Which of the following body compartments is sterile in healthy individuals?

Cerebrospinal fluid is considered sterile in healthy individuals because it is normally free of microbes. This fluid surrounds the brain and spinal cord, providing protection and structural support while also facilitating the exchange of nutrients and waste. The sterility of cerebrospinal fluid is crucial, as any infection in this compartment can lead to serious conditions such as meningitis or encephalitis.

In contrast, other body compartments harbor microbial populations. The skin is home to a wide variety of bacteria and fungi as part of the normal flora, which play roles in protection against pathogens. The urinary tract can also contain bacteria, although the bladder is typically sterile in healthy individuals until a urinary tract infection occurs. The intestinal tract is known for its diverse and abundant microbial community, which aids in digestion and other metabolic functions. Thus, cerebrospinal fluid stands out as the only completely sterile compartment under healthy conditions.