Aetiology and assessment of spontaneous bacterial peritonitis
Spontaneous bacterial peritonitis (SBP) is usually a complication of large-volume ascites in patients with cirrhosis. In adults, the most common pathogens are Enterobacterales (such as Escherichia coli and Klebsiella species). Streptococcus pneumoniae, other streptococci, and enterococci occasionally cause infection. Anaerobic bacteria are uncommon pathogens. In children, spontaneous bacterial peritonitis may occur as a primary phenomenon (not related to other intra-abdominal conditions) or as a complication of nephrotic syndrome; in both cases S. pneumoniae is the most common cause.
Spontaneous bacterial peritonitis can cause rapid or unexpected deterioration in patients with ascites. Abdominal tenderness may be absent. Unless there is an alternative explanation, perform an ascitic tap for patients with chronic liver disease and ascites who have any ofBiggins, 2021:
- fever (temperature higher than 38°C)
- hypothermia (temperature lower than 35°C)Biggins, 2021
- encephalopathy
- septic shock
- deteriorating kidney function.
Send ascitic fluid in a specimen container for microscopy (for Gram stain and cell count). Inoculate additional ascitic fluid directly into blood culture bottles for culture and susceptibility testing. Microscopy of ascitic fluid that identifies a neutrophil count more than 0.25 x 109/L is diagnostic of spontaneous bacterial peritonitis.