Occurring in otherwise healthy individuals with no neurological or structural abnormalities, acute, symptomatic, uncomplicated urinary tract infection (UTI) may be the most common infection after the common cold and flu. Most UTIs are bladder infections.
Natural Defense Mechanisms.
The greatest defense mechanism against bacterial inflammation
and adherence to the bladder or urethral lining is urine: invading bacteria
stimulate urination. Voiding washes out bacteria from the bladder and urethra and dilutes bacterial concentrations, preventing adherence. The surface cells of the bladder are coated with a special urinary mucus. This thin negatively-charged surface layer attracts water molecules and forms a barrier between the bladder and urine, preventing bacterial adherence. White blood cells
will also move into the bladder and urine to kill the invading bacteria
. The kidneys
produce a protein which contains mannose residues that block the attachment points of some types of E. coli
. This prevents their attachment to the bladder and encourages their excretion.
Incidence; Causes and Development; Contributing Risk Factors
Acute bacterial cystitis
affects 8-10 million Americans each year. An acute UTI
will be experienced by 25 to 40% of females in their lives, and up to 6% of women will have one or more UTIs in a given year.
Cystitis is a common occurrence in women, but it is less common and a potentially more serious condition for men.E. coli
is responsible for more than 80% of all acute female bladder infections
. However, S. saprophyticus
is more often isolated from women using spermicide-coated condoms (74%) and diaphragms than is E. coli
. Other bacteria
such as Proteus, Klebsiella or Enterobacter are occasionally isolated from uncomplicated UTIs. Vaginitis
caused by sexually transmitted pathogens such as herpes simplex
may mimic cystitis
For men the cause can be an underlying bladder or prostate
infection, an obstruction or tumor
, or an enlarged prostate.
The largest risk factor for acquiring and developing an acute UTI
is being female. This is because the short female urethra provides greater access to the bladder, and the nearby vagina provides a favorable environment for bacterial
colonization and growth.
The risk of acquiring an acute infection is more than 3-fold among women with a previous infection compared to women with no history of UTI.Sex and Cystitis
Once referred to as "honeymoon-cystitis", many women acquire their first infection after their first sexual experience. A study has shown that, compared to women who have not been sexually active during the previous week, the relative risk of a UTI among unmarried women increases 2.6 times for women who have engaged in sexual intercourse 3 times per week, and 9.0 times for women who have had intercourse seven times during the previous week. New sex partners and intercourse methods introduce bacteria
into the vagina and urethral area. If bacteria are not removed by voiding or cleaning, they will colonize in this area, posing a risk of infection.
Barrier methods of birth control can also increase the risk of acquiring a UTI
. Condoms increase the risk of vaginal tears, allowing bacteria to invade and adhere. Contraceptive sponges, foams, creams, gels and condoms use nonoxynol-9 (N-9) as a spermicide. Lactobacilli, the normal flora of the vagina, provide protection from external bacteria overgrowth, but are eradicated by N-9. The removal of lactobacilli by N-9 or other antibiotics alters the vaginal pH and natural flora, allowing Escherichia coli
) and Staphylococcus saprophyticus
to proliferate, colonize and adhere to the vaginal mucosa
. The odds that a woman exposed to condoms coated with N-9 would get a UTI were found to be 3 times higher than for sexually active women who did not use coated condoms. Diaphragms that are worn for more than 24 hours or improperly fitted can harbor bacteria or irritate tissue. A cervical cap, however, may not be associated with an increased UTI risk; less spermicide is used inside the enclosed cap, causing less alteration of the vaginal flora. Using extra lubricant during sex to decrease friction and irritation can help prevent the development of an infection.
Signs and Symptoms
Signs and symptoms of a complicated infection include nausea
, vomiting, flank pain, fever and chills. Treatment may require hospitalization and longer, more expensive antibiotic treatment.
Diagnosis and Tests
As a man, if you experience the symptoms of cystitis
, you should see your doctor immediately. An analysis and culture/sensitivity of your urine will be performed which should identify the kind of bacteria
causing the infection and the antibiotic most likely to help.
esterase (LE) dipstick test is used to screen for pyuria (presence of pus
in the urine when voided). LE, an enzyme found in neutrophil
granules, reacts with an impregnated reagent pad to produce a blue color within 2-5 minutes. A positive test indicates the presence of white blood cells
). When compared to standard methods of defining UTIs (isolating >=105 CFU/mL of pathogenic bacteria
)11 or significant pyuria (>=10 WBC/mm3 urine) the sensitivity is 75%-96% and the specificity is 94%-98%.15 Pyuria indicates inflammation
and not necessarily an infection. This is an efficient, cost-effective method for determining the presence of pyuria when routine microscopy is unavailable, impractical or for an outpatient evaluation.15 Vitamin C
and phenazopyridine10 may cause false-negative or unreadable results.
The nitrate test is also widely available, for use at home or in the office. The nitrate test is qualitative in that it is used as a surrogate to detect Gram-negative bacteria
, since only Gram-negative bacteria are able to produce nitrate. An aromatic amine-impregnated pad produces an azo color within 60 seconds if urinary nitrites are present. Urinary nitrites are produced by the action of Gram-negative bacteria (Enterobacteriaceae) metabolism on dietary nitrates through nitrate reductase. False-negatives can result from recent antibiotic therapy, low urinary pH (as occurs with high doses of ascorbic acid
), lack of dietary nitrates, or when diuresis
has created insufficient urinary nitrate levels. False-negatives also occur when Pseudomonas sp. or Gram-positive bacteria such as Staphylococcus
sp., or Enterococcus sp., which lack nitrate reductase, are unable to produce nitrite.15 Sensitivity of the test ranges between 35%-85%, and the specificity ranges between 92%-100%.
Treatment and Prevention
When promptly treated, the period of discomfort can be shortened and the potential for more serious damage and recurrence is reduced. Treatment is usually recommended because if the infection progresses and spreads to the kidneys
it is then classified as a complicated infection.
In the past, the treatment of acute female cystitis
with an antibiotic for 7-14 days was the standard procedure. Although very effective, the associated adverse events, poor compliance and unnecessary costs necessitated a re-evaluation. Single-dose therapy is generally less effective than the same antimicrobial
used for 7-14 days, but most antimicrobials given for three days are as effective as the same antimicrobial given for 7-14 days.
in men is not serious if treated promptly, but the discomfort can be chronic and disabling. Untreated bladder infections
can cause kidney
infections and damage.