Urinary Tract Infections: When It Is Simple, and When It Is Not
Urinary tract infections are extremely common, particularly in women, and most are straightforward. The reason they still matter is that a small proportion climb from bladder to kidney, where the illness is entirely different in severity.
Why women get them more
The female urethra is short and close to the anus, giving gut bacteria a brief trip to the bladder. Escherichia coli from the bowel causes the majority of infections.
Risk rises with sexual activity, use of spermicides and diaphragms, pregnancy, menopause through loss of oestrogen in vaginal and urethral tissue, diabetes, urinary retention, catheters, stones and anatomical abnormalities.
In men, UTIs are much less common and are more often associated with an underlying problem such as prostate enlargement, so a UTI in a man generally warrants more investigation than one in a woman.
Lower versus upper
Cystitis, a bladder infection:
- Burning or stinging on passing urine
- Frequency, passing small amounts often
- Urgency
- Lower abdominal discomfort
- Cloudy, strong-smelling urine
- Sometimes visible blood
- No fever, or only a mild one
Pyelonephritis, a kidney infection:
- Fever, often above 38°C, with chills and rigors
- Pain in the flank or loin, or back pain
- Nausea and vomiting
- Feeling systemically unwell
- With or without the bladder symptoms
The second is a different illness, often needs different and longer antibiotics, sometimes intravenously, and should be assessed the same day.
In older adults, the picture changes
Classic symptoms are frequently absent. Confusion, falls, reduced appetite or sudden functional decline can be the presentation.
An important caveat: bacteria in the urine without symptoms, called asymptomatic bacteriuria, is extremely common in older adults and generally should not be treated. Treating it does not help and drives resistance and side effects. Confusion in an older person has many causes, and a positive urine dipstick does not prove the UTI is responsible. This is one of the most frequent diagnostic traps in general practice.
The main exceptions where asymptomatic bacteriuria is treated are pregnancy and before certain urological procedures.
Diagnosis
For a healthy non-pregnant woman with classic symptoms and no complicating features, treatment is often started on symptoms alone.
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A urine culture is appropriate for: men, pregnancy, children, suspected kidney infection, recurrent infection, treatment failure, recent antibiotics, catheters, and anyone with risk factors for resistance. Culture identifies the organism and its sensitivities, which matters increasingly as resistance rises.
Treatment
Short courses, typically three to five days depending on the drug, are sufficient for simple cystitis in women. Longer courses do not work better and cause more side effects.
Which antibiotic depends on local resistance patterns, so there is no universal answer. Nitrofurantoin, fosfomycin and trimethoprim are common first choices in many places; fluoroquinolones are generally reserved because of side effect profiles and resistance concerns.
Finish the course as prescribed, and seek review if symptoms have not improved within 48 hours.
Supportive measures: drink more fluid, pass urine frequently rather than holding, and simple analgesia. Urinary alkalinisers provide some symptom relief but do not treat the infection, and should not be combined with nitrofurantoin, which works better in acidic urine.
Recurrent infections
Defined as two or more in six months or three or more in a year. This deserves a plan rather than repeated identical prescriptions.
Measures with evidence:
- Adequate fluid intake. A trial showed increasing water intake substantially reduced recurrence in women who drank little
- Passing urine after sex
- Avoiding spermicides and diaphragms
- Vaginal oestrogen in post-menopausal women. This is among the most effective interventions and is substantially underused. It restores the protective environment and significantly reduces recurrence, with minimal systemic absorption
- D-mannose, with modest and mixed evidence, but low risk
- Cranberry products, with weak and inconsistent evidence, mostly for prevention rather than treatment, and no benefit once infection is established
- Methenamine hippurate as a non-antibiotic preventive, with reasonable recent evidence
- Low-dose preventive antibiotics, continuous or after sex, as a last resort given resistance concerns
- Self-start treatment, where a reliable patient holds a prescription to begin at symptom onset
Investigation for recurrent infection may include ultrasound and, depending on the pattern, further urological assessment to exclude stones, incomplete emptying or structural problems.
In pregnancy
UTIs in pregnancy are treated more aggressively, including asymptomatic bacteriuria, because of the risk of pyelonephritis and preterm labour. Antibiotic choice is restricted, so self-treatment with leftover tablets is particularly unwise here.
Seek urgent care for
- Fever with flank or back pain
- Shaking chills
- Vomiting that prevents taking medication
- Confusion or marked drowsiness
- Symptoms in pregnancy
- Symptoms not improving after 48 hours of antibiotics
- Visible blood with clots, or difficulty passing urine at all
The short version
A simple bladder infection in a healthy woman needs a short antibiotic course and nothing more. Fever with flank pain is a kidney infection and needs same-day care. For recurrent infections after menopause, vaginal oestrogen is the measure most often missed, and in older adults bacteria in the urine without symptoms is usually best left alone.