Ceftriaxone Dosing for Suspected Spontaneous Bacterial Peritonitis
For suspected SBP, administer ceftriaxone 2 grams intravenously once daily (every 24 hours) or 1 gram every 12 hours for 5-10 days. 1
Recommended Dosing Regimens
The standard dosing is ceftriaxone 2 grams IV once daily, which has demonstrated resolution rates of 73-100% in clinical trials. 1 Alternative dosing of 1 gram every 12 hours is equally effective. 1
- Once-daily dosing (2 grams every 24 hours) is preferred as it simplifies administration while maintaining excellent ascitic fluid penetration and therapeutic efficacy 1, 2
- The every 12-hour regimen (1 gram twice daily) showed similar resolution rates in comparative studies 3, 4
- Both regimens achieve adequate ascitic fluid concentrations to cover the most common pathogens: E. coli, Klebsiella pneumoniae, and Streptococcus species 1
Treatment Duration
Standard treatment duration is 5-10 days, with 5 days being sufficient for most uncomplicated cases. 1
- A randomized controlled trial demonstrated that 5 days of treatment is as efficacious as 10 days in carefully characterized SBP patients 1
- Treatment can be discontinued after 5 days if the ascitic fluid PMN count drops below 250 cells/mm³ 4
- Extend therapy beyond 5 days if clinical response is inadequate or if culture results indicate resistant organisms 1
Critical Adjunctive Therapy
Administer intravenous albumin in addition to ceftriaxone for patients with high-risk features to reduce mortality from 29% to 10%. 1
- Give 1.5 g/kg body weight within 6 hours of diagnosis, followed by 1.0 g/kg on day 3 1
- Albumin is indicated when serum creatinine ≥1 mg/dL, blood urea nitrogen ≥30 mg/dL, or total bilirubin ≥4 mg/dL 1
- Albumin is not necessary for patients who do not meet these high-risk criteria 1
Monitoring and Response Assessment
Perform a repeat paracentesis at 48 hours to assess treatment response. 1, 2
- Expect a marked decrease in PMN count by day 4 of treatment (from thousands to <250-400 cells/mm³) 3
- Resolution is defined as PMN count <250 cells/mm³ and sterile cultures 5
- If no clinical improvement occurs by 48-72 hours, suspect treatment failure due to resistant organisms or secondary bacterial peritonitis 1, 2
Important Caveats and Pitfalls
Avoid underdosing: Studies using 2 grams daily show better outcomes than 1 gram daily regimens. 6 While 1 gram every 12 hours (total 2 grams/day) is acceptable, single daily dosing of only 1 gram total per day is suboptimal.
- Ceftriaxone is highly protein-bound, which may limit penetration into low-protein ascitic fluid 1 - this is a theoretical concern but has not proven clinically significant in practice
- Do not use quinolones (ciprofloxacin, ofloxacin) as first-line therapy if the patient has received quinolone prophylaxis, as resistance rates are high in this population 1
- Hospital-acquired SBP may require broader coverage due to increased antibiotic resistance, particularly ESBL-producing organisms 1, 2
- Adjust antibiotics based on culture results and clinical response, narrowing coverage when sensitivities are available 1