Dr. med. Dirk Manski

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Urinary Tract Infections

Urinary Tract Infection: Definitions and Epidemiology

Guidelines: (German S3 Guideline UTI), EAU Guidelines Urological Infections.

Definitions of Urinary Tract Infections

UTI is an inflammatory response of the urothelium to bacterial invasion that is usually associated with bacteriuria and pyuria \parencite{Campbell}. Depending on the affected organ, various forms of urinary tract infection (UTI) exist, some of which occur simultaneously:

Bladder infection (Acute Cystitis):

Acute cystitis is a common infection of the bladder, most often with coliform bacteria [see section bacterial cystitis and urinary tract infections in pregnancy].

Acute Pyelonephritis:

Acute pyelonephritis is an acute bacterial infection of the renal pelvis and renal parenchyma causing fever, chills and flank pain [see section acute pyelonephritis].

Acute Prostatitis:

Acute prostatitis is the bacterial infection of the prostate with fever, painful swelling of prostate and voiding symptoms [see section bacterial prostatitis].


Epididymitis is a bacterial infection of the epididymis causing scrotal swelling, pain and fever.


Acute urethritis is the bacterial infection of the urethra causing dysuria and urethral secretions, usually without signs of bladder infection [see section Gonorrhea and Non-gonococcal urethritis].

Uncomplicated urinary tract infection:

Acute, sporadic or recurrent lower UTI or uncomplicated pyelonephritis, limited to non-pregnant, pre-menopausal women with no known relevant anatomical and functional abnormalities within the urinary tract or comorbidities.

Complicated urinary tract infection:

Any UTI which is not classified as "uncomplicated": UTI in men or pregnant women, patients with relevant anatomical and functional abnormalities within the urinary tract, indwelling urinary catheters, renal diseases, and/or with other concomitant immunocompromising diseases.

Recurrent urinary tract infections:

Recurrent urinary tract infections exist if the recurrence rate is ≥ 2 symptomatic episodes per half-year or ≥ 3 symptomatic episodes per year.

Nosocomial urinary tract infection:

Hospital-acquired urinary tract infection (or every UTI with onset after more than 4 days in hospital). Most nosocomial UTI are caused by bladder catheters: catheter-associated urinary tract infection (CAUTI).


Urosepsis is life threatening organ dysfunction caused by a disregulated host response to infection originating from the urinary tract and/or male genital organs.

Further Definitions of Associated Situations


Bacteriuria is the presence of bacteria in the urine. Depending on the urine collection, different bacteria concentrations exist to distinguish significant bacteriuria from contamination or insignificant bacteriuria.

Acute Urethral Syndrome:

The acute urethral syndrome is defined by dysuria and urinary frequency without significant bacteriuria. There are many possible causes for the acute urethral syndrome, see differential diagnosis of LUTS.

Chronic Pyelonephritis:

Chronic pyelonephritis is a primarily radiological diagnosis with typical renal scars and deformity of the pyelocalyceal system. Bacteriuria and signs of infection are not mandatory.

Chronic Prostatitis:

Chronic prostatitis is an inaccurate term for diseases such as chronic bacterial prostatitis, chronic non-bacterial prostatitis or chronic pelvic pain syndrome [see definition of prostatitis by NIH].


Malacoplakia is a chronic infection/inflammation of the urinary tract with the formation of whitish-gray deposits.

Epidemiology of Urinary Tract Infections

Prevalence of Urinary Tract Infections:

Women are much more likely to suffer from urinary tract infection than men, see the following table. The lifetime risk for UTI is near to 50% for women. After the first UTI, women have a relevant risk for recurrent infections (0.3–3 UTIs/year).

Prevalence of urinary tract infections according to age and gender.
Age Prevalence Ratio (male:female)
Neonatal 1% 1.5:1
Preschool 2–3% 1:10
Pupils 1–2% 1:30
Adults 2.5% 1:50
Old age, at home 20–30% 1:10 to 1:2
Old age, nursing home 30% 1:1

Premenopausal women:

Incidence 50–100/1000 women, depending on age and study.

Young men:

Incidence 6–8 UTI per 10.000 young men/year (age 21–50).

Prevalence of Asymptomatic bacteriurie:

Under 1% in young men, 5% in healthy premenopausal women, 4–19% in elderly healthy patients, 15–50% in institutionalized patients and up to 90% in patients with spinal cord injury.

Nosocomial infections:

Urinary tract infections cause 20–40% of nosocomial infections.

Causes of Urinary Tract Infections

See section causes of urinary tract infection.

Diagnostic Workup in Urinary Tract Infections

See section diagnostic workup.

Antibiotic Therapy and Prevention of Urinary Tract Infections

See section antibiotic treatment and prevention.

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


G. Bonkat, R. Bartoletti, F. Bruyère, S. E. Geerlings, F. Wagenlehner, and B. Wullt, “EAU Guideline: Urological Infections.” [Online]. Available: https://uroweb.org/guidelines/urological-infections/

Deutsche Gesellschaft für Urologie, S3-guideline for urinary tract infection
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  Deutsche Version: Harnwegsinfektion