In wound microbiology, which statement best differentiates colonization from infection?

• A. Colonization is the presence of microbes without tissue invasion; infection involves tissue invasion and inflammation.
• B. Colonization involves tissue invasion and inflammation; infection is mere presence without invasion.
• C. Colonization happens only in sterile sites; infection cannot.
• D. Colonization requires antibiotics; infection does not.

Answer: (A)

The main idea here is distinguishing presence of microbes on a wound from the microbes actually invading tissue and provoking a body response. Colonization means organisms are present on the wound surface or within tissues but have not breached tissue barriers and do not trigger tissue damage or the inflammatory reaction. Infection means the microbes have invaded the tissue, causing damage and an inflammatory response, which you observe as redness, warmth, swelling, pain, or pus.

So, the best statement says colonization is the presence of microbes without tissue invasion, while infection involves tissue invasion and inflammation. The other ideas—colonization with invasion, infection without invasion, colonization only at sterile sites, or colonization needing antibiotics—don’t fit the clinical distinction between just being present and actively invading with an immune response.