Lincosamides

Agent: clindamycin

Clindamycin can be considered a mix of vancomycin and metronidazole; it has attributes of each drug, but it is not quite as good as either one alone.  Clindamycin is an alternative when treatment requires Gram-positive activity (as with beta-lactam allergies), but it has more variable activity than vancomycin against such pathogens as MRSA and S. pyogenes. Clindamycin also covers many anaerobic organisms, but there is a higher level of resistance among the Gram-negative anaerobes (such as  B. fragilis) than with metronidazole. Because of these limitations and clindamycin’s tendency to cause GI toxicity, it is best used empirically for non-severe infections of the skin and oral cavity, or as definitive therapy when susceptibilities are known.

Spectrum: clindamycin

Good: many Gram-positive anaerobes, Plasmodium species (malaria)

Moderate: Staphylococcus aureus (including some MRSA), Streptococcus pyogenes, Gram-negative anaerobes, Chlamydia trachomatis, Pneumocystis jirovecii, Actinomyces, Toxoplasma

Poor : enterococci,  Clostridium difficile, Gram-negative aerobes

Adverse Effects

Gastrointestinal: Diarrhea is one of the most common adverse effects associated with clindamycin. Clindamycin itself can cause relatively benign, self-limiting diarrhea or can result in more severe diarrhea resulting from superinfection with  Clostridium difficile. C.  difficile–associated diarrhea and colitis can  occur during or after clindamycin therapy and can be life threatening. Patients with diarrhea need evaluation for C. difficile disease, especially if it is severe, associated with fever, or persists after the end of clindamycin therapy.

Dermatologic: Rash may occur with clindamycin,  very rarely with severe manifestations such as Stevens-Johnson syndrome.

Important Facts

• Clindamycin is a reasonable alternative drug for the treatment of staphylococcal infections; however, care must be taken in interpreting the antibiotic susceptibility of these isolates. A significant proportion of organisms that are reported as clindamycin-susceptible but erythromycin-resistant may harbor a  gene for resistance that may lead to high-level clindamycin resistance during therapy. Erythromycin-resistant, clindamycin-susceptible strains should be screened with a D-test  (the microbiology lab will know what you mean) before using clindamycin. If the D-test is positive, then inducible clindamycin resistance is present and clindamycin should not be used.

• Clindamycin’s inhibition of protein synthesis and activity against organisms in stationary-phase growth has been utilized in the treatment of necrotizing fasciitis and other toxin-mediated diseases. Consider the addition of clindamycin to beta-lactam-based therapy when treating these types of infections.

• Clindamycin is nearly 100% orally bioavailable, but oral doses are generally lower than IV doses in order to improve GI tolerance.

What It’s Good For

Treatment of skin and soft-tissue infections, infections of the oral cavity, and anaerobic intra-abdominal infections. It is used topically in the treatment of acne. Clindamycin is a second-line agent (in combination with primaquine) in the treatment of P. jirovecii pneumonia. It is also used to treat malaria in combination with other drugs,  to treat bacterial vaginosis, and in the prophylaxis of bacterial endocarditis.

Don’t Forget!

Almost all antibiotics have been associated with an increased risk of C. difficile disease; however, some studies suggest that clindamycin may confer an especially high risk (note that this is a popular board exam question). Although it is a convenient and relatively well-tolerated drug, clindamycin should not be used lightly because of this risk.

References

Gallagher ,J.C. and MacDougall ,c. (2012). Antibiotics Simplified. Second Edition. Jones & Bartlett Learning, LLC.