What term describes the human microbial community that normally inhabits surfaces and mucous membranes?

• A. The normal microbiota (normal flora)
• B. Transient microbiota
• C. Pathogenic microbiota
• D. Commensal viruses

Answer: (A)

The normal microbiota, also called normal flora, are the microorganisms that normally inhabit surfaces and mucous membranes such as the skin, mouth, gut, and genital tract. They establish stable populations that typically do not cause disease and can help protect the host by occupying niches and producing substances that inhibit invading pathogens. This resident community differs from transient microbiota, which are only temporary visitors that can be washed away or outcompeted. Pathogenic microbiota refer to microbes capable of causing disease when conditions allow. Commensal viruses is not the standard label for this resident community, since the term normal microbiota mainly describes bacteria and other organisms that normally colonize these sites.