Empirical Antibiotic Therapy Must Be Initiated Immediately—Do Not Wait for Ascitic Fluid Analysis Results
You should start empirical antibiotic therapy immediately after performing the diagnostic paracentesis, without waiting for the 3-day ascitic fluid analysis results. Delaying treatment until culture results are available can result in death from overwhelming infection and significantly worsens patient outcomes 1.
Why Immediate Treatment Is Critical
The ascitic fluid polymorphonuclear neutrophil (PMN) count is the most sensitive and rapidly available test for determining who needs empirical antibiotic treatment 1. If the PMN count is ≥250 cells/mm³, this confirms the diagnosis of spontaneous bacterial peritonitis (SBP) and mandates immediate empirical antibiotic therapy 1, 2.
- The PMN count should be available within hours of paracentesis, not 3 days 1
- Culture results take longer but should not delay treatment 1
- Ascitic fluid cultures are frequently negative even when infection is present, occurring in up to 40% of cases (culture-negative neutrocytic ascites) 1, 3
Recommended Empirical Antibiotic Regimen
Start cefotaxime 2g intravenously every 8 hours immediately after diagnosis 1, 2. This third-generation cephalosporin:
- Covers 95% of causative organisms including E. coli, Klebsiella pneumoniae, and Streptococcus species 1
- Achieves excellent ascitic fluid concentrations (20-fold killing power after one dose) 1
- Has been extensively validated in multiple controlled trials 1
- A 5-day treatment course is as effective as 10 days 1, 4
Alternative Regimens
- Amoxicillin-clavulanic acid (1g/0.2g IV every 8 hours initially, then 0.5g/0.125g PO every 8 hours) shows similar efficacy to cefotaxime with lower cost 1
- Oral ofloxacin (400mg twice daily) can be used ONLY in uncomplicated cases without vomiting, shock, grade II or higher hepatic encephalopathy, or serum creatinine >3 mg/dL 1, 2
Critical Adjunctive Therapy
Administer intravenous albumin alongside antibiotics: 1.5 g/kg at diagnosis, followed by 1 g/kg on day 3 4, 2. This significantly reduces:
When to Consider Healthcare-Associated Infection
If the patient developed ascites or was hospitalized >48 hours before symptoms, consider nosocomial SBP with broader coverage 1:
- Carbapenems (meropenem) or piperacillin-tazobactam may be necessary due to multidrug-resistant organisms 1, 5, 6
- Local resistance patterns should guide this decision 1
Monitoring Treatment Response
Perform a repeat paracentesis at 48 hours to assess treatment efficacy 1:
- Treatment failure is defined as failure of ascitic PMN count to decrease to <25% of pre-treatment value 1
- If treatment fails, suspect antibiotic resistance or secondary bacterial peritonitis 1
- Consider CT imaging if secondary peritonitis is suspected (multiple organisms, very high PMN count, inadequate response) 1
Dosing Considerations
There is no "gram per hour" dosing for SBP antibiotics—these are given as intermittent bolus doses:
- Cefotaxime: 2g IV every 8 hours (not continuous infusion) 1, 2
- Ceftriaxone: 1-2g IV every 12-24 hours 7, 5
- Treatment duration: 5 days for uncomplicated SBP 1, 4
Common Pitfalls to Avoid
- Never delay antibiotics waiting for culture results—this increases mortality 1
- Never use aminoglycosides (gentamicin, tobramycin) as they are nephrotoxic and contraindicated 1, 7
- Do not forget albumin administration—it is as important as antibiotics for reducing mortality 4, 2
- Avoid quinolones if patient was on quinolone prophylaxis—resistance is likely 1, 7, 8
- Obtain cultures BEFORE starting antibiotics but do not delay treatment 1
Culture Results Guide De-escalation, Not Initiation
Once culture and sensitivity results return after 2-3 days: