Urinary Tract Infection (UTI)

Definition

Urinary Tract Infections (UTIs) are infections that can occur anywhere in the urinary system, which includes the kidneys, ureters, bladder, and urethra. Lower UTIs, such as cystitis, affect the bladder and urethra, while upper UTIs, such as pyelonephritis, affect the kidneys and ureters.

Aetiology

UTIs are commonly caused by bacteria, with Escherichia coli (E. coli) being the most frequent pathogen. Other causative organisms include Staphylococcus saprophyticus, Klebsiella pneumoniae, and Proteus mirabilis.

Pathophysiology

Bacteria enter the urinary tract through the urethra and multiply in the bladder. The infection can ascend from the bladder to the kidneys in upper UTIs. The presence of bacteria triggers an inflammatory response, leading to the typical symptoms of UTI.

Risk Factors

Female gender: Women have a shorter urethra, making it easier for bacteria to reach the bladder.
Sexual activity: Increases the risk of introducing bacteria into the urinary tract.
Urinary tract abnormalities: Structural or functional abnormalities can impede urine flow and increase infection risk.
Catheter use: Indwelling urinary catheters can introduce bacteria into the urinary tract.
Immunosuppression: Conditions like diabetes or medications that suppress the immune system.

Signs and Symptoms

Lower UTI (Cystitis)

Dysuria (painful urination).
Increased frequency and urgency of urination.
Suprapubic pain or discomfort.
Haematuria (blood in the urine).
Cloudy or foul-smelling urine.

Upper UTI (Pyelonephritis)

Fever and chills.
Flank or back pain.
Nausea and vomiting.
Severe abdominal pain.
Signs of systemic infection (e.g., malaise, fatigue).

Investigations

Clinical history and physical examination.
Urinalysis: To detect presence of bacteria, white blood cells, red blood cells, and nitrites.
Urine culture: To identify the causative organism and determine antibiotic sensitivity.
Blood tests: Full blood count (FBC), C-reactive protein (CRP), and renal function tests if upper UTI is suspected.
Imaging: Ultrasound or CT scan in complicated cases or recurrent infections to identify anatomical abnormalities.

Management

Primary Care Management

Empirical antibiotic therapy: Based on local guidelines and resistance patterns. For uncomplicated lower UTI, nitrofurantoin or trimethoprim is commonly used.
Analgesia: To manage pain and discomfort, paracetamol or ibuprofen can be used.
Hydration: Encourage increased fluid intake to help flush out bacteria.
Patient education: Advise on completing the full course of antibiotics, even if symptoms improve.
Referral to a specialist: If symptoms persist, recur frequently, or if an upper UTI is suspected.

Specialist Management

Advanced antibiotics: For upper UTIs or complicated infections, broader spectrum antibiotics may be required (e.g., ciprofloxacin or co-amoxiclav).
Hospital admission: In severe cases of upper UTI or if the patient is systemically unwell.
Imaging studies: To assess for complications such as abscess formation or anatomical abnormalities.
Management of underlying conditions: Addressing any contributing factors such as structural abnormalities or immune suppression.

Example Management for Urinary Tract Infection

A patient presenting with symptoms of a lower UTI, such as dysuria and increased frequency of urination, should be treated with empirical antibiotics such as nitrofurantoin 100 mg twice daily for 3 days or trimethoprim 200 mg twice daily for 3 days. Pain can be managed with paracetamol or ibuprofen, and the patient should be advised to increase fluid intake. If symptoms persist, recur frequently, or if an upper UTI is suspected, the patient should be referred to a specialist for further evaluation and management, which may include imaging studies and broader spectrum antibiotics.

Example Management for Pyelonephritis

A patient presenting with symptoms of pyelonephritis, such as fever, flank pain, and nausea, should be assessed for severity. For mild cases, oral antibiotics such as Cefalexin 500 mg twice or three times daily for 7-10 days or ciprofloxacin 500 mg twice daily for 7-14 days. Severe cases require hospital admission for intravenous antibiotics, such as ceftriaxone or gentamicin, and supportive care including adequate hydration and pain management. Regular follow-up and repeat urine cultures are essential to ensure complete resolution of the infection and to monitor for complications. Referral to a specialist is recommended for recurrent infections or if there are underlying structural abnormalities.

References

NICE. (2024). Urinary Tract Infections: Diagnosis and Management. Retrieved from NICE
NHS. (2023). Urinary Tract Infection (UTI). Retrieved from NHS
British Medical Journal (BMJ). (2021). Urinary Tract Infection: Clinical Review. BMJ.
European Association of Urology (EAU). (2021). Guidelines on Urological Infections. EAU.