What is the appropriate next step for a female patient with a cat bite wound that remains erythematous, mildly tender, with a palpable bump after one week of amoxicillin‑clavulanate (Augmentin) therapy?

Inadequate Response to Augmentin: Escalate Management Now

This patient requires immediate imaging (ultrasound or CT) to evaluate for abscess or deeper infection, continuation of amoxicillin-clavulanate with extended duration (3-4 weeks minimum), and urgent surgical consultation if imaging reveals fluid collection or if hand/joint involvement is present. 1

Why This Wound Is Not Healing

The persistent erythema, tenderness, and palpable bump after one week of appropriate antibiotics strongly suggests one of three scenarios:

• Deep abscess or fluid collection requiring drainage—cat bites have a 19% abscess rate and frequently cause deep tissue infections that antibiotics alone cannot resolve 2
• Osteomyelitis or septic arthritis—cat bites have higher rates of bone/joint involvement than dog bites due to their needle-like teeth penetrating deeply 1
• Atypical or resistant organism—though less common, Mycobacterium chelonae 3, Bacteroides pyogenes 4, or fungal infections 5 can cause non-healing wounds despite standard therapy

Immediate Diagnostic Steps

Order imaging immediately to identify fluid collections that require drainage:

• Ultrasound is first-line for superficial soft tissue evaluation 4
• CT scan if deeper structures or bone involvement suspected 4
• The presence of a "bump" is concerning for abscess formation requiring incision and drainage 4

If imaging shows fluid collection, surgical drainage is mandatory—antibiotics cannot adequately penetrate abscesses, and operative debridement is required 4

Antibiotic Management Algorithm

Continue amoxicillin-clavulanate 875/125 mg twice daily as it remains the correct choice, but extend duration based on findings: 1

• Uncomplicated soft tissue infection: 7-10 days total (you're at day 7, continue 3 more days minimum) 1
• If abscess drained: 3-4 weeks 1
• If septic arthritis confirmed: 3-4 weeks 1
• If osteomyelitis confirmed: 4-6 weeks 1

The Infectious Diseases Society of America confirms amoxicillin-clavulanate provides comprehensive coverage against Pasteurella multocida (present in 75% of cat bites), anaerobes including Bacteroides species, staphylococci, and streptococci 2, 1

Critical Red Flags Requiring Urgent Intervention

Hand wounds are surgical emergencies until proven otherwise—they have the highest infection and complication rates 1, 6. If this bite is on the hand, immediate surgical consultation is warranted regardless of imaging findings.

Joint involvement requires arthrocentesis—if the bump is near a joint, aspirate to rule out septic arthritis, which requires 3-4 weeks of antibiotics and often surgical washout 1

When to Consider Alternative Diagnoses

If the wound continues to worsen despite drainage (if needed) and extended antibiotics, send both aerobic AND anaerobic cultures from any drainage procedure: 4

• Bacteroides pyogenes can cause intramuscular abscesses and may require 4 weeks of therapy 4
• Mycobacterium chelonae presents as persistent infection despite standard antibiotics and requires clarithromycin-based regimens 3
• Fungal infections (sporotrichosis) can mimic bacterial infection and require antifungal therapy 5

Essential Adjunctive Measures

• Elevate the affected area continuously for the first few days to reduce swelling and accelerate healing 1
• Do not close the wound—infected wounds must heal by secondary intention 1
• Update tetanus if not current within 10 years 1
• Follow-up within 24 hours after any intervention to assess response 1

Common Pitfalls to Avoid

Never assume one week of antibiotics is sufficient for cat bites—these wounds are deceptively dangerous despite appearing less traumatic than dog bites, with higher rates of deep infection, osteomyelitis, and septic arthritis 1, 6

Never switch to first-generation cephalosporins, macrolides, or clindamycin monotherapy—these have poor activity against P. multocida and will lead to treatment failure 1

Never ignore a palpable bump—this physical finding mandates imaging to exclude abscess, as clinical examination alone cannot reliably detect deep fluid collections 4