The clinical picture of urinary tract infection includes infections of the lower urinary tract (bladder, urethra) and the upper urinary tract / renal pelvis (i.e., pyelonephritis). The most typical presentation is ‘acute simple cystitis’, where there is no indication that the infection has extended beyond the bladder. This is generally caused by infection with the microbe Escherichia coli, a normal intestinal coloniser. Other bacteria such as Klebsiella pneumoniae and Proteus mirabilis are occasional causes of acute simple cystitis. Due to anatomic differences, a urinary tract infection is much more common in women than in men.
Symptoms of a urinary tract infection are dysuria (painful voiding), frequent voiding and (lower) abdominal pain. Symptoms are less typical in elderly patients and children, in whom a urinary tract infection may present with general illness or confusion.
Current guidelines distinguish urinary tract infections with or without tissue invasion. Tissue invasion implies that the infection involves the upper urinary tract tissue, which is accompanied by general symptoms such as fever, illness or pain in the flank. Examples are pyelonephritis and prostatitis.
Diagnosing urinary tract infection is relatively simple. When the symptoms are typical, it is sufficient to demonstrate nitrite in the urine or the actual presence of bacteria in the urine (with a sediment or a ‘dipslide’ – a culture method in general practice). If needed, a culture to identify the causative microbe (and to determine antibiotic resistance) can prove the diagnosis and guide treatment.
Urinary tract infections are generally treated with antibiotics. However, conservative treatment may suffice sometimes, e.g. analgesics and extra drinking.
An (isolated) urethritis (in men) is generally caused by a sexually transmittable pathogen (e.g. Neisseria gonorrhoea, Chlamydia trachomatis) and considered a different clinical picture.
A urinary tract infection can be recorded with three ICPC codes from the ‘Urological’ (U) chapter, namely U70 (pyelonephritis / pyelitis), U71 (cystitis) or U72 (urethritis). FaMeNet records U71 for ‘acute simple cystitis’. U70 (pyelonephritis / pyelitis) is recorded in patients with bacteriuria and clinical signs of involvement of the renal pelvis (e.g. fever, pain in the flank, serious illness).
U72 is used in cases of urethritis where no microbe has been demonstrated justifying a specific alternative diagnosis (e.g. gonorrhoea, chlamydia).
In this section, we focus on cystitis (U71).
Prostatitis is coded separately in the ‘male genital’ chapter (Y73).
Sexually transmittable diseases with a demonstrated pathogen should be distinguished from urinary tract infections. They are coded in the ‘female genital’ chapter (e.g. ICPC codes X70, X71, X72, X73) or in the ‘male genital’ chapter (e.g. ICPC codes Y70, Y71, Y72).
In patients presenting with symptoms, but in whom a urinary tract infection cannot be demonstrated, FaMe-Net records the most prominent symptom as symptom diagnosis, e.g. dysuria (U01), frequent voiding (U02) or ‘other urination problem’ (U05).
Urinary tract infection (U71) is one of the most common diagnoses GPs make, following acute respiratory infection (R74) and close to excessive ear wax (H81). Link/Table 1 The incidence is 46.6 per 1000 patient years, meaning 47 diagnoses per year in a practice with 1000 patients. The diagnosis is significantly more common among women, with an incidence of 81.3 per 1000 patient years, compared to 10.3 per 1000 patient years among men. Link/Figure 2
Among women, urinary tract infection is the most commonly made new (incident) diagnosis. Link/Table 3 The sex difference in the incidence of urinary tract infection between women and men is most prominent in the age group 15-25. These young women have a high incidence (91.0 new diagnoses per 1000 patient years), while a urinary tract infection in young men is rare (1.2 per 1000 patient years). The incidence of urinary tract infection rises in patients over 65 years of age, with an obvious peak among the eldest (75+) in whom the incidence reaches 192.2 per 1000 patient years. The difference between women and men in the incidence of urinary tract infection becomes much smaller in the oldest age group (only two and a half times higher in women).
The incidence of the symptom diagnosis dysuria (U01) is 16.4 per 1000 patient years (26.6 in women and 5.9 in men (Link/Figure 4), and the incidence of frequent voiding (urinary frequency, U02) is 13.1 per 1000 patient years (18.1 in women and 7.1 in men). Link/Figure 5
The prevalence of urinary tract infection is 43.0 per 1000 patient years, meaning that per 1000 patients, 43 individual persons have a urinary tract infection and contact their GP for it throughout the year. Link/Figure 6
The higher incidence number compared to prevalence indicates that urinary tract infections may recur in the same person within a year. Urinary tract infection is among the most common conditions for which patients seek help from their GP throughout the year. Link/Figure 7
Commonly, patients themselves suspect that something is wrong: the most common reason for encounter (RFE) in episodes of urinary tract infection is a request to check the urine. A self-suspected diagnosis of urinary tract infection (U71) is another prevailing RFE. Link/Table 8 The Positive Predictive Value (PPV) for patients presenting with the RFE ‘urinary tract infection’ is quite high: 73% are eventually diagnosed with a urinary tract infection. Link/Table 9
Common symptoms coded as RFEs are dysuria (U01), frequent voiding (U02) or abdominal pain (D06). A request for medication for cystitis (*50) is also a common RFE. Link/Table 8
Compared to women, men with a urinary tract infection are relatively more likely to present with fever (RFE A03) or haematuria (U06). Link/Table 10 Women on the contrary present more often with abdominal pain (D06). Link/Table 11 In young children with a urinary tract infection (0-4 years) fever is a common RFE. Link/Table 12
In most episodes of urinary tract infection, medication is prescribed. Link/Table 13 The most commonly prescribed types of antibiotics are nitrofurantoin, followed (with distance) by fosfomycin (‘other antibacterials, J01XX’), fluoroquinolones and trimethoprim. Link/Table 14 Medication classes can be looked up in the ATC classification.
Another (obvious) intervention recorded in most episodes is the investigation of urine. Microbiological investigation occurs sometimes. Referrals are needed in only 2% of the episodes of urinary tract infection. Link/Table 13 This includes referrals in the acute phase or later in the episode, for example, when complaints persist or recur. Referrals are mainly to urology, paediatrics or internal medicine. Link/Table 15
Dutch guideline: https://richtlijnen.nhg.org/standaarden/urineweginfecties#volledigetekst (2020)
Gupta K. Acute simple cystitis in females. In: UpToDate, Calderwood SB, Bloom A (Eds), UpToDate, Waltham, MA, 2023