What is the best treatment for a patient with a malodorous coccyx wound, containing small amounts of pus, and culture results showing many polymorphonuclear leukocytes (PMNs), red blood cells (RBCs), squamous epithelial cells, and Gram-positive cocci?

Treatment of Malodorous Coccyx Wound with Gram-Positive Cocci

This infected coccyx wound requires immediate incision and drainage combined with systemic antibiotics targeting Gram-positive cocci, specifically using an anti-staphylococcal agent such as cefazolin or clindamycin, with the choice depending on local MRSA prevalence and patient factors. 1

Immediate Surgical Management

Incision and drainage is the cornerstone of treatment for this purulent wound and must be performed urgently. 1, 2

• The presence of pus, even in small amounts, mandates surgical drainage as antibiotics alone provide no clinical benefit for established abscesses 1, 3
• The coccyx location is particularly prone to abscess formation and requires thorough debridement of any necrotic tissue 1
• After drainage, simply covering the wound with a dry sterile dressing is usually most effective; packing causes more pain without improving healing 1

Culture-Guided Approach

Obtain deep tissue cultures after cleansing and debriding the wound, but before initiating antibiotics. 1

• The culture showing many PMNs, RBCs, and Gram-positive cocci confirms active infection requiring treatment 1
• Gram-positive cocci in this setting are most likely Staphylococcus aureus or streptococci 1
• The malodorous nature suggests possible anaerobic co-infection, though the Gram stain doesn't show this 1

Empiric Antibiotic Selection

For Methicillin-Susceptible Organisms (MSSA):

Cefazolin 1-2 grams IV every 8 hours is the preferred first-line agent for moderate-to-severe infections. 1, 4

• Cefazolin provides excellent coverage against methicillin-susceptible S. aureus and streptococci 1, 4
• Alternative oral option: Cephalexin 500 mg four times daily for less severe cases 1

For MRSA Risk Factors:

Add empiric MRSA coverage if local prevalence exceeds 20%, or if the patient has recent healthcare exposure or prior MRSA infection. 1

MRSA-active options include:

• Vancomycin 15 mg/kg IV every 12 hours for severe infections requiring parenteral therapy 2
• Clindamycin 300-450 mg PO every 6 hours for moderate infections suitable for oral therapy 1, 5
• Trimethoprim-sulfamethoxazole or doxycycline as alternatives 1, 2

Special Consideration for Malodorous Wounds:

If the wound remains malodorous after initial debridement, add metronidazole 500 mg IV/PO every 8 hours for anaerobic coverage. 1, 6

• Foul-smelling wounds suggest anaerobic involvement requiring specific coverage 1
• Metronidazole targets Bacteroides and other anaerobes not covered by anti-staphylococcal agents 6, 7

Duration of Therapy

Continue antibiotics for 5-10 days after adequate drainage for purulent skin infections. 2

• For mild-to-moderate infections: 7-14 days is typically sufficient 1
• Extend therapy beyond 5 days if clinical improvement is inadequate 2
• If underlying osteomyelitis is suspected (given coccyx location), 4-6 weeks of therapy is required 1

De-escalation Strategy

Narrow antibiotic coverage once culture and susceptibility results return. 2, 6

• If cultures grow only methicillin-susceptible S. aureus, switch from vancomycin to cefazolin or an oral agent 1
• If streptococci alone are isolated, penicillin becomes the drug of choice 1
• Clinical response (reduced fever, decreased erythema, improved wound appearance) guides treatment success more than repeat cultures 6

Critical Pitfalls to Avoid

Do not continue antibiotics without adequate surgical drainage—this approach has no evidence of benefit. 3

• Antibiotics are adjunctive to drainage, not a substitute 1
• If fever persists beyond 3-5 days despite antibiotics, re-evaluate for inadequate drainage or resistant organisms 3

Maintain high suspicion for necrotizing fasciitis, especially if pain is disproportionate to physical findings. 1, 3

• Red flags include: hard, woody subcutaneous tissue; edema extending beyond erythema; skin necrosis; bullae; or crepitus 1, 3
• Necrotizing infection requires immediate surgical consultation and broad-spectrum antibiotics (vancomycin plus piperacillin-tazobactam) 1, 3

Do not use topical antibiotics alone for this infected wound with systemic signs. 1

• Topical therapy (mupirocin, retapamulin) is only appropriate for superficial impetigo, not deeper infections with pus 1

Adjunctive Measures

• Optimize glycemic control if diabetic, as this significantly impacts wound healing 1
• Ensure adequate off-loading of the coccyx area to prevent further pressure injury 1
• Elevation and local wound care with dressing changes facilitate drainage 2