Terms are used very loosely, and this can lead to confusion. Bacteraemia is the presence of bacteria in the blood. This is a common occurrence, but some authors use this term to refer to the occasions when the presence of bacteria is clinically apparent. The general term 'sepsis' can also be misleading. Some authors use it when referring to any infectious process whilst others use it to refer to conditions associated with septicaemia.
Blood is generally an inhospitable environment for microbes.
Although nutrients are well supplied in the bloodstream, there are also numerous defences. To overcome these problems, a few pathogens have opted for an intracellular life-style. This is perhaps best illustrated by the malaria parasites that protect themselves from our host defences by living within red blood cells. It is not unusual to find microbes in the bloodstream. Enthusiastic brushing or flossing of teeth, or even simply chewing particularly sticky toffees causes movement of the teeth in their sockets and this, in turn, leads to a flush of oral commensal microbes through the bloodstream.