26th June 2023

Investigation and treatment

In adults below the age of 65 with risk factors for complicated UTI, urine dipstick can be a basis to start treatment. A dipstick positive for nitrites or leucocytes and blood suggests a UTI. The sample should then be sent for microscopy and culture. Asymptomatic bacteriuria (the presence of bacteria in urine) should be treated in pregnancy as it increases the risk of preterm rupture of membranes. Note that the presence of bacteriuria is common in those over 65 and usually does not need to be treated unless symptomatic.

Antibiotic choice should be guided by sensitivities from culture, but the following are often used:

• Nitrofurantoin 100mg modified-release twice a day for three days
  • must be avoided if eGFR ≤45ml/minute
  • must be avoided in the last trimester of pregnancy due to the risk of haemolytic anaemia of the newborn
  • poor penetration of the kidney so not for complicated UTI
• Trimethoprim 200mg twice a day for three days (if low risk of resistance)

In pregnancy, cefalexin 500mg twice a day can also be considered. Men and pregnant women should be treated for seven rather than three days.