Nontuberculous mycobacteria

MOTT ( mycobacteria other than tuberculosis engl. ) is a clinically common abbreviation for so-called atypical nontuberculous mycobacteria, that is all for the people potentially ( optional) pathogenic mycobacteria other than the agents of tuberculosis (the " Mycobacterium tuberculosis complex " ) and Mycobacterium leprae, the causative agent of leprosy.

The non-tuberculous mycobacteria or atypical long time after the description of Mycobacterium tuberculosis and M. leprae was only paid attention to. The non-tuberculous mycobacteria effect rarely pathogenic, especially in immunocompromised patients such as AIDS patients, affected by MOTT infections. The in recent decades due to advances in biochemistry and genetic engineering ( DNA analysis, PCR) improved differentiation and detection methods have led to a description of more pathogenic under certain circumstances acting bacterial species in this group.

Typical clinical pictures, non-tuberculous mycobacteria are caused by lung infections, skin infections, lymphadenitis, a morbid swelling of lymph nodes. Highlights of the example species are Mycobacterium avium (among lung infections, especially in AIDS patients ) and Mycobacterium ulcerans ( Buruli ulcer, a skin infection). The lung disease can not be distinguished from the typical tuberculosis itself, the diagnosis is necessary, cultivation.

To some extent, too MOTT except the optional, potentially pathogenic all (for now) as a non-pathogenic, so as not pathogenic, described mycobacteria. Other common names are: " Nontuberculous mycobacteria " (NTM ) or " non-tuberculous mycobacteria ." The term " Potentially pathogenic environment (environmental ) mycobacteria " ( PPUM or PPEM ) refers exclusively to the facultative pathogenic species and to the fact in contrast to the typical tuberculosis bacteria, which can multiply only within the host that they freely occur in the environment.

Features

Mycobacterium is the only genus of the family Mycobacteriaceae, which is one of the Actinobacteria. As described above, the non-tubercular mycobacteria are defined within the genus of the genus Mycobacterium leprae and Mycobacterium tuberculosis Complex. For the latter traditionally include the species Mycobacterium tuberculosis, M. africanum, M. bovis and M. microti. In recent years, continue the species Mycobacterium canettii, M. caprae and M. pinnipedii were asked to this group. It is the causative agent of "classic" tuberculosis of mammals and man.

As with Mycobacterium leprae and Mycobacterium tuberculosis for the species complex are not tuberculous mycobacteria rod-shaped, non-spore forming and need oxygen, which is why they are referred to as obligate aerobic. Perform a chemo organic, aerobic metabolism and are among the gram- positive bacteria.

An important feature is a cell wall covering layer of wax. It consists among other things of mycolic acids, which ( eg antibiotics ) creates a special resistance to external influences. The special cell wall construction allows for the acid-fast property ( engl.: acid -fast ) of these bacteria. This property can be detected by Ziehl- Neelsen staining: Acid-resistant bacteria remain after staining with Carbolfuchsinlösung and subsequent acid treatment dyed red. Acid resistant are only a few other bacteria, such as some species of Nocardia, Rhodococcus and Corynebacterium. Due to the acid strength also the Gram stain can be difficult or even impossible to perform.

Occurrence in the environment

The nichttuberkulären mycobacteria, the vast majority among the mycobacteria and live freely under normal circumstances in the environment and feed on dead organic material ( saprophytes ). They were detected from natural habitats such as dust, soil, marshes, freshwater, groundwater and sea water .. Even artificial, created by people living places such as drinking water or sewage sludge are inhabited by various mycobacteria. Some species, such as M. kansasii and M. xenopi have been found so far exclusively in artificial habitats, such as drinking water, the natural habitat is still unknown.

In soils were most commonly M. fortuitum, a cause of skin infections and infections of bones or joints, and found representatives of the M. terrae complex ( M. terrae and M. nonchromogenicum ). M. fortuitum has a high resistance to disinfectants, the bacterium is thus in the hospital a risk; infection by M. fortuitum have performed with the use of implants, for example.

More often proven worldwide in soil samples species M. gordonae, M. vaccae, M. scrofulaceum and M. smegmatis. Representatives of the M. terrae complex and M. fortuitum have been common worldwide also detected in house dust. M. fortuitum was isolated from sea water, other species found here are M. chelonae, M. marinum and M. gordonae.

In drinking water Mycobacterium gordonae is an important type of non-tuberculous mycobacteria. More here frequently isolated species are the representatives of the MAC complex ( M. avium and M. intracellulare ), M. gastri, M. kansasii and M. xenopi. Here M. kansasii was most frequently isolated from drinking water systems in Europe and USA. Some species, such as M. kansasii and M. avium are obviously also be able to multiply in the ( distilled ) water, a property that can be a hazard especially for hospitals.

Some species of atypical mycobacteria are natural pathogens in animals. Mycobacterium avium can cause tuberculosis in poultry birds.

