Clindamycin is a lincosamide antibiotic Lincosamides, Oxazolidinones, and Streptogramins Lincosamides (clindamycin), oxazolidinones (linezolid, tedizolid), and streptogramins (dalfopristin [streptogramin A] and quinupristin [streptogramin B]) are structurally different but are grouped... read more that is primarily bacteriostatic. It binds to the 50S subunit of the ribosome, thus inhibiting bacterial protein synthesis.
Pharmacokinetics
Clindamycin is absorbed well orally and can be given parenterally. Clindamycin diffuses well into body fluids except cerebrospinal fluid; it is concentrated in phagocytes. Most of the drug is metabolized; metabolites are excreted in bile and urine.
Indications for Clindamycin
The spectrum of activity for clindamycin is similar to that of the macrolide erythromycin (see table Some Clinical Uses of Macrolides Some Clinical Uses of Macrolides Macrolides (see table Macrolides) are antibiotics that are primarily bacteriostatic; by binding to the 50S subunit of the ribosome, they inhibit bacterial protein synthesis. Macrolides are relatively... read more ) except that clindamycin is
Effective for infections due to anaerobes Overview of Anaerobic Bacteria Bacteria can be classified by their need and tolerance for oxygen: Facultative: Grow aerobically or anaerobically in the presence or absence of oxygen Microaerophilic: Require a low oxygen concentration... read more (particularly Bacteroides Mixed Anaerobic Infections Anaerobes can infect normal hosts and hosts with compromised resistance or damaged tissues. Mixed anaerobic infections can include both single anaerobic species or multiple anaerobic species... read more species, including Bacteroides fragilis), community-acquired methicillin-resistant Staphylococcus aureus Staphylococcal Infections Staphylococci are gram-positive aerobic organisms. Staphylococcus aureus is the most pathogenic; it typically causes skin infections and sometimes pneumonia, endocarditis, and osteomyelitis... read more
, and macrolide-resistant, clindamycin-susceptible Streptococcus pneumoniae Streptococcal Infections Streptococci are gram-positive aerobic organisms that cause many disorders, including pharyngitis, pneumonia, wound and skin infections, sepsis, and endocarditis. Symptoms vary with the organ... read more 
Not reliably active against mycoplasmas Mycoplasmas Mycoplasmas are ubiquitous bacteria that differ from other prokaryotes in that they lack a cell wall. Mycoplasma pneumoniae is a common cause of pneumonia, particularly community-acquired pneumonia... read more , chlamydiae Chlamydia Three species of Chlamydia cause human disease, including sexually transmitted infections and respiratory infections. All are susceptible to macrolides (eg, azithromycin), tetracyclines (eg... read more , Chlamydophila species, and legionellae Legionella Infections Legionella pneumophila is a gram-negative bacillus that most often causes pneumonia with extrapulmonary features. Diagnosis requires specific growth media, serologic or urine antigen testing... read more
Aerobic gram-negative bacilli and enterococci are resistant.
Clindamycin is usually used for anaerobic infections; however, clindamycin resistance has emerged among these organisms in some regions. Because these infections often also involve aerobic gram-negative bacilli, additional antibiotics are also used. Clindamycin is part of combination therapy for the following:
With penicillin for infections caused by toxigenic streptococci (because clindamycin decreases the bacteria’s toxin production)
With quinine for babesiosis Babesiosis Babesiosis is infection with Babesia species of protozoa. Infections can be asymptomatic or cause a malaria-like illness with fever and hemolytic anemia. Disease is most severe in asplenic patients... read more
or falciparum malaria Falciparum malaria Malaria is infection with Plasmodium species. Symptoms and signs include fever (which may be periodic), chills, rigors, sweating, diarrhea, abdominal pain, respiratory distress, confusion, seizures... read more
Clindamycin can be used for infections (eg, skin and soft-tissue infections) in communities where community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is common; whether clindamycin is useful depends on local resistance patterns.
Clindamycin can be used for infections due to clindamycin- and erythromycin-susceptible strains. However, some CA-MRSA strains are clindamycin-susceptible and erythromycin-resistant; erythromycin resistance in these strains may be due to an active efflux mechanism or modification of the ribosomal target. If the infecting strain of clindamycin-susceptible CA-MRSA is resistant to erythromycin because of the efflux mechanism, patients can be expected to respond to clindamycin. However, if the strain is erythromycin-resistant because of modification of the ribosomal target, patients may not respond clinically to clindamycin because certain mutants can emerge during clindamycin therapy; these mutants are resistant to clindamycin and erythromycin because of constitutive modification of the ribosomal target. (Constitutive means that resistance is always present regardless of whether an inducer, such as erythromycin, is present.)
Erythromycin resistance due to efflux can be differentiated from that due to inducible ribosomal target modification with a commonly used double disk diffusion assay (D test). A clindamycin disk is placed at a standard distance from an erythromycin disk on an agar plate streaked with a standard inoculum of the CA-MRSA strain in question. Zone of growth inhibition (shaped like the letter “D”) around the clindamycin disk, with a flattened zone nearest the erythromycin disk indicates inducible ribosomal resistance. Patients who have moderate to severe infection with an inducible ribosomal-resistant CA-MRSA strain and a positive D test should not be treated with clindamycin.
Clindamycin cannot be used for central nervous system infections (other than cerebral toxoplasmosis) because penetration into the brain and cerebrospinal fluid is poor.
Contraindications to Clindamycin
Clindamycin is contraindicated in patients who have had an allergic reaction to it, and it should be used with caution in those who have a history of regional enteritis, ulcerative colitis, or antibiotic-associated colitis.
Use During Pregnancy and Breastfeeding
Animal reproduction studies with clindamycin have not shown risk to the fetus. In clinical trials with pregnant women, clindamycin given during the 2nd and 3rd trimesters has not been associated with an increased frequency of birth defects. If medically indicated, clindamycin can be used during pregnancy.
Clindamycin enters breast milk. Use during breastfeeding is not recommended.
Adverse Effects of Clindamycin
The main adverse effect of clindamycin is
Clostridioides (formerly Clostridium) difficile–associated diarrhea Clostridioides (formerly Clostridium) difficile–Induced Diarrhea Toxins produced by Clostridioides difficile strains in the gastrointestinal tract cause pseudomembranous colitis, typically after antibiotic use. Symptoms are diarrhea, sometimes bloody, rarely... read more (pseudomembranous colitis)
Clindamycin, penicillins Penicillins Penicillins (see table Penicillins) are beta-lactamantibiotics that are bactericidal by unknown mechanisms but perhaps by activating autolytic enzymes that destroy the cell wall in some bacteria... read more , cephalosporins Cephalosporins Cephalosporins are bactericidal beta-lactamantibiotics. They inhibit enzymes in the cell wall of susceptible bacteria, disrupting cell synthesis. There are 5 generations of cephalosporins (see... read more , and, most recently, fluoroquinolones Fluoroquinolones Fluoroquinolones (see table Fluoroquinolones) exhibit concentration-dependent bactericidal activity by inhibiting the activity of DNA gyrase and topoisomerase, enzymes essential for bacterial... read more have been associated with C. difficile–associated diarrhea. Clindamycin has been associated with C. difficile–associated diarrhea in up to 10% of patients regardless of route, including topical.
Hypersensitivity reactions may occur. If not swallowed with water, clindamycin may cause esophagitis.
Dosing Considerations for Clindamycin
Dose adjustments are not required for renal failure. Clindamycin is given every 6 to 8 hours.
