Episode 123: Spontaneous Bacterial Peritonitis.
Kaitlen defines spontaneous bacterial peritonitis (SBP) and also explains the diagnosis and management.
Written by Kaitlen Roy-Ross, MS4, Ross University School of Medicine. Moderated by Hector Arreaza, MD.
Definition:
An ascitic fluid infection with no obvious surgically treatable intra-abdominal source (bowel perforation, abscess, perforated ulcer). Commonly seen in patients with cirrhosis and ascites.
Patients may have symptoms of fever, abdominal pain, abdominal tenderness, altered mental status, and hypotension.
Etiology: The most common pathogens (75%) are gram-negative aerobic organisms. Klebsiellapneumoniae accounts for 50% of the cases. Gram-positive aerobic bacteria (Streptococcus pneumoniae or viridans group streptococcus) account for the remaining cases.
Some report E. coli as the most common cause of SBP. Random information: in Korea, Aeromonas hydrophila is an important pathogen of SBP during the summer.
Diagnosis: To diagnose SBP, a paracentesis should be performed to analyze the ascitic fluid prior to treating the patient with antibiotics.
The ascitic fluid should be analyzed for the following:
- PMN (Polymorphonuclear cell) count: > or = to 250 cells/mm3
- Aerobic and anaerobic cultures
- Serum ascites albumin gradient (serum albumin-ascitic albumin): this measures portal pressure.
If the gradient is > 1.1 = portal HTN is present (cirrhosis, heart failure, large liver malignancy, alcoholic hepatitis, portal vein thrombosis) – SBP is likely.
If the gradient is <1.1= portal HTN NOT present (peritoneal carcinomatosis or tuberculosis, pancreatitis, nephrotic syndrome) – SBP less likely.
- Ascites fluid total protein concentration: (<1 g/dL): When protein concentration in ascitic fluid is less than 1 g/dL, there is a low concentration of ópsonins (proteins that bound to bacteria to induce phagocytosis) and patients are at high risk for SBP. The concentration of protein in the peritoneal fluid does not change during SBP. So, if the protein concentration is high, think about secondary bacterial peritonitis.
- Glucose: > 50 mg/dL
- LDH: 43 +/- 20
- Amylase- will be increased in pancreatitis or gut perforation. No SBP.
- Bilirubin- increased bilirubin in ascitic fluid greater than serum bilirubin or > 6 mg/ suggests a gallbladder perforation. No SBP.
Treatment:
The treatment for spontaneous bacterial peritonitis is broad-spectrum antibiotics.
Empiric treatment is indicated if a patient with ascites has any of the following:
- Temperature > 100 F
- Abdominal pain or tenderness
- Altered mental status
- PMN in ascitic fluid > 250 (but if there is bacteria in ascitic fluid, start antibiotics stat)
- Alcohol-induced hepatitis
*Important note: Patients on beta blockers should have them permanently discontinued prior to treatment for SBP as beta blockers are associated with worse outcomes. In one study, patients on beta blockers had a 58% increase in mortality risk compared to patients not treated with beta-blockers. Beta-blockers were also associated with higher rates of hepatorenal syndrome and longer lengths of hospital stay.
1st line treatment- 3rd generation Cephalosporin Cefotaxime 2g IV Q8H (preferred) or Ceftriaxone 2 g per day
2nd line treatment- Carbapenems. Usually reserved for patients with severe disease/critical illness.
3rd line- Fluoroquinolones- Cipro 400 mg IV BID to patients with normal renal function. (Patients should not get this if they already receiving it prophylactically.)
Duration of treatment:
5 days, then re-assess the patient’s PMN count:
PMN <250: Stop ABX treatment
PMN >250 or greater than pre-treatment PMN count > look for a surgical source of infection.
If PMN is > 250 but less than pre-treatment value, continue ABX for 48 more hours and then repeat paracentesis.
Note: In general, ascitic fluid PMN count should be reduced by at least 25% after 48 hours of antibiotic therapy.
Renal failure is the major cause of death in patients with SBP and develops in 30-40 % of the patients. We can decrease this risk by administering IV albumin. IV albumin should be given when the creatinine is > 1 mg/dl, the blood urea nitrogen is > 30 mg/dl, or the total bilirubin is > 4 mg/dl. Treatment with octreotide or midodrine is helpful if renal failure develops.
Prevention:
Antibiotic prophylaxis can be given to patients with risk factors for SBP. Some risk factors include prior history of SBP, variceal hemorrhage, or an ascites fluid protein concentration of <1 g/dL.
Early preventative measures in patients with risk factors are:
- Early diagnosis and treatment of infections to prevent bacteremia (any infections). (Add comments)
- Diuretic therapy. (Add comments)
- Restriction of PPI’s. (Add comments)
Prophylaxis with antibiotics is indicated for:
- Patients with cirrhosis who are hospitalized for reasons other than SBP or GI bleeding:
- Oral TMP-SMX (1 DS tablet daily) with discontinuation of the drug at discharge.
- Patients with a history of 1 or more SBP episodes and patients with low protein ascites along with either renal or liver failure:
- Prolonged outpatient TMP-SMX (1 tablet DS daily). Alternative: Ciprofloxacin 500 mg per day.
- Patients with advanced cirrhosis and GI bleeding
- Ceftriaxone 1 g IV and switch to oral TMP-SMX (1 DS tablet 2x daily) once bleeding has stopped and the patient is stable.
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Conclusion: Now we conclude our episode number 123 “Spontaneous Bacterial Peritonitis.” Let’s not hesitate in the diagnosis of SBP in patients with cirrhosis who present with typical symptoms. The analysis of peritoneal fluid is key in the diagnosis and management of SBP, remember that a peritoneal fluid with PMN above 250 and low protein is highly suggestive of SBP, so, start empiric antibiotics promptly.
This week we thank Hector Arreaza, Kaitlen Roy-Ross, and Gaga Kooner. Audio edition by Adrianne Silva.
Even without trying, every night you go to bed a little wiser. Thanks for listening to Rio Bravo qWeek Podcast. We want to hear from you, send us an email at RioBravoqWeek@clinicasierravista.org, or visit our website riobravofmrp.org/qweek. See you next week!
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Links:
- Runyon, Bruce A. Spontaneous bacterial peritonitis in adults: Treatment and prophylaxis, Up to Date, last updated: March 21, 2022. https://www.uptodate.com/contents/spontaneous-bacterial-peritonitis-in-adults-treatment-and-prophylaxis. Accessed December 13, 2022.
- Ameer MA, Foris LA, Mandiga P, et al. Spontaneous Bacterial Peritonitis. [Updated 2022 Jul 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK448208/
- Royalty-free music used for this episode: Space Orbit by Scott Holmes, downloaded on July 20, 2022, from https://freemusicarchive.org/music/Scott_Holmes/.
