Urinary Tract Infections

Urinary tract infections involve infection in the bladder causing cystitis (inflammation of the bladder). They can spread up to the kidneys and cause pyelonephritis. They are far more common in women where the urethra is much shorter making it easy for bacteria to get into the bladder.

The main source of bacteria for urinary tract infections is from the faeces where the normal intestinal bacteria such as E. coli can easily make the short journey to the urethral opening from the anus. Sexual activity is a key method for spreading bacteria around the perineum. They are also very common in women where incontinence or hygiene are a problem.

Urinary catheters are a key source of infection and catheter-associated urinary tract infections tend to be more significant and difficult to treat.



Lower urinary tract infections present with:

  • Dysuria (pain, stinging or burning when passing urine)
  • Suprapubic pain or discomfort
  • Frequency
  • Urgency
  • Incontinence
  • Confusion is commonly the only symptom in older more frail patients

Pyelonephritis presents with:

  • Fever is a more prominent feature than lower urinary tract infections.
  • Loin, suprapubic or back pain. This may be bilateral or unilateral.
  • Looking and feeling generally unwell
  • Vomiting
  • Loss of appetite
  • Haematuria
  • Renal angle tenderness on examination


Urine Dipstick

Nitrites – gram negative bacteria (such as E. coli) breakdown nitrates, a normal waste product in urine, into nitrites. The presence of nitrites suggest bacteria presence.

Leukocytes – this means white blood cells. There are normally a small number of leukocytes in the urine but a significant rise can be the result of an infection or other cause of inflammation. Urine dipsticks test for leukocyte esterase, a product of leukocytes that gives an indication to the number of leukocytes in the urine.

Nitrites are a better indication of infection than leukocytes. If both are present then the patient should be treated as a UTI. If only nitrites are present then it is worth treating as a UTI however if only leukocytes are present then the patient should not be treated as a UTI unless there is clinical evidence that they have a UTI.

If nitrites or leukocytes are present the urine should be sent to the microbiology lab. If neither are present the patient is unlikely to have a UTI.

Send a midstream urine (MSU) sample to the microbiology lab to be cultured and to have sensitivity testing.



Most common cause is Escherichia coli (E. coli). This is a gram-negative, anaerobic, rod-shaped bacteria that is part of the normal lower intestinal microbiome. It is found in faeces and can easily spread to the bladder.

 Other causes:

  • Klebsiella pneumoniae (gram-negative anaerobic rod)
  • Enterococcus
  • Pseudomonas aeruginosa
  • Staphylococcus saprophyticus
  • Candida albicans (fungal)



Duration of antibiotics:

  • 3 days of antibiotics for a simple lower urinary tract infection in women
  • 5-10 days of antibiotics for women that are immunosuppressed, have abnormal anatomy or impaired kidney function
  • 7 days of antibiotics for men, pregnant women or catheter related UTIs

It is worth noting that NICE recommend changing the catheter when someone is diagnosed with a catheter related urinary tract infection.

Antibiotics Choice

An appropriate initial antibiotic in the community would be:

  • Trimethoprim
  • Nitrofurantoin


  • Pivmecillinam
  • Amoxicillin
  • Cefalexin



Urinary tract infections in pregnancy increase the risk of pyelonephritis, premature rupture of membranes and pre-term labour.

Management in pregnancy:

  • 7 days of antibiotics (even with asymptomatic bacteruria)
  • Urine for culture and sensitivities
  • First line: nitrofurantoin
  • Second line: cefalexin or amoxicillin

Nitrofurantoin is generally avoided in the third trimester as it is linked with haemolytic anaemia in the newborn.

Trimethoprim is generally considered safe in pregnancy but avoided in the first trimester or if they are on another medication that affects folic acid (such as anti-epileptics) due to the anti-folate effects.


Management of Pyelonephritis

Referral to hospital if there are features of sepsis.

NICE recommend the following first line antibiotics for 7-10 days when treating pyelonephritis in the community:

  • Cefalexin
  • Co-amoxiclav
  • Trimethoprim
  • Ciprofloxacin


Last updated March 2019