Written by: Kevin Dyer, MD (NUEM PGY-4) Edited by: Paul Trinquero, MD (NUEM Alum ‘19) Expert commentary by: Steven K. Herrine, MD
Background
Spontaneous bacterial peritonitis (SBP) is an infection of ascitic fluid without an evident intra-abdominal or surgically-treatable source [1]. The pathophysiology is poorly understood, but likely relates to bacterial translocation across an edematous bowel wall (due to portal hypertension) into the immunologically impaired ascitic fluid. SBP is common in patients with severe hepatic dysfunction (present in 20% of hospitalized patients with ascites) and carries a mortality rate of 10% [2,3]. The high incidence, grave mortality, and potential benefit of early treatment make SBP a can’t-miss diagnosis for the emergency physician.
Clinical Features
The classic triad of SBP is fever, abdominal pain, and increasing ascites [4]. However, like most other “classic triads” in medicine, patients rarely present with all three and instead are much more likely to have only 1 or 2 of these features. The most common signs and symptoms are fever (69%), abdominal pain (59%), altered mental status (54%), and abdominal tenderness (49%). Other less common signs and symptoms include diarrhea (32%), paralytic ileus (30%), hypotension (21%), and hypothermia (17%) [5]. In one study, 13% of patients with SBP were asymptomatic [6].
Importance of Paracentesis
As mentioned above, the clinical signs and symptoms of SBP are variable and sometimes subtle, making it a difficult clinical diagnosis. Instead, diagnosis hinges on the results of an ascitic fluid sample obtained via a diagnostic paracentesis. Ascitic fluid findings indicative of SBP include an elevated absolute polymorphonuclear leukocyte (PMN) count ≥250 cells/mm3, a positive ascitic fluid bacterial culture, and exclusion of secondary causes of bacterial peritonitis (e.g. perforated viscous, intra-abdominal abscess). For the ED physician, a PMN level ≥250 cells/mm3 necessitates initiation of antibiotics as soon as possible, if they were not already started empirically [7].
Not only do patients at risk for SBP need a diagnostic paracentesis, but because treatment is time sensitive, it should be performed as quickly as is feasible. A study by Kim et al showed a 3.3 percent increase in in-hospital mortality for each hour paracentesis was delayed and revealed that delayed paracentesis for patients ultimately diagnosed with SBP led to a 2.7-fold increased risk of death [8-9].
Treatment
Empiric therapy should be initiated in patients with ascites who have a temperature >100°F, abdominal pain and/or tenderness, altered mental status, or ascitic PMNs ≥250 cells/mm3. First line treatment is a third-generation cephalosporin such as Ceftriaxone 2g per day or Cefotaxime 2g q8hrs [10]. For those with a severe penicillin allergy, fluoroquinolones are a viable alternative provided the patient has not been on a prophylactic fluoroquinolone. Common choices are levofloxacin 750mg daily or ofloxacin 400mg BID [10-11].
An additional therapeutic consideration is albumin infusion. Current guidelines from the American Association for the Study of Liver Diseases (AASLD) recommend the administration of albumin at a dose of 1.5g/kg for patients with either a BUN >30mg/dL, a serum creatinine >1.30mg/dL, or a total bilirubin >4mg/dL. A meta-analysis of 4 studies demonstrated a significant reduction in renal impairment (8% vs 31%) and a decrease in mortality (16% vs 35%) in patients who received 1.5g/kg of albumin within 6 hours of diagnosis of SBP [12-13].
Take Home Points
Spontaneous bacterial peritonitis is an infection of ascitic fluid without an evident intra-abdominal or surgically-treatable source.
Diagnosis is nearly impossible to make clinically due to variable, and sometimes subtle, presenting symptoms and therefore hinges on obtaining a fluid sample via a diagnostic paracentesis.
Early diagnostic paracentesis in the ED may improve mortality for hospitalized patients with ascites.
Polymorphonuclear leukocyte (PMN) count ≥250 cells/mm3 raises suspicion for SBP and should prompt initiation of empiric antibiotics - first line is 2g of Ceftriaxone and second line is a fluoroquinolone.
In addition, AASLD guidelines recommend 1.5g/kg of albumin for patients with SBP who have BUN >30mg/dL, creatinine >1.3mg/dL, or bilirubin >4mg/dL as this may decrease mortality and reduce the incidence of renal impairment.
Expert Commentary
The blog authors make many excellent points about the recognition and management of SBP in the emergency department. From the standpoint of a hepatologists, several concepts and developments regarding this dangerous diagnosis are worth emphasizing.
