Dr. med. Dirk Manski

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Etiology and Symtoms of Bladder Infection (bacterial cystitis)


Acute cystitis is a bacterial infection of the urinary bladder, the most common manifestation of urinary tract infection (Fihn, 2003) (Krieger, 2003) (S3 German Guideline), EAU Guidelines.

Epidemiology of Bladder Infection

Prevalence of dysuria:

20–30% of adult women have an episode of dysuric symptoms one or more times a year, half of which corresponds to acute cystitis.

Prevalence of asymptomatic bacteriuria:

Below 1% in young men, 5% in healthy premenopausal women. 4–19% in old healthy patients, 15–50% in nursing home residents and up to 90% in patients with paraplegia.

Etiology (Causes) of Bladder Infection

Principles, pathogenesis and causes of UTI see section urinary tract infection.

Pathogen spectrum of acute uncomplicated cystitis in German women, modified from S3 German Guideline
Erreger %
Gramnegative bacteria:
Escherichia coli 77
Proteus mirabilis 5
Klebsiella pneumoniae 2–3
Enterobacter spp. 1
Citrobacter spp. < 1
Other Enterobacteriaceae 2
Grampositive bacteria
Staphylococcus saprophyticus 3
Staphylococcus aureus 2
Andere Staphylokokken 4
Enterococcus spp. 3
Streptococcus spp. < 1

Pathology of Bacterial Cystitis

In the early stages of acute cystitis, the bladder wall shows hyperemia, edema, and infiltration by neutrophil granulocytes. In later stages, the mucosa is replaced by easily vulnerable granulation tissue. Small ulcers may develop. The lamina muscularis is usually not involved in the inflammation. Without treatment, hemorrhage and necrosis are possible.

Signs and Symptoms

Emphysematous cystitis in i.v. urography: gas formation within the urinary bladder wall is a sign of severe disease with risk of sepsis. Transurethral catheterization and intravenous antibiotic therapy are recommended as therapy. With kind permission from Harzmann, R. et al. (1985). Verhandlungsbericht der Deutschen Gesellschaft für Urologie, Vol 36. Springer, Berlin, Heidelberg.
figure Emphysematous cystitis in i.v. urography

Diagnosis of Bladder Infection

Diagnostic Workup of Uncomplicated Cystitis in Healthy Women

Healthy women with typical symptoms of bacterial cystitis (dysuria and urinary frequency without vaginal discharge) may be treated with antibiotics with no further diagnostic workup. Urinalysis, urine culture or imaging are not absolutely necessary, since the probability for bacterial cystitis is over 70%, and the diagnostic accuracy will not improve with further workup [DGU (2009) S3-guideline for UTI].

Diagnostic Workup of Bladder Infections

Diagnostic workup of bladder infection is necessary for patients with fever, all men, patients with complicated UTI, and after failed treatment of uncomplicated cystits.


Urinalysis is performed with a dipstick or microscopic examination of the urine. Signs of a bladder infection are pyuria, bacteriuria, hematuria, or a positive nitrite test.

Urine culture:

A urine culture is recommended for complicated UTIs. 105 colony-forming units CFU/ml in a cleanly collected midstream urine indicate a UTI (Kass, 2002). A colony count from 103–104 CFU/ml may be significant in patients with typical symptoms and if typical uropathogens in pure culture (no mixed bacterial growth) are found. Forced diuresis or pollakiuria leads to a shorter retention time of the urine in the urinary bladder and can thus result in false-low bacterial counts despite UTI. Bacterial growth in a urine sample collected by catheterization or urinary bladder puncture is always pathological.

Ultrasound imaging of bladder and kidneys:

Renal ultrasound: Obstructive uropathy? Anatomical variants? Bladder ultrasound: Postvoid residual volume? Diverticula of the bladder? Bladder stones?

Vaginal examination:

Vaginal discharge should initiate a vaginal examination to diagnose vaginitis or pelvic inflammatory disease, and swabs for microbiological diagnosis are collected.

Intravenous urography:

IVU is an option in recurrent cystitis to diagnose e.g., infection stones, obstructive uropathy, diverticula or ureterocele of the bladder.


Cystoscopy should be considered in recurrent cystitis and for differential diagnosis of hematuria (after treated acute bladder infection).

Voiding cystourethrogram:

VCUG for patients with recurrent cystitis or pyelonephritis to exclude vesicoureteral reflux, especially in children and patients with ectasia of the upper urinary tract.

Differential Diagnosis of Bladder Infection

Index: 1–9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z


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In: J Urol
173 (2005), Nr. 1, S. 21–6

Krieger 2003 KRIEGER, J. N.: Urinary tract infections: what’s new?
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  Deutsche Version: Diagnose und Therapie der akuten Zystitis