What is the most effective antibiotic for treating a wound infection caused by Enterococcus?

From the Guidelines

For wound infections with Enterococcus, linezolid 600 mg IV or PO every 12 hours is the most effective antibiotic treatment, as recommended by the most recent guidelines 1. The treatment duration is dependent on the site of infection and clinical response, and it is essential to obtain wound cultures before starting antibiotics to confirm the specific Enterococcus species and its susceptibility pattern. Some key points to consider when treating wound infections with Enterococcus include:

• The importance of surgical debridement of the wound alongside antibiotic therapy
• The need to consider combination therapy with other antibiotics, such as daptomycin or gentamicin, in cases of ampicillin-resistant strains or more serious infections
• The potential for Enterococci to be resistant to many antibiotics, including cephalosporins and trimethoprim-sulfamethoxazole, which is why targeted therapy with linezolid or other effective antibiotics is crucial for effective treatment. It is also important to note that the treatment of Enterococcal infections can be complex and may require consultation with an infectious disease specialist, especially in cases of multidrug-resistant strains or complicated infections 1.

From the FDA Drug Label

Table 16: Clinical Success Rates by Infecting Pathogen in the cSSSI Trials in Adult Patients (Population: Microbiologically Evaluable) Pathogen Success Rate n/N (%) Daptomycin for Injection Comparator* Enterococcus faecalis (vancomycin-susceptible only) 27/37 (73%) 40/53 (76%)

The most effective antibiotic for treating a wound infection caused by Enterococcus is not clearly established in the provided drug labels, as comparative efficacy is not explicitly stated. However, according to the clinical success rates, daptomycin and the comparator (vancomycin or an anti-staphylococcal semi-synthetic penicillin) have similar success rates for treating Enterococcus faecalis (vancomycin-susceptible only) infections, with success rates of 73% and 76%, respectively 2.

From the Research

Treatment Options for Enterococcus Infections

• The most effective antibiotic for treating a wound infection caused by Enterococcus is not explicitly stated, but several options are discussed in the literature 3, 4, 5, 6, 7.
• Aminopenicillins are preferred over other agents when enterococci are susceptible and patients can tolerate them 3.
• Daptomycin and linezolid have demonstrated clinical efficacy against vancomycin-resistant enterococci (VRE) 3, 4, 6, 7.
• Quinupristin/dalfopristin is a streptogramin that impairs bacterial protein synthesis and has bacteriostatic activity against VRE, but its use is limited by resistance and adverse effects 4.
• Linezolid, an oxazolidinone compound, has bacteriostatic activity against both VRE and Enterococcus faecalis, and has been shown to be effective in treating complicated skin and soft tissue infections, as well as bloodstream infections 4, 7.
• Daptomycin has been shown to be effective in treating severe enterococcal infections, including peritonitis, and has been approved for use in complicated skin and skin structure infections induced by Enterococcus faecalis 6.
• A meta-analysis comparing the efficacy and safety of daptomycin and linezolid for the treatment of VRE bloodstream infections found similar crude overall mortality, clinical cure, microbiological cure, and relapse rates between the two groups 7.

Mechanisms of Action and Resistance

• The mechanisms of action and resistance to currently available anti-VRE antimicrobial agents, including newer agents such as oritavancin and dalbavancin, are complex and involve multiple factors 5.
• Daptomycin works by disrupting the bacterial cell membrane, while linezolid inhibits the bacterial pre-translational initiation complex formation 4, 6.
• Quinupristin/dalfopristin impairs bacterial protein synthesis at both early peptide chain elongation and late peptide chain extrusion steps 4.

Combination Therapy

• Synergistic combinations of antibiotics are often warranted in complex infections of high inoculum and biofilms, while monotherapies are generally appropriate for uncomplicated infections 3.
• Combination therapy with β-lactams and fosfomycin has shown promising results in in vitro, animal studies, and clinical experience in the treatment of VRE faecium 5, 6.