Spontaneous Bacterial Peritonitis
Spontaneous bacterial peritonitis (SBP) is a bacterial infection of ascites without an identifiable source and is defined as polymorphonuclear leukocytes (PMN) count > 250 cells/mm3 and presence of a single organism in ascitic fluid.
- A potentially fatal but reversible cause of deterioration in patients with advanced cirrhosis and should be suspected in any patient with cirrhosis and ascites.
- Mortality rates increase by 10% for every hour delay in initiating antimicrobial therapy in patients with cirrhosis who are in septic shock.
- Intestinal bacterial overgrowth with subsequent translocation to mesenteric lymph nodes with failure of the immune system in part due to diminished opsonic activity.
- Fever (50-75%), abdominal pain (27-72%) or tenderness (30-40%) almost exclusively in context of ascites.
- Can be asymptomatic in small but significant proportions (up to 13%) of patients.
Indications for paracentesis in cirrhotics with ascites include any of the following:
- at time of admission (consider asymptomatic SBP).
- change in clinical status.
- development of lab abnormalities.
- during episodes of variceal bleeding, prior to antibiotics.
- Fluid PMN count > 250 cells/mm3 is the single best test in diagnosing ascitic fluid infection.
- Ascitic fluid culture should be immediately inoculated at bedside in one aerobic and one anaerobic bottle, prior to initiation of antimicrobial therapy.
- Due to considerable mortality, there should be low threshold to perform diagnostic abdominal paracentesis even in context of coagulopathy.
EXCLUDING SECONDARY BACTERIAL PERITONITIS
- Defined as bacterial infection of ascites with surgically treatable intra-abdominal source of infection (e.g., perforated viscus or intra-abdominal abscess) with PMN count > 250 cells/mm3.
Secondary bacterial peritonitis should be suspected if 2 of 3 of the following on paracentesis fluid analysis:
- Glucose < 2.8mmol/L.
- Total protein > 0.62mmol/L.
- LDH > Upper limit of normal for serum.
If above criteria are met OR polymicrobial ascitic culture, perform upright XR/chest to look for free air and consider CT to investigate for cause of secondary bacterial peritonitis.
- Serum albumin and ascites albumin to confirm portal hypertension (if status unknown).
- Other studies such as ascites fluid pH have limited utility in the diagnosis of SBP.
TREATMENT: ANTIMICROBIAL THERAPY
- Monomicrobial infection with Escherichia coli and gram positives (streptococcus, enterococcus) most common organisms.
- Indications for empiric antimicrobial therapy to be initiated AFTER cultures are obtained if:
- Fluid PMN > 250 cells/mm3 OR.
- Clinical signs/symptoms of infection (e.g., fever, abdominal pain/tenderness).
- In most cases, start with Cefotaxime 2g IV q8h.
- If nosocomial infection, recent hospitalization, or ICU admission, consider piperacillin-tazobactam or carbapenem +/- vancomycin.
- Duration of antimicrobial therapy is 5-7 days.
- Consider repeating diagnostic paracentesis in 48h to assess response.
TREATMENT: ALBUMIN / OTHER CONSIDERATIONS
- Start Albumin 1.5g/kg at day 1 and 1g/kg at day 3.
- Consider holding non-selective beta blockers in patients with SBP who develop hypotension (<65mmHg) or AKI.
- In patients with cirrhosis and UGIB, start Ceftriaxone 1g IV q24h until hemorrhage has resolved for maximum of 7 days.
- Antimicrobial prophylaxis should be also considered in patients with cirrhosis who have low protein ascites (<1.5g/L) and severe renal or liver dysfunction (Child-Pugh >9).
Quality Of Evidence?
We are highly confident that the true effect lies close to that of the estimate of the effect. There is a wide range of studies included in the analyses with no major limitations, there is little variation between studies, and the summary estimate has a narrow confidence interval.
We consider that the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. There are only a few studies and some have limitations but not major flaws, there are some variations between studies, or the confidence interval of the summary estimate is wide.
When the true effect may be substantially different from the estimate of the effect. The studies have major flaws, there is important variations between studies, of the confidence interval of the summary estimate is very wide.
- Diagnostic value of Fluid PMN count: HIGH. Meta-analysis of prospective studies.
Diagnostic value of Fluid pH: LOW. Data from prospective studies published over 20 years ago.
- Empiric antimicrobial therapy with Cefotaxime: HIGH. Multiple RCTs.
- Effect of albumin on reducing mortality in SBP: HIGH. Multiple RCTs.
- Antibiotic prophylaxis to prevent SBP in cirrhosis: LOW. Low-certainty evidence in recent Cochrane review.
OTHER RELEVANT INFORMATION
Optimal Management of Cirrhotic Ascites: A review for Internal Medicine Physicians
Gallo, A. Dedionigi, C. Civitelli, et al. 2020 Dec 31.
-US National Library of Medicine National Institutes of Health Search database
Diagnosis, Evaluation and Management of Ascites, Spontaneous Bacterial Peritonitis and Hepatorenal Syndrome 2021: Practice Guidelines by the American Association for the Study of Liver Diseases.
Biggins S.W et al. . 2021;74:1014-1048.
The purpose of this document is to provide health care professionals with key facts and recommendations for the diagnosis and treatment of patients in the emergency department. This summary was produced by Emergency Care BC (formerly the BC Emergency Medicine Network) and uses the best available knowledge at the time of publication. However, healthcare professionals should continue to use their own judgment and take into consideration context, resources and other relevant factors. Emergency Care BC is not liable for any damages, claims, liabilities, costs or obligations arising from the use of this document including loss or damages arising from any claims made by a third party. Emergency Care BC also assumes no responsibility or liability for changes made to this document without its consent.
Last Updated Jan 19, 2022
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