bacteria blood care cell cells chemical chemicals disease drop exam graphic health healthcare hiv hospital illustration immunity laboratorium liquid medic medical microbe microbes microscope microscopic petri petri-dish test abstract background bacterium blue blur bubbles hi-res lava light navy orange wallpaper water abstraction black colour colours cyan green microcosmos pink red texture white yellow analyse backdrop blood analysis cleaning clusters concept contamination culture disinfect fungus germs health care illness immune immune system infection medicine sample science sickness slides swab tissue unclean virus color probiotics system blood cells hemoglobin iron