A 7-year-old boy from Delhi presents with fever, left eye swelling, and proptosis for 2 days. On examination, the left eye shows chemosis, lid edema, and ophthalmoplegia (restricted upward and medial gaze). Fundoscopy reveals disc edema. CT orbit shows diffuse infiltration of orbital fat with stranding. Blood culture is pending. Which of the following is the most appropriate immediate next step in management?

Explanation

## Clinical Diagnosis: Acute Orbital Cellulitis **Key Point:** Orbital cellulitis is a medical emergency presenting with fever, proptosis, chemosis, ophthalmoplegia, and disc edema — this child has classic signs. **High-Yield:** The presence of ophthalmoplegia (restricted eye movements) and disc edema indicates severe inflammation and risk of vision loss. Imaging shows diffuse infiltration without loculation, consistent with cellulitis rather than abscess. ### Pathophysiology Orbital cellulitis is typically caused by: - *Streptococcus pneumoniae* (most common in children) - *Staphylococcus aureus* (including MRSA) - Gram-negative organisms (especially if sinusitis source) - Polymicrobial infection in immunocompromised hosts The infection spreads from adjacent paranasal sinuses (ethmoid most common), dental sources, or hematogenously. ### Management Algorithm ```mermaid flowchart TD A[Suspected orbital cellulitis]:::outcome --> B{Systemic toxicity + ophthalmoplegia?}:::decision B -->|Yes| C[Admit to hospital]:::action C --> D[Blood culture + imaging]:::action D --> E[Start IV antibiotics immediately]:::action E --> F[Ceftriaxone 2g IV 6-hourly + Vancomycin 15-20 mg/kg IV 6-hourly]:::action F --> G{Response in 48-72 hrs?}:::decision G -->|Yes| H[Continue IV antibiotics 7-10 days, then oral switch]:::action G -->|No| I[Repeat imaging to exclude abscess]:::decision I -->|Abscess present| J[Surgical drainage + antibiotics]:::urgent I -->|No abscess| K[Consider immunocompromise, change antibiotics]:::action ``` **Clinical Pearl:** Do NOT wait for culture results — orbital cellulitis can progress to cavernous sinus thrombosis, meningitis, or blindness within hours. Empiric broad-spectrum coverage is mandatory. **Antibiotic Regimen (Age-adjusted):** - **First-line:** Ceftriaxone 2 g IV 6-hourly + Vancomycin 15–20 mg/kg IV 6-hourly - **Rationale:** Covers *S. pneumoniae*, *S. aureus* (including MRSA), and gram-negatives - **Duration:** 7–10 days IV, then oral switch (amoxicillin-clavulanate or cephalexin) for 2–3 weeks total **Imaging Role:** - CT/MRI to confirm cellulitis vs. abscess - Assess for sinusitis (source control) - Exclude cavernous sinus involvement - Abscess formation requires surgical drainage in addition to antibiotics **Monitoring for Complications:** - Vision loss (optic neuropathy, retinal ischemia) - Cavernous sinus thrombosis (bilateral signs, altered consciousness) - Meningitis (neck stiffness, headache) **Tip:** Ophthalmoplegia + disc edema = severe inflammation; this patient needs ICU-level monitoring and aggressive IV therapy, not outpatient oral antibiotics. [cite:Khurana Ophthalmology Ch 12]