What is the management for a [AGE]-year-old female with vesicular lesions resembling chickenpox on the abdomen, no high fever, coriza, or persistent cough, on doxycycline (doxy) for 2 days for bacterial sinusitis?

Management of Vesicular Rash in Context of Bacterial Sinusitis Treatment

Immediate Clinical Assessment

This presentation requires immediate evaluation for varicella-zoster virus (VZV) infection, with discontinuation of doxycycline and initiation of oral acyclovir if varicella is confirmed.

The vesicular rash described is highly suspicious for primary varicella (chickenpox) or potentially disseminated herpes zoster, particularly given the absence of high fever and the localized abdominal distribution. The concurrent treatment with doxycycline for bacterial sinusitis is appropriate to continue for the sinusitis indication, but the new vesicular eruption requires separate diagnostic and therapeutic consideration 1, 2.

Diagnostic Approach

Key Clinical Features to Assess

• Rash characteristics: Vesicular lesions on the abdomen suggest VZV infection, which typically presents with crops of lesions in various stages (macules, papules, vesicles, crusts) 3
• Distribution pattern: Localized abdominal involvement could represent either early varicella or dermatomal herpes zoster 4, 5
• Constitutional symptoms: The absence of high fever does not exclude VZV infection, as many cases in adults are afebrile or have low-grade fever 4
• Exposure history: Recent contact with individuals with chickenpox or shingles is diagnostically significant 4

Diagnostic Testing

Obtain PCR testing from vesicle fluid to definitively distinguish between varicella-zoster virus, herpes simplex virus, and other vesicular eruptions 3. This is particularly important in sexually active individuals where differential diagnosis includes herpes simplex and, in certain epidemiologic contexts, monkeypox 3.

Treatment Recommendations

Antiviral Therapy

Initiate oral acyclovir 800 mg five times daily for 7-10 days if varicella or herpes zoster is confirmed 6, 4. Adults are considered a risk group for VZV complications, including pneumonitis, visceral dissemination, and secondary bacterial infections 4, 5.

• Treatment is most effective when started within 24-72 hours of rash onset 6
• Acyclovir reduces the duration of new lesion formation, accelerates healing, and prevents viral complications 6, 4
• Intravenous acyclovir (750 mg three times daily) is reserved for severe cases with complications such as pneumonia or hemorrhagic rash 4

Management of Concurrent Bacterial Sinusitis

Continue doxycycline for the bacterial sinusitis as prescribed 1, 7. The sinusitis treatment course should be completed (typically 5-7 days for uncomplicated cases) 1, 8.

• Doxycycline is an appropriate alternative agent for bacterial sinusitis in patients with penicillin allergy 9, 7
• The 2-day treatment duration suggests early therapy; reassess sinusitis symptoms at 72 hours 9, 1
• If sinusitis symptoms worsen or fail to improve after 72 hours, consider switching to high-dose amoxicillin-clavulanate (if no penicillin allergy) 9

Monitoring for Complications

VZV-Related Complications in Adults

Adults with varicella are at higher risk for:

• Pneumonitis: Monitor for dyspnea, cough, or chest pain 4, 5
• Secondary bacterial skin infections: Assess for increasing erythema, warmth, or purulent drainage from lesions 4
• Visceral dissemination: Watch for severe systemic symptoms, altered mental status, or hemorrhagic rash 4

Sinusitis Complications

• Orbital complications: Assess for periorbital swelling, proptosis, or impaired extraocular movements 9
• Intracranial complications: Evaluate for severe headache, altered mental status, or focal neurologic findings 9

Critical Pitfalls to Avoid

• Do not delay antiviral therapy while awaiting PCR results if clinical presentation strongly suggests VZV infection, as treatment efficacy decreases significantly after 72 hours 6, 4
• Do not assume the vesicular rash is urticaria or a drug reaction to doxycycline without proper evaluation, as this could delay appropriate antiviral treatment 3
• Do not discontinue sinusitis antibiotics prematurely unless there is clear evidence of drug reaction; bacterial sinusitis and VZV infection can coexist 4
• Do not rely on fever absence to exclude serious VZV infection, as many adult cases are afebrile yet still develop complications 4

Follow-Up Plan

• Reassess within 24-48 hours to evaluate response to antiviral therapy and monitor for complications 4
• Complete the full 7-10 day course of acyclovir even if symptoms improve earlier 6, 5
• Evaluate sinusitis response at 72 hours of doxycycline therapy and adjust antibiotics if needed 9, 1
• Consider underlying immunodeficiency evaluation if varicella is confirmed, as recurrent or severe VZV infections may indicate immune impairment 3