Graphic Text: How the Bacteria Invade a Living Cell
Detroit Free Press
Chatter: These cells, shown magnified 1,000 times, trace how a listeria infection grows in laboratory rats.
WHAT IS SHOWN: A bluish-white listeria bacterium has just entered a cell, shown in red. Here it will feed on sugars and amino acids, getting ready to multiply.
WHAT IT MEANS: In healthy people, the cell uses its internal defenses to kill the bacterium. Those more vulnerable include the pregnant, the elderly, the newborn, and those suffering from cancer, diabetes, AIDS, or kidney disease, as well as others with weakened immune systems.
WHAT IS SHOWN: Listeria have multiplied—they double their number every 45 minutes. In time-lapse photography, they look like comets. Listeria are ready to spread from this cell to others. At this stage, the host cell is sickened but not defeated.
WHAT IT MEANS: In people, an infection requires that thousands of listeria attack multiple host cells. People in the "vulnerable" categories begin to feel ill as the bacteria successfully multiply and invade millions of cells.
WHAT IS SHOWN: Pictured are 20 to 30 host cells dying as listeria continue to replicate and spread. Most of the cells' nutrients have been used up by the bacteria. Organs would have ceased to function before reaching this high density of infection.
WHAT IT MEANS: In humans, the most common death from listeriosis occurs from meningitis, after the bacteria have spread to the spinal cord, brain and other parts of the central nervous system. In pregnant women, the bacteria can infect the fetus.
Source: Wayne State University Medical School Department of Immunology and Microbiology