberculin skin test, acid-fast stain, culture, and polymerase chain reaction.
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.
Mycobacterium leprae is one of the two species of bacteria that cause Hansen's disease (leprosy), a chronic but curable infectious disease that damages the peripheral nerves and targets the skin, eyes, nose, and muscles.
Mycobacterium bovis is a slow-growing aerobic bacterium and the causative agent of tuberculosis in cattle. It is related to Mycobacterium tuberculosis, the bacterium which causes tuberculosis in humans. M. bovis can jump the species barrier and cause tuberculosis-like infection in humans and other mammals.
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.
The Ziehl-Neelsen stain, also known as the acid-fast stain, is a bacteriological staining technique used in cytopathology and microbiology to identify acid-fast bacteria under microscopy, particularly members of the Mycobacterium genus. This staining method was initially introduced by Paul Ehrlich (1854–1915) and subsequently modified by the German bacteriologists Franz Ziehl (1859–1926) and Friedrich Neelsen (1854–1898) during the late 19th century.
Acid-fastness is a physical property of certain bacterial and eukaryotic cells, as well as some sub-cellular structures, specifically their resistance to decolorization by acids during laboratory staining procedures. Once stained as part of a sample, these organisms can resist the acid and/or ethanol-based decolorization procedures common in many staining protocols, hence the name acid-fast.
Tuberculosis is diagnosed by finding Mycobacterium tuberculosis bacteria in a clinical specimen taken from the patient. While other investigations may strongly suggest tuberculosis as the diagnosis, they cannot confirm it.
Mycobacterium smegmatis is an acid-fast bacterial species in the phylum Actinomycetota and the genus Mycobacterium. It is 3.0 to 5.0 µm long with a bacillus shape and can be stained by Ziehl–Neelsen method and the auramine-rhodamine fluorescent method. It was first reported in November 1884 by Lustgarten, who found a bacillus with the staining appearance of tubercle bacilli in syphilitic chancres. Subsequent to this, Alvarez and Tavel found organisms similar to that described by Lustgarten also in normal genital secretions (smegma). This organism was later named M. smegmatis.
Peripheral tuberculous lymphadenitis is a form of tuberculosis infection occurring outside of the lungs. In general, it describes tuberculosis infection of the lymph nodes, leading to lymphadenopathy. When cervical lymph nodes are affected, it is commonly referred to as "Scrofula." A majority of tuberculosis infections affect the lungs, and extra-pulmonary tuberculosis infections account for the remainder; these most commonly involve the lymphatic system. Although the cervical region is most commonly affected, tuberculous lymphadenitis can occur all around the body, including the axillary and inguinal regions.
Mycobacterium marinum is a slow growing fresh and saltwater mycobacterium (SGM) belonging to the genus Mycobacterium and the phylum Actinobacteria. It was formerly known as Mycobacterium balnei. The strain marinum was first identified by Joseph D. Aronson in 1926 and it is observed as a pathogenic mycobacterium causing tuberculosis-like infections in fish (mycobacteriosis) and skin lesions in humans. The bacteria grows optimal at a temperature around 30 °C.
Mycobacterium fortuitum is a nontuberculous 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.
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.
Mycolicibacter terrae is a slow-growing species of mycobacteria. It is an ungrouped member of the third Runyon. It is known to cause serious skin infections, which are "relatively resistant to antibiotic therapy".
Mycobacterium ulcerans is a species of bacteria found in various aquatic environments. The bacteria can infect humans and some other animals, causing persistent open wounds called Buruli ulcer. M. ulcerans is closely related to Mycobacterium marinum, from which it evolved around one million years ago, and more distantly to the mycobacteria which cause tuberculosis and leprosy.
Mycobacteroides salmoniphilum is a species of bacteria from the phylum Actinomycetota belonging to the genus Mycobacteroides. It was first identified as the causative agent of mycobacteriosis in chinook salmon and steelhead trout, but has since been found to cause disease in Atlantic cod, Atlantic salmon, burbot, coho salmon, freshwater ornamental fish, and Russian sturgeon. It has also been isolated from tap water. It is not known to infect humans. M. salmoniphilum is susceptible to amikacin.