Understanding Pyelonephritis (Kidney Infections)
New Section
This section provides an introduction to pyelonephritis, its causes, risk factors, and presentation.
Pyelonephritis
- Pyelonephritis refers to inflammation of the kidney resulting from bacterial infection. It affects the renal pelvis and the tissue of the kidney.
- Risk factors for pyelonephritis include female sex, urological abnormalities, visico ureteric reflux (more common in children), pregnancy, and diabetes.
- The most common cause of pyelonephritis is Escherichia coli (E. coli), which is a gram-negative anaerobic rod-shaped bacteria found in feces. Other causes include Klebsiella pneumoniae, enterococcus species, pseudomonas eryginosa, staphylococcus saprophyticus, and candida albicans (fungal infection).
New Section
This section discusses the presentation and investigations for pyelonephritis.
Presentation
- Patients with pyelonephritis have a similar presentation to lower urinary tract infections with symptoms such as dysuria, suprapubic discomfort, and increased frequency of urination.
- Additional symptoms specific to pyelonephritis include fever, loin or back pain (bilateral or unilateral), nausea or vomiting.
- Systemic illness may be present with patients becoming systemically unwell or septic. Other symptoms may include loss of appetite, hematuria (blood in urine), and renal angle tenderness on examination.
Investigations
- Urine dipstick shows signs of infection including nitrites, leukocytes, and blood.
- Midstream urine (MSU) can be sent for microscopy culture and sensitivity testing to establish the causative organism. It is important to collect the sample before starting antibiotics.
- Blood tests show a raised white blood cell count and raised inflammatory markers (e.g., CRP).
- Imaging investigations such as ultrasound or CT of the abdomen may be used to exclude other pathology like kidney stones or abscesses.
New Section
This section covers the management of pyelonephritis, including antibiotic choices and considerations for patients with significant symptoms.
Management
- Referral to hospital is required if there are features of sepsis or it's not safe to manage the patient in the community.
- First-line antibiotics for treating pyelonephritis in the community, according to NICE guidelines from 2018, include cephalexin, co-amoxiclav, trimethoprim (if culture results are available), or ciprofloxacin (considering the risk of tendon damage and lower seizure threshold).
- Patients admitted to hospital with sepsis require the sepsis 6 protocol, which includes three tests (blood lactate level, blood cultures, urine output monitoring) and three treatments (oxygen therapy, empirical broad-spectrum IV antibiotics according to local guidelines, IV fluids).
- Renal abscess or kidney stones obstructing the ureter should be considered in patients with significant symptoms or poor response to treatment.
New Section
This section discusses chronic pyelonephritis and its consequences.
Chronic Pyelonephritis
- Chronic pyelonephritis presents with recurrent episodes of infection in the kidneys.
- Recurrent infections lead to scarring of renal parenchyma and can progress to chronic kidney disease and end-stage renal failure.
- DMSA scan can be used to investigate kidney damage after chronic pyelonephritis. It involves injecting radio-labeled DMSA, which accumulates in healthy kidney tissue. Gamma cameras are used to image the kidneys, and areas that do not take up DMSA suggest damage or scarring.
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