Atlas of pathophysiology, 2 Edition

Part II - Disorders


Cystitis and urethritis, the two forms of lower urinary tract infection (UTI), are nearly 10 times more common in women than in men and affect about 10% to 20% of all women at least once. Lower UTI is also a prevalent bacterial disease in children, most commonly in girls. Men are less vulnerable because their urethras are longer and their prostatic fluid serves as an antibacterial shield. In both men and women, infection usually ascends from the urethra to the bladder. UTIs generally respond readily to treatment, but recurrence and resistant bacterial flare-up during therapy are possible.

Clinical Tip

All children with a proven UTI should receive a workup to exclude an abnormality of the urinary tract that would predispose them to renal damage.


Ascending infection by a single, gram-negative, enteric species of bacteria, such as Escherichia (commonly E. coli), Klebsiella, Proteus, Enterobacter, Pseudomonas, or Serratia

In women

·   Predisposition to infection by bacteria from vagina, perineum, rectum, or a sexual partner, a possible result of a short urethra.

In men and children

·   Commonly related to anatomic or physiologic abnormalities


·   In 99% of patients, reinfection by the same organism or a new pathogen

·   Persistent infection—usually from renal calculi, chronic bacterial prostatitis, or a structural anomaly that harbors bacteria

Age Alert

As a person ages, progressive weakening of bladder muscles may result in incomplete bladder emptying and chronic urine retention—factors that predispose the older person to bladder infections.


Infection results from a breakdown in local defense mechanisms in the bladder that allow bacteria to invade the bladder mucosa and multiply. These bacteria can't be readily eliminated by normal micturition.

Signs and symptoms

·   Urgency, frequency, dysuria

·   Cramps or spasms of the bladder

·   Itching, feeling of warmth or burning during urination

·   Nocturia

·   Urethral discharge in males

·   Hematuria

·   Fever, chills

·   Other common features:

§  malaise

§  nausea, vomiting

§  low back pain, flank pain

§  abdominal pain, tenderness over the bladder area

Diagnostic test results

·   Microscopic urinalysis is positive for pyuria, hematuria, or bacteriuria.

·   Bacterial count in clean-catch midstream urine specimen reveals more than 100,000 bacteria per milliliter.

·   Sensitivity testing determines the appropriate therapeutic antimicrobial agent.

·   Blood test or stained smear of the discharge rules out sexually transmitted disease.

·   Voiding cystoureterography or excretory urography detects congenital anomalies that predispose the patient to recurrent UTIs.


·   Appropriate antimicrobials:

§  single-dose therapy with amoxicillin or co-trimoxazole may be effective in women with acute noncomplicated UTI

·   If urine isn't sterile after 3 days:

§  bacterial resistance likely

§  use of a different antimicrobial necessary

·   Sitz baths or warm compresses

·   Increased fluid intake

·   Phenazopyridine hydrochloride (Pyridium)

Recurrent infections

·   Infected renal calculi, chronic prostatitis, or structural abnormality—possible surgery

·   Prostatitis—long-term antibiotic therapy

·   In absence of predisposing conditions—long-term, low-dose antibiotic therapy




Clinical Tip: Routes of Infection in the Urinary Tract


Bladder wall—Endoscopic view


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