Bacteria is made up of single-celled organisms that can both multiply and divide themselves relatively rapidly. Bacteria can be found everywhere, including inside our bodies and on everything we touch. While not every type of bacteria is harmful, there are strains which carry very serious health risks, so the less the bacteria that is spread, the better. The most common way in which bacteria is spread is through contact. Touching a bacteria-laden doorknob, or shaking hands with an individual with a cold who is unwittingly carrying bacteria on them is a reliable way to spread bacteria. Simply touching food with dirty hands will spread it. Bacteria easily spreads from person to person, from person to object or from object to person. Nothing is safe, especially if regular hygiene is not kept up.
Through Exchange of Bodily Fluids
Sneezing and coughing are two efficient ways to ensure bacteria is spread. If you sneeze, cough or blow your nose while in a crowd, you are essentially sharing your bodily fluids with the people around you, and therefore ensuring their contamination. Any time bacteria could possibly be present, it's best to avoid the exchange of bodily fluids whether it's through coughing, sneezing or even kissing.
Through the Air
Bacteria can be easily passed through the air. If bodily fluids are launched into the air through sneezing or coughing, it can affect the people in the area, due to its airborne properties. If the bacteria is in the air, anyone is fair game.
Through Poor Hygiene
If it's during cold or flu season, the best way to prevent the spread of bacteria is through proper hygiene. That means washing your hands regularly and using antibacterial wipes whenever necessary. If the hygiene of a location is poor, then the bacteria will be more readily spread through personal contact, bodily fluids and the air because the bacteria is present and thriving. Not all preventative measures will put a halt to the spread of all bacteria, but it should curtail it.
Through Rapid Growth
Bacteria is an organism that is able to grow and divide at a surprisingly rapid rate. Because bacteria is reproduced mostly by asexual reproduction, it can multiply relatively efficiently. Even the growth of bacteria can be increased merely by warmth and moisture. If the conditions are just right, the bacteria will grow and spread quite easily.