What is the most probable diagnosis for a child who develops fever and shivering after receiving intravenous (IV) antibiotics, also experiencing pain during administration?

Catheter-Related Bloodstream Infection (CRBSI) or Infusion-Related Phlebitis

The most probable diagnosis is a catheter-related bloodstream infection (CRBSI) or infusion-related phlebitis/thrombophlebitis, given the acute onset of fever with rigors immediately following IV antibiotic administration in a previously afebrile child with IV line access.

Clinical Reasoning

The temporal relationship between IV antibiotic administration and symptom onset is the critical diagnostic clue here:

• Immediate fever with rigors following IV medication administration, combined with pain during infusion, strongly suggests either bacterial contamination of the IV line/medication or chemical/mechanical irritation causing phlebitis 1
• The child was afebrile before the antibiotic administration, making the IV line and infusion the most likely culprit rather than progression of an underlying infection 1
• Pain during IV administration indicates either infiltration, phlebitis, or chemical irritation from the medication itself 1

Differential Diagnosis Priority

Most Likely: Catheter-Related Bloodstream Infection

• CRBSI presents with acute fever and rigors during or immediately after infusion when bacteria from a colonized catheter enter the bloodstream 1
• The presence of an indwelling IV line is the primary risk factor 1
• Immediate action required: Stop the infusion immediately, obtain blood cultures (both from the catheter and peripherally if possible), and remove the IV line 1

Second Most Likely: Infusion-Related Phlebitis/Thrombophlebitis

• Chemical phlebitis from the antibiotic itself can cause pain, swelling, and fever 1
• Certain antibiotics (particularly vancomycin, beta-lactams at high concentrations) are known to cause chemical irritation 1
• The pain during administration supports this mechanism 1

Less Likely but Consider: Drug Fever

• Drug fever typically occurs after 7-10 days of drug administration in nonsensitized individuals, not immediately 2, 3
• While antibiotics (especially beta-lactams) are common causes of drug fever, the immediate temporal relationship makes this less likely 2, 4
• Drug fever is generally well-tolerated without rigors, which contradicts this presentation 5

Immediate Management Algorithm

Step 1: Stop the infusion immediately 1

• Leave the cannula in place initially only if you need to draw blood cultures through it 1
• Do NOT flush the line 1

Step 2: Assess for systemic infection

• Monitor vital signs every 4 hours (temperature, pulse, blood pressure, respiratory rate) 1
• Obtain blood cultures from the IV line (if still in place) and from a peripheral site 1
• Look for signs of sepsis: tachycardia, hypotension, altered mental status 1

Step 3: Examine the IV site

• Check for swelling, redness, warmth, or purulent drainage indicating local infection or phlebitis 1
• Assess for infiltration: swelling, bruising, coolness, blanching 1
• Evaluate for thrombophlebitis: palpable cord along vein, unilateral arm swelling 1

Step 4: Remove the IV line

• Send the catheter tip for culture if CRBSI is suspected 1
• Apply direct pressure if bleeding, but avoid occluding outflow distal to the site 1

Step 5: Initiate empiric antibiotics if CRBSI suspected

• Cover for common catheter-associated organisms (Staphylococcus aureus, coagulase-negative staphylococci, Gram-negative bacilli)
• This is separate from the antibiotic that caused the reaction

Critical Red Flags Requiring Escalation

• Unilateral arm swelling: Obtain urgent duplex ultrasound to rule out upper extremity deep vein thrombosis (UEDVT) 1
• Dyspnea or chest pain: Order chest X-ray to rule out air embolism or septic emboli 1
• Vascular compromise: Increasing pain, numbness, coolness, or color changes require immediate emergency evaluation 6, 1
• Signs of septic shock: Hypotension, altered mental status, poor perfusion require immediate intensive care 1

Common Pitfalls to Avoid

• Do not dismiss this as simple drug fever given the immediate onset and presence of rigors—this suggests bacteremia or severe inflammatory response 2, 5
• Do not continue the infusion while investigating—this worsens outcomes if CRBSI or phlebitis is present 1
• Do not apply pressure distal to the IV site if infiltration is present, as this increases intraluminal pressure 1
• Do not assume the antibiotic itself is treating any line infection—the line must be removed and appropriate cultures obtained 1

Prevention for Future IV Access

• Select large veins in the forearm, avoiding joints, inner wrist, or areas with poor venous access 1
• Use flexible cannulae rather than steel needles 1
• Check for blood return before administering medications and regularly throughout infusions 1
• Ensure proper aseptic technique during line insertion and medication preparation 1