Clindamycin Spectrum of Activity
Clindamycin is primarily effective against gram-positive aerobic bacteria (including methicillin-susceptible Staphylococcus aureus and streptococci), most anaerobic bacteria, but has no activity against most gram-negative aerobic bacteria. 1, 2
Spectrum of Activity
Effective Against:
Gram-positive aerobic bacteria:
- Staphylococcus aureus (methicillin-susceptible strains)
- Staphylococcus epidermidis (methicillin-susceptible strains)
- Streptococcus pneumoniae (penicillin-susceptible strains)
- Streptococcus pyogenes (Group A strep)
- Streptococcus agalactiae (Group B strep)
- Streptococcus anginosus
- Streptococcus mitis
- Streptococcus oralis 2
Anaerobic bacteria:
- Clostridium perfringens
- Clostridium clostridioforme
- Fusobacterium necrophorum
- Fusobacterium nucleatum
- Peptostreptococcus anaerobius
- Prevotella melaninogenica
- Prevotella bivia
- Prevotella intermedia
- Actinomyces israelii
- Eggerthella lenta
- Finegoldia (Peptostreptococcus) magna
- Micromonas (Peptostreptococcus) micros
- Cutibacterium acnes 1, 2
Other organisms:
- Chlamydia trachomatis 3
- Select protozoa (Toxoplasma gondii, Plasmodium falciparum, Babesia spp.)
- Select fungi (Pneumocystis jirovecii) 4
Not Effective Against:
Clinical Applications
Clindamycin is recommended for:
- Skin and soft tissue infections, especially those caused by S. aureus (including some MRSA) and streptococci 1
- Mixed aerobic/anaerobic infections 1
- Necrotizing fasciitis (particularly when combined with penicillin for Group A streptococcal infections) 1
- Gynecological infections (endometritis, tubo-ovarian abscess, pelvic inflammatory disease) often combined with gentamicin for polymicrobial coverage 1, 3, 5
- Diabetic foot infections 1
- Animal and human bite wounds 1
Important Considerations
Mechanism of Action
Clindamycin inhibits bacterial protein synthesis by binding to the 23S RNA of the 50S ribosomal subunit, making it bacteriostatic rather than bactericidal 1, 2
Resistance Concerns
- Resistance to clindamycin is most often caused by modification of specific bases of the 23S ribosomal RNA 2
- Cross-resistance between clindamycin and lincomycin is complete 2
- Macrolide-inducible resistance to clindamycin occurs in some isolates of macrolide-resistant bacteria 2
- D-zone testing is recommended to screen for inducible clindamycin resistance in macrolide-resistant staphylococci and beta-hemolytic streptococci 1, 2, 6
Adverse Effects
- Clostridioides difficile-associated diarrhea (pseudomembranous colitis) is a significant concern, though it responds well to discontinuation of clindamycin and treatment with vancomycin or metronidazole 1, 5
Pharmacokinetics
- Average biological half-life: 2.4 hours
- Excellent tissue penetration
- Almost completely absorbed after oral administration, with peak serum levels reached in 45-60 minutes
- Predominantly metabolized by CYP3A4 1, 2, 3
Dosing
- Serious infections: 600-900 mg IV every 8 hours
- Mild to moderate infections: 300-450 mg PO every 6-8 hours 1
Clindamycin remains a valuable antibiotic for treating specific infections, particularly those involving gram-positive and anaerobic bacteria, despite over 40 years of clinical use. However, increasing resistance is a growing concern that may limit its future utility 4.