From the Guidelines
Clindamycin does not reliably cover gram-negative rods, and its use should be limited to infections where gram-positive or anaerobic coverage is sufficient, or in combination with another antibiotic that provides gram-negative coverage. According to the most recent and highest quality study available, 1, clindamycin has good activity against staphylococci, streptococci, and anaerobes, but misses P. multocida, a type of gram-negative rod. This is consistent with the general understanding of clindamycin's mechanism of action, which involves binding to the 50S ribosomal subunit to inhibit bacterial protein synthesis, but is limited by the cell walls of most gram-negative rods that prevent sufficient penetration of the drug to reach effective concentrations.
Some key points to consider when using clindamycin include:
- Clindamycin is effective against gram-positive organisms, including Staphylococcus aureus and Streptococcus species
- Clindamycin has activity against some anaerobic gram-negative bacteria, but lacks reliable activity against aerobic gram-negative rods
- Clindamycin should be combined with another antibiotic that provides gram-negative coverage when treating infections potentially involving gram-negative rods
- Alternative antibiotics or combination therapy should be selected based on the suspected pathogens and local resistance patterns when gram-negative coverage is essential
It's worth noting that the evidence from 1 and other studies, such as 1 and 1, consistently shows that clindamycin has limited activity against gram-negative rods, and its use should be guided by the specific clinical context and local resistance patterns. However, based on the most recent and highest quality study available, 1, clindamycin is not a reliable option for covering gram-negative rods, and alternative antibiotics or combination therapy should be considered.
From the Research
Clindamycin Coverage
- Clindamycin is known for its activity against anaerobic bacteria, particularly beta-lactamase-producing strains of the Bacteroides species 2.
- It also has good activity against aerobic gram-positive cocci, such as group B streptococci 2.
- However, clindamycin has an absence of activity against aerobic gram-negative rods, such as E. coli 2.
Gram-Negative Rods
- Clindamycin is not effective against gram-negative rods, including E. coli 2.
- Metronidazole is effective in the treatment of infections involving gram-negative anaerobes, but it is unreliable in the treatment of gram-positive anaerobic infections and is ineffective in treating aerobic infections 3.
- The emergence of clindamycin-resistant anaerobic gram-negative rods following therapy is of concern 4.
Susceptibility
- Clindamycin was active against 94% of Bacteroides, Prevotella, and Porphyromonas spp., but was active against only 70% of fusobacteria and 53% of clostridia 5.
- Clindamycin-resistant subpopulations of P. bivia and black-pigmented Prevotella species emerged 7 to 12 days after therapy even among women colonized initially by clindamycin-susceptible strains 4.
- These resistant subpopulations persisted at high frequencies (42 to 50%) 70 to 90 days following therapy 4.