Pathogen obligate

There are three categories of bacterial pathogens. Obligate pathogens are those bacteria that must cause disease in order to be transmitted from one host to another. These bacteria must also infect a host in order to survive, in contrast to other bacteria that are capable of survival outside of a host. Examples of obligate bacterial pathogens include Mycobacterium tuberculosis and Treponema pallidum. 

The identification of bacteria has traditionally required the establishment of a pure culture before any other steps are taken. Pure cultures of bacteria may sometimes be obtained from blood and spinal fluid, which are normally sterile, or from extreme environments like hot springs. However, because there are few such situations in nature, individual bacteria must generally be isolated from other cells and grown for one to five days to obtain pure cultures before identification. Some pathogenic bacteria are obligate intracellular parasites that are difficult or impossible to grow outside their mammalian host cells 37 for these, pure cultures are not feasible. 

Genome loss and specific host adaptive features in obligate intracellular pathogens... 

The cultivar Green Pod 407 that did not produce the polymer (Fig. 1) was well inoculated. The bean rust pathogen is an obligate parasite therefore, it is difficult to determine if an essential growth factor was immobilized and not available to the rust organism or whether the pathogen was inhibited by phenols or o-quinones. 

Culture Filtrates. SchBnbeck et al. (26) applied culture filtrates from various fungi and bacteria to beans and induced resistance to bean rust. The induction of resistance occurred at a distance from the site where the inducer was applied indicating it was systemic. A period of at least two days was required for the Initiation of the resistance response. The phenomenon appeared to be nonspecific since the culture filtrates induced resistance in other plants and against various pathogens however, only against obligate parasites. The active compounds in the culture filtrates have not been identified and their mechanism of action is unknown. 

Environmentally mediated host predisposition to disease have been linked with obligate pathogen performance, and included exposure to cold (Schulz and Bateman, 1969), low light intensity, or short day lengths (Foster and Walker, 1947), salinity stress (MacDonald, 1982), high temperature (Edmunds, 1964), and drought or moisture stress (Boyer, 1995 Duniway, 1977). 

Stanier RY, van Niel CB (1962) The concept of a bacterium. Arch Mikrobiol 42 17-35 Stephens RS, Kalman S, Lammel C, Fan J, Marathe R, Aravind L et al (1998) Genome sequence of an obligate intracellular pathogen of humans Chlamydia trachomatis. Science 282 754-759... 

Tetanus is a condition characterised by prolonged, involuntary contraction of the skeletal muscles. The condition can be localised or generalised. Tetanus is caused by the bacterium Clostridium tetani, an obligate, anaerobic, Gram-positive rod-shaped bacterium. The pathogen produces an exotoxin called tetanospasmin. Tetanospasmin is a potent neurotoxin which blocks neurotransmitter release from inhibitory neurons resulting in muscular contractions. C. tetani is not an invasive microbe, rather the spread of the toxin is due to... 

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