Oral Step-Down from Ampicillin-Sulbactam
Amoxicillin-clavulanate is the preferred oral step-down antibiotic for patients previously treated with intravenous ampicillin-sulbactam, as it provides equivalent antimicrobial spectrum coverage against gram-positive organisms, gram-negative bacteria, and anaerobes. 1
Antimicrobial Spectrum Coverage
- Amoxicillin-clavulanate covers the same spectrum as ampicillin-sulbactam, including methicillin-sensitive Staphylococcus aureus, streptococci, E. coli, Proteus, Klebsiella, Bacteroides fragilis, and Clostridium species 1
- This makes it the most appropriate oral equivalent for maintaining therapeutic coverage after IV therapy 1
Dosing Recommendations
- Standard dosing: 875 mg/125 mg twice daily for most infections 1
- High-dose formulations: 2000 mg/125 mg twice daily may be necessary for more severe infections or resistant organisms 1
- The higher dose formulation provides enhanced coverage when treating more serious infections that required initial IV therapy 1
Criteria for Switching to Oral Therapy
Switch to oral therapy when the patient meets these four criteria:
- Improvement in primary symptoms (cough, dyspnea, or infection-specific symptoms) 2
- Afebrile (≤100°F) on two occasions 8 hours apart 2
- White blood cell count decreasing 2
- Functioning gastrointestinal tract with adequate oral intake 2
Important Timing Considerations
- The switch can occur even if the patient is not completely afebrile, provided the overall clinical response is favorable 2
- Antibiotic therapy should not be changed within the first 72 hours unless there is marked clinical deterioration or bacteriologic data necessitate a change 2
- For pelvic inflammatory disease specifically, parenteral therapy can be discontinued 24 hours after clinical improvement, with oral amoxicillin-clavulanate completing a 14-day course 2
Clinical Applications by Infection Type
Skin and Soft Tissue Infections
- The IDSA recommends transitioning to oral amoxicillin-clavulanate after clinical stability is achieved 1
- This approach is supported for both community-acquired and healthcare-associated infections 1
Intra-Abdominal Infections
- The CDC recommends amoxicillin-clavulanate for step-down therapy in mild-to-moderate intra-abdominal infections 1
- Continue therapy until clinical resolution is achieved 1
Respiratory Tract Infections
- Amoxicillin-clavulanate is recommended for community-acquired pneumonia, sinusitis, and other respiratory infections 1
- For pneumonia specifically, switch therapy can be accomplished once clinical stability criteria are met, typically by hospital day 3 2
Pelvic Inflammatory Disease
- After 24 hours of clinical improvement on IV ampicillin-sulbactam plus doxycycline, switch to oral therapy 2
- Continue doxycycline 100 mg twice daily to complete 14 days total 2
- When tubo-ovarian abscess is present, many providers add metronidazole or clindamycin for enhanced anaerobic coverage 2
Critical Limitations and Coverage Gaps
Amoxicillin-clavulanate does NOT cover:
- Pseudomonas aeruginosa 1
- Extended-spectrum beta-lactamase (ESBL) producing organisms 1
- Methicillin-resistant Staphylococcus aureus (MRSA) 1
Alternative Agents for MRSA Coverage
If MRSA coverage is needed, add or substitute with: 1
Common Pitfalls to Avoid
- Do not switch to oral therapy before 72 hours unless bacteriologic data support a change 2
- Ensure adequate gastrointestinal function before switching, as oral bioavailability depends on absorption 2
- Avoid antacids and certain foods that interfere with drug absorption 2
- For bacteremic patients, ensure clinical stability before switching; S. aureus bacteremia requires longer IV therapy to prevent endocarditis 2
- Do not use amoxicillin-clavulanate monotherapy if ESBL organisms or Pseudomonas are suspected or documented 1