Keyboard bacteria. Scanning electron micrograph (SEM) of bacteria from a computer keyboard. Research has found that keyboards can have high levels of bacteria on them and that shared keyboards tend to have more bacteria than those used by only one person. Even more disturbing, research by University of Arizona researchers also found that the average desktop has 400 times more bacteria than the average toilet seat. Keyboards were high in levels of five bacteria, including E. coli, Klebsiella pneumonia, Streptococcus, Salmonella and Staphylococcus aureus. Magnification: x6000 when printed at 10 centimetres wide.