What oral antibiotics are effective against enterococcus?

From the Guidelines

Oral antibiotics effective against enterococcus include linezolid, amoxicillin, ampicillin, nitrofurantoin, and fosfomycin, with the choice of antibiotic depending on the severity and site of infection, as well as the specific enterococcal species and its resistance pattern 1.

Key Considerations

• For uncomplicated urinary tract infections, options include a single dose of fosfomycin 3g PO, nitrofurantoin 100mg PO four times daily, or amoxicillin 500mg PO every 8 hours daily 1.
• Linezolid 600mg PO twice daily is recommended for more serious infections, including pneumonia and bloodstream infections, due to its strong recommendation and effectiveness against enterococcal infections 1.
• The treatment duration should be individualized based on the infection site, source control, underlying comorbidities, and initial response to therapy, with durations ranging from 3-14 days 1.

Antibiotic Resistance and Combination Therapy

• Enterococci are intrinsically resistant to many antibiotics, including cephalosporins and trimethoprim-sulfamethoxazole, making antibiotic selection challenging 1.
• Combination therapy with an aminoglycoside may be necessary for synergistic effect in severe infections, though this typically requires intravenous administration 1.

Conclusion Not Applicable - Direct Answer Only

The most effective oral antibiotic for enterococcus is linezolid 600mg PO twice daily, due to its strong recommendation and effectiveness against enterococcal infections, including vancomycin-resistant enterococci (VRE) 1. Some key points to consider when choosing an antibiotic include:

• The severity and site of infection
• The specific enterococcal species and its resistance pattern
• The potential need for combination therapy with an aminoglycoside
• The individualized treatment duration based on the patient's response to therapy 1.

From the FDA Drug Label

The FDA drug label does not answer the question.

From the Research

Oral Antibiotics Effective Against Enterococcus

• Linezolid is an oral antibiotic that has been shown to be effective against vancomycin-resistant Enterococcus faecium (VRE) and Enterococcus faecalis 2.
• Quinupristin/dalfopristin is another antibiotic that has been approved for the treatment of VRE, but it is not active against Enterococcus faecalis 2.
• Doxycycline and chloramphenicol are other oral antibiotics that have been used to treat enterococcal infections, although their effectiveness against VRE is limited 2.
• Tedizolid is a second-generation oxazolidinone that has been shown to be active against some linezolid-resistant VRE isolates, but its effectiveness is limited by the presence of specific resistance mechanisms 3.

Combination Therapy

• Combination therapy with linezolid and other antibiotics, such as rifampin or fosfomycin, has been shown to have synergistic effects against Enterococcus spp. in some studies 4.
• However, the clinical use of combination therapy remains unestablished, and the choice of antibiotics should be guided by reasoned empiric therapy or targeted therapy based on microbiological results 4.
• Other combination therapies, such as β-lactams and fosfomycin, have also been studied, but more research is needed to determine their effectiveness 5.

Susceptibility Testing

• Susceptibility testing is crucial for determining the effectiveness of antibiotics against enterococcal infections 6.
• Broth microdilution and Etest are commonly used methods for susceptibility testing, but their accuracy can vary depending on the antibiotic and the specific enterococcal isolate 6.
• Disc diffusion assays can also be used to detect vancomycin resistance, but their accuracy can be limited by the presence of specific resistance genes 6.