Acute urinary tract infections
Urinary tract infection is the presence of organisms in the usually sterile urine. UTIs account for 1-3% of all consultations in general practice per year. UTIs are included in a number of wider syndromes, including pyelonephritis, cystitis, urethritis, epididymitis and prostatitis. UTIs are significantly more common in women than men, due to the much shorter urethra (3cm).
E.coli is by far the most common causative agent of UTIs,followed by Staphylococcus saprophyticus. Other important causes include Klebsiella pneumoniae, Enterobacter spp, and S. aureus.
Risk factors for UTIs include genetics (being a nonsecretor of the ABH blood group antigen) while sex is the biggest behavioural risk factor for premenopausal women, although not so for postmenopausal women.
UTIs can be uncomplicated (these without any underlying structural lesions) or complicated (seen in patients who have had recent instrumentation, obstruction, anatomical or physiological abnormalities). Examples of complicated UTIs include chronic pyelonephritis, perinephric abscess and renal abscess.
Clinical manifestations:
- Cystitis (lower UTI)
- Frequency
- Dysuria
- Urgency
- Stranguria (difficulty in micturition)
- Suprapubic pain
- Hematuria
- Pyelonephritis (upper UTI)
- Costovertebral angle pain or tenderness
- Fever
- Chills
- Cystitis symptoms may or may not be present
- Urosepsis
- Fever
- Chills, rigors
- Sepsis syndrome
Laboratory analysis of urine is the most useful method for determination of UTIs. Perform urine dipstick test to see if nitrites and leukocytes are present, if so, treat prior to return of mid stream urine sample results. If negative but symptomatic, send for MSU to confirm. If patient is feeling systemically unwell, perform blood analysis to check for ‘urosepsis’.
Unstained urine microscopy in a bacterial UTI: numerous white blood cells (pus cells, pyuria) with many small rod-shaped bacteria (bacteriuria).
Image: “Bacterial UTI picture of urine microscopy showing plenty of pus cells and bacteria” by Ajay Kumar Chaurasiya, CC BY-SA 4.0, via Wikimedia Commons.
GP NOTEBOOK SAYS In primary care, a women with uncomplicated cystitis, there is no need for a urinary culture, a simple +ve dipstick test for nitrites and leukocytes is adequate. If the patient has symptoms and the dipstick test is -ve however, send for MSU.
Treatment of non-pregnant women with lower UTI
- First line: Trimethoprim 200mg/12h OR Nitrofurantoin 50mg/6h OR Amoxicillin 500mg/8h 3-6 days
- Second line: Cephalexin 1g/12h
- NOTE - if uncomplicated, consider delayed prescription, avoiding overuse of antibiotics, as often can self resolve and are self limiting.
Treatment of non-pregnant women with upper UTI
- Co-amoxiclav 1.2g/8h IV for 7 days
Treatment of men with UTI