What are the appropriate admission orders for an adult patient with suspected acute pyelonephritis, including required laboratory tests, imaging, empiric intravenous antibiotics, fluid management, and monitoring parameters?

Admission Orders for Acute Pyelonephritis

Initiate intravenous ceftriaxone 1–2 grams once daily immediately after obtaining urine and blood cultures, establish IV hydration, and monitor vital signs every 4 hours with reassessment at 48–72 hours for defervescence. 1

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Initial Laboratory Assessment

Obtain the following tests before starting antibiotics:

• Urine culture with antimicrobial susceptibility testing – mandatory in all cases to guide definitive therapy 1, 2, 3
• Urinalysis with microscopy – evaluate for pyuria (>5 WBC/μL), bacteriuria, nitrites, and leukocyte esterase 1, 2
• Blood cultures (two sets from different sites) – recommended if the patient appears systemically ill, has high fever, or shows signs of sepsis 1, 3
• Complete blood count (CBC) – assess for leukocytosis and evaluate severity of systemic response 4
• Basic metabolic panel (BMP) – check renal function (creatinine, eGFR) and electrolytes, particularly in complicated cases 4, 5
• C-reactive protein (CRP) – baseline inflammatory marker useful for tracking treatment response 1

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Empiric Intravenous Antibiotic Therapy

Start antibiotics immediately after cultures are obtained:

• Ceftriaxone 1–2 grams IV once daily – first-line parenteral agent for hospitalized patients 1, 3
• Alternative regimens (if ceftriaxone unavailable or contraindicated):
  • Ciprofloxacin 400 mg IV twice daily 1
  • Levofloxacin 750 mg IV once daily 1
  • Cefotaxime 2 grams IV three times daily 1
  • Cefepime 1–2 grams IV twice daily 1

For patients with sepsis or risk of multidrug-resistant organisms, consider broader coverage with activity against extended-spectrum beta-lactamase (ESBL) producers 3

Plan to transition to oral therapy once the patient is afebrile for 24–48 hours and shows clinical improvement, using culture-directed agents (ciprofloxacin, levofloxacin, or trimethoprim-sulfamethoxazole based on susceptibilities) 1

Total treatment duration: 7–14 days 1, 6, 3

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Intravenous Fluid Management

• Initiate normal saline or lactated Ringer's at 100–150 mL/hour initially, adjusting based on hemodynamic status, urine output, and comorbidities 4
• Goal urine output ≥0.5 mL/kg/hour to ensure adequate renal perfusion and facilitate bacterial clearance 4
• Reduce rate once patient tolerates oral fluids and shows clinical improvement 5

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Monitoring Parameters

Vital signs every 4 hours:

• Temperature, heart rate, blood pressure, respiratory rate, and oxygen saturation 4, 5

Daily assessments:

• Flank pain severity and costovertebral angle tenderness 2, 7
• Ability to tolerate oral intake 5, 3
• Urine output (goal ≥0.5 mL/kg/hour) 4

Expected clinical response:

• 95% of patients become afebrile within 48 hours of appropriate antibiotic therapy 1, 8
• Nearly 100% are afebrile by 72 hours 1, 8

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Imaging Strategy

Initial imaging is NOT required for uncomplicated pyelonephritis in patients responding to therapy 1, 8, 2

Obtain contrast-enhanced CT abdomen/pelvis if:

• Fever persists beyond 72 hours despite appropriate antibiotics 1, 8
• Clinical deterioration occurs at any time 1, 8
• Patient has diabetes (50% lack typical flank tenderness; higher risk for abscess or emphysematous pyelonephritis) 8, 2
• History of urolithiasis, anatomic abnormalities, or immunocompromise 1, 8
• Suspicion of obstruction, abscess, or other complications 1, 8

Renal ultrasound may be used initially to evaluate for hydronephrosis or obstruction, particularly in pregnancy or when contrast is contraindicated, but has limited sensitivity (40%) for parenchymal abnormalities compared to CT (84.4%) 8

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Admission Criteria

Hospitalize patients with:

• Sepsis or hemodynamic instability 5, 3
• Inability to tolerate oral medications due to persistent vomiting 6, 5
• Suspected complicated infection (obstruction, abscess, immunocompromise, diabetes, pregnancy) 6, 5, 3
• Failed outpatient therapy 6, 5
• Extremes of age with significant comorbidities 6
• Solitary kidney or baseline renal insufficiency 4

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Additional Orders

• NPO initially if severe nausea/vomiting, then advance diet as tolerated 5
• Pain management: acetaminophen for fever and NSAIDs or opioids for flank pain as needed 7
• Antiemetics (ondansetron 4–8 mg IV every 8 hours PRN) if nausea/vomiting present 5
• Urinary catheter only if urinary retention or accurate output monitoring required; avoid routine catheterization to prevent nosocomial infection 4

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Common Pitfalls to Avoid

• Delaying urine and blood cultures until after antibiotics are started – reduces diagnostic yield and susceptibility data 2, 3
• Ordering imaging in uncomplicated cases responding to therapy within 48–72 hours – adds unnecessary cost and radiation without improving outcomes 1, 8
• Failing to image when fever persists beyond 72 hours – delays diagnosis of abscess, obstruction, or emphysematous pyelonephritis 1, 8
• Using empiric oral beta-lactams or trimethoprim-sulfamethoxazole without susceptibility data – high resistance rates make these inappropriate for empiric therapy 1, 7
• Assuming all male patients have prostatitis – uncomplicated pyelonephritis can occur in men and may be managed with standard 7–14 day regimens 1

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Follow-Up

• Repeat urine culture 1–2 weeks after completion of antibiotics to document microbiologic cure 6
• If no clinical improvement by 48–72 hours, obtain imaging (CT), repeat blood and urine cultures, and consider alternative diagnoses or resistant organisms 6, 3
• Evaluate for underlying anatomic or functional abnormalities in patients with recurrent pyelonephritis 6, 5