Cultivation is the process of growing microorganisms in culture by taking bacteria from the infection site (i.e., the in vivo environment) by some means of specimen collection and growing them in the artificial environment of the laboratory (i.e., the in vitro environment). Once grown in culture, most bacterial populations are easily observed without microscopy and are present in sufficient quantities to allow laboratory identification procedures to be performed.
The successful transition from the in vivo to the in vitro environment requires that the nutritional and environmental growth requirements of bacterial pathogens be met. The in vivo to in vitro transition is not necessarily easy for bacteria. In vivo they are utilizing various complex metabolic and physiologic pathways developed for survival on or within the human host. Then, relatively suddenly, they are exposed to the artificial in vitro environment of the laboratory. The bacteria must adjust to survive and multiply in vitro. Of importance, their survival depends on the availability of essential nutrients and appropriate environmental conditions.
Although growth conditions can be met for most known bacterial pathogens, the needs of certain clinically relevant bacteria are not sufficiently under stood to allow for the ready development of in vitro growth conditions. Examples include Treponema pallidum (the causative agent of syphilis) and Mycobacterium leprae (the causative agent of leprosy).
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