What are the ascites findings in Spontaneous Bacterial Peritonitis (SBP)?

From the Guidelines

Spontaneous bacterial peritonitis (SBP) is diagnosed when ascitic fluid analysis reveals an elevated polymorphonuclear (PMN) cell count ≥250 cells/mm³ in the absence of an intra-abdominal source of infection, as recommended by the most recent guidelines 1. The diagnosis of SBP is primarily based on the analysis of ascitic fluid, which should be performed without delay in all cirrhotic patients with ascites on hospital admission, as well as in patients with GI bleeding, shock, fever, or other signs of systemic inflammation, gastrointestinal symptoms, hepatic encephalopathy, and in patients with worsening liver or renal function 1. Some key findings in ascitic fluid that support the diagnosis of SBP include:

• An elevated PMN cell count ≥250 cells/mm³, which is considered the gold standard for diagnosis and can be performed by manual microscopy or automated counts based on flow cytometry 1
• A positive bacterial culture of the ascitic fluid, although cultures are negative in approximately 40% of cases
• An elevated total white blood cell count, typically >500 cells/mm³
• Decreased glucose levels compared to serum
• Low protein content in the ascitic fluid, usually <1 g/dL, reflecting compromised immune defense in the peritoneal cavity
• A pH of infected ascitic fluid often lower than normal (<7.35) and elevated lactate levels
• An elevated serum-ascites albumin gradient (SAAG) ≥1.1 g/dL, consistent with portal hypertension When SBP is suspected, immediate empiric antibiotic therapy should be initiated, typically with a third-generation cephalosporin like ceftriaxone 1-2g IV daily for 5-7 days, while awaiting culture results, as recommended by recent guidelines 1. For patients with renal dysfunction or a history of SBP, adding albumin (1.5 g/kg on day 1 and 1 g/kg on day 3) improves outcomes by preventing hepatorenal syndrome 1. It is essential to note that the choice of antibiotic should be guided by local resistance patterns and protocol, and a second diagnostic paracentesis at 48 hours from the start of treatment may be considered to check the efficacy of antibiotic therapy 1.

From the Research

Ascites Findings in Spontaneous Bacterial Peritonitis

• Ascites is a common complication in patients with liver cirrhosis, and spontaneous bacterial peritonitis (SBP) is a severe and often fatal infection in these patients 2, 3.
• The diagnosis of SBP requires the analysis of ascites and the presence of > 250 mm3 neutrophil polymorphonuclear (PMN) in ascites 4.
• The most common microorganisms identified in SBP are gram-negative bacteria, such as Escherichia coli, Klebsiella spp, and Streptococcus spp, although there is an increasing trend of gram-positive bacteria and multidrug-resistant bacteria 2, 3, 4.

Treatment and Prophylaxis

• The treatment of SBP involves the use of non-nephrotoxic broad-spectrum antibiotics, such as cefotaxime, ceftriaxone, and ciprofloxacin, which are effective against the typical bacterial flora associated with SBP 2, 5, 6.
• The antibiotic regimen is adjusted based on the results of ascitic fluid cultures, and selective albumin supplementation is an important adjunct in SBP treatment 2, 3.
• Prophylaxis with antibiotics, such as norfloxacin, is recommended for patients with low-protein ascites, severe ascites, and advanced liver failure, as well as for those with a history of SBP 2, 3.

Risk Factors and Mortality

• The risk factors for SBP include advanced liver disease, ascites, and previous episodes of SBP 2, 3.
• The mortality rate for SBP remains high, despite prompt and effective treatment, due to the severe underlying liver disease and the development of complications such as renal failure 2, 5.