"Chain of infection" is the process by which infections are spread. The biggest way that the chain of infection can be broken is by following proper hand washing procedures.
Transmission of bacteria from person to person requires these three things: a source of the infection, a host and transmission. If one of these elements can be broken, then the chain of infection itself will be broken. Say for example a person comes goes to the hospital because he has strep throat. A healthcare worker examines the patient. Without washing his hands the health care worker moves on to the next patient and spreads the bacteria. If he would have washed his hands prior to examining the next patient, the chain of infection would have been broken.
The chain of infection refers to how pathogenic microorganisms are transmitted. All "links in the chain" must be present in order for infection to occur. The sequence is as follows:
1. There must be a causitive agent or pathogen.
2. There must be a source or resorvoir, example, a carrier.
3. There must be a portal of exit. The microbe must leave the body by some means.
4. There must be a mode of transmission. example, sneezing.
5. There must be a portal of entry. example, respiratory tract.
6. There must be a susceptible host. If someone is not susceptible to disease, the disease can't be transmitted.
A goal of all health care workers is to try and break the chain of infection by utilizing preventative measures. Commonly, health care workers are guilty of spreading infections due to incorrect and sloppy practices.