Pyelonephritis and Cystitis

 Pyelonephritis and Cystitis

Causes, Pathophysiology, Symptoms, and Management

Introduction

Urinary tract infections (UTIs) are among the most common bacterial infections, predominantly affecting females due to anatomical and hormonal factors. Cystitis refers to inflammation of the urinary bladder, whereas Pyelonephritis denotes infection and inflammation of the renal pelvis and kidney parenchyma. Both conditions are usually caused by ascending bacterial infection from the lower urinary tract but differ in severity, location, and systemic involvement.

Cystitis

Definition

Cystitis is an infection or inflammation of the urinary bladder mucosa, typically resulting from bacterial invasion through the urethra.

Pathophysiology

The infection commonly begins with colonization of the periurethral area by uropathogenic bacteria, predominantly Escherichia coli. Bacteria ascend the urethra and attach to the bladder epithelium via fimbriae (adhesins). The host immune response causes mucosal inflammation, leading to symptoms of dysuria, urgency, and suprapubic pain.

Prolonged or untreated cystitis may allow bacteria to ascend further into the ureters and kidneys, resulting in pyelonephritis.

Common Causes

Bacterial pathogens:

·         Escherichia coli (most common)

·         Klebsiella pneumoniae

·         Proteus mirabilis

·         Enterococcus faecalis

·         Staphylococcus saprophyticus

 Predisposing factors:

·         Female gender (short urethra)

·         Poor perineal hygiene

·         Sexual activity

·         Pregnancy

·         Diabetes mellitus

·         Indwelling catheters

·         Urinary tract obstruction

Clinical Features

• Dysuria (painful urination)
• Urgency and frequency
• Suprapubic pain or discomfort
• Cloudy, foul-smelling urine
• Occasionally, mild hematuria
• Absence of systemic symptoms (fever, chills)

Diagnosis

• Urinalysis: Pyuria, bacteriuria, positive nitrites and leukocyte esterase.
• Urine culture: Confirms the pathogen (>10⁵ CFU/mL is diagnostic).
• Ultrasound/Imaging: Only indicated in recurrent or complicated cases.

Management

Antibiotic therapy (Empiric, then targeted):

Hydration: Increases urinary flow to flush bacteria.

Analgesics: Phenazopyridine for urinary discomfort.

      Prevention:

·         Adequate hydration.

·         Post-coital voiding.

·         Avoiding irritants (bubble baths, perfumed products).

·         Prophylactic antibiotics in recurrent cases.

 Pyelonephritis

Definition

Pyelonephritis is a bacterial infection of the kidney parenchyma and renal pelvis, often resulting from ascending infection from the bladder. It may be acute or chronic.

Pathophysiology

In acute pyelonephritis, bacteria ascend from the bladder via the ureters to the kidneys. The infection causes inflammatory infiltration (mainly neutrophils) within the interstitium and tubular system, leading to tissue edema and necrosis.

In chronic pyelonephritis, recurrent or persistent infections, often due to obstruction or vesicoureteric reflux, cause progressive renal scarring, tubular atrophy, and eventual renal insufficiency.

Common Causes

Bacterial agents:

·         E. coli (most common)

·         Klebsiella spp.

·         Proteus spp.

·         Enterobacter spp.

·         Pseudomonas aeruginosa (especially in hospital-acquired cases)

Predisposing factors:

·         Vesicoureteral reflux

·         Urinary obstruction (stones, strictures)

·         Neurogenic bladder

·         Indwelling catheters

·         Diabetes mellitus

·         Pregnancy

Clinical Features

• High-grade fever with chills
• Flank pain or costovertebral angle tenderness
• Nausea and vomiting
• Malaise
• Dysuria, frequency, urgency (if lower UTI coexists)
• In severe cases: sepsis, hypotension, or renal dysfunction

Diagnosis

• Urinalysis: Pyuria, bacteriuria, WBC casts (specific for renal involvement).
• Urine culture: Identifies causative organism.
• Blood tests: Leukocytosis, elevated ESR/CRP, possible bacteremia. Blood culture and sensitivity.
• Imaging (Ultrasound or CT): Detects obstruction, abscesses, or scarring.

