Peritonitis is inflammation of the membranes lining the
abdominal wall and organs, caused by pathogens such as bacteria or other causes
such as chemical exposure. Acute bacterial peritonitis (ABP) is a life
threatening emergency that needs prompt medical treatment.
Peritonitis may be classified as primary/spontaneous
peritonitis, secondary and tertiary peritonitis. In primary peritonitis, the infectious
bacteria enter the peritoneal cavity through the circulatory or lymphatic
system. Secondary peritonitis
occurs due to infectious bacteria from a source within the peritoneum.
Secondary infection is relatively common, taking the form of either generalized
peritonitis or localized abscesses. Tertiary peritonitis
is persistent or
recurrent peritonitis that reappears at least 48 hours after the resolution of
a primary or secondary peritonitis.
ABP in patients with cirrhosis
is considered to be due to bacterial translocation. Bacterial translocation is
the process through which viable or non-viable bacteria and bacterial products
(bacterial DNA or endotoxins) cross the intestinal lumen and come into the
peritoneal cavity. This triggers an inflammatory process, which results
in fluid shift into the peritoneal cavity. This accumulation of fluid coupled
with decreased intestinal motility leads to abdominal distention.
The clinical presentation of ABP is highly variable.
Presenting signs and symptoms can include fever, abdominal tenderness, nausea,
or vomiting. Bacterial and endotoxin absorption into the bloodstream could lead
to sepsis, affecting organ systems, and ultimately result in death.
Hypoalbuminemia caused by protein loss and pulmonary complications like
pneumonia may worsen the prognosis.
It is important to note that fluid displacement into the
abdomen (known as third-spacing)
could result in decreased blood volume or hypovolemia, which could further lead
to low blood pressure and shock. Hypovolemia could lead to organ failure;
therefore, rapid fluid resuscitation is very important in all patients with
peritonitis so as to promote physiological stability.
It should be noted that more
aggressive restoration of intravascular volume should be provided to those with
septic shock and organ failure.
Treating the cause and drainage
of abscesses are the main desired outcomes in peritonitis. Secondary goals of
treatment are elimination of infection and protection from adverse drug events
as well as end-organ damage, including that to the lungs, liver, heart, and
According to the Infectious Diseases
Society of America (IDSA), it is recommended that antibiotics covering a wide
range of organisms should be initiated within the first hour of the recognition
of peritonitis in patients with compromised hemodynamic or organ function. It is important to consider the appropriate
selection, dosing, and duration of antibiotics.
For ABP, a 10- to
14-day course of antibiotics is recommended. A repeat peritoneal fluid analysis
may be done to confirm effect of the treatment.
If improvement in ascitic fluid or clinical
condition does not occur within 48 hours, further evaluation is required to
rule out bowel perforation or intra-abdominal abscess. Evaluation may include a
combination of radiography, CT scanning, intraluminal contrast studies, or
Traditionally, a combination of an aminoglycoside
and ampicillin was used to treat ABP. Vancomycin is recommended when
methicillin-resistant Staphylococcus aureus (
MRSA) is the causative organism.
More recently, the third-generation
cephalosporins cefotaxime and ceftriaxone have been demonstrated to be as
efficacious as the ampicillin/aminoglycoside combination, and they are not
toxic to the kidneys in cirrhotic patients.
Patients should be evaluated after 48 hours to
determine whether expanded antibiotic therapy is still warranted.
Acute renal failure is a vital predictor of death
in spontaneous bacterial peritonitis (SBP) patients. Albumin has been used in
SBP to cause plasma volume expansion to decrease the incidence of renal failure
in patients with cirrhosis undergoing large-volume paracentesis. Prophylactic
antibiotics (antibiotics used to prevent infection) should be administered to
all patients who have had an episode of ABP and to patients admitted to a
health center with gastrointestinal bleeding. Primary prophylaxis with
fluoroquinolones in patients with a low ascitic fluid protein concentration is
Acute Bacterial Peritonitis in Adults; Michele Reed
et al; US Pharmacist 2012.