What are the presentation signs, symptoms, investigations, and treatment for a patient with suspected Spontaneous Bacterial Peritonitis (SBP) and a history of liver disease, presenting with abdominal pain, fever, and ascites?

Spontaneous Bacterial Peritonitis: Presentation, Diagnosis, and Treatment

Clinical Presentation

Perform diagnostic paracentesis immediately in any cirrhotic patient with ascites who presents to the emergency department or is hospitalized, regardless of whether symptoms are present, because up to one-third of SBP patients are completely asymptomatic. 1, 2

Classic Abdominal Manifestations

• Abdominal pain and tenderness occur in 74-95% of cases, typically with or without rebound tenderness 2
• Guarding and abdominal rigidity are present in 82.5% of symptomatic patients 1
• Ileus with decreased bowel sounds may be present 1
• Nausea and vomiting occur in 35% of cases 1

Systemic Signs of Infection

• Fever >38.5°C occurs in only 38% of cases—absence of fever does not exclude SBP 1
• Hypothermia or chills may occur instead of fever 1
• Tachycardia is present in 62.5% of patients 1
• Hypotension indicating progression to septic shock is a critical complication 1

Non-Specific Presentations (Critical Pitfall)

• Hepatic encephalopathy alone may be the sole manifestation in up to one-third of patients without any abdominal symptoms 1, 2
• Acute kidney injury without other symptoms can be the presenting sign 1, 2
• Unexplained clinical deterioration or worsening jaundice should prompt immediate paracentesis 1

Laboratory Abnormalities

• Leukocytosis with left shift is present in only 40% of cases—normal white blood cell count does not exclude SBP 1
• Elevated C-reactive protein is commonly seen 1
• Increased serum lactate may indicate progression to sepsis 1
• Rising creatinine (>50% above baseline) can signal SBP 1

Diagnostic Investigations

The diagnosis of SBP is established by ascitic fluid absolute neutrophil count >250 cells/mm³, regardless of culture results. 3

Paracentesis Technique and Timing

• Perform diagnostic paracentesis immediately upon hospital admission in all cirrhotic patients with ascites, even without symptoms of infection 3
• Ultrasound guidance should be used to optimize the procedure 4
• Inoculate at least 10 mL of ascitic fluid into blood culture bottles at the bedside before starting antibiotics, which increases culture sensitivity to >90% 3
• Obtain simultaneous blood cultures to increase likelihood of isolating the causative organism 3

Diagnostic Criteria

• Ascitic fluid absolute neutrophil count >250 cells/mm³ confirms the diagnosis 3
• Absence of an intra-abdominal surgically treatable source of infection must be verified 3
• Culture-negative neutrocytic ascites should be treated identically to culture-positive SBP, as clinical outcomes and mortality are similar 3
• Leukocyte esterase reagent strips can be used for rapid diagnosis if available 4

Repeat Paracentesis

• Repeat paracentesis after 48 hours of treatment to reassess ascitic fluid neutrophil count—it should be less than 50% of the original value if antimicrobial therapy is appropriate 5
• Monomicrobial bacterascites requires repeat paracentesis when culture results return 3

Treatment

Start empirical antibiotics immediately after obtaining cultures if clinical suspicion is high, because mortality increases by 10% for every hour's delay in initiating antibiotics in patients with septic shock from SBP. 1, 2, 3

First-Line Antibiotic Therapy

• Cefotaxime 2 grams IV every 8-12 hours is the traditional first-line treatment 6, 7
• Third-generation cephalosporins remain a good initial choice for community-acquired SBP 4, 8
• Levofloxacin is an acceptable alternative for patients not receiving long-term fluoroquinolone prophylaxis or for those with penicillin allergy 8

Broad-Spectrum Coverage Considerations

• Piperacillin-tazobactam or carbopenems should be considered for patients with nosocomial SBP, healthcare-associated infections, or those who fail to improve on traditional antibiotic regimens 4, 8
• Gram-positive cocci (Staphylococcus, Enterococcus) and multi-resistant bacteria have become increasingly common pathogens, changing the conventional approach to treatment 8

Duration of Therapy

• 5-10 days of parenteral antibiotics is appropriate, with most studies supporting 5 days for uncomplicated cases 7
• Early oral switch therapy is reasonable for uncomplicated SBP 8
• Total resolution after 5 days of therapy occurs in approximately 73% of patients 7

Albumin Supplementation (Critical for Mortality Reduction)

• Albumin infusion is associated with reduced risk of renal impairment and mortality 4
• Selective albumin supplementation remains an important adjunct in SBP treatment 8
• Albumin 1.5 g/kg IV within 6 hours of diagnosis, followed by 1 g/kg on day 3 is the standard regimen based on guideline recommendations 9

Monitoring and Response to Treatment

• 94% of patients respond to therapy after 48 hours of appropriate treatment 7
• Reassess clinical status and consider repeat paracentesis at 48 hours if no improvement 5
• In-hospital mortality ranges from 15-30% and is related to the severity of underlying liver disease 7, 10

Special Considerations

• Coagulation panel abnormalities are common, but routine transfusion is not recommended 4
• Withholding acid suppressive medication deserves strong consideration, as these medications are strongly associated with SBP in at-risk individuals 8
• Discontinuing beta-adrenergic antagonist therapy in patients with end-stage liver disease and resistant ascites is standard care 8
• Liver transplant evaluation should be undertaken for patients who develop SBP barring contraindications 8