A 59 year old male with a history of alcoholic cirrhosis presents complaining of shortness of breath and a rectal temperature of 101.1F. With knowing just this information the differential is vast. However, just like with any patient, a thorough search of the etiology of the fever is important. The patient does not have any abdominal tenderness, but a bedside sono shows the liver swimming in ascites. You wonder if this patient has SBP, and if so, what is the best way to treat it.
What is it? Spontaneous bacterial peritonitis is an infection that occurs in patients with cirrhosis and ascites. It is thought to be due to translocation of normal gut flora, and is a common infection in patients with decompensated cirrhosis. As such, the most common bacteria isolated from patients with SBP is E. coli. Other multi-drug resistant organisms can also be responsible and include Klebsiella strains, Enterococcus fecium, and Acinetobacter.
Why do I care? SBP is an infection, and like any infection can cause (severe) sepsis. However, it can also be complicated by acute renal failure and hepatorenal syndrome (HRS). If HRS is present, there is a 90% mortality rate, which is kinda high. Good news is there is something we can do to help prevent this.
What do I need to know? First step is to know that this is a possibility. The typical presentation is what we would expect: fever, chills, pain, diarrhea, and hepatic encephalopathy. However this is not always the case. An estimated 25% of patients with SBP will not have symptoms of the disease. Sometimes the disease is suggested in a patient with ascites and acute decompensation. But now on to the diagnostic criteria, which are based on findgins in the ascitic fluid.
- PMN (neutrophil) count > 250 cells/mm3
- Positive culture
Something else to know is that there may be bacteria that grow on culture, but it can be due to secondary peritonitis. Basically, the other causes of intra-abdominal infection (cholecystitis, diverticulitis, bowel perforation) can occur in these patients too. Diagnostic studies of ascitic fluid can help to separate primary from secondary disease. If suspected, this is what you should order:
- Glucose
- LDH
- Protein concentration
- Amylase
- Bilirubin
If two or more of the following are present, then secondary peritonitis is confirmed: Ascites glucose < 50 mg/mL, ascites LDH > serum LDH, or ascites protein > 1.5 g/dL. If amylase and bilirubin are present, if suggest bowel perforation.
What do I need to do? Plain and simple, you need to perform a diagnostic paracentesis. Although this will be case by case, it is a procedure and diagnosis that should be considered in every patient with decompensated cirrhosis.
Once the diagnosis is made, treatment generally consists of a five day course of third-generation cephalosporin, quinolone or oxacillin. Typical treatment examples include:
- Ceftriaxone 1 g daily
- Cefotaxime 2 g TID
If a multi-drug resistant organism is suspected or on culture in the patient's history, add a second line agent such as Zosyn.
One last thing. As mentioned, HRS can complicate SBP. A treatment that has been shown to reduce the incidence of HRS, and death, is high dose albumin. As a bonus, you can give albumin 1.5 g/kg after the diagnosis is established. Treatment is 1.5 g/kg on day one and 1.0 g/kg on day three.
Case conclusion: You successfully perform a diagnostic paracentesis on your patient and find a PMN count of 320 cell/mm3. You start cefotaxime 2 g and with consultation with the inpatient team, give the patient 1.5 g/kg of albumin. The patient is admitted and has an uneventful hospital course.
References:
Salerno F, La Mura V. Treatment of spontaneous bacterial peritonitis. Dig Dis. 2015;33(4):582-5.
Matt and Mike Ultrasound podcast - paracentesis - not difficult, but like most things...better with ultrasound!
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