Which term describes bacteria that do not cause disease?

• A. Pathogenic
• B. Nonpathogenic
• C. Opportunistic
• D. Commensal

Answer: (B)

Meaning: some bacteria never cause disease, while others do. The term that fits describes bacteria that do not cause disease at all. These nonpathogenic organisms are typically part of normal flora on skin or mucous membranes and are harmless in ordinary conditions; they may even be beneficial in some contexts.

In contrast, pathogenic bacteria are capable of causing disease. Opportunistic bacteria only cause disease when the host’s defenses are weakened or when they are in the wrong place in the body. Commensal bacteria live on or in the body without causing harm under normal conditions, though the balance can change if the environment or host changes.

So, bacteria that do not cause disease are described as nonpathogenic.