Author:
Matthew D.Bitner
WilliamManning
Description
- Inflammation of the renal pelvis and kidney
- Severity of illness can vary from mild symptoms to septic shock
- Frequently complication of a lower UTI by bacterial ascension into the upper urinary tract
- Primarily a clinical diagnosis
- Incidence lower in males in every age group
- >50% lifetime incidence in females in some studies
- Male/female ratio:
- 1:10 in first years of life
- 1:5 in children
- 1:50 in reproductive years
- 1:1 in fifth decade and later
- Bilateral infection in up to 25% of cases, hence no lateralizing signs (in some studies)
Etiology
- Bacteriology:
- Escherichia coli (>90% in young women)
- Uropathogens:
- Klebsiella species
- Citrobacter species
- Enterobacter species
- Others:
- Staphylococcus saprophyticus 5-15%
- Proteus mirabilis
- Serratia species
- Pseudomonas species
- Staphylococcus aureus (increasing)
- Cand ida species (rare)
- Predisposing factors (consider complicated infections):
- Recent instrumentation:
- Catheterization
- Cystoscopy
- Urinary retention:
- Mechanical (see Obstruction)
- Medications (e.g., anticholinergics)
- Other infections (e.g., herpes simplex)
- Urinary obstruction:
- Stricture
- Renal calculi
- Prostatic hypertrophy
- Anatomic abnormalities:
- Hypospadias
- Ureteral ectopia
- Bifid ureter
- Renal scarring
- Ureterovesicular reflux (UVR)
- Posterior urethral valves
- Neurologic conditions:
- Neurogenic bladder
- Spinal cord injury
- Abnormal urodynamics
- Previous UTIs (in childhood, >3 in last year)
- Recent pyelonephritis (within 1 yr)
- Diabetes mellitus
- Immunosuppression
- Pregnancy
- Advanced age (>65 yr of age)
Signs and Symptoms
- No consensus on diagnostic criteria
- Typically a combination of both local and systemic inflammation
- Local signs/symptoms:
- Dysuria, urgency, frequency
- Back, flank, or abdominal pain
- Costovertebral angle/suprapubic tenderness
- Systemic signs/symptoms:
- Fever, chills
- Arthralgias, myalgias, malaise
- Nausea and /or vomiting
- Ill/toxic appearing
- Dehydration
- Occult pyelonephritis:
- Invasion of upper urinary tract without clinical symptoms
- Suspect in lower UTI that does not resolve with stand ard treatment
Pediatric Considerations |
- Fever, irritability, vomiting, lethargy, poor feeding, or jaundice may be only symptom in infants
- Enuresis in previously toilet-trained child
- Common cause of a serious bacterial infection (SBI) in neonates, young children, and the immunocompromised (hematogenous spread)
- Renal scarring:
- More common sequelae in young children than in adults
- Group B streptococci
- Etiologic agents in neonates
- Constipation/bowel dysfunction predisposes
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Geriatric Considerations |
Commonly present atypically:- Absence of classic dysuria/frequency
- Instead nausea/vomiting, diarrhea, fever, or altered mental status may predominate
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Essential Workup
- Urinalysis (UA):
- Clean-catch or catheterized urine specimen; catheterized specimen if:
- Vaginal discharge or bleeding
- Contaminated specimen
- Pyuria: 5-10 WBCs, plus leukocyte esterase, plus nitrites:
- If not present, consider alternate diagnosis
- Nitrite represents gram-negative pathogens that convert dietary nitrates to nitrites
- Note that some uropathogens such as Pseudomonas, Enterococcus, and S. saprophyticus are not nitrate reducers
- Hematuria:
- White cell cast: Renal origin of pyuria
- Urine culture and sensitivity (gold stand ard diagnostic confirmatory test):
- Obtain in:
- Suspected pyelonephritis
- Unclear diagnosis
- Treatment failures, recurrent infections
- High clinical suspicion, with negative UA
- >10,000 colony-forming units (CFU)/mL of a uropathogen is positive
- 102-104 CFU considered positive in:
- Early infection
- Clinical scenario consistent with UTI
- Catheter or suprapubic specimen
- Males
