StatisticsMen: incidence <1% between 20 and 60 years of age
Women: 1 in 2 will be treated during their lifetime
1 in 3 will be treated by 24 years of age
PathophysiologyCommon organisms:
E. coli = 70%
Staph saprophyticus = 15%
Proteus mirabilus = 10%
Proteus, klebsiella, enterobacter and enterococcus are rare.
Pseudomonas and candida are hospital acquired.
Clinical Features
It is important to make sure you ask about all the history features:
- Frequency
- Urgency
- Dysuria - In patients who can explain their symptoms, dysuria is the most diagnostic symptom in older and younger women.
- Nocturia
- Haematuria
- Suprapubic pain
- Fever
In male patients ask about:
- Poor stream
- Terminal dribbling
- Incomplete voiding
- Overflow incontinence
Investigations
The role of urinalysis is controversial. Most sources recommend not using urinalysis in patients under 65 years of age, with three or more classic features. 90% of these patients are likely to have a positive urine culture.
For women under 65 years with mild or up to two symptoms, a urine sample is required to:
Assess its cloudiness
Consider urinalysis
Consider a urine culture
Remember that urinalysis requires the sample having enough time to contact the bladder - frequency may affect quality of results.
False-negative nitrite tests are common, but false positives are uncommon
Leukocyte esterase detects the presence of pyuria which can be a non-specific finding.
The absence of both nitrites and leukocyte esterase reliably excludes UTI.
Blood and/or protein in urine are consistent with UTI, but are often non-specific findings
Diagnosis
Most laboratories take 105 colony-forming units per millilitre (cfu/ml) as the threshold for diagnosing significant bacteriuria.
Lower counts such as 103 or 104 of a pure growth of Escherichia coli (E. coli) or Staphylococcus saprophyticus may be significant if women have definitive symptoms of a urinary tract infection and there are white cells present on microscopy.
Epithelial cells with mixed growth may suggest contamination of the specimen.
Sterile pyuria may be due to Chlamydia. Tuberculosis is less likely but still recognised as an important cause of sterile pyuria. Other causes include STIs, renal tumour or calculus, genitourinary tuberculosis, and antibiotic therapy prior to collecting an MSU
No white cells indicates a lack of an immune reaction. This could indicate that bacteriuria is contamination but it also occurs in the immunosuppressed.
Management
Patients with visible haematuria and those over forty years old with microscopic haematuria should be referred for a 2 week wait urology appointment to exclude malignancy.
Antibiotics:
3 days for women, 7 days for men.
In nitrofurantoin, nausea is less likely if you use the modified release formulation (100mg twice daily).
One study suggests that NSAIDs are as effective as antibiotics!
Do not treat asymptomatic bacteriuria, even if catheter associated, which occurs in 25% of women >65years, and 10% of men >65years. A positive urine culture or dipstick test will not differentiate between a urinary tract infection or asymptomatic bacteriuria. Pregnant people should be treated for asymptomatic bacturia, and then have regular urine cultures at each antenatal visit.
Dietary Advice
Cranberry juice might interfere with the attachment of bacterial to uroepithelial cells. It is not useful acutely as treatment of UTIs. Increased oral hydration has little benefit in the acute management of an established UTI and reduced the concentration of antibiotics in the urine. Tea, coffee (caffeine-containing drinks), and alcoholic and citrus drinks should be avoided until symptoms have resolved as they can cause bladder irritation. These drinks should be replaced by water.
Recurrent UTI
- diabetes mellitus
- obesity
- chronic constipation
- poor fluid intake and infrequent voiding of urine
- atrophic vaginitis
- use of tampons
Differential Diagnoses
Atrophic Vaginitis
Presents with superficial stinging and burning on urination and watery non-odourous vaginal discharge. Examination is likely to show mild atrophic vaginal changes only. This is likely due to menopausal changes, and might respond to vaginal oestrogen from cream, pessarys or rings.
Acute ProstatitisCan present similarly to UTIs, but is more likely to also have systemic symptoms such as lower back pain, genital pain and a fever.
Interstitial CystitisOccurs in young people with suprapubic pain and fullness and frequency especially after consuming alcohol. Advise patients to keep a urinary symptom diary, monitor fluid intake and avoid irritants such as caffeine and alcohol.
Need urology follow up.
Purple Bag SyndromeThis is a rare sign of UTI, caused by gram negative bacteria. Treatment is directed towards the underlying bacterial infection and changing the catheter.
DeleriumAcute delirium in elderly patients is a common clinical scenario with protean aetiology, including UTI. Do not treat a positive dipstick in a delirious patient unless there are other indicators of a UTI.
References
http://academiclifeinem.com/paucis-verbis-card-urinary-tract-infection/http://academiclifeinem.com/uncomplicated-urinary-tract-infection-older-adults-diagnosis-treatment-1/
https://jama.jamanetwork.com/article.aspx?articleid=1832516
http://bestbets.org/bets/bet.php?id=1324
http://bestbets.org/bets/bet.php?id=2422http://www.enlightenme.org/learning-zone/spot-diagnosis
http://www.doctors.net.uk/ecme/wfrmNewIntro.aspx?moduleid=1529
http://www.enlightenme.org/learning-zone/have-you-ever-seen
http://elearning.rcgp.org.uk/course/info.php?id=117
http://www.npc.nhs.uk/therapeutics/common_infections/uti/quiz.php
