Reviewed by Rishi Desai, MD, MPH
Urinary tract infection
A urinary tract infection is an infection that affects part of the urinary tract. When it affects the lower urinary tract it is known as a bladder infection (cystitis) and when it affects the upper urinary tract it is known as kidney infection (pyelonephritis). Symptoms from a lower urinary tract include pain with urination, frequent urination, and feeling the need to urinate despite having an empty bladder. Symptoms of a kidney infection include fever and flank pain usually in addition to the symptoms of a lower urinary tract infection. The most common causes of bacterial urinary tract infection is from Escherichia coli, and Staphylococcus saprophyticus in young women. Risk factors include female anatomy, sexual intercourse, diabetes, obesity, and family history. Although sexual intercourse is a risk factor, urinary tract infections are not classified as sexually transmitted infections.
Cystitis is inflammation of the urinary bladder that presents with suprapubic pain, dysuria, urinary frequency, and urinary urgency. Systemic signs like a high fever or chills are usually absent. Risk factors include female gender, sexual intercourse (honeymoon cystitis), indwelling catheters, diabetes, and impaired bladder emptying. Escherichia coli is the most common cause. Lab findings include positive leukocyte esterase and nitrites indicating gram negative organisms. Sterile pyuria and negative urine cultures suggest urethritis and/or cystitis by Neisseria gonorrhoeae or Chlamydia trachomatis.