Oral Antibiotic Regimen for Discharge in Cholangitis with Enterobacter Bacteremia
For an elderly female with cholangitis and Enterobacter bacteremia who has received 4 days of IV cefepime and metronidazole, discharge her on oral ciprofloxacin 750 mg twice daily for a total treatment duration of 7-10 days (including the 4 days already completed). 1
Rationale for Fluoroquinolone Selection
Ciprofloxacin provides excellent oral bioavailability and biliary penetration, making it the preferred oral step-down option for gram-negative biliary infections 1, 2
For Enterobacter species specifically, ciprofloxacin 750 mg twice daily is the recommended oral regimen for complicated intra-abdominal infections including cholangitis 1
The higher dose (750 mg vs 500 mg) is critical for more severe infections and gram-negative organisms like Enterobacter to ensure adequate tissue penetration 2
Total Duration of Therapy
Complete a total of 7-10 days of antibiotic therapy (4 days IV already completed + 3-6 additional days oral) for cholangitis with adequate source control 1, 3, 4
For elderly or immunocompromised patients, extend toward the 10-day total duration rather than stopping at 7 days 3, 4
If the patient remains critically ill or has inadequate source control, do not discharge on oral therapy—continue IV antibiotics until clinical improvement 1
Discontinue Metronidazole
Anaerobic coverage with metronidazole is NOT necessary for cholangitis unless there is a biliary-enteric anastomosis present 3, 5
The initial regimen of cefepime plus metronidazole was appropriate empirically, but metronidazole should be discontinued once Enterobacter (a facultative gram-negative organism) is identified 1, 3
Alternative Oral Options (If Fluoroquinolone Contraindicated)
If ciprofloxacin cannot be used (allergy, QT prolongation, tendon disorders), consider oral amoxicillin-clavulanate 875/125 mg twice daily, though this has less reliable activity against Enterobacter 1, 3
Verify local antibiogram susceptibilities for Enterobacter to fluoroquinolones before discharge, as resistance rates vary geographically 1, 6, 7
Critical Pitfalls to Avoid
Do not use oral cephalosporins for Enterobacter due to high rates of AmpC β-lactamase-mediated resistance and risk of treatment failure 6, 8
Do not discharge on oral antibiotics if the patient has persistent fever, leukocytosis, or inadequate biliary drainage—these patients require continued IV therapy 1, 9
Ensure adequate source control was achieved (ERCP with stone extraction/stent placement or surgical drainage) before transitioning to oral therapy, as antibiotics alone will not sterilize obstructed bile 9, 6
Monitor for fluoroquinolone-associated adverse effects in elderly patients, including tendinopathy, CNS effects (confusion, dizziness), and QT prolongation 2