Overview
Definition:
Pyelonephritis is an acute bacterial infection of the kidney parenchyma and renal pelvis
It is a severe form of urinary tract infection (UTI) characterized by fever, flank pain, and systemic signs of illness
In older children, differentiating appropriate antibiotic routes of administration is crucial for effective management and preventing complications.
Epidemiology:
Febrile UTIs, including pyelonephritis, are common in children
While incidence decreases with age, it remains a significant concern
Boys have a higher risk in infancy, but girls have a higher lifetime risk
E
coli is the most common pathogen
Risk factors include vesicoureteral reflux (VUR), urinary tract abnormalities, and constipation.
Clinical Significance:
Prompt and appropriate treatment of pyelonephritis is vital to prevent renal scarring, which can lead to hypertension, chronic kidney disease, and impaired renal function later in life
The choice between intravenous (IV) and oral antibiotics impacts treatment duration, hospitalization rates, and patient outcomes, making it a key consideration for DNB and NEET SS preparation.
Clinical Presentation
Symptoms:
Fever, typically >38.5°C
Chills and rigors
Flank pain or costovertebral angle tenderness
Nausea and vomiting
Abdominal pain
Irritability or lethargy in younger children
Dysuria, frequency, or urgency may be present but are less specific in older children than in lower UTIs.
Signs:
Fever
Tachycardia
Tenderness to percussion over the costovertebral angle
Signs of dehydration
Poor feeding in infants
Abdominal distension
Sometimes signs of sepsis: hypotension, poor perfusion.
Diagnostic Criteria:
Diagnosis is typically based on clinical suspicion combined with laboratory findings
Key criteria include fever (>38.5°C) and evidence of UTI, usually confirmed by urinalysis (pyuria, bacteriuria) and urine culture (growth of >10^5 CFU/mL of a uropathogen).
Diagnostic Approach
History Taking:
Duration and pattern of fever
Presence and location of pain
Associated gastrointestinal symptoms
Voiding symptoms
History of previous UTIs, VUR, or urinary tract anomalies
Recent antibiotic use
Fluid intake and output
Bowel habits (constipation is a risk factor).
Physical Examination:
Assess vital signs, including temperature, heart rate, and blood pressure
Perform a thorough abdominal examination to assess for tenderness or masses
Palpate for costovertebral angle tenderness
Assess hydration status
Examine the genitalia for any abnormalities.
Investigations:
Urinalysis: Leukocyte esterase, nitrites, microscopic pyuria (>10 WBCs/HPF), bacteriuria
Urine Culture and Sensitivity: Gold standard for diagnosis and guiding antibiotic therapy
report significant bacteriuria (>10^5 CFU/mL for clean-catch, >10^4 CFU/mL for catheterized)
Blood tests: Complete blood count (leukocytosis), C-reactive protein (elevated), blood cultures (if sepsis is suspected)
Renal and Bladder Ultrasound: To assess for hydronephrosis, renal abscesses, structural abnormalities, and bladder abnormalities
Consider Voiding Cystourethrography (VCUG) or radionuclide cystography after the acute episode if indicated (e.g., recurrent pyelonephritis, significant hydronephrosis) to assess for VUR
Renal Scarring: DMSA scan is the gold standard for detecting renal scarring, usually performed 4-6 months post-episode.
Differential Diagnosis:
Appendicitis
Mesenteric adenitis
Pneumonia (especially lower lobe)
Gastroenteritis
Constipation
Pelvic inflammatory disease (in adolescents)
Nephrolithiasis (less common in children)
Intussusception.
Management
Initial Management:
Hospitalization is generally recommended for infants <2 months, children with signs of sepsis, those who are vomiting or unable to tolerate oral intake, or when IV therapy is required
Oral rehydration and antipyretics (acetaminophen or ibuprofen) for fever management.
