# Spontaneous Bacterial Peritonitis

Diagnose SBP with prompt diagnostic paracentesis and ascitic neutrophil count, begin empiric therapy when PMNs reach 250/mm3, prevent renal deterioration with albumin when indicated, and actively exclude secondary peritonitis when the clinical or fluid profile is atypical.

**Clinical question:** How should clinicians diagnose, treat, reassess, and prevent spontaneous bacterial peritonitis in patients with cirrhotic ascites?

Updated: 2026-09-15T22:09:08.120449+00:00

## What matters in practice
- Perform diagnostic paracentesis promptly in patients with cirrhosis and ascites when SBP is suspected; SBP is diagnosed when ascitic PMNs are greater than 250/mm3 regardless of culture result. [17][20]
- Treat immediately with empiric antibiotics when ascitic PMNs exceed 250/mm3; do not wait for culture results. [17]
- For SBP, intravenous albumin 1.5 g/kg at diagnosis followed by 1 g/kg on day 3 reduces type 1 hepatorenal syndrome and mortality when coadministered with cefotaxime. [1]
- A nonresponse to initial therapy or fluid findings suggesting a surgically treatable source should redirect evaluation toward secondary bacterial peritonitis. [14][22]
- After an SBP episode, use long-term secondary prophylaxis with daily norfloxacin or trimethoprim-sulfamethoxazole; patients with cirrhosis and gastrointestinal hemorrhage require 7 days of antibiotic prophylaxis. [12]

## Who needs immediate diagnostic paracentesis?

Use paracentesis to establish infection rather than relying on symptoms or Gram stain.

Perform diagnostic paracentesis in a patient with cirrhosis and ascites when SBP is clinically suspected, including fever, abdominal pain or tenderness, or other evidence of infection. Diagnostic paracentesis is the basis of diagnosis, and ascites is associated with substantial SBP risk: prevalence is approximately 1.5% to 3.5% among outpatients and about 10% among hospitalized patients with cirrhosis. [10][17]

Send ascitic fluid for cell count with differential and culture. Culture-negative neutrocytic ascites is managed as SBP when the PMN count is greater than 250/mm3. Gram stain is frequently negative and should not delay empiric treatment. [2][17]

Obtain targeted ascitic studies when the presentation points away from uncomplicated SBP: add ascitic amylase for suspected pancreatic ascites, mycobacterial culture or PCR when tuberculosis is suspected, and cytology when malignancy is suspected. Ascitic glucose and lactate dehydrogenase help assess for secondary peritonitis. [9][22]
- PMN count greater than 250/mm3: diagnose SBP and start empiric antibiotics, irrespective of ascitic culture result. [17]
- PMN count less than 250/mm3 with fever above 37.8 degrees C, abdominal pain, or tenderness: give empiric antibiotics while cultures are pending. [17]
- Do not use a negative Gram stain to exclude SBP. [2]

*Ascitic fluid findings that direct immediate management. [17][22]*

| Finding | Interpretation | Immediate action |
| --- | --- | --- |
| PMNs >250/mm3 | SBP, including culture-negative neutrocytic ascites. [17] | Start empiric antibacterial therapy without waiting for culture results. [17] |
| PMNs <250/mm3 plus fever >37.8 degrees C, abdominal pain, or tenderness | Infection remains clinically concerning while culture is pending. [17] | Begin empiric antibiotics pending culture results. [17] |
| Elevated ascitic amylase in an appropriate clinical setting | Supports pancreatic ascites evaluation. [9][22] | Pursue pancreatic etiology rather than attributing fluid abnormalities to uncomplicated SBP. [9][22] |
| Ascitic glucose and LDH pattern concerning for secondary peritonitis | Raises concern for a nonspontaneous intra-abdominal source. [22] | Escalate diagnostic evaluation for secondary peritonitis. [14][22] |

## Start empiric antibiotics once the PMN threshold is met

Select initial therapy by acquisition setting, local resistance patterns, and renal toxicity risk.

For presumed community-acquired SBP, a third-generation cephalosporin is a standard empiric option. Cefotaxime has guideline support and effective regimens include 2 g intravenously every 6 hours or every 12 hours; ceftriaxone 2 g intravenously every 24 hours is another reported regimen. Third-generation cephalosporins avoid the nephrotoxicity associated with aminoglycoside-containing empiric regimens. [1][2][9]

Obtain ascitic fluid culture before antibiotics when this does not delay treatment, then narrow or modify therapy according to organism identification and susceptibility testing. Common implicated organisms include Escherichia coli, Klebsiella species, enterococci, and other gram-negative enteric flora; healthcare-associated and nosocomial SBP have greater multidrug-resistant and gram-positive pathogen concerns. [1][5][13]

For healthcare-associated or nosocomial SBP, do not assume a community-acquired cephalosporin regimen will be adequate. EASL 2018 guidance emphasized adding gram-positive-active agents such as a glycopeptide, daptomycin, or linezolid in settings with high gram-positive infection prevalence; choose the regimen in conjunction with local antibiograms and the patient's prior antimicrobial exposure. [13]
- Cefotaxime: 2 g IV every 6 hours or every 12 hours; reported total daily doses range from 4 to 12 g/day. [1]
- Ceftriaxone: 2 g IV every 24 hours. [1]
- Ceftazidime: 2 g IV every 8 to 12 hours. [1]
- Amoxicillin-clavulanate: 1 g/0.2 g IV every 8 hours is a reported alternative regimen. [1]
- Modify empiric therapy when culture and susceptibility results are available. [1][2]

### When to broaden beyond a standard cephalosporin regimen

Treat healthcare-associated and nosocomial SBP as a resistance-risk phenotype. Prior healthcare exposure, recent antimicrobials, or local high prevalence of multidrug-resistant organisms should trigger empiric regimen selection based on local microbiology rather than routine community-acquired coverage. [5][13]
- In high-prevalence gram-positive settings, guidance discusses glycopeptides, daptomycin, or linezolid as gram-positive-active components for healthcare-associated or nosocomial SBP. [13]
- Avoid aminoglycoside-based empiric regimens when an effective third-generation cephalosporin option is available because of nephrotoxicity risk. [2]

*Empiric antibacterial options reported for SBP. [1][2][13]*

| Clinical context | Regimen | Decision point |
| --- | --- | --- |
| Presumed community-acquired SBP | Cefotaxime 2 g IV every 6 or 12 hours. [1] | Begin after diagnostic paracentesis when PMNs are >250/mm3; adjust to culture susceptibilities. [1][17] |
| Presumed community-acquired SBP | Ceftriaxone 2 g IV every 24 hours. [1] | Alternative third-generation cephalosporin regimen. [1] |
| Presumed community-acquired SBP | Ceftazidime 2 g IV every 8 to 12 hours or amoxicillin-clavulanate 1 g/0.2 g IV every 8 hours. [1] | Use only when clinically appropriate; tailor once susceptibility data return. [1] |
| Healthcare-associated or nosocomial SBP with high gram-positive prevalence | Consider adding a glycopeptide, daptomycin, or linezolid to empiric therapy. [13] | Base selection on local resistance epidemiology and patient-specific resistance risk. [13] |

## Use albumin to reduce hepatorenal complications

Treat SBP as a renal-risk event, not only an intra-abdominal infection.

Co-administer intravenous albumin with antibacterial therapy in SBP using 1.5 g/kg at diagnosis and 1 g/kg on day 3. In patients treated with cefotaxime, this strategy reduced the incidence of type 1 hepatorenal syndrome and mortality. [1]

Follow renal function during acute infection because renal impairment after SBP has major prognostic implications and SBP is linked to hepatorenal syndrome. Worsening kidney function should prompt reassessment of infection control, circulatory status, and competing renal injury mechanisms rather than assuming uncomplicated SBP is resolving. [1][17][20]
- Day 1: albumin 1.5 g/kg IV at SBP diagnosis. [1]
- Day 3: albumin 1 g/kg IV. [1]
- Monitor kidney function closely during treatment because SBP can precipitate hepatorenal syndrome. [1][20]

*Albumin regimen for SBP-associated renal-risk reduction. [1]*

| Timing | Albumin dose | Purpose |
| --- | --- | --- |
| At SBP diagnosis | 1.5 g/kg IV. [1] | Reduces type 1 hepatorenal syndrome and mortality when used with cefotaxime. [1] |
| Day 3 | 1 g/kg IV. [1] | Completes the studied two-dose regimen. [1] |

## When should SBP be reconsidered as secondary peritonitis?

Failure of expected clinical improvement requires a search for a surgically or procedurally correctable source.

SBP requires infection of ascites without a contiguous intra-abdominal source such as bowel perforation or intra-abdominal abscess. If abdominal findings are disproportionate, the ascitic fluid profile is atypical, or the patient fails to improve on appropriate empiric therapy, evaluate for secondary bacterial peritonitis rather than simply extending the original regimen. [1][14][22]

Use ascitic glucose and lactate dehydrogenase as part of the secondary-peritonitis assessment, then direct imaging and source-control evaluation to the suspected pathology. Pancreatitis and tuberculosis should be pursued selectively with ascitic amylase and mycobacterial culture or PCR, respectively, rather than applying those tests routinely. [9][22]

Do not equate ascitic culture negativity with treatment failure or diagnostic exclusion. A PMN count greater than 250/mm3 establishes SBP even if cultures are negative; the key reassessment question is whether the clinical course and fluid findings remain consistent with a spontaneous rather than secondary source. [17][24]
- Possible perforation or abscess: investigate for secondary peritonitis and source control. [1][14]
- Suspected pancreatic process: obtain ascitic amylase. [9][22]
- Suspected peritoneal tuberculosis: obtain mycobacterial culture or PCR. [9]
- Suspected malignancy: send ascitic cytology. [9]

*Alternative diagnoses to pursue when SBP is atypical or treatment response is inadequate. [1][9][14][22]*

| Clinical concern | Targeted test | What the result changes |
| --- | --- | --- |
| Secondary bacterial peritonitis | Ascitic glucose and LDH; evaluate for intra-abdominal source. [22] | Redirects care toward imaging and source control rather than management as uncomplicated SBP. [1][14][22] |
| Pancreatic ascites | Ascitic amylase. [9][22] | Supports pancreatic-source evaluation and management. [9][22] |
| Tuberculous peritonitis | Ascitic mycobacterial culture or PCR. [9] | Directs organism-specific diagnosis and treatment. [9] |
| Malignant ascites | Ascitic cytology. [9] | Directs oncologic or malignancy-focused evaluation. [9] |

## Who needs antibiotic prophylaxis after SBP or gastrointestinal bleeding?

Use prophylaxis in the highest-risk settings while accounting for resistance selection.

After recovery from SBP, prescribe long-term secondary prophylaxis with daily norfloxacin or trimethoprim-sulfamethoxazole. Norfloxacin and trimethoprim-sulfamethoxazole have similar efficacy for SBP prevention. [3][12]

During gastrointestinal hemorrhage in a patient with cirrhosis, give antibacterial prophylaxis for 7 days. AASLD guidance cited intravenous ceftriaxone or oral norfloxacin; start with a parenteral antibiotic during active bleeding and transition to an oral agent when oral intake resumes, completing 7 days total. [12]

For primary prophylaxis in selected patients with cirrhosis and ascites, guideline appraisals describe long-term norfloxacin 400 mg daily in those with low ascitic fluid protein. Ciprofloxacin is an alternative to norfloxacin, but AASLD preference for daily rather than weekly ciprofloxacin reflects concern that weekly dosing may increase quinolone resistance. [12][13]
- Secondary prophylaxis after prior SBP: daily norfloxacin or daily trimethoprim-sulfamethoxazole. [12]
- Gastrointestinal hemorrhage: ceftriaxone IV or norfloxacin orally for a total of 7 days; begin parenterally during active bleeding if needed. [12]
- Primary prophylaxis described in guideline appraisals: norfloxacin 400 mg orally daily in patients with low ascitic fluid protein. [13]
- Ciprofloxacin is an alternative, but daily dosing is preferred over weekly dosing in AASLD-cited guidance because of quinolone-resistance concerns. [12]

*Antibiotic prophylaxis settings in cirrhosis. [12][13]*

| Indication | Regimen described | Duration or operational rule |
| --- | --- | --- |
| Previous SBP | Daily norfloxacin or daily trimethoprim-sulfamethoxazole. [12] | Long-term secondary prophylaxis. [12] |
| Cirrhosis with gastrointestinal hemorrhage | IV ceftriaxone or oral norfloxacin. [12] | Total 7 days; begin parenteral therapy during active bleeding and switch to oral therapy when oral intake resumes. [12] |
| Selected primary prophylaxis candidates with low ascitic fluid protein | Norfloxacin 400 mg orally daily. [13] | Long-term prophylaxis is described in appraised guidelines. [13] |
| Alternative fluoroquinolone approach | Ciprofloxacin. [12] | Daily dosing is preferred over weekly dosing in AASLD-cited guidance because weekly administration may promote quinolone resistance. [12] |

## References
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2. Peritoneum Exudate - an overview | ScienceDirect Topics — www.sciencedirect.com — https://www.sciencedirect.com/topics/pharmacology-toxicology-and-pharmaceutical-science/peritoneum-exudate
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## Editorial note

Prepared from cited clinical literature using Astra's research workflow. Verify recommendations against current guidance and patient-specific factors.