The highest incidence of urinary tract infections is found in, but not at all limited to, those who are sexually active, especially females.
Most kidney infections are a result of infection spread from the lower tract.
The urine may be cloudy, have a foul odor, or be bloody. Fever, vomiting, or pain in the back just below where the rib cage meets the muscles next to the spine indicate kidney involvement. Females may have associated vaginitis with vaginal itching, burning, or increased odor, while men often have associated prostatitis with low back pain, fever, or pain between the scrotum and anus. Symptoms may be subtle, so a high level of suspicion is appropriate. Once suspicion is aroused, the presence or absence of a urinary infection is confirmed by an examination of the urine at a medical facility.