Which statement describes infection?

Which statement describes infection?

• A. Contamination or invasion of body tissue by pathogenic organisms
• B. A mild allergic reaction
• C. The presence of nonpathogenic organisms only on the skin
• D. A condition cured by antibiotics

Answer: (A)

Infection happens when pathogenic organisms invade body tissue and multiply, causing harm. It’s not just having microbes present; the key is that they breach defenses, replicate, and lead to tissue damage or inflammation. This differs from contamination, where microbes are present on surfaces or tissues without invading or harming them, and from colonization, where microbes live on or in the body without causing disease. It’s also not a description of an allergic reaction, which is an immune response to a harmless substance rather than an invading pathogen. And while antibiotics are used to treat many bacterial infections, the definition of infection isn’t “cured by antibiotics”—some infections are viral and won’t be cured by antibiotics, and not every infection is immediately resolved by treatment. So the statement that infection involves invasion and multiplication of pathogenic organisms in body tissue best captures the concept.

Infection happens when pathogenic organisms invade body tissue and multiply, causing harm. It’s not just having microbes present; the key is that they breach defenses, replicate, and lead to tissue damage or inflammation. This differs from contamination, where microbes are present on surfaces or tissues without invading or harming them, and from colonization, where microbes live on or in the body without causing disease. It’s also not a description of an allergic reaction, which is an immune response to a harmless substance rather than an invading pathogen. And while antibiotics are used to treat many bacterial infections, the definition of infection isn’t “cured by antibiotics”—some infections are viral and won’t be cured by antibiotics, and not every infection is immediately resolved by treatment. So the statement that infection involves invasion and multiplication of pathogenic organisms in body tissue best captures the concept.