Question

Which statement regarding normal microbiota of the human respiratory system is FALSE?

• The trachea normally may contain a few bacteria.
• The ciliary escalator in the bronchial tubes keeps the lower respiratory tract nearly sterile.
• Potentially pathogenic microorganisms are present in nonsterile portions of the respiratory tract but usually do not cause disease.

Answer 1

The statement "Potentially pathogenic microorganisms are present in nonsterile portions of the respiratory tract but usually do not cause disease" is FALSE regarding normal microbiota of the human respiratory system.

While it is true that the trachea normally may contain a few bacteria and the ciliary escalator in the bronchial tubes keeps the lower respiratory tract nearly sterile, the presence of potentially pathogenic microorganisms in nonsterile portions of the respiratory tract does not necessarily mean that they will not cause disease.

In fact, certain conditions, such as a weakened immune system, chronic lung disease, or prolonged antibiotic use, can increase the risk of these microorganisms causing infections. Some examples of potentially pathogenic microorganisms in the respiratory system include Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis.