What is the recommended approach for ruling out infection in a patient with cirrhosis?

Ruling Out Infection in Patients with Cirrhosis

All hospitalized patients with cirrhosis and ascites should undergo diagnostic paracentesis immediately upon admission, even without symptoms of infection, as bacterial infections occur 4-5 times more frequently in cirrhotic patients and account for one-third to one-half of deaths in this population. 1, 2

Diagnostic Approach

Immediate Paracentesis Indications

• Perform diagnostic paracentesis in every cirrhotic patient with ascites who is emergently hospitalized for any reason, regardless of symptoms 1
• Obtain paracentesis whenever signs suggestive of infection develop (fever, abdominal pain, unexplained encephalopathy, unexplained deterioration, or worsening hepatic encephalopathy) 1, 2
• In patients with tense ascites and acute kidney injury, perform paracentesis to exclude spontaneous bacterial peritonitis (SBP) as the cause 1

Ascitic Fluid Analysis

• The diagnosis of SBP is established with ascitic fluid polymorphonuclear (PMN) leukocyte count >250/mm³ 1
• Inoculate at least 10 mL of ascitic fluid into blood culture bottles at the bedside before administering antibiotics—this increases culture sensitivity to >90% 1
• Obtain simultaneous blood cultures to increase the likelihood of isolating a causative organism 1
• Culture both aerobic and anaerobic bottles 1

Additional Diagnostic Considerations

• If pleural effusion is present without ascites, or when diagnostic paracentesis has ruled out SBP but bacterial infection is still suspected, perform diagnostic thoracentesis 1
• C-reactive protein and procalcitonin can be used for detecting infection and defining severity, though their role in antibiotic stewardship requires further investigation 1
• C-reactive protein thresholds decrease with cirrhosis severity: 10 mg/L in mild cirrhosis, 5 mg/L in Child C patients 2

Key Clinical Pitfalls

Distinguishing Infection Types

• Suspect secondary bacterial peritonitis (not SBP) when patients have: 1
  • Localized abdominal symptoms or signs
  • Very high ascitic neutrophil count
  • Multiple organisms on ascitic culture
  • Inadequate response to treatment
• Perform cross-sectional imaging (CT) with early surgical consultation in suspected secondary peritonitis 1

Special Populations

• Patients with alcoholic hepatitis may have fever, leukocytosis, and abdominal pain mimicking SBP, but an elevated PMN count must still be presumed to represent infection 1
• Empiric antibiotic treatment can be discontinued after 48 hours if ascitic fluid, blood, and urine cultures show no growth 1

Monitoring Treatment Response

• Consider a second diagnostic tap at 48 hours if inadequate clinical response occurs 1
• If ascitic fluid neutrophil count fails to decrease to <25% of pretreatment value, suspect antibiotic resistance or secondary peritonitis 1
• If no response to broad-spectrum antibiotics, consider fungal infection (including fungal SBP), multidrug-resistant/extensively drug-resistant bacteria, or secondary peritonitis 2, 3

Microbiological Patterns

Common Organisms

• Approximately 60% of spontaneous infections are caused by gram-negative bacteria (most commonly E. coli and Klebsiella pneumoniae) 1
• Gram-positive cocci (mainly streptococcus species and enterococci) account for a significant proportion 1
• Recent shift toward gram-positive and multidrug-resistant organisms, particularly in nosocomial and healthcare-associated infections 1
• Fungi represent <5% of infections overall but carry >50% mortality with fungemia and peritonitis 1

Resistance Patterns

• Multidrug-resistant organisms (MDROs) represent 35% of overall infections in cirrhotic patients 1, 2
• Resistance rates to third-generation cephalosporins average 33% in community-acquired infections and 66% in healthcare-associated infections 2
• Nosocomial infections have higher mortality (25-48%) than community-acquired infections (7-21%) due to MDR bacteria 1

Critical Timing

• Empirical antibiotic therapy must be initiated immediately at suspicion of infection—each hour of delay in septic shock increases mortality risk by 1.86 times 2
• Start IV antibiotics empirically before obtaining culture results in all patients with ascites PMN count >250/mm³ 1
• Patients with convincing signs or symptoms of infection should receive empiric treatment regardless of PMN count until culture results are known 1