Diagnostic Tests & Interpretation
Lab
- CBC:
- Leukocytosis
- Does not rule in or out upper tract infection
- Blood cultures:
- Not needed unless patient is septic; positive cultures do not correlate with more severe disease
- Bacteria identified more readily on urine culture
- Chemistries:
- For patients with significant risk for electrolytes abnormalities (severe nausea/vomiting, or medication use)
- Inflammatory markers:
- Serum procalcitonin correlates more closely than CRP, WBC, or ESR with disease severity scores (e.g., SOFA) and can help differentiate between severities of sepsis. None of the inflammatory accurately predict mortality
Imaging
- Reserve for patients with sepsis/septic shock, known/suspected urolithiasis, urine pH >7, new decrease in GFR <40 (suggests obstruction)
- Imaging is required to differentiate pyelitis (no parenchymal involvement) and pyelonephritis (parenchymal involvement); however, this typically does not alter ED treatment
- Bedside renal US:
- Limited value for characterization but more sensitive than CT for detecting hydro/pyonephrosis/obstruction with experienced operator
- Helical CT:
- Superior to renal US in detecting abnormalities/characterizing extent of disease
- Consistent or concerning findings:
- Strand ing or inflammation and edema of parenchyma
- Perinephric fluid
- Calculi, obstruction
- Renal/perinephric abscess
- Intraparenchymal gas formation (emphysematous pyelonephritis)
- MRI:
- Useful in:
- Pregnant patients (lack of radiation)
- Renal failure (lack of iodinated contrast)
- Cost/availability limit usefulness in the ED
- Obtain imaging if:
- Concomitant stone/obstruction
- At risk for emphysematous pyelonephritis/abscess (diabetes mellitus, immunocompromised, elderly)
- Elective evaluation of genitourinary tract in males with pyelonephritis
Pediatric Considerations |
- Obtain catheter urine specimen:
- Vast majority of bag urine specimens will result in positive cultures (contaminants)
- Clean catch sensitivity 75-100%, specificity 57-100% vs. catheterized or suprapubic specimen
- Helpful only for excluding disease if culture is negative
- Catheterized or suprapubic specimen with >1,000 CFU is positive. Blood cultures usually performed for children <1 yr of age (due to risk for SBI)
- All children with first episode of pyelonephritis should have urinary tract imaging performed later to evaluate for UVR
- Renal US:
- Within 48 hr if no clinical improvement
- Within 3-6 wk if clinical improvement
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Diagnostic Procedures/Surgery
Suprapubic bladder aspiration:
- When urethral catheterization is not successful, or not possible (phimosis, urethral stricture, etc.)
- Contraindicated when there is a overlying infection, a known anatomic abnormality (tumor), recent complete voiding/micturition
Differential Diagnosis
- Abdominal aortic aneurysm or dissection
- Appendicitis
- Cholecystitis
- Cystitis
- Diverticulitis
- Cervicitis/pelvic inflammatory disease
- Endometritis/salpingitis
- Inferior pneumonia
- Prostatitis/epididymitis
- Nephrolithiasis/urolithiasis
- Renal/perinephric abscess
- Urethritis
- Paraspinous muscle disorders
Prehospital
IV access for the ill/toxic-appearing patient with appropriate fluid resuscitation
Initial Stabilization/Therapy
Treat shock with 0.9% normal saline 30 mL/kg (peds: 20 mL/kg) IV fluid bolus
- While shock needs to be treated aggressively, be cognizant of fluid overload in patients with comorbidities (renal failure, congestive heart failure)
ED Treatment/Procedures
- Parental antibiotics for:
- Inability to tolerate oral therapy
- Extremes of age, immunosuppression, and pregnancy
- Failure of oral/outpatient therapy
- Urinary obstruction
- Suspected antibiotic-resistant organisms
- Empiric IV antibiotics:
- Fluoroquinolones (not approved in children)
- Aminoglycoside (gentamicin) plus ampicillin
- Third-generation cephalosporin (ceftriaxone)
- In pregnancy:
