Understanding Pyelonephritis: Causes, Symptoms, Treatment & Preventions

What is Pyelonephritis?

Pyelonephritis is a type of urinary tract infection where one or both kidneys become infected. These infections are typically caused by bacteria but can also be due to viruses in rare cases. Pyelonephritis can make individuals feel severely ill and often requires prompt medical treatment.

A kidney infection, also known as pyelonephritis, usually develops when bacteria from an untreated urinary tract infectiontravel up from the bladder to the kidneys. This condition leads to inflammation of the renal pelvis (the junction between the kidney and ureter) and the kidney tissue (parenchyma). It is generally a complication of an ascending urinary tract infection that spreads from the bladder to the kidneys.

Pyelonephritis is one of the most common kidney diseases and can occur in individuals of all ages. Certain populations, such as pregnant women, pediatric patients, and renal transplant recipients, are at higher risk of developing the condition. The symptoms of pyelonephritis often include fever, flank pain, nausea, vomiting, increased urinary frequency, urgency, and a burning sensation during urination. If left untreated, pyelonephritis can lead to complications such as kidney damage or bloodstream infections.

Other factors that increase the risk of a Kidney Infection

Being a Female:The urethra is shorter in women than in men, making it easier for bacteria to travel from outside the body to the bladder. The urethra's proximity to the vagina and anus also makes bacterial entry more likely. Pregnant women are at even higher risk of a kidney infection.

Having a Urinary Tract Blockage:Anything that slows urine flow or prevents complete bladder emptying can raise the risk of a kidney infection. This includes kidney stones,a narrowed urethra,or an enlarged prostate gland.

Having a Weakened Immune System:Medical conditions like diabetesand HIV can weaken the immune system. Certain medications, such as those taken after an organ transplant, can also lower immunity and increase infection risk.

Having Nerve Damage Around the Bladder:Spinal cord injuries or nerve disorders can block the sensation of a bladder infection, making it difficult to recognize an infection that spreads to the kidneys.

Using a Urinary Catheter:Urinary catheters, a medical tube that drain urine from the bladder, can introduce bacteria and increase the risk of kidney infections.These are often used after surgeries or in individuals confined to a bed.

Having a Condition That Causes Urine to Flow Backward:In vesicoureteral reflux, small amounts of urine flow from the bladder back into the tubes connecting the bladder and kidneys. This condition increases the risk of kidney infections, particularly in children and adults with reflux

Causes of Pyelonephritis

The majority of pyelonephritis cases are caused by bacterial infections, with Escherichia coli (E. coli) being the most common culprit about approximately 80% of cases. E. coli is a gram-negative, anaerobic, rod-shaped bacterium that are part of the normal intestinal microbiome and are found in feces and can easily spread to the bladder. When they enter the urinary tract through the urethra, they can travel up to the bladder and potentially reach the kidneys, leading to pyelonephritis. However, several other bacteria and even fungal infections can also lead to kidney infections.

• Klebsiella pneumoniae – A gram-negative, anaerobic rod-shaped bacterium that can infect the urinary tract.
• Enterobacter species – A group of bacteria that can contribute to kidney infections in hospitalized or immunocompromised individuals.
• Proteus mirabilis – A bacterium that produces urease, which can lead to kidney stone formation, increasing the risk of infection.
• Pseudomonas aeruginosa – An opportunistic pathogen that is resistant to many antibiotics, making treatment more challenging.
• Staphylococcus saprophyticus – A bacterium that is commonly associated with UTIs,particularly in young women.
• Enterococcus – A gram-positive bacterium commonly found in the gastrointestinal tract that can cause UTIs and kidney infections.
• Candida albicans – A type of yeast that can infect the urinary tract and kidneys, particularly in people with diabetes,those on long-term antibiotic therapy, or immunocompromised individuals.
• Fungal infections mostly occur, especially in individuals with weakened immune systems.

Pathophysiology of Pyelonephritis

Acute pyelonephritis is primarily caused by Escherichia coli (E. coli)due to its specialized ability to attach to and colonize the urinary tract and kidneys. E. coli possesses adhesive structures known as P-fimbriae, which bind to specific receptors on the surface of uroepithelial cells, facilitating bacterial ascent.

When the kidneys become infected with E. coli, they trigger an immune reaction, releasing chemokines and other inflammatory mediators. This local response, while aimed at combating infection, can also lead to renal parenchymal scarring. A combination of disrupted renal cell barriers, localized inflammation, cytokine release, clotting, and reduced oxygen supply contributes to this scarring. Additionally, inflammatory cytokines, bacterial toxins, and other immune responses can cause widespread kidney involvement, leading to sepsis and, in severe cases, septic shock.

