Optimal Antibiotic Therapy for Intra-abdominal Infections Secondary to Cancer

First-Line Treatment Options

The American College of Physicians recommends piperacillin-tazobactam 3.375g IV every 6 hours as the preferred first-line agent for non-critically ill patients with healthcare-associated intra-abdominal infections, including those secondary to cancer 1
For patients with more severe infections or at risk for resistant organisms, carbapenems such as meropenem 1g IV every 8 hours by extended infusion are excellent alternatives 2
Imipenem/cilastatin 500mg IV every 6 hours by extended infusion is also a recommended alternative for patients with severe infections or at risk for resistant organisms 2, 3
Imipenem/cilastatin/relebactam 1.25g IV every 6 hours is another option for patients with severe infections or at risk for resistant organisms 2, 4

For patients with beta-lactam allergies, eravacycline 1mg/kg IV every 12 hours is a recommended alternative 2
Ciprofloxacin 400mg IV every 12 hours plus metronidazole 500mg IV every 6 hours is another option for patients with beta-lactam allergies 1
Tigecycline 100mg IV loading dose, then 50mg IV every 12 hours is also a recommended alternative for patients with beta-lactam allergies 1, 4

Cancer patients often have compromised immune systems and may have had prior antibiotic exposure, increasing their risk for resistant organisms 1
For patients with recent chemotherapy or neutropenia, consider adding coverage for Pseudomonas aeruginosa and potentially resistant Enterobacteriaceae 1, 4
In patients at high risk for intra-abdominal candidiasis, consider adding an echinocandin such as caspofungin 70mg loading dose, then 50mg daily 2
Anidulafungin 200mg loading dose, then 100mg daily is another option for patients at high risk for intra-abdominal candidiasis 2
Micafungin 100mg daily is also a recommended option for patients at high risk for intra-abdominal candidiasis 2

Limit antimicrobial therapy to 4-7 days unless source control is difficult to achieve 1
Longer durations have not been associated with improved outcomes and may increase the risk of resistance 1
For cancer patients with persistent neutropenia or immunosuppression, therapy may need to be extended based on clinical response 1, 4

Source control through surgical intervention or drainage remains the cornerstone of treatment for intra-abdominal infections, even in cancer patients 1
Initial inadequate antimicrobial therapy is associated with increased morbidity, mortality, and length of hospital stay 1
Tailor therapy when culture and susceptibility reports become available to reduce the risk of resistance development 1
Local resistance patterns should guide empiric therapy choices, particularly in cancer centers where resistant organisms may be more prevalent 1

Delaying appropriate antimicrobial therapy increases risk of death, necessity for reoperation, and prolonged hospitalization 1
Using overly broad spectrum antibiotics for mild-to-moderate community-acquired infections may increase toxicity and facilitate acquisition of resistant organisms 1
Failing to adjust therapy based on culture results once available 1
Continuing antibiotics beyond 7 days when adequate source control has been achieved 1
Using ampicillin-sulbactam due to high rates of resistance among community-acquired E. coli 1
Using cefotetan or clindamycin due to increasing resistance among Bacteroides fragilis group 1