Pyelonephritis
Doctor Instruction:
You are currently a senior surgical doctor on call. Your next patient is Jane – a 35-year-old woman presenting with a fever. Please take a history and perform a relevant examination.
Patient History:
Jane Doe - a 35-year-old female - office worker.
You have been feeling unwell for the past few days. Today you took a temperature which was found to be 38.0 degrees C as you had some shivering. Before the fever started, you remember developing a sudden worsening back pain on the lower left side which is associated with nausea and vomiting (no blood or faecal matter – just food). Pain comes in waves and is sharp – rating it a 7/10 pain score. Your urine also looks darker than usual and smells nasty, with blood in it. You have been going to the toilet more often than usual. You feel unwell. You currently have a poor appetite.
Not known to use a catheter. No diarrhoea. No cough. No breathlessness. No flu-like symptoms. No weight loss. No night sweats. Haven't eaten anything abnormal lately.
Ideas, Concerns, Expectations:
You have no idea what is going on. You think you have an infection but do not know what might be causing it. It might be renal stones. You are concerned because of not feeling your usual self. You want to receive some antibiotics.
Past Medical History:
High BMI, diabetes type 2 + renal stones (no known urological problems/ procedure in the past) + HIV (positive)
Drug History:
Metformin NKDA
Family History:
Renal stones
Social History:
You live alone in a flat.
Ex-smoker – used to smoke 10 cigarettes a day for 10 years.
You do not drink.
You currently work as an office worker.
Examination Findings:
Renal angle tenderness (left) + suprapubic tenderness without guarding.
No obvious lymphadenopathy.
Differentials:
Pyelonephritis
Cystitis / Urethritis
Renal stones / hydronephrosis / post renal problems
LUTI
Pelvic inflammatory disease/ gynae problems
Investigations:
Bedside:
Observations
Pregnancy test (to rule out pregnancy/ectopic)
Urine Dipstick /MSU
Bloods:
Blood sugar level, hba1c (diabetes control due to being a risk factor, FBC/ CRP (raised WBC/ CRP in infection) + U&E (renal function) + LFT / bone profile (baseline / rule out any liver pathology causing high temperature), blood culture
Imaging/Special Test:
CT KUB (if diagnosis in doubt/ no improvement after 72 hours of treatment/ deterioration)
USS KUB (post-renal/ structural abnormalities/ stones)
Consider MRI ( in pregnancy/children where renal infection, masses and urinary obstruction are suspected)
Consider MCUG (to identify reflux)
Consider intravenous pyelogram (small kidneys/ ureteric/ caliceal dilatation/blunting with cortical scarring)
Consider renal biopsy (to exclude papillary necrosis – risk is increased )
For recurrent/ chronic pyelonephritis, consider DMSA (to check for scarring and renal damage)
Management (Pyelonephritis):
Conservative:
Rest, hydration, analgesia, /anti-pyrexetics / safety netting / patient education
Admit (indication: pregnant women, severe vomiting, relapse of symptoms, inadequate access to follow-up, social issues, non-concordance with treatment, uncertain diagnosis, oliguria/ anuria, urinary tract obstruction, severe pain, dehydration, inability to take fluids/ medication, signs of sepsis, co-morbidities e.g. diabetes)
Withhold nephrotoxic medications in acute pyelonephritis
Medical:
Antibiotics e.g. cefalexin/ co-amoxiclav/ trimethoprim/ ciprofloxacin. (avoid ciprofloxacin/trimethoprim in pregnancy)
Initiate sepsis 6
Severe cases: dialysis / renal transplantation
Surgery:
If the patient does not respond well to treatment, consider renal abscess or kidney stone causing an obstruction. Consider urology referral - surgery to drain renal/perinephric abscesses / to relieve obstructions causing infection e.g. stones / stenting
Prevention:
Consider prophylactic treatment for those who have symptomatic infection >=3x a year e.g. trimethoprim
Viva Questions:
Explain the pathophysiology of pyelonephritis.
Bacterial Entry: Bacteria, commonly Escherichia coli, enter the urinary tract, often from the urethra, and ascend towards the kidneys. These bacteria multiply, causing infection.
Inflammation of Renal Tissue: The bacteria invade the renal parenchyma, leading to inflammation in the renal pelvis and the kidney tissue.
Release of Inflammatory Mediators: This invasion triggers an immune response, leading to the release of inflammatory mediators, causing damage to the renal tissues.
Obstruction or Reflux: Factors like urinary tract obstructions or vesicoureteral reflux (backward flow of urine from the bladder to the kidneys) can contribute to the persistence and severity of the infection.
Symptoms: Patients experience symptoms like fever, chills, flank pain, abdominal pain, nausea, vomiting, and urinary symptoms like frequent urination and pain during urination.
Complications: Without proper treatment, pyelonephritis can lead to abscess formation, sepsis, kidney damage, and potential scarring of renal tissue.
What are the risk factors of pyelonephritis?
Urinary Tract Abnormalities: Structural issues like kidney stones, blockages, or conditions that cause urine to flow backward towards the kidneys (vesicoureteral reflux) increase the risk.
Urinary Tract Obstructions: Conditions that hinder normal urine flow, such as an enlarged prostate, tumors, or strictures, can raise the likelihood of infection.
Catheter Use: Individuals with urinary catheters are at a higher risk due to the potential for introducing bacteria into the urinary tract.
Gender: Women have a higher susceptibility due to shorter urethras, which make it easier for bacteria to enter the urinary tract.
Pregnancy: Changes in the urinary tract during pregnancy can increase the risk of urinary tract infections, including pyelonephritis.
Weakened Immune System: Conditions or treatments that compromise the immune system, such as diabetes, HIV/AIDS, chemotherapy, or certain medications, can elevate susceptibility to infections.
Recurrent Urinary Tract Infections: Individuals with a history of frequent UTIs are at a higher risk of developing pyelonephritis.
What are the most common pathogens causing urinary tract infections?
The most common pathogens causing urinary tract infections (UTIs) include:
Escherichia coli (E. coli): E. coli is the most prevalent bacteria responsible for the majority of urinary tract infections.
Staphylococcus saprophyticus: Particularly common in young sexually active females, this bacterium is another frequent cause of UTIs.
Klebsiella pneumoniae: This bacterium is known to cause UTIs, particularly in individuals with a compromised immune system.
Proteus mirabilis: Commonly found in complicated UTIs, this bacterium is known to form kidney stones and contribute to recurrent infections.
Enterococcus species: Enterococci are becoming more prevalent as causative agents of UTIs, especially in healthcare settings.
What are the complications of pyelonephritis?
Sepsis: The infection can spread to the bloodstream, causing sepsis, a severe and life-threatening condition.
Kidney Scarring: Prolonged or recurrent infections can lead to scarring of kidney tissue, potentially affecting kidney function.
Kidney Abscess: Formation of abscesses in the kidney, leading to localized collections of pus.
Chronic Kidney Disease (CKD): Severe or untreated pyelonephritis can contribute to the development of chronic kidney disease.
High Blood Pressure (Hypertension): Kidney damage due to persistent infection can lead to hypertension.
Renal Papillary Necrosis: A rare but severe complication causing the death of kidney tissue.