From the Guidelines
For gram-negative bacteremia with E. coli and Enterobacter in a patient with colorectal cancer on chemotherapy following perirectal abscess drainage, I recommend starting with Ceftazidime/avibactam 2.5 g IV every 8 hours, as it is a recommended treatment option for bloodstream infections due to multidrug-resistant organisms, including carbapenem-resistant Enterobacterales (CRE) 1. This patient likely has a healthcare-associated infection with potential for resistant organisms, especially given the Enterobacter which often carries AmpC beta-lactamases. Ceftazidime/avibactam provides broad coverage against both organisms, including potential extended-spectrum beta-lactamase (ESBL) producers. Some key points to consider in the management of this patient include:
- The choice of antibiotic should be based on the susceptibility test results, and combination antimicrobial therapy may be necessary in clinically unstable patients 1.
- The treatment duration should be individualized according to the infection site, source control, underlying comorbidities, and initial response to therapy, but typically ranges from 7-14 days 1.
- Blood cultures should be repeated to confirm clearance of bacteremia, and the patient's neutrophil count should be monitored, as chemotherapy-induced neutropenia may necessitate longer treatment.
- Given the patient's immunocompromised status from chemotherapy, infectious disease consultation would be beneficial for optimizing antimicrobial management. It's also important to note that other treatment options, such as Meropenem/vaborbactam or Imipenem/cilastatin/relebactam, may be considered, but Ceftazidime/avibactam is a recommended option for bloodstream infections due to multidrug-resistant organisms 1.
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Antibiotic Treatment for Gram-Negative Bacteremia
- The patient has gram-negative bacteremia with E. coli and Enterobacter, and has colorectal cancer on chemotherapy after perirectal abscess incision and drainage.
- The choice of antibiotic treatment should be based on the susceptibility of the bacteria and the severity of the infection.
Considerations for Antibiotic Selection
- Piperacillin-tazobactam may be an effective "carbapenem-sparing" option to treat extended-spectrum β-lactamase (ESBL) producers, but its use is controversial 2, 3, 4.
- Carbapenems are often considered the drug of choice for treatment of infections due to ESBL-producing Enterobacteriaceae, but their use can lead to increased resistance 5, 6.
- Cefepime and piperacillin-tazobactam may be considered as empiric therapy for ESBL-producing E. coli bacteremia in patients with hematologic malignancy, but their role is limited due to prolonged fever and persistent bacteremia 6.
Duration of Antibiotic Therapy
- The optimal duration of antimicrobial treatment for gram-negative bacteremia is unknown, but reducing the length of antibiotic courses to 7-8 days may minimize the consequences of antibiotic overuse 5.
- Biomarkers like C-reactive protein (CRP) and procalcitonin (PCT) may be useful in guiding antibiotic duration, but should be interpreted cautiously in the context of the clinical situation 5.
Recommendations
- The choice of antibiotic treatment should be individualized based on the patient's specific circumstances, including the susceptibility of the bacteria, the severity of the infection, and the patient's underlying medical conditions.
- Carbapenems may be considered as the initial empiric therapy, but piperacillin-tazobactam or cefepime may be alternative options in certain situations 2, 3, 6, 4.