Acute upper urinary tract infection (pyelonephritis/urosepsis) (Antimicrobial)

TAM (Treatments and Medicines) NHS Highland
NHS Highland

Upper urinary-tract infection (pyelonephritis) in men, women

Send urine sample to bacteriology before treatment commences. If no response to oral treatment in 24 hours consider hospital admission.

NOTE: Avoid co-amoxiclav due to increased resistance in Gram negative pathogens associated with urinary tract infection

NOTE: Avoid ciprofloxacin due to MHRA restrictions (updated January 2024) on the use of fluoroquinolone antibiotics following a review of disabling and potentially long-lasting side effects mainly involving muscles, tendons, bones and the nervous system.  Whilst these antibiotics are likely to be effective in upper urinary tract infection, they should be avoided unless ALL OTHER ORAL ANTIBIOTICS ARE UNSUITABLE.

Co-trimoxazole should be used with caution in severe renal impairment (eGFR less than 30mL/min).  Use with caution with drugs that promote hyperkalaemia and monitor serum potassium levels if used for longer than 3 days.

Due to competition for renal secretion, serum creatinine may rise in any patient without change in glomerular filtration rate – use with caution in renal transplant patients as the rise can be difficult to interpret.

For management of kidney transplant patients, immunocompromised patients and known or suspected infections with multi-drug resistant pathogens including ESBLs, contact Microbiology for discussion of treatment options.

Discuss antimicrobial cover for urinary catheter exchange in a patient with a recent joint replacement with Microbiology.

NOTE: Long-term catheters should be changed after starting antibiotic treatment.

For glossary of terms see Glossary.

Drug details

For moderate illness with systemic upset not requiring hospital admission.

Cefalexin 1 gram, 3 times daily

7 days

In beta-lactam allergy (beware of side effect risk, see notes above)

Co-trimoxazole 960mg, twice daily.  When sensitivities are known, suitable oral agents include amoxicillin and trimethoprim, in addition to those recommended above.

7 days

For severe infection (hospital treated)

Mandatory review of gentamicin following culture and sensitivity information.

Check SCi Store for urinary pathogens isolated in last 6 months not covered by gentamicin and seek advice from Microbiology.

Gentamicin (intravenous) - refer to NHS Highland gentamicin dosing guidelines.

7 to 14 days

In severe renal impairment (CrCl less than 10ml/min) or renal replacement therapy or where gentamicin unsuitable. Review dose if renal function improves.

Cefuroxime (intravenous) 1.5 gram every 24 hours (CrCl <10ml/min or renal dialysis)

1.5 gram every 8 hours in normal renal function

7 to 14 days

When switching to oral therapy without positive microbiology results

Follow recommendations for moderate illness.

For infections arising within 24 hours of surgery where gentamicin has been given as part of surgical prophylaxis

Check gentamicin level. 

  • If <1mg/l, start treatment dose gentamicin as per NHS Highland gentamicin guidelines. 
  • If 1mg/l or higher, substitute gentamicin for cefuroxime (intravenous) 1.5 gram every 8 hours in non-severe penicillin allergy and co-trimoxazole (intravenous) 960mg every 12 hours in severe penicillin allergy. 

ONLY AFTER POSITIVE RESULT FROM MICROBIOLOGY

The tables below are ONLY AFTER POSITIVE RESULT from Microbiology for the current infective episode.
For empiric treatment of urinary tract infection, see table above.
  • The drugs are listed in order of preference from narrow spectrum and limited side effects to broad spectrum with significant side effects.
  • Note: in line with MHRA advice (January 2024) ciprofloxacin should ONLY be used if no other agents are suitable, due to the risk of adverse drug reactions.

First line

ONLY AFTER POSITIVE MICROBIOLOGY RESULT

Trimethoprim 200mg twice daily

OR Amoxicillin 1g three times daily

OR Cefalexin 1g three times daily

  • Trimethoprim: 14 days (evidence for improved outcome versus 7 days)
  • Others: 7 days

Second line

ONLY AFTER POSITIVE MICROBIOLOGY RESULT

Co-trimoxazole 960mg twice daily

7 days

Third line

ONLY AFTER POSITIVE MICROBIOLOGY RESULT

Co-amoxiclav 625mg three times daily

PLUS Amoxicillin 500mg three times daily

7 days

No other suitable option

ONLY AFTER POSITIVE MICROBIOLOGY RESULT

ONLY IF NO OTHER SUITABLE OPTIONS DUE TO SIDE EFFECT

Ciprofloxacin 500mg twice daily

7 days

Editorial Information

Last reviewed: 10/09/2026

Next review date: 10/09/2029

Author(s): Antimicrobial Management Team.

Version: 4

Approved By: TAM Subgroup of ADTC

Reviewer name(s): A MacDonald, Area Antimicrobial Pharmacist.

Document Id: AMT180