This is a picture of Escherichia coli, better known as E-Coli 0157. It exists in the stomachs of cattle and sheep, and is easily passed down the food chain by improper meat handling procedures. People can develop serious illness from this strain of E-Coli, and some die from its effects.
You don't want to know how many will fit onto a pinhead.
Always use a clean surface for food preparations. Make sure no items such as handbags, pet food dishes, shopping bags etc have been temporarily in touch with the surface. Tools like cutting boards and knives should be ready to be used to avoid opening drawers at the last minute. Grocery stores carry disposable cleaning towels and plastic gloves. Wiping surfaces with a damp cloth is not an answer. This action only serves to spread and enhance the bacteria reproduction rate. Avoid sponges or re-usable cloths for clean-up. Use disinfecting disposable towels for jobs like that.
If you drop food onto the floor, THROW IT OUT. E-Coli 0157 and its relatives have no concept of time. The Five Second Rule is a myth, as are the three, seven and ten second rules. Bacteria instantly attach to whatever surface is acceptable. There is NO safe period of time.