What is the first‑line antibiotic for a secondarily infected molluscum contagiosum lesion in an otherwise healthy patient?

Best Antibiotic for Infected Molluscum Contagiosum

True bacterial superinfection of molluscum contagiosum lesions is rare (occurring in only 12% of cultured cases), and antibiotics should not be routinely prescribed without culture confirmation, as most inflamed lesions represent normal immune-mediated inflammation rather than bacterial infection. 1

Understanding Inflamed vs. Infected Lesions

The critical distinction is that erythema and inflammation around molluscum lesions typically represent a normal inflammatory response as the immune system clears the virus, not bacterial superinfection. 2 This physiologic inflammation is often misinterpreted as infection, leading to unnecessary antibiotic use.

When to Suspect True Bacterial Superinfection

Look for these specific features that suggest actual bacterial infection rather than normal inflammation:

• Purulent drainage (not the typical white cheesy core of molluscum) 1
• Expanding erythema beyond the immediate perilesional area 1
• Warmth, tenderness, and fluctuance suggesting abscess formation 1
• Systemic signs like fever 1

Diagnostic Approach Before Prescribing Antibiotics

Obtain bacterial culture of suspected infected lesions before initiating antibiotic therapy. 1 A recent study demonstrated that despite 71% of patients receiving topical antibiotics and 63% receiving systemic antibiotics, only 12% of cultures actually grew pathogenic bacteria. 1

Culture-Guided Antibiotic Selection

When culture confirms bacterial superinfection (which is uncommon):

• The specific pathogen isolated should guide antibiotic choice 1
• Most commonly isolated organisms in the rare cases of true superinfection are typical skin flora (Staphylococcus aureus and Streptococcus species) 1
• First-line empiric coverage while awaiting culture results should target these common skin pathogens with agents like cephalexin or dicloxacillin for oral therapy, or mupirocin for localized topical therapy 1

The Preferred Management Strategy

Physical removal of the molluscum lesions themselves (curettage, cryotherapy, or excision) is the appropriate first-line intervention rather than antibiotics, as this addresses the underlying viral infection and prevents ongoing inflammation. 2, 3

Treatment Algorithm for Inflamed Molluscum

1. Assess whether true bacterial infection is present (purulence, expanding cellulitis, systemic signs) vs. normal perilesional inflammation 2, 1

2. If true superinfection is suspected, obtain bacterial culture before prescribing antibiotics 1

3. Consider brief observation (24-48 hours) for preliminary culture results when clinically appropriate, as this dramatically reduces unnecessary antibiotic use 1

4. Proceed with physical removal of molluscum lesions (the definitive treatment) regardless of inflammation status 2, 3

5. Reserve antibiotics only for culture-confirmed bacterial superinfection, selecting agent based on isolated pathogen and sensitivities 1

Critical Pitfalls to Avoid

Do not prescribe antibiotics based solely on erythema or inflammation around molluscum lesions, as 47% of pediatricians report never culturing suspected superinfected lesions, yet antibiotics are routinely prescribed despite the 88% rate of negative cultures. 1 This practice contributes significantly to antibiotic overuse and resistance.

The inflamed appearance that often precedes spontaneous resolution of molluscum is frequently mistaken for bacterial infection, leading to unnecessary treatment. 2, 1 This "beginning of the end" inflammation actually indicates the immune system is successfully clearing the virus. 2