What is a good oral antibiotic regimen to cover for surgical site infection in the setting of an intra-abdominal (in the abdomen) contaminated case?

From the Guidelines

For surgical site infections following contaminated intraabdominal cases, I recommend a broad-spectrum antibiotic regimen of piperacillin-tazobactam 3.375g IV every 6 hours or 4.5g IV every 8 hours, as supported by the most recent guidelines 1. This regimen is preferred due to its broad-spectrum activity against gram-negative organisms, including E. coli and Klebsiella, as well as gram-positive bacteria, including Enterococcus, and anaerobes, such as Bacteroides fragilis. Alternative regimens include:

• A combination of ceftriaxone 1-2g IV daily plus metronidazole 500mg IV every 8 hours
• Ciprofloxacin 400mg IV every 12 hours plus metronidazole 500mg IV every 8 hours for patients with penicillin allergies These regimens should be adjusted according to culture and susceptibility results, as recommended by the guidelines 1. It is also important to note that the use of quinolones should be avoided unless hospital surveys indicate ≥90% susceptibility of E. coli to quinolones 1. Additionally, the optimal knowledge and use of the pharmacokinetic/pharmacodynamic characteristics of antibiotics are important to evaluate when additional antibiotic doses should be administered intraoperatively in patients with intra-abdominal infections undergoing emergency surgery 1. Transition to oral antibiotics, such as amoxicillin-clavulanate 875/125mg twice daily or ciprofloxacin 500mg twice daily plus metronidazole 500mg three times daily, can be considered when the patient is clinically improving and able to tolerate oral intake.

From the FDA Drug Label

INTRA‑ABDOMINAL INFECTIONS, including peritonitis, intra‑abdominal abscess, and liver abscess, caused by Bacteroides species including the B. fragilis group (B. fragilis, B. distasonis, B. ovatus, B. thetaiotaomicron, B vulgatus), Clostridium species, Eubacterium species, Peptococcusniger, and Peptostreptococcus species. To reduce the development of drug-resistant bacteria and maintain the effectiveness of metronidazole tablets and other antibacterial drugs, metronidazole tablets should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria The overall clinical success rates in the clinically evaluable patients are shown in Table 18 Table 18: Clinical Success Rates in Patients with Complicated Intra-Abdominal Infections StudyMoxifloxacin Hydrochloride n/N (%) Comparator n/N (%) 95% Confidence Intervala North America (overall) 146/183 (79.8%)153/196 (78.1%)(-7.4%, 9.3%)

A good oral antibiotic regimen to cover for surgical site infection in the setting of an intra-abdominal contaminated case could be:

• Metronidazole 2 for coverage of anaerobic bacteria, including Bacteroides and Clostridium species.
• Moxifloxacin 3 as it has been shown to be effective in the treatment of complicated intra-abdominal infections, including peritonitis and intra-abdominal abscess, with a clinical success rate of 79.8% in the North America study. Key points to consider:
• The choice of antibiotic should be based on the suspected or confirmed causative pathogens and their susceptibility patterns.
• The use of antibiotics should be guided by local epidemiology and susceptibility patterns.
• Surgical intervention, such as incision and drainage or debridement, may be necessary in addition to antibiotic therapy.

From the Research

Surgical Site Infection Prevention

To prevent surgical site infections (SSIs) in the setting of intraabdominal contaminated cases, the choice of oral antibiotic regimen is crucial. The following points highlight the key considerations:

• Antibiotic Prophylaxis: There is strong evidence for the use of prophylactic antibiotics in reducing the risk of SSI, as stated in 4 and 5.
• Choice of Antibiotics: The study 6 compares the use of preoperative ceftriaxone and metronidazole versus cefoxitin in patients undergoing traumatic exploratory laparotomy, showing no statistical difference in the development of SSIs between the two groups.
• Importance of Timing: The timing of prophylactic intravenous antibiotics is important, with administration before caesarean incision reducing SSI risk, as noted in 7.
• Combination Therapy: The use of combination antibiotics, such as ceftriaxone and metronidazole, may be effective in preventing SSIs, as suggested in 6.

Key Considerations

When selecting an oral antibiotic regimen to cover for surgical site infection in the setting of intraabdominal contaminated cases, consider the following:

• The type of surgery and the level of contamination
• The patient's underlying health conditions and allergies
• The local antimicrobial resistance patterns
• The need for combination therapy to cover a broad spectrum of pathogens

Available Evidence

The available evidence suggests that:

• Prophylactic antibiotics can reduce the risk of SSI, as stated in 4, 5, and 7
• The choice of antibiotics and timing of administration are important considerations, as noted in 7 and 6
• Combination therapy may be effective in preventing SSIs, as suggested in 6