Spontaneous bacterial peritonitis is the development of peritonitis despite the absence of an obvious
source for the infection. It occurs almost exclusively in people with portal hypertension,
usually as a result of cirrhosis of the liver. It can also occur in patients with nephrotic
syndrome. The diagnosis of SBP requires paracentesis
from the abdominal cavity. If the fluid contains bacteria or large numbers of neutrophil granulocytes,
infection is confirmed and antibiotics are required to avoid complications. In addition
to antibiotics, infusions of albumin are usually administered.
Symptoms Symptoms include fevers, chills, nausea, vomiting,
abdominal tenderness and general malaise. Patients may complain of abdominal pain and
worsening ascites. Thirteen percent of patients have no signs or symptoms. Hepatic encephalopathy
may be the only manifestation of SBP; in the absence of a clear precipitant for the encephalopathy,
all patients should undergo paracentesis, or sampling of the ascites fluid, in order
to assess for SBP. Pathogenesis
SBP is thought to result from a combination of factors inherent in cirrhosis and ascites,
such as prolonged bacteremia secondary to compromised host defenses, intrahepatic shunting
of colonized blood, and defective bactericidal activity within the ascitic fluid. Pharmacologic
acid suppression has also been associated with SBP in patients with advanced cirrhosis.
Contrary to earlier theories, transmucosal migration of bacteria from the gut to the
ascitic fluid is no longer considered to play a major role in the etiology of SBP.
With respect to compromised host defenses, patients with severe acute or chronic liver
disease are often deficient in complement and may also have malfunctioning of the neutrophilic
and reticuloendothelial systems. As for the significance of ascitic fluid proteins,
it was demonstrated that cirrhotic patients with ascitic protein concentrations below
1 g/dL were 10 times more likely to develop SBP than individuals with higher concentrations.
It is thought that the antibacterial, or opsonic, activity of ascitic fluid is closely correlated
with the protein concentration. Additional studies have confirmed the validity of the
ascitic fluid protein concentration as the best predictor of the first episode of SBP.
Diagnosis Diagnosis is made by paracentesis. SBP is
diagnosed if the fluid contains neutrophils at greater than 250 cells per mm³ fluid in
the absence of another reason for this. The fluid is also cultured to identify bacteria.
If the sample is sent in a plain sterile container 40% of samples will identify an organism,
while if the sample is sent in a bottle with culture medium the sensitivity increases to
72-90%. Treatment
Antibiotics After confirmation of SBP, patients need hospital
admission for intravenous antibiotics. They will often also receive intravenous albumin.
A repeat paracentesis in 48 hours is sometimes performed to ensure control of infection.
Once patients have recovered from SBP, they require regular prophylactic antibiotics as
long as they still have ascites.For spontaneous bacterial peritonitis drug of choice antibiotic
is ceftazidime. Prokinetics
The addition of a prokinetic drug to an antibiotic regime reduces the incidence of spontaneous
bacterial peritonitis possibly via decreasing small intestinal bacterial overgrowth.
Intravenous albumin A randomized controlled trial found that intravenous
albumin on the day of admission and on hospital day 3 can reduce renal impairment.
Prevention/screening All cirrhotic patients might benefit from
antibiotics if: Ascitic fluid protein <1.0 g/dL. Patients
with fluid protein <15 g/L and either Child-Pugh score of at least 9 or impaired renal function
may also benefit. Previous SBP
Cirrhotic patients admitted to the hospital should receive prophylactic antibiotics if:
They have bleeding esophageal varices Epidemiology
Patients with ascites underwent routine paracentesis, the incidence of active SBP ranged from 10%
to 27% at the time of hospital admission. History
SBP was first described in 1964 by Prof Harold O. Conn.
References