Final answer:
The presence of nitrites in urine typically indicates an infection caused by bacteria that convert naturally occurring nitrates into nitrites.
Step-by-step explanation:
Nitrites in urine signify the presence of certain types of bacteria, such as Gram-negative bacteria, that metabolize nitrate into nitrite. The detection of nitrites in urine usually indicates an infection, which can be identified using urine test strips. While nitrates (NO3-) are normally present in urine, the conversion to nitrites is an indirect evidence of a urinary tract infection or the presence of bacteria in the urinary system.