From the FDA Drug Label
Complicated Skin and Skin Structure Infections Adult patients with clinically documented complicated skin and skin structure infections were enrolled in a randomized, multi-center, double-blind, double-dummy trial comparing study medications administered IV followed by medications given orally for a total of 10 to 21 days of treatment. One group of patients received ZYVOX I. V. Injection 600 mg q12h followed by ZYVOX Tablets 600 mg q12h; the other group received oxacillin 2 g every 6 hours (q6h) IV followed by dicloxacillin 500 mg q6h orally. A separate study provided additional experience with the use of ZYVOX in the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections. This was a randomized, open-label trial in hospitalized adult patients with documented or suspected MRSA infection. One group of patients received ZYVOX I. V. Injection 600 mg q12h followed by ZYVOX Tablets 600 mg q12h. The other group of patients received vancomycin 1 g q12h IV.
The IV antibiotic that can be used as a step-up therapy from Amoxicillin and Doxycycline is Linezolid or Vancomycin.
- Linezolid is effective against MRSA and other Gram-positive pathogens.
- Vancomycin is also effective against MRSA and can be used as an alternative. 1
From the Research
When stepping up from oral Amoxicillin and Doxycycline to intravenous therapy, Ceftriaxone is the recommended IV antibiotic of choice, typically administered at 1 gram IV once daily, as it provides broader coverage against gram-negative organisms while maintaining good activity against many gram-positive bacteria, as supported by the most recent study 2.
Key Considerations
- The choice of IV antibiotic should be guided by the suspected pathogens, site of infection, local resistance patterns, and patient factors such as renal function.
- Ceftriaxone offers enhanced penetration into tissues and achieves higher blood concentrations than oral antibiotics, making it a suitable option for patients requiring IV therapy.
- For patients with penicillin allergies, alternatives include IV fluoroquinolones like Levofloxacin (750 mg IV daily) or, in cases of suspected MRSA, Vancomycin (15-20 mg/kg IV every 8-12 hours), although the combination of Vancomycin with piperacillin/tazobactam should be used with caution due to the increased risk of nephrotoxicity, as noted in 3.
Important Factors to Consider
- Obtain appropriate cultures before starting antibiotics if possible.
- Monitor for infusion reactions.
- Regularly assess the need to step down to oral therapy once clinical improvement occurs, typically after 2-3 days of IV treatment.
- Consider the findings of 2, which suggest that 1 gram of Ceftriaxone per day may be sufficient for the treatment of community-acquired pneumonia, with a decreased rate of C. difficile infection and shorter length of stay compared to 2 grams per day.