Epidemiology

The " typical " Tuberculosis and Leprosy pathogens are obligate parasites and can multiply only within the host. In contrast, the atypical mycobacteria are free-living and are found worldwide in water and soil. The infections with these pathogens happen dust, soil, food ( raw milk, water or meat). Direct transmission from animals to humans have not been documented. They are rarely pathogenic to humans. In immunocompromised people (eg AIDS) and non-specific lung diseases but they can lead to opportunistic infections.

Triggered by mycobacterial diseases are generally called mycobacteriosis.

Clinic

Often the MOTT can lead (eg, Mycobacterium marinum ) to granulomas ( Schwimmbadgranulom ). Other MOTT cause tuberculosis -like pulmonary disease ( eg, Mycobacterium kansasii ) with weak tuberculin reaction. In children, cervical lymphadenitis can be caused inter alia by Mycobacterium avium. In AIDS patients, the infections are often called by Mycobacterium avium or Mycobacterium intracellulare. Disseminated infections occur during this lowering of the T- lymphocytes, for example, in liver, spleen and small intestine. In these patients, lung involvement is rare.

Diagnosis

Most by history, clinical, and the specific detection of pathogens from blood, stool, urine, or biopsy samples.

Systematics and subdivision

From the number of species, the non-tuberculous mycobacteria dominate free-living, actually represent the proliferating only in the host, obligate pathogenic mycobacteria ( Mycobacterium tuberculosis complex and Mycobacterium leprae ), the minority is, therefore, the term is to be regarded as atypical mycobacteria outdated.

The sub division of the non-tubercular mycobacteria after Runyon occurs on the growth rate and formation of pigment during exposure (known as Photochromogenität ).

• Group I: Photochromogene ( pigment formation only in the light ), slow growth ( slow growers ) MOTT: eg Mycobacterium kansasii
• Group II: Skotochromogene (visual in the dark pigments) slow growers MOTT, such as Mycobacterium xenopi.
• Group III: Nichtchromogene ( non-pigmented ) slow growers such as Mycobacterium avium and Mycobacterium ulcerans.
• Group IV: Fast growing, such as Mycobacterium fortuitum

The rapidly growing mycobacteria ( group IV), also referred to as "rapid growers " have a generation time of 1-4 hours, the cultures are clearly visible within a week without a microscope and are apothogen for the most part to humans. Mycobacteria with a generation time of 6-24 hours are called " Slow growers " ( slow growing) refers to the cultures take longer than 7 days to become macroscopically visible. Within the "slow growers " the majority of previously documented, facultative human pathogenic species is represented. The entire Mycobacterium tuberculosis complex and Mycobacterium leprae are to Group III. The cultures of slowly growing mycobacteria are visible at the earliest after 7 days with the naked eye.

The pigment behavior does not reflect phylogenetic relationships, but phylogenetically relevant is the growth rate. The subdivision into slowly and rapidly growing mycobacteria can be used as a basis for the creation of phylogenetic trees of mycobacteria.

Representatives (selection)

A list of some representatives after Runyon principle with information on the occurrence and related diseases:

Group I ( Photochromogene slow-growing )

• M. kansasii: Especially in Europe and the United States occurring pathogen of tuberculosis- like diseases of the lung.
• M. marinum: Worldwide common trigger of Schwimmbadgranuloms.
• Other representatives: M. asiaticum and M. simiae

Group II ( Skotochromogene slow-growing )

• M. scrofulaceum: a worldwide common causative agent of lymphadenitis.
• M. gordonae: This saprophytic representatives is ubiquitous, he was isolated from soil and water. Since he was also isolated from tap water, M. gordonae in English under the name " tap water bacillus " known. Mycobacterium aquae is a synonym.
• M. szulgae: A possible cause of lung disease was the most isolated from patients, the actual habitat ( soil, water) is still unclear.
• M. xenopi: excitation of lung diseases, grows at temperatures up to 45 ° C and has been observed in Europe and Canada.
• Other representatives: M. scrophulaceum ( lymphadenitis ), M. flavescens and M. szulgae

Group III ( non-pigmented slow-growing )

• Mycobacterium avium complex (MAC): MAC to include Mycobacterium avium and Mycobacterium intracellulare. They are found worldwide and causing lung disease and lymphadenitis.
• M. ulcerans: The initiator of Buruli ulcer ( a skin infection ) occurs mainly in the tropics ( in Australia ).
• M. haemophilum: The causes of skin infections occurs in Australia and the USA. In contrast to other mycobacteria cultivation is only possible with the addition of iron.
• M. malmoense: is most common in England, Northern Europe and Scandinavia and is causing lung diseases.

Group IV ( fast-growing )

• M. fortuitum: rash, high resistance in disinfectants: infections of foreign bodies, such as with the use of implants
• M. abcessus: lung disease, in Europe and especially common in the U.S..
• M. chelonae: skin or soft tissue infections, abscesses and bone, joint infections.

Some non-pathogenic species

The following species are considered non-pathogenic, that is, they were able to not be associated with human diseases (all are among the fast-growing mycobacteria) now:

• M. brumae
• M. chitae
• M. Confluentis
• M. fallax
• M. moriokaense

Swell