Staphylococcus epidermidis Susceptibility to Clindamycin
Staphylococcus epidermidis shows variable susceptibility to clindamycin, with approximately 10% resistance rates in general populations, but clindamycin is NOT recommended as first-line therapy for S. epidermidis infections, particularly in serious infections like septicemia and endocarditis where resistance rates are significantly higher. 1
Susceptibility Profile
The FDA drug label confirms that at least 90% of methicillin-susceptible S. epidermidis strains exhibit in vitro susceptibility to clindamycin, though clinical efficacy has not been established in adequate controlled trials 2
Historical surveillance data from UK centers showed 10% resistance among S. epidermidis isolates, with resistant strains distributed across geographic regions and uniformly resistant to erythromycin 3
Clindamycin demonstrates poor activity against methicillin-resistant S. epidermidis (MRSE), with no difference in MICs between slime-producing and non-slime-producing strains 4
Critical Clinical Limitations
When NOT to Use Clindamycin for S. epidermidis
S. epidermidis septicemia and endocarditis are NOT suitable for clindamycin therapy due to high resistance rates 1
The Infectious Diseases Society of America recommends vancomycin as empiric therapy for coagulase-negative staphylococcal infections because most are methicillin-resistant, particularly in healthcare-associated infections 5
Clindamycin is bacteriostatic and therefore not recommended for endovascular infections such as infective endocarditis or septic thrombophlebitis 6
Problematic Biofilm Induction
Subinhibitory concentrations of clindamycin induce biofilm formation in MRSE strains, with up-regulation of biofilm-associated genes (atlE and icaA) by 0.18 to 1.4 folds 7
This biofilm induction increases bacterial survival and persistence on device surfaces, worsening device-associated infections 7
When Clindamycin May Be Appropriate
Mixed staphylococcal and anaerobic infections in skin, subcutaneous tissue, diabetic foot, bone and joints are primary indications where clindamycin provides dual coverage 1
Clindamycin demonstrates excellent tissue penetration, particularly in bone and abscesses, though CSF penetration is limited 6
The Infectious Diseases Society of America recommends clindamycin only when local resistance rates are <10% 8
Recommended Alternative Approach
Switch to vancomycin targeting trough levels of 10-15 mg/L for most coagulase-negative staphylococcal infections 5
De-escalate to a semisynthetic penicillin (nafcillin, oxacillin) or first-generation cephalosporin (cefazolin) if susceptibility testing confirms methicillin susceptibility, as beta-lactams are superior to vancomycin for susceptible organisms 5
For prosthetic valve endocarditis caused by S. epidermidis, treat for minimum 6 weeks with vancomycin plus rifampin, adding gentamicin for the first 2 weeks 5
Key Pitfall to Avoid
Do not use clindamycin for serious S. epidermidis infections (bacteremia, endocarditis, device-related infections) where resistance rates are high and bactericidal activity is required 1
Always perform D-zone testing for erythromycin-resistant, clindamycin-susceptible isolates to detect inducible clindamycin resistance 6