From the Guidelines
Listeria myositis treatment should be initiated promptly with intravenous ampicillin plus gentamicin, as this combination is recommended for the treatment of Listeria monocytogenes infections 1. The treatment regimen typically consists of intravenous ampicillin at 2 grams every 4 hours for adults, combined with gentamicin (1.7 mg/kg every 8 hours) for a synergistic effect, particularly in the first 5-7 days.
- Key considerations for treatment include:
- Duration of treatment: at least 2-3 weeks for uncomplicated cases and 3-6 weeks for severe or complicated infections.
- Alternative therapy for penicillin-allergic patients: trimethoprim-sulfamethoxazole (15-20 mg/kg/day of the trimethoprim component, divided into doses every 8 hours) is recommended as an alternative 1.
- Supportive care: pain management, physical therapy, and possibly surgical drainage of abscesses may be necessary.
- It is crucial to note that Listeria monocytogenes is an intracellular pathogen that can directly invade muscle tissue, causing focal infection and inflammation, and is naturally resistant to many cephalosporins, making proper antibiotic selection crucial 1.
- High-risk patients, including immunocompromised individuals, pregnant women, and the elderly, require aggressive treatment and close monitoring due to higher risks of complications and mortality.
- Follow-up imaging may be necessary to ensure resolution of muscle inflammation and to guide the total treatment duration.
From the Research
Treatment of Listeria Myositis
- The treatment of listeriosis, which can manifest as myositis, typically involves antibiotic therapy 2, 3, 4, 5, 6.
- Ampicillin alone or in combination with gentamicin is often considered the treatment of choice for listeriosis 2, 3, 4, 5, 6.
- Alternative therapies, such as trimethoprim/sulfamethoxazole, erythromycin, vancomycin, and fluoroquinolones, may be considered for patients with allergies or certain disease states 2, 3, 5.
- The combination of ampicillin and gentamicin has been shown to have synergistic effects against Listeria monocytogenes, making it a potentially effective treatment option 3, 6.
- Penicillin-based therapy, such as high-dose penicillin or amoxicillin, in combination with gentamicin, is also recommended for invasive infection 4.
- It is essential to note that cephalosporins are not active against Listeria monocytogenes 2, 3.
Antibiotic Susceptibility and Synergy
- Rifampin and trimethoprim-sulfamethoxazole have been found to be potent single drugs against Listeria monocytogenes 5.
- Approximately 80% of Listeria monocytogenes strains have demonstrated full synergistic bactericidal activity with rifampin in combination with penicillin or ampicillin 5.
- The combination of ampicillin and gentamicin has been shown to be bactericidal against Listeria monocytogenes, making it a potentially effective treatment option 6.
Prevention and High-Risk Groups
- Vulnerable individuals, such as pregnant women, should be counseled on preventative strategies, including avoiding foods commonly contaminated with L. monocytogenes 4.
- High-risk patient groups, including those with weakened immune systems, should be aware of the risks of listeriosis and take precautions to avoid infection 2, 3, 4.