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Management of Pyelonephritis in Adults

A urinary tract infection is described by location: urethritis, cystitis and pyelonephritis.

Acute pyelonephritis is an infection of the renal parenchyma and pelvic-calyceal system as result of bacterial ascent along the ureters from the bladder to the kidneys. Although rare, pyelonephritis can occur by haematogenous spread, more commonly occurring in immunocompromised patients or neonates and the common organism is the highly virulent Staphylococcus Aureus. It is a clinical syndrome characterised by urinary symptoms (frequency, urgency, dysuria) and flank pain, fever and nausea or vomiting.

Pyelonephritis can progress to septic shock, renal failure +/- multi-organ failure. The female population, ages 15-29, predominate.

Escherichia Coli is the most prevalent organism >80%. 5-20% prevalence are Klebsiella species, Proteus species, Enterbacter species or Pseudomonas species.


The following populations should be considered complicated pyelonephritis or high risk, have a low threshold for admission and prior to consideration of discharge should be discussed with Renal or General Medical Team:

  • Male sex
  • Elderly
  • Pregnancy
  • History of recurrent UTIs
  • Chronic renal disease
  • Renal transplant
  • Anatomic abnormality of urinary tract
  • Recent Genitourinary instrumentation
  • Co-morbidities (Diabetes Mellitus, immunocompromised)
  • Advanced neurological disease

Yes, if uncomplicated:

Healthy, non-pregnant female. They must tick the following criteria:

  • Look well
  • Haemodynamic stability-normal pulse rate, normal blood pressure
  • Tolerating oral fluids and able to take oral medication
  • Stable social set up with access to follow up within 72 hours


  • Mid Stream Urine (MSU) for dipstick and culture, will be done on all patients where the diagnosis of pyelonephritis is considered.
  • Positive dipstick is leucocyte positive, or nitrite positive or both. Be aware you can get false positives and false negatives so go on clinical suspicion. Urine microscopy is positive WCC >10 x 106 and bacterial colony count >106 (pure growth).
  • FBC and EUC should be done for most patients, and blood cultures sent if febrile.
  • Imaging is generally not required for the stable uncomplicated patient who is being discharged but is recommended if the patient is being admitted, or represents with deterioration or no improvement at follow-up in 72 hours.
  • Ultrasound is generally considered first line where imaging is indicated for pyelonephritis. Although it is not sensitive for changes of pyelonephritis - only 25% of patients will abnormalities on USS - it is useful to assess for local complications of pyelonephritis - hydronephrosis, renal abscess, renal infarct and perinephric collections.
  • Indications for US WA imaging pathways.
  • CT is more sensitive than USS in evaluating the renal tract, however, because of its ionizing radiation dose it is considered second line in young patients.
  • Indication for urgent imaging in the ED:
    • Patient risk factors - immunosuppression, single kidney, renal transplant, diabetes, recurrent episodes, congenital abnormalities
    • Patient severity - any concern for obstruction, abnormal renal function, sepsis, failure to respond to antibiotics
    • Diagnosis - equivocal diagnosis or if an alternative serious diagnosis is being considered.


  • Analgesia for pain
  • Antibiotic therapy as per Therapeutic Guidelines.


Can your patient be discharged home?

No, not if your patient has:

  • Respirations <10 or >25 per minute
  • SpO2 <95%
  • Systolic blood pressure <100mmHg
  • Pulse <50 or >120 per minute
  • Altered LOC or change in cognitive status
  • Temperature <35.5oC or >38.5oC.

Please refer to the Sepsis Pathway.

Discharge advice

At discharge the patient must be aware they should be followed up within 72 hours. Advise them to return to the Emergency Department if they experience any worsening of symptoms / persistent fevers / night sweats. They should see their GP within 72 hours for review of the results of the urine culture.

Further References and Resources

  1. eTG complete [Internet]. Melbourne: Therapeutic Guidelines Limited; 2012 Jul. Available at: eTG - Therapeutic Guidelines Accessed 2 June 2023
  2. Emergency Medicine: A Comprehensive Study Guide 7th edition 2012. Judith Tintinalli, Gabor Kelen, J. Stapczynski, American College of Emergency Physicians
  3. Textbook of Adult Emergency Medicine 3rd edition 2011. Peter Cameron, George Jelinek, Anne-Maree Kelly, Lindsay Murray, Anthony F. T. Brow
  5. International clinical practice guidelines for the treatment of acute uncomplicated cystitis and pyelonephritis in women: A 2010 update by the Infectious Diseases Society of America and the European Society for Microbiology and Infectious Diseases. Gupta K, Hooton TM, Naber KG, Wullt B, Colgan R, Miller LG, Moran GJ, Nicolle LE, Raz R, Schaeffer AJ, et al. Clin Infect Dis. 2011 Mar 1; 52(5):e103-20
  6. M. Grabe (chairman), T.E. Bjerklund-Johansen, H. Botto, B. Wullt, M. Çek, K.G. Naber, R.S., Pickard, P. Tenke. Guidelines on Urological Infections. Uroweb 2011. Available at: Accessed 2 June 2023
  7. Fulop T. (2013, March 4) Acute Pyelonephritis. Available at . Accessed 15 March 2013.

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