Medical Management:
Antibiotic Choice (IV vs Oral): The decision depends on the child's age, severity of illness, ability to tolerate oral intake, and local resistance patterns
\n\nIV Antibiotics (Indications: Moderate to severe illness, dehydration, vomiting, inability to take oral meds, sepsis): \n- Ceftriaxone: 50-100 mg/kg/day IV divided every 24 hours (max 2g/day)
\n- Gentamicin: 1-2 mg/kg/dose IV/IM every 8 hours (for neonates and older children, monitor renal function and drug levels)
\n- Cefotaxime: 50 mg/kg/dose IV every 6-8 hours
\n\nOral Antibiotics (Indications: Mild to moderate illness, able to tolerate oral intake, transitioned from IV): \n- Cephalexin: 10-20 mg/kg/day PO divided every 6-8 hours
\n- Trimethoprim-sulfamethoxazole (TMP-SMX): 8-12 mg/kg/day PO divided every 12 hours (consider local resistance patterns)
\n- Amoxicillin-clavulanate: 10-20 mg/kg/day PO divided every 8 hours
\n- Fluoroquinolones (e.g., Ciprofloxacin): Generally reserved for older children and adolescents with documented resistance to other agents, or complicated infections, given potential for cartilage damage (e.g., 15-20 mg/kg/day PO divided every 12 hours)
\n\nDuration of Therapy: Typically 7-14 days
Shorter courses (e.g., 7 days) may be sufficient for uncomplicated pyelonephritis in older children who respond well to oral agents
Longer courses may be needed for complicated cases or those with renal abscesses
Transition to oral therapy once afebrile for 24-48 hours and tolerating oral intake
Empirical therapy should be adjusted based on urine culture and sensitivity results.
Surgical Management:
Rarely indicated in the acute phase
Indications include a suspected or confirmed renal abscess that does not improve with antibiotics, or urinary obstruction
Percutaneous drainage may be considered for abscesses
Surgical intervention for underlying structural abnormalities (e.g., VUR with recurrent infections) is typically performed after resolution of the acute infection.
Supportive Care:
Intravenous fluid resuscitation for dehydration
Antipyretics for fever
Pain management
Monitor vital signs closely
Monitor urine output
Strict intake and output charting
Nutritional support as tolerated.
Complications
Early Complications:
Renal abscess formation
Perinephric abscess
Sepsis
Bacteremia
Acute kidney injury.
Late Complications:
Renal scarring leading to chronic hypertension
Impaired renal function
Recurrent pyelonephritis
Chronic kidney disease.
Prevention Strategies:
Prompt diagnosis and adequate antibiotic treatment
Identification and management of predisposing factors like VUR or urinary tract obstruction
Good hydration
Encouraging complete bladder emptying
Prompt treatment of constipation.
Prognosis
Factors Affecting Prognosis:
Severity of initial infection
Promptness and appropriateness of treatment
Presence of underlying urinary tract abnormalities (e.g., VUR, obstruction)
Age of the child at initial infection
Number of prior febrile UTIs.
Outcomes:
With appropriate and timely treatment, most children recover completely without long-term sequelae
However, a significant proportion may develop renal scarring, especially after severe infections or in the presence of VUR
Early detection and management of VUR are key to preventing long-term morbidity.
Follow Up:
Close follow-up is recommended
For children with confirmed pyelonephritis, especially those with risk factors, consider imaging (ultrasound, possibly VCUG/DMSA) to assess for structural abnormalities or scarring
Educate parents on signs of recurrent infection and importance of hydration and voiding habits
Monitor blood pressure periodically in children with known renal scarring.
Key Points
Exam Focus:
The choice between IV and oral antibiotics in pyelonephritis depends on the severity of illness and the child's ability to tolerate oral intake
Ceftriaxone is a common IV choice
Cephalexin and TMP-SMX are frequently used oral agents
Antibiotic duration is typically 7-14 days
Renal scarring is a significant long-term complication.
Clinical Pearls:
Always obtain a urine culture and sensitivity, even if starting empirical antibiotics
Consider renal and bladder ultrasound in all infants and young children with pyelonephritis
VCUG is indicated after the acute episode in selected children to evaluate for VUR
Don't forget to consider constipation as a contributing factor to UTIs.
Common Mistakes:
Inadequate duration of antibiotic therapy
Failure to obtain urine culture
Delaying treatment due to mild symptoms in a potentially severe illness
Not considering underlying structural abnormalities
Over-reliance on imaging before acute infection resolves
Incorrect interpretation of antibiotic sensitivity patterns.