A 57-year-old man is brought to the emergency department for fever and confusion. His partner states that he has been increasingly confused over the past 24 hours and appears more lethargic than usual. The patient has a past medical history of cirrhosis due to untreated hepatitis C. His current medications are furosemide and spironolactone. Temperature is 38.5℃ (101.3℉), pulse is 102/min, respiratory rate is 14/min, blood pressure is 90/58 mmHg, and oxygen saturation is 99% on room air. The patient is oriented to self and place, but not to month or year. Abdominal examination shows moderate ascites with diffuse tenderness to palpation. Laboratory tests are shown below. Diagnostic paracentesis shows a neutrophil count of 325/μL. Which of the following is the best next step in management?
| Laboratory Test | Result |
| Hemoglobin | 11.1 g/dL |
| Leukocyte count | 5,500/μL |
| Platelet count | 110,000/μL |
| Creatinine | 1.4 mg/dL |
| BUN | 34 mg/dL |
| Total bilirubin | 3.9 mg/dL |
A. Oral trimethoprim-sulfamethoxazole
B. Large-volume paracentesis
C. Oral cefpodoxime
D. Intravenous albumin and cefotaxime
E. Rifaximin
Scroll down for the correct answer!
The correct answer to today’s USMLE® Step 2 CK Question is…
D. Intravenous albumin and cefotaxime
Before we get to the Main Explanation, let’s see why the answer wasn’t A, B, C, or E. Skip to the bottom if you want to see the correct answer right away!
Incorrect answer explanations
Today’s incorrect answers are…
A. Oral trimethoprim-sulfamethoxazole
Incorrect: Trimethoprim-sulfamethoxazole can be used for secondary prophylaxis of spontaneous bacterial peritonitis (SBP), but is not appropriate for initial treatment. This patient’s initial episode of SBP should be treated with intravenous albumin and cefotaxime.
B. Large-volume paracentesis
Incorrect: Large-volume paracentesis is not recommended in cases where spontaneous bacterial peritonitis (SBP) is suspected due to the potential for shifts in fluid from the vascular system to the peritoneal cavity. This can reduce effective circulating blood volume, trigger activation of the renin-angiotensin system, and potentially lead to hepatorenal syndrome.
C. Oral cefpodoxime
Incorrect: Cefpodoxime is a third-generation cephalosporin that can be used for primary or secondary prevention of spontaneous bacterial peritonitis (SBP). It is not, however, used as the initial treatment of SBP as it may not achieve necessary ascitic fluid levels as rapidly as intravenous options.
E. Rifaximin
Incorrect: Rifaximin can be used as prophylaxis to prevent hepatic encephalopathy recurrence in patients with cirrhosis. It is not effective for the acute treatment of spontaneous bacterial peritonitis (SBP).
Main Explanation
This patient with a past medical history of cirrhosis presents with fever, confusion, hypotension, ascites, and abdominal tenderness. Diagnostic paracentesis shows an elevated ascitic fluid neutrophil count (>250/µL) confirming the diagnosis of spontaneous bacterial peritonitis (SBP). This patient who is at high risk for renal impairment (creatinine > 1.0 mg/dL) should be started on intravenous albumin and cefotaxime.
SBP is a bacterial infection of ascitic fluid without an intra-abdominal, surgically treatable source. The condition typically occurs in patients with advanced liver disease and ascites. SBP primarily develops due to bacterial translocation, where gut bacteria (e.g., E. coli, Klebsiella) penetrate the intestinal wall and enter the mesenteric lymph nodes before migrating to and infecting the ascitic fluid. This process is facilitated by impaired immune defenses and altered gut permeability seen in patients with cirrhosis and is exacerbated by factors like liver dysfunction and portal hypertension. SBP should be suspected in patients with cirrhosis and ascites who present with symptoms suggestive of infection (e.g., fever, abdominal pain) or decompensation (e.g., worsening encephalopathy or renal function).
Third-generation cephalosporins, such as cefotaxime or ceftriaxone, are used as first-line treatment since they provide good coverage for the organisms commonly associated with SBP (e.g., Escherichia coli, Klebsiella pneumoniae). Albumin is administered in addition to antibiotics in patients with SBP who are at high risk for renal impairment (eg, total bilirubin >4 mg/dL, blood urea nitrogen >30 mg/dL, creatinine >1.0 mg/dL).
Major takeaway
Spontaneous bacterial peritonitis (SBP) occurs in patients with advanced liver disease due to bacterial translocation from the gut. Patients should be treated with intravenous antibiotics (third-generation cephalosporins) and albumin if they are at high risk for renal impairment.
References
Biggins SW, Angeli P, Garcia-Tsao G, et al. Diagnosis, Evaluation, and Management of Ascites, Spontaneous Bacterial Peritonitis and Hepatorenal Syndrome: 2021 Practice Guidance by the American Association for the Study of Liver Diseases. Hepatology. 2021;74(2):1014-1048. doi:10.1002/hep.31884
Dever JB, Sheikh MY. Review article: spontaneous bacterial peritonitis–bacteriology, diagnosis, treatment, risk factors and prevention. Aliment Pharmacol Ther. 2015 Jun;41(11):1116-31. doi: 10.1111/apt.13172. Epub 2015 Mar 26. PMID: 25819304. ––––––––––––
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