Clindamycin is active in-vitro against many strains of SA and is indicated in the treatment of SA mild-to-moderate skin and soft tissue infections (SSTIs), including some methicillin-resistant strains ^1,2.  However, evidence for its use as monotherapy against SA infections in other body sites is limited or lacking.   For example, in adults with pneumonia, efficacy of clindamycin is based solely on case series that excluded monotherapy³.  For bone and joint infections, clindamycin has limited evidence of efficacy in adults, and is not recommended in the treatment of endovascular or central nervous system infections².

 Emergence of resistance to clindamycin in previously susceptible SA isolates may also occur during therapy conferred by erythromycin resistance methylase (erm) gene which is typically screened for by the “D-zone” test² (Figure).  Increasing resistance of SA to clindamycin has led to recommendation against its empiric use for severe or complicated SSTIs (e.g. large abscess or deep infections)⁴.  

Fig. The “E” disk (on left) contains erythromycin; “CC” disk (on right) contains clindamycin. The test detects inducible clindamycin resistance in erythromycin-resistant , clindamycin- susceptible isolates (http://www.cdc.gov/groupbstrep/images/lab-positivegbs-lg.jpg).

References:

1. Miller LG, Daum RS, Creech CB, Young D, Downing MD, Eells SJ, Pettibone S, Hoagland RJ, Chambers HF. Clindamycin versus trimethoprim–sulfamethoxazole for uncomplicated skin infections. N Engl J Med 2015;372:1093-103. 
2. Liu C, Bayer A, Cosgrove SE, Daum RS, Fridkin SK, Gorwitz RJ, Kaplan SL, Karchmer AW, Levine DP, Murray BE, Rybak MJ. Clinical practice guidelines by the Infectious Diseases Society of America for the treatment of methicillin-resistant Staphylococcus aureus infections in adults and children. Clin Infect Dis 2011;52:e18-55. 
3. Lobo LJ, Reed KD, Wunderink RG. Expanded clinical presentation of community-acquired methicillin-resistant Staphylococcus aureus pneumonia. Chest 2010; 138:130-6. 
4. VanEperen AS, Segreti J. Empirical therapy in Methicillin-resistant Staphylococcus Aureus infections: An Up-To-Date approach. J Infect Chemother 2016;22:351-9.

Contributed by Nathan T. Georgette, 4th year, Harvard Medical School student