From the Guidelines
Clindamycin is generally effective against Staphylococcus aureus, but its sensitivity varies depending on the specific strain, and it is crucial to perform antibiotic susceptibility testing before initiating treatment. Many strains of S. aureus remain susceptible to clindamycin, making it a useful antibiotic option for treating staph infections, particularly skin and soft tissue infections 1. However, resistance is increasingly common, especially in methicillin-resistant S. aureus (MRSA). A phenomenon called inducible clindamycin resistance can occur where bacteria appear sensitive in initial lab tests but develop resistance during treatment. For this reason, laboratories perform a D-test to detect this potential for resistance.
Some key points to consider when using clindamycin for S. aureus infections include:
- Typical adult dosing is 300-450 mg orally every 6-8 hours or 600-900 mg IV every 8 hours, with treatment duration varying by infection type, usually 7-14 days 1.
- Clindamycin is effective against both methicillin-susceptible S. aureus (MSSA) and MRSA, but its use should be guided by antibiotic susceptibility testing results 1.
- The drug can be used for various types of skin and soft tissue infections, including impetigo, cellulitis, and abscesses 1.
- Potential side effects and complications, such as Clostridium difficile-associated disease, should be monitored and managed appropriately 1.
It is essential to note that the effectiveness of clindamycin against S. aureus can vary depending on the specific strain and local resistance patterns. Therefore, antibiotic susceptibility testing should always be performed before initiating treatment to ensure the specific S. aureus strain is truly sensitive to clindamycin 1.
From the FDA Drug Label
Clindamycin has been shown to be active against most of the isolates of the following microorganisms, both in vitro and in clinical infections [see Indications and Usage (1)]: Gram-positive bacteria Staphylococcus aureus (methicillin-susceptible strains)
Clindamycin is sensitive to methicillin-susceptible strains of Staphylococcus aureus. However, it is essential to note that this sensitivity is specific to methicillin-susceptible strains, and resistance may occur in methicillin-resistant strains 2.
- Key points:
- Clindamycin is active against methicillin-susceptible Staphylococcus aureus.
- Resistance may occur in methicillin-resistant strains.
- Macrolide-resistant isolates of staphylococci should be screened for induction of clindamycin resistance using the D-zone test 2.
From the Research
Clindamycin Sensitivity to Staphylococcus aureus
- Clindamycin is not considered a first-line drug for single Staphylococcus aureus infections, but it may be useful in treating S. aureus diseases resulting in large abscesses 3.
- Clindamycin has been used successfully to treat pneumonia and soft-tissue and musculoskeletal infections due to MRSA in adults and children, but there is a concern over the possibility of emergence of clindamycin resistance during therapy 4.
- A study found that there were no significant differences between vancomycin and clindamycin for the treatment of hospitalized patients with MRSA skin infections, based on clinical outcomes data 5.
- The prevalence of inducible clindamycin resistance in S. aureus isolates was found to be 25.8% in a study conducted in Ethiopia 6.
- Clindamycin's activity against inducible clindamycin resistance strains of CA-MRSA is partially impacted by inoculum size, and alternatives such as daptomycin, vancomycin, doxycycline, linezolid, and trimethoprim-sulfamethoxazole may be promising for treating these strains 7.
Factors Affecting Clindamycin Resistance
- Family size, inpatient status, illness in the previous 4 weeks, and history of chronic disease were found to be associated with S. aureus infection 6.
- Inducible clindamycin resistance was found to be more common in MRSA isolates, with 21.2% of S. aureus isolates being MRSA 6.
Treatment Options
- Clindamycin, vancomycin, daptomycin, doxycycline, linezolid, and trimethoprim-sulfamethoxazole are potential treatment options for S. aureus infections, including those with inducible clindamycin resistance 4, 5, 7.
- The D-test should be routinely performed to rule out clindamycin susceptibility testing and detect inducible clindamycin resistance 6.