Signs & Symptoms of Pyelonephritis

Symptoms of a kidney infection can appear suddenly and worsen quickly. Common signs include:

• Pain in the back or sides
• Fever and chills
• Nausea and vomiting
• General unwell feeling

A kidney infection may be preceded by symptoms of a lower urinary tract infection (cystitis), These may include:

• Frequent urination
• Pain or burning sensation while urinating
• Urgent need to urinate
• Blood in the urine
• Cloudy or foul-smelling urine

• Loin, Groin, flank, or lower back pain (bilateral or unilateral)
• Abdominal pain
• Systemic illness
• Fever
• Loss of appetite

Diagnostic Test & Investigations

The diagnosis of pyelonephritis involves various laboratory and imaging tests to confirm infection, identify the causative bacteria, and rule out other conditions that may present with similar symptoms.

• History taking
• Physical examination
• A urine dipstick test detects signs of infection, including nitrites, leukocytes, and blood in the urine.
• Midstream urine (MSU) sample is collected for microscopy, culture, and sensitivity testing to determine the bacteria responsible for the infection. It is recommended to obtain this sample before initiating antibiotic therapy.
• Urine culture and sensitivity. Bacteria may grow in urine culture within a few days. Results helps to determine the best antibiotic for treatment
• Full blood count (FBC): Elevated white blood cell count indicates an infection.
• Inflammatory markers such as C-reactive protein (CRP) may be raised.
• Blood cultures can identify bacterial infections that have spread into the bloodstream.
Imaging Studies
• Ultrasound: Helps identify kidney stones, abscesses, or other urinary tract obstructions.
• Computed Tomography (CT) Scan: CT scan provides detailed images of the kidneys and urinary tract to detect structural abnormalities or complications.
• Magnetic Resonance Imaging (MRI): MRI produces high-resolution images of the kidneys and surrounding soft tissues.
• Radionuclide Scan: Uses a small amount of radioactive material to assess kidney function.

Treatment of Pyelonephritis

Antibiotics are the first line of treatment for kidney infections, with additional supportive measures to relieve symptoms and prevent complications. The choice of antibiotics and the duration of treatment depend on the severity of the infection, the patient’s overall health, and laboratory findings.
Symptoms typically begin to improve within a few days of starting antibiotics; however, completing the full prescribed course is essential, even if symptoms resolve early.
In some cases, a follow-up urine culture may be necessary to confirm that the infection has been completely eradicated. If bacteria are still present, an additional course of antibiotics may be required. In most uncomplicated cases, oral antibiotics are effective, with treatment lasting between 7 to 10 days. Common antibiotics used include:

• Trimethoprim-sulfamethoxazole (Bactrim, others)
• Ciprofloxacin (Cipro) or Levofloxacin (Levaquin)
• Cefalexin, co-amoxiclav or trimethoprim.
• Ceftriaxone, Cefotaxime, Ceftazidime, Cefuroxime

The most frequent cause of acute pyelonephritis is E. coli, a combinations of drugs such as oral cephalosporins, sulfamethoxazole-trimethoprim, or fluoroquinolones are commonly prescribed.

Management and Supportive Care

For young, healthy, non-pregnant women with uncomplicated pyelonephritis, outpatient treatment is typically sufficient. The standard treatment regimen includes:

• Antibiotics (initially chosen based on local resistance patterns and adjusted according to urine culture results)
• Analgesics and antipyretics for pain and fever relief, with NSAIDs (nonsteroidal anti-inflammatory drugs) like ibuprofen being commonly used
• Adequate hydration to support kidney function and aid in bacterial clearance

Nursing Management of Pyelonephritis

The subsequent measures are essential for effectively caring for patients with Pyelonephritis

• Monitor vital signs
• Assess patient for level of pain
• Administer analgesics and antipyretics as ordered
• Give antibiotics as prescribed
• Encourage patient to take in copious fluids if not contraindicated
• Keep accurate records of intake and output
• Monitor patients for side effect of Nitrofuratoin or drug reactions such as nausea, vomiting and skin rash
• Examine specimen of urine and culture after decontamination of antimicrobial drugs

Prevention of Pyelonephritis

Reducing the risk of pyelonephritis begins with preventing urinary tract infections (UTIs),as kidney infections typically develop from untreated or recurrent UTIs. Certain lifestyle habits and hygiene practices can significantly lower the likelihood of developing an infection, particularly in individuals prone to UTIs (females).

• Drink plenty of fluids, especially water, to help flush bacteria out of the urinary tract. Proper hydration supports kidney function and reduces bacterial buildup.
• Urinate as soon as you feel the urge instead of delaying, as holding in urine can allow bacteria to multiply in the bladder.
• Empty the bladder completely after sexual activity to help remove bacteria that may have entered the urethra.
• Control blood sugar level to reduces your chance of a urine infection, if you are diabetic
• Wipe from front to back after urinating or having a bowel movement to prevent bacteria from spreading to the urethra.
• Avoid using irritating products in the genital area, such as deodorant sprays or douches, as these can disrupt the natural balance of bacteria and increase the risk of infection.

Differential diagnosis

Some common conditions that also mimics pyelonephritis include:

• Appendicitis
• Cholecystitis
• Ectopic pregnancy
• Endometritis
• Nephrolithiasis
• Pancreatitis
• Pelvic inflammatory disease