Clinical context is vital in making management decisions: a patient with advanced chronic liver disease, manifested by high MELD score, is more likely to have SBP than an individual with acute or less advanced disease.
Prompt paracentesis is the key to proper management. It is considered safe to perform diagnostic paracentesis in all patients but those with evident hyperfibrinolysis or those in DIC. Some have advocated for midline paracentesis to avoid vascular structures, but LLQ has been demonstrated to be safer. (Sakai 2005)
Only a small amounts of fluid is required to make the diagnosis of PMN > 250 cells/mL. Even a drop in a hemocytometer can be sufficient
Patients on prophylactic antibiotics due to previous SBP or low-protein ascites should raise concern for resistant organisms. It is important to sample the ascites in these individuals before commencing antibiotic therapy.
The use of dipstick (leukocyte esterase) diagnosis is supported by some literature but use has been limited mostly to developing nations (Mendler 2010)
There is a growing body of literature that supports initial intravenous therapy followed by transition to oral antibiotics in clinical scenarios meeting certain conditions. (Angeli 2006)
References:
Sakai H, Sheer TA, Mendler MH, Runyon BA. Choosing the location for non-image guided abdominal paracentesis. Liver International 2005;25:984-986.
Mendler MH, Agarwal A, Trimzi M, Magridal E, Tsushima M, Joo E, Santiago M, et al. A new highly sensitive point of care screen for spontaneous bacterial peritonitis using a leukocyte esterase method. J Hepatol 2010;53:477-483
Angeli P, Guarda S, Fasolato S, Miola E, Craighhero R, Del Piccolo F, Antona C, et al. Switch therapy with ciprofloxacin vs intravenous ceftazidime in the treatment of spontaneous bacterial peritonitis in patients with cirrhosis: similar efficacy at lower cost. Aliment Pharmacol Ther 2006;23:75-84
Steven K. Herrine, MD
Professor of Medicine, Division of Gastroenterology and Hepatology
Vice Dean for Academic Affairs
Sidney Kimmel Medical College at Thomas Jefferson University
How to Cite this Post
[Peer-Reviewed, Web Publication] Dyer K, Trinquero P. (2019, July 29). Spontaneous Bacterial Peritonitis. [NUEM Blog. Expert Commentary by Herrine S]. Retrieved from http://www.nuemblog.com/blog/sbp.
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References:
Such J, Runyon BA. Spontaneous bacterial peritonitis. Clin Infect Dis 1998; 27:669.
Nickson, Chris. “Spontaneous Bacterial Peritonitis.” Life in the Fast Lane Medical Blog, 17 Dec. 2012, https://www.lifeinthefastlane.com/ccc/spontaneous-bacterial-peritonitis
Guiney, Allan. “Should All Admitted Patients with Ascites Get a Paracentesis?” Core EM, 7 Dec. 2017, coreem.net/journal-reviews/paracentesis-for-all
“Episode 123.0 – Paracentesis Journal Update.” Core EM, 27 Nov. 2017, coreem.net/podcast/episode-123-0
McHutchison JG, Runyon BA. Spontaneous bacterial peritonitis. In Surawicz CM, Owen RL (Eds.), Gastrointestinal and Hepatic Infections, WB Saunders Company, Philadelphia 1995. P.455.
Runyon BA. Monomicrobial nonneutrocytic bacterascites: a variant of spontaneous bacterial peritonitis. Hepatology 1990; 12:710Runyon BA. Monomicrobial nonneutrocytic bacterascites: a variant of spontaneous bacterial peritonitis. Hepatology 1990; 12:710.
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Kim JJ, Tsukamoto MM, Mathur AK, et al. Delayed paracentesis is associated with increased in-hospital mortality in patients with spontaneous bacterial peritonitis. Am J Gastroenterol 2014; 109:1436.
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Runyon, B. (2018) Spontaneous bacterial peritonitis in adults: Treatment and prophylaxis. In K.D. Lindor (Ed.), UpToDate. Retrieved April 2, 2018, from https://www.uptodate.com/contents/spontaneous-bacterial-peritonitis-in-adults-treatment-and-prophylaxis
Navasa M, Follo A, Llovet JM, et al. Randomized, comparative study of oral ofloxacin versus intravenous cefotaxime in spontaneous bacterial peritonitis. Gastroenterology 1996; 111:1011.
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Pescatore, Rick. “Should You Give Albumin in Spontaneous Bacterial Peritonitis (SBP)?” R.E.B.E.L. EM - Emergency Medicine Blog, 6 July 2017, rebelem.com/should-you-give-albumin-in-spontaneous-bacterial-peritonitis-sbp