Urinary tract infection, lower
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 approximately 10% to 20% of all women at least once. Lower UTI is also a prevalent bacterial disease in children, with girls also most commonly affected.
Gender InfluenceThe high incidence of lower UTI among women may result from the shortness of the female urethra (1¼″ to 2″ [3 to 5 cm]), which predisposes women to infection caused by bacteria from the vagina, perineum, rectum, or a sexual partner. Men are less vulnerable because their urethras are longer (7¾″ [19.68 cm]) and their prostatic fluid serves as an antibacterial shield. In men and women, infection usually ascends from the urethra to the bladder.
In men and children, lower UTIs are frequently related to anatomic or physiologic abnormalities and therefore require extremely close evaluation. UTIs often respond readily to treatment, but recurrence and resistant bacterial flare-up during therapy are possible.
Causes
Most lower UTIs result from ascending infection by a single gram-negative enteric bacterium, such as Escherichia coli, Klebsiella, Proteus, Enterobacter, Pseudomonas, or Serratia. However, in a patient with neurogenic bladder, an indwelling urinary catheter, or a fistula between the intestine and bladder, lower UTI may result from simultaneous infection with multiple pathogens.
Infection may result from a breakdown in local defense mechanisms in the bladder that allow bacteria to invade the bladder mucosa and multiply. These bacteria cannot be readily eliminated by normal micturition.
The risk of cystitis is higher when the bladder or urethra becomes blocked and urine flow stops. It can occur when instruments are inserted into the urinary tract during procedures such as catheterization or cystoscopy. Other risks include pregnancy, diabetes, and a history of analgesic or reflux nephropathy. The elderly are at increased risk for developing UTIs due to incomplete emptying of the bladder; this is associated with conditions such as benign prostatic hyperplasia (BPH), prostatitis, and urethral strictures. Also, lack of adequate fluids, bowel incontinence, immobility or decreased mobility, indwelling urinary catheters, and placement in a nursing
home all place the person at risk for developing an infection.
home all place the person at risk for developing an infection.
Bacterial flare-up
During treatment, bacterial flare-up is generally caused by the pathogenic organism’s resistance to the prescribed antimicrobial therapy. The presence of even a small number (less than 10,000/ml) of bacteria in a midstream urine sample obtained during treatment casts doubt on the treatment’s effectiveness.
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