Treatment of Dermabacter hominis Infections
Vancomycin is the drug of choice for clinically significant Dermabacter hominis infections, given the high penicillin resistance rate of 84% and universal susceptibility to vancomycin. 1, 2, 3
Key Clinical Context
D. hominis is often a contaminant or colonizer rather than a true pathogen - it was isolated from clinical samples in only 14% of cases where it had definitive or possible clinical significance, with polymicrobial growth evident in 88% of specimens 3
Clinical significance should be determined by: presence of systemic signs (fever, hemodynamic instability), multiple positive blood culture sets, isolation from normally sterile sites, and correlation with clinical presentation 1, 4
Most patients with D. hominis bacteremia have severe underlying conditions including immunosuppression, chronic kidney disease requiring dialysis, or multiple comorbidities 1, 4
Antimicrobial Treatment Algorithm
First-Line Therapy
- Vancomycin - 100% susceptibility across all tested isolates 1, 2
- Use for confirmed infections, particularly bacteremia or serious soft tissue infections
- Standard dosing based on renal function with therapeutic drug monitoring
Alternative Agents (for susceptible isolates)
Linezolid - 100% susceptibility 1, 2
- Excellent oral bioavailability for step-down therapy or outpatient management
Rifampin - 100% susceptibility 1, 2
- Consider as combination therapy for serious infections, though monotherapy data are limited
Agents with Variable Susceptibility
Ampicillin - 83% susceptibility 2
- May be considered only after susceptibility testing confirms sensitivity
Ceftriaxone - 37% susceptibility 2
- Not recommended for empiric therapy given low susceptibility rates
Agents to Avoid
- Benzylpenicillin - universal resistance 1, 2
- Daptomycin - intrinsic high-level resistance (MICs 8-48 mg/L in 93% of isolates) 1, 2
- Erythromycin - 100% resistance 1
- Clindamycin - 73-78.5% resistance 1, 2
Clinical Scenarios and Management
Bacteremia with Systemic Signs
- Initiate vancomycin immediately while awaiting susceptibility results 1
- Obtain at least 2 sets of blood cultures before starting antibiotics 5
- Search for source (catheter-related, soft tissue focus, peritoneal dialysis-related) 1
- Remove infected catheters if present 1
- Duration: 2-3 weeks for uncomplicated bacteremia 6
Soft Tissue Infections
- For immunocompromised patients with suspected D. hominis: empiric vancomycin plus antipseudomonal coverage (piperacillin-tazobactam or carbapenem) until organism identification and susceptibility available 5, 6
- Surgical debridement is essential for necrotic tissue or abscess formation 5, 6
- Obtain tissue biopsy for culture (bacterial, fungal, mycobacterial) if black eschar or recurrent infections present 6
Single Positive Blood Culture or Contamination
- Do not treat if: single positive culture in clinically stable patient without systemic signs, polymicrobial growth suggesting skin contamination, or no clinical correlation 1, 3
- Repeat blood cultures to confirm clinical significance 1
Important Caveats
Daptomycin resistance is intrinsic and near-universal - do not use despite its typical activity against gram-positive organisms 1, 2
Penicillin-based regimens fail in 84% of cases - always use vancomycin or linezolid for empiric therapy 3
Susceptibility testing is critical given variable resistance patterns to multiple agents including fluoroquinolones (21% resistance), gentamicin (7%), and beta-lactams 1, 2
Consider underlying immunosuppression in patients with recurrent or severe D. hominis infections, including HIV testing and assessment for diabetes mellitus 6
Implement decolonization strategies for recurrent infections once acute infection controlled: intranasal mupirocin, chlorhexidine body washes, and treatment of household contacts 6