Clindamycin Dosing When Used With Zosyn
For adult patients with surgical site infections receiving Zosyn (piperacillin-tazobactam), clindamycin should be dosed at 600-900 mg IV every 8 hours when used as adjunctive therapy for anaerobic and gram-positive coverage. 1
Standard Dosing Regimens
For Surgical Prophylaxis (Beta-Lactam Allergy)
- Initial dose: 900 mg IV slow infusion 1
- Re-dosing: 600 mg IV if surgical duration exceeds 4 hours 1
- Maximum duration: Single dose for most procedures; up to 48 hours maximum for contaminated wounds 1
For Treatment of Established Infections
- Standard dose: 600-900 mg IV every 8 hours 1
- Pediatric equivalent: 10-13 mg/kg/dose IV every 6-8 hours (not to exceed 40 mg/kg/day) 1
- This dosing applies to complicated skin and soft tissue infections, necrotizing fasciitis, and osteomyelitis 1
Key Considerations With Concurrent Zosyn Use
Why Clindamycin May Be Added to Zosyn
- Toxin suppression: Clindamycin provides superior toxin suppression in streptococcal infections, particularly necrotizing fasciitis caused by group A streptococci 1
- Enhanced anaerobic coverage: While Zosyn covers many anaerobes, clindamycin provides additional coverage against gram-positive anaerobic cocci 1
- MRSA coverage: Clindamycin adds coverage for community-acquired MRSA when clindamycin resistance rates are low (<10%) 1
Specific Clinical Scenarios
Necrotizing Fasciitis (Group A Streptococcus)
- Clindamycin 600-900 mg IV every 8 hours PLUS penicillin (not Zosyn alone) 1
- Clindamycin is essential due to toxin suppression and superior efficacy versus beta-lactams alone 1
Mixed Polymicrobial Infections
- Zosyn alone may be sufficient for most mixed aerobic-anaerobic infections 2, 3
- Add clindamycin 600-900 mg IV every 8 hours only if specific gram-positive or toxin-mediated pathology is suspected 1
Surgical Prophylaxis in Beta-Lactam Allergic Patients
- Clindamycin 900 mg IV + gentamicin 5 mg/kg/day as single doses 1
- This replaces (not supplements) standard cephalosporin or Zosyn prophylaxis 1
Renal Function Adjustments
For Clindamycin
- No dose adjustment needed for renal impairment, as clindamycin is primarily hepatically metabolized 1
- This is a major advantage when Zosyn requires dose reduction for renal dysfunction
For Zosyn (Concurrent Consideration)
- Zosyn requires dose adjustment for CrCl <40 mL/min, but clindamycin does not 3
- In severe renal impairment, clindamycin maintains consistent dosing while Zosyn is reduced
Duration of Therapy
Prophylaxis
- Single dose for most clean-contaminated procedures 1, 4
- 48 hours maximum for contaminated wounds or high-risk procedures 1
Treatment
- Complicated SSTI: Minimum 7-14 days depending on clinical response 1
- Osteomyelitis: Minimum 8 weeks, potentially longer with rifampin-based combination 1
- Necrotizing infections: Continue until no further debridement needed and clinical improvement documented 1
Critical Pitfalls to Avoid
- Do not use clindamycin monotherapy for serious gram-negative infections—Zosyn provides essential gram-negative coverage that clindamycin lacks 1
- Check local resistance patterns: Clindamycin should only be used empirically for MRSA if local resistance rates are <10% 1
- Inducible clindamycin resistance: In erythromycin-resistant MRSA, perform D-test to detect inducible clindamycin resistance 1
- Re-dosing intervals: Clindamycin requires re-dosing every 4 hours intraoperatively (not every 2 hours like cephalosporins) due to longer half-life 5
- Pseudomembranous colitis risk: Monitor for Clostridioides difficile infection, particularly with prolonged courses 6