What is the difference between infection and contamination / colonization ?

The basic difference between these two conditions lies in the concentration of organisms in the wound. An infected wound contains a larger number of microorganisms than a contaminated wound. Proper wound cleansing and debridement should prevent bacterial colonization from proceeding to the point of clinical infection.

A contaminated wound will heal, an infected wound will not.

Are all wounds infected ?

All wounds (including surgical) are contaminated with microorganisms. A contaminated wound will heal, an infected wound will not. Wound exudate contains bacteria killing enzymes that will help prevent an infection. Proper cleansing, debridement and maintenance of a moist wound environment will all create a condition that lessens the risk of infection.