SIGNS AND SYMPTOMS 
- Dysuria, urgency, frequency
- Back, flank, or abdominal pain
- Fever, chills
- Arthralgias, myalgias, malaise
- Nausea and/or vomiting
- Costovertebral angle/suprapubic tenderness
- Ill/toxic appearing
- Dehydration
- Occult pyelonephritis:
- Invasion of upper urinary tract without clinical symptoms:
- Suspect in lower UTI that does not resolve with standard treatment.
Pediatric Considerations
- Fever, irritability, 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
Geriatric Considerations
Commonly present atypically:
ESSENTIAL WORKUP
- Urinalysis (UA):
- Clean-catch or catheterized urine specimen; catheterized specimen if:
- Pyuria: 5–10 WBCs, plus leukocyte esterase, plus nitrites:
- If not present, consider alternate diagnosis.
- Nitrite represents a gram-negative pathogens are present that is converting 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:
- Obtain in:
- Suspected pyelonephritis
- Unclear diagnosis
- Treatment failures, recurrent infections
- High clinical suspicion, with negative UA
- > 100,000 colony-forming units (CFU)/mL is positive.
- 102–104 CFU considered positive in:
- Early infection
- Clinical scenario consistent with UTI
- Catheter or suprapubic specimen
- Males
DIAGNOSIS TESTS & INTERPRETATION
Lab
- CBC:
- 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)
Imaging
- 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 except for detecting hydro/pyonephrosis/obstruction
- Helical CT:
- Superior to renal US in detecting abnormalities/characterizing extent of disease
- Consistent or concerning findings:
- Stranding 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).
- 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 1st 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
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
[Outline]
PRE-HOSPITAL
IV access for the ill/toxic-appearing patient with appropriate fluid resuscitation
INITIAL STABILIZATION/THERAPY
Treat shock with 0.9% normal saline 500 mL–1 L (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
- 3rd-generation cephalosporin (ceftriaxone)
- In pregnancy:
- Outpatient oral antibiotics:
- For nontoxic and otherwise healthy patient:
- Fluoroquinolone: 7–14 day course
- May administer 1 dose of parenteral antibiotics prior to oral antibiotics:
- Ensures prompt cessation of bacterial proliferation
- No literature addressing efficacy
- Antiemetics and analgesics
MEDICATION
- Oral antibiotics:
- 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/24h PO TID
- Amoxicillin/clavulanic acid: 45 mg/kg/24h PO TID
- Cefixime: 8 mg/kg PO daily
- Cefpodoxime: 10 mg/kg/24h PO BID
- Cephalexin: 50–75 mg/kg/24h PO QID
- Erythromycin/sulfisoxazole: 50 mg erythromycin/kg/24h PO QID
- Parenteral antibiotics for admitted children:
- Age 0–3 mo:
- Cefotaxime (50–180 mg/kg/d TID) + ampicillin (50–100 mg/kg/d QID)
- Gentamicin (1–2.5 mg/kg/d TID) + ampicillin
- Age > 3 mo:
- May substitute ceftriaxone (50–100 mg/kg/d BID to daily) for cefotaxime
[Outline]
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
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.
[Outline]
- Abraham G, Reddy Y, George G. Diagnosis of acute pyelonephritis with recent trends in management. Nephrol Dial Transplant. 2012;27:3391–3394.
- Lane D, Takher S. Diagnosis and management of UTI and pyelonephritis. Emerg Med Clin N Am. 2011;29:539–552.
- Piccoli BG, Cresto E, Ragni F, et al. The clinical spectrum of acute uncomplicated pyelonephritis from an emergency medicine perspective. Int J Antimicrob Agents. 2008;31(suppl S):S46–S53.
- Talan D, Krishnadasan A, Abrahamian F, et al. Prevalence and risk factor analysis of trimethoprim-sulfamethoxazole and fluoroquinolone resistant E. coli infection among emergency department patients with pyelonephritis. Clin Infect Dis. 2008;47:1150–1158.
See Also (Topic, Algorithm, Electronic Media Element)
Acknowledgment
The author gratefully acknowledges the contribution of Ingrid Carter for previous editions of this chapter.