Bacteremia is bacterial infection in the blood. Possible sources of bacteremia are from complication of infections, surgery involving mucous membranes, and via infected catheters or syringe administered through the arteries or veins. Bacteria in the blood can be dangerous because they can cause infections to distant sites apart from the focal site of infection. Possible consequences include sepsis, endocarditis, and osteomyelitis from hematogenous spread. Bacteremia is usually treated with intravenous antibiotics. When the causative-agent of bacteremia is gram-positive, this means that the bacterial species has a thick cell wall. The thick cell wall is due to the thick layer of crosslinked peptidoglycan chains. The cell wall in gram-positive bacteria makes them appear violet or bluish in color under the microscope through gram staining.
Gram's method is a useful and simple tool in classifying bacteria as gram-positive or gram-negative. This method uses a primary dye, crystal violet, that stains bacterial cells violet. Grams iodine solution is also used to fix the stain in cells. Bacteria that are susceptible to washing and decolorizing by an alcohol-acetone mix (particularly those without the thick cell wall) will lose the violet stain and take the color of the counterstain instead (which is pink). Thus, a gram-positive bacteremia will be one that which is caused by bacterial species that test positive to Gram's method.