Management

1. Antibiotic therapy:
2. Supportive care:

·         Adequate hydration

·         Antipyretics and analgesics

3. Address underlying cause:

·         Relief of obstruction

·         Management of reflux or stones

·         Removal or replacement of catheters

4. Follow-up:

·         Repeat urine culture after therapy

·         Imaging in recurrent cases to rule out structural abnormalities

Complications

Cystitis	Pyelonephritis
Recurrent infections	Renal abscess
Hematuria	Papillary necrosis
Chronic cystitis	Sepsis
Ascending infection → pyelonephritis	Chronic renal scarring and renal failure

Conclusion

Cystitis and Pyelonephritis represent a continuum of urinary tract infection severity,  from localized bladder inflammation to systemic renal infection. Prompt diagnosis, appropriate antimicrobial therapy, and management of underlying risk factors are crucial in preventing recurrence and long-term renal damage.

Frequently Asked Questions (FAQ) on Pyelonephritis and Cystitis

1. What is the difference between cystitis and pyelonephritis?

Cystitis is an infection or inflammation of the urinary bladder, usually presenting with pain during urination, urgency, and frequency.
Pyelonephritis, on the other hand, is a more severe infection involving the kidneys, often causing high fever, flank pain, and systemic symptoms like nausea and chills.

2. What causes cystitis and pyelonephritis?

Both are primarily caused by bacteria from the intestinal tract, especially Escherichia coli.

• In cystitis, bacteria enter the bladder through the urethra.
• In pyelonephritis, the infection ascends from the bladder to the kidneys or, less commonly, spreads through the bloodstream.

3. Who is at higher risk of developing these infections?

Women are more susceptible due to their shorter urethra. Other risk factors include:

• Diabetes mellitus
• Urinary tract obstruction (stones, tumors)
• Pregnancy
• Indwelling catheters
• Poor hygiene
• Recurrent urinary tract infections

4. What are the common symptoms of cystitis?

Symptoms of cystitis include:

• Burning sensation while urinating (dysuria)
• Frequent urge to urinate
• Suprapubic pain or discomfort
• Cloudy or foul-smelling urine
• Occasionally, mild blood in the urine (hematuria)

5. What are the signs of pyelonephritis?

Pyelonephritis usually presents with:

• High-grade fever and chills
• Flank or back pain
• Nausea and vomiting
• Fatigue and malaise
• Painful urination and urinary frequency

6. How are these conditions diagnosed?

Both conditions are diagnosed using:

• Urinalysis: Detects white blood cells, nitrites, and bacteria.
• Urine culture: Identifies the specific bacteria and their antibiotic sensitivity.
• Imaging (CT or Ultrasound): Used for complicated or recurrent infections to detect obstruction or abscesses.

7. What antibiotics are used to treat cystitis and pyelonephritis?

• Cystitis: Commonly treated with antibiotics recommended by your physician. 
• Pyelonephritis: Requires stronger or intravenous antibiotics such as Ciprofloxacin, Ceftriaxone, or Piperacillin-tazobactam, depending on severity and culture results, and recommended by your physician.  

8. Can untreated cystitis lead to kidney infection?

Yes. If cystitis is not treated promptly, the bacteria can ascend through the ureters to infect the kidneys, resulting in pyelonephritis, which is a more serious and potentially life-threatening condition.

9. How can I prevent recurrent urinary tract infections?

To prevent recurrent infections:

• Drink plenty of fluids daily.
• Maintain good genital hygiene.
• Avoid holding urine for long periods.
• Urinate after sexual intercourse.
• Avoid irritants like perfumed soaps or bubble baths.
• Manage chronic health conditions such as diabetes effectively.

10. When should I see a doctor?

Seek medical attention if you experience:

• Persistent fever or flank pain
• Blood in urine
• Nausea, vomiting, or chills
• Recurrent urinary symptoms
• No improvement after taking antibiotics