This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
With regard to surgical site infection, what is it called if bacteria are dividing and have invaded wound surface 
Select and explain. 
A. Contamination, B. Colonization, C. Tropical infection, D. Local infection
C: Tropical infection
Answer: C: Tropical infection 
Explanation: Contamination
Bacteria are on the wound surface. No division occurring


Colonization 
Bacteria are dividing


Tropical infection (Critical colonization)
Bacteria are dividing and have invaded the wound surface. There may be an increasing variety of bacteria present ; Biofilm may be present


Local infection
Bacteria and  / or their products have invaded the local tissue