All of the following organisms are intrinsically resistant to clindamycin EXCEPT:

Clindamycin is effective against many gram-positive cocci and anaerobes. Streptococcus viridans (viridans group streptococci) are generally susceptible to clindamycin and this is why clindamycin is an alternative to amoxicillin for endocarditis prophylaxis in penicillin-allergic patients. Pseudomonas aeruginosa is intrinsically resistant to clindamycin (gram-negative rod with outer membrane barrier). MRSA can have inducible clindamycin resistance (D-zone test detects this). Enterococcus species are intrinsically resistant to clindamycin. Clindamycin's spectrum covers gram-positive organisms (streptococci, staphylococci) and anaerobes, but NOT Pseudomonas or Enterococcus.