- Outpatient oral antibiotics:
- For nontoxic and otherwise healthy patient:
- Fluoroquinolone: 7-14-d course
- May administer 1 dose of parenteral antibiotics prior to oral antibiotics:
- Ensures prompt cessation of bacterial proliferation
- No literature addressing efficacy
- Consider narrower spectrum antibiotics for outpatient therapy (rates of resistance are lower in patients suitable for outpatient therapy)
- Antiemetics and analgesics
Medication
- Oral antibiotics: In patients without urogenital abnormalities, 7-14-d antibiotic courses may be acceptable, while in patients with urogenital abnormalities, a 10-14-d course is recommended:
- IV antibiotics:
- Ceftriaxone: 1 g IV q24h
- Ciprofloxacin: 400 mg IV q12h
- Ampicillin/sulbactam: 3 g IV q6h
- Cefazolin: 1-1.5 g IV q8h
- Gentamicin: 3-5 mg/kg IV load
- Levofloxacin: 500 mg IV daily
- Piperacillin-tazobactam: 3.375 g IV q8h
Pediatric Considerations |
- Oral antibiotic liquid preparations for children:
- Amoxicillin: 30-50 mg/kg/24 hr PO t.i.d
- Amoxicillin/clavulanic acid: 45 mg/kg/24 hr PO t.i.d
- Cefixime: 8 mg/kg PO daily
- Cefpodoxime: 10 mg/kg/24 hr PO b.i.d
- Cephalexin: 50-75 mg/kg/24 hr PO q.i.d
- Erythromycin/sulfisoxazole: 50 mg erythromycin/kg/24 hr PO q.i.d
- Parenteral antibiotics for admitted children:
- Age 0-3 mo:
- Cefotaxime (50-180 mg/kg/d t.i.d) + ampicillin (50-100 mg/kg/d q.i.d)
- Gentamicin (1-2.5 mg/kg/d t.i.d) + ampicillin
- Age >3 mo:
- May substitute ceftriaxone (50-100 mg/kg/d b.i.d to daily) for cefotaxime
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Disposition
Admission Criteria
- Sepsis, ill/toxic appearance
- Inability to tolerate oral therapy
- Intractable nausea/vomiting
- Social situation prevents compliance
- Pregnancy
- Indwelling urinary catheter
- Urinary obstruction/anatomic abnormalities
- Proximal obstruction,
- Immunosuppression/diabetes mellitus
- Extremes of age (children <2-6 mo)
- Failure of outpatient therapy/recent antibiotics
- Need for procedure as guided by imaging
Discharge Criteria
- Clinical course improving in ED
- Ability to maintain oral hydration
- Pain controlled with oral analgesic
- Normal renal function
- Follow-up in 48-72 hr
Follow-up Recommendations
- Uncomplicated cases in patients without comorbidities can safely follow up with their primary care physicians
- If cultures were obtained, patient will need to follow up on results for possible therapy change once antibiotic sensitivities are known
- Pediatric patients all need to follow up with their pediatrician for required imaging for anatomic abnormalities
- Pregnant patients need repeat UA to assess for resolution/recurrence and possible suppressive therapy
- Patients with recurrent infections and those with identified unusual or resistant organisms require close follow-up with urologic and /or infectious disease consultation
- Eliakim-RazN, YahavD, PaulM, et al. Duration of antibiotic treatment for acute pyelonephritis and septic urinary tract infection - 7 days or less versus longer treatment: Systematic review and meta-anaylsis of rand omized controlled trials . J Antimicrob Chemother. 2013;68(10):2183-2191.
- GrodinL, ConigliaroMA, LeeS, et al. Comparison of UTI antibiograms stratified by ED patient disposition . Am J Emerg Med. 2017;35(9):1269-1275.
- JohnsonJR, RussoTA. Acute pyelonephritis in adults . New Eng J Med. 2018;378(1):48-59.
- KorbelL, HowellM, SpencerJD. The clinical diagnosis and management of urinary tract infections in children and adolescents . Paediatr Int Child Health. 2017;37(4):273-279.
- ParkJH, WeeJH, ChoiSP, et al. Serum procalcitonin level for the prediction of severity in women with acute pyelonephritis in the ED: Value of procalcitonin in acute pyelonephritis . Am J Emerg Med. 2013;31(7):1092-1097.
See Also (Topic, Algorithm, Electronic Media Element)
The authors gratefully acknowledge Ingrid Carter for his contribution to the previous edition of this chapter.