What are the recommended medications for a patient with spontaneous bacterial peritonitis?

Medications for Spontaneous Bacterial Peritonitis

First-Line Empirical Antibiotic Therapy

For community-acquired SBP, initiate intravenous cefotaxime 2g every 8 hours immediately upon diagnosis (ascitic fluid PMN count >250 cells/mm³), which achieves infection resolution in 77-98% of patients. 1, 2

Primary Treatment Options:

• Cefotaxime 2g IV every 8 hours for 5-7 days is the gold standard, with 4g/day being as effective as 8g/day 1, 2, 3
• Ceftriaxone 1-2g IV every 12-24 hours is equally effective as an alternative third-generation cephalosporin, with resolution rates of 73-100% 1, 2, 4, 5
• Amoxicillin-clavulanic acid 1g/0.2g IV every 8 hours (then switch to 0.5g/0.125g PO every 8 hours) achieves 87% resolution rates, similar to cefotaxime, though based on limited data 1, 2

Alternative Oral Therapy (Highly Selective):

• Oral ofloxacin 400mg twice daily can substitute for IV therapy ONLY in uncomplicated cases without prior quinolone exposure, vomiting, shock, grade II or higher hepatic encephalopathy, renal failure, or gastrointestinal bleeding 1, 2
• Oral ciprofloxacin 500mg every 12 hours for 5-7 days is acceptable for clinically stable, community-acquired SBP or as step-down therapy after 2 days of IV treatment 2, 4

Critical caveat: Never use quinolones as first-line therapy in patients already on norfloxacin prophylaxis due to high resistance rates 2, 4, 6

Nosocomial or Healthcare-Associated SBP

For hospital-acquired SBP, use broader-spectrum coverage with meropenem 1g IV every 8 hours plus daptomycin 6mg/kg/day, particularly in ICU patients, recent hospitalizations, or septic shock, due to 35% multidrug-resistant organism rates. 2

• Piperacillin-tazobactam provides 73% coverage compared to 57% for cephalosporins in settings with high gram-positive cocci prevalence and should be considered when cephalosporins fail 6, 7
• Gram-positive cocci (Staphylococcus, Enterococcus) now account for nearly half of SBP isolates, representing a significant shift from historical gram-negative predominance 6, 7

Mandatory Adjunctive Therapy: Intravenous Albumin

Administer IV albumin 1.5 g/kg body weight within 6 hours of diagnosis, followed by 1.0 g/kg on day 3, which reduces hepatorenal syndrome from 30% to 10% and mortality from 29% to 10%. 1, 2, 4, 8

This intervention is particularly critical for patients with serum creatinine ≥1 mg/dL, blood urea nitrogen ≥30 mg/dL, or total bilirubin ≥4 mg/dL 2, 4

Monitoring Treatment Response

• Perform repeat paracentesis at 48 hours to assess neutrophil count decrease 1, 2, 4, 8
• Treatment failure is defined as ascitic neutrophil count failing to decrease to <25% of pre-treatment value 1, 2, 4
• If inadequate response occurs, broaden antibiotic coverage and investigate for secondary peritonitis or resistant organisms 1, 2, 8

Treatment Duration

Five days of antibiotic therapy is as effective as 10 days for uncomplicated SBP, allowing for shorter treatment courses 1, 2, 3

Extend therapy beyond 5 days only if clinical response is inadequate or culture results indicate resistant organisms 2, 4

Long-Term Secondary Prophylaxis (Post-SBP)

All patients surviving an SBP episode require indefinite antibiotic prophylaxis until liver transplantation or death, with norfloxacin 400mg daily being the most studied regimen, reducing recurrence from 68% to 20%. 1, 2, 4, 8

• Ciprofloxacin 500mg daily is an acceptable alternative to norfloxacin 2, 4
• Trimethoprim-sulfamethoxazole 800mg/160mg daily is another option, particularly where quinolone resistance is prevalent 1, 4
• The 1-year SBP recurrence rate without prophylaxis is approximately 70%, making indefinite prophylaxis essential 4

Critical Pitfalls to Avoid

• Never delay antibiotics waiting for culture results—start empirical therapy immediately upon diagnosis (PMN >250/mm³) 1, 2, 8
• Avoid aminoglycosides (e.g., tobramycin) due to nephrotoxicity in this vulnerable population 1
• Do not use quinolones in patients already on quinolone prophylaxis or with recent quinolone exposure due to resistance 2, 4, 6
• Recognize secondary peritonitis if setting, symptoms, ascitic fluid analysis (protein >1 g/dL, LDH elevated, glucose <50 mg/dL), multiple organisms, or poor response are atypical—these patients require anaerobic coverage and surgical evaluation 1
• Consider local resistance patterns when selecting prophylactic antibiotics, as increasing quinolone resistance is a global concern 2, 4, 6, 7