Author:
AlisonFoster-Goldman
Christopher T.Richards
Description
- Infection of ascitic fluid without an evident intra-abdominal surgically treatable source:
- Ascitic fluid polymorphonuclear leukocyte count (PMN) >250/mL with a positive bacterial peritoneal fluid culture
- Must be distinguished from secondary bacterial peritonitis (from an intra-abdominal visceral infection):
- Nonsurgical management of secondary bacterial peritonitis carries 100% mortality
- Surgical management of spontaneous bacterial peritonitis (SBP) carries 80% mortality
- Up to 30% yearly incidence of SBP in patients with ascites
Etiology
- Mechanism:
- Portal hypertension causes translocation of intestinal bacteria through edematous gut mucosa to the peritoneal cavity
- Variceal bleeding increases the risk of SBP due to a compromised barrier between the gastrointestinal (GI) tract and blood stream
- Transient bacteremia with low serum complement
- Decreased host defense mechanisms
- Impaired activity of reticuloendothelial system phagocytosis and opsonization
- Can also seed ascitic fluid via bacteremia from extra-abdominal infections
- Usually seen in the setting of cirrhosis:
- Predominant organisms:
- 63% aerobic gram-negative (Escherichia coli, Klebsiella, others)
- 15% gram-positive (Streptococci/Staphylococci)
- 6-10% enterococci
- <1% anaerobic
- Gram-positives account for 50% of cases in patients who are on prophylactic therapy with fluoroquinolones
Signs and Symptoms
Up to 30% of patients with SBP have no signs or symptoms of infection
History
- Abdominal pain: Diffuse, constant, can be mild
- Fever or hypothermia
- Diarrhea from bacterial overgrowth
- Worsening ascites
- Altered mental status
- Fatigue, myalgias
- Hypotension
Physical Exam
- Fever is the most common sign:
- A lower temperature threshold for fever (i.e., >37.8°C or >100°F) is maintained for cirrhotic patients owing to baseline hypothermia
- 69% of patients with SBP have fevers
- Altered mental status
- Abdominal tenderness and pain:
- Development of a rigid abdomen may not occur because of the separation of visceral and parietal pleura due to ascites
- Loose stool
- Paralytic ileus
Essential Workup
- Paracentesis is the mainstay of diagnosis unless patient has peritoneal dialysis
- Coagulopathy (i.e., elevated INR/PTT) does not have to be corrected before the procedure (except for platelets <20,000)
- A low clinical suspicion does not obviate the need for workup
- Delay in paracentesis has been associated with a significant increase in in-patient mortality
- Should be done before antibiotic administration
- Procedure:
- Use ultrasound guidance when available
- Location (with patient supine):
- 3-5 cm cephalad and medial to anterosuperior iliac spine, lateral to the rectus sheath OR
- 2 cm caudad to the umbilicus (ensure bladder emptying beforehand )
- 40-50 mL should be aspirated, then change needles to avoid contamination:
- 10 mL for each culture bottle
- 10 mL for cell count, chemistries, Gram stain (lithium-heparin tube, EDTA tube, and sterile container)
- Inoculate culture bottles with peritoneal fluid immediately at the bedside
Diagnostic Tests & Interpretation
Lab
- Routine ascitic fluid assays:
- Cell count and differential:
- Total protein
- Albumin
- Culture
- Gram stain
- Optional fluid assays:
- Glucose
- LDH (from lysed PMNs)
- Amylase
- Characteristics of ascitic fluid consistent with SBP:
- PMNs >250/mm3
- Diagnosis suggested when:
- WBC >1,000/mm3
- WBC >250/mm3 with >50% PMNs
- Total protein <1 g/dL
- pH < 7.34
- Glucose ≥50 mg/dL
- Normal amylase
- Positive culture:
- Only 30-50% of cultures become positive; this rate increases with high volume bedside inoculation of culture bottles
- Positive Gram stain
- Ascites LDH > serum LDH
- Serum-ascites albumin gradient >1.1 g/dL consistent with portal hypertension
- If hemorrhagic ascites (>10,000 RBC/mm3), subtract 1 PMN/mm3 for every 250 RBC/mm3 in ascites fluid interpretation
- Blood tests (usually reflect underlying disease):
- CBC with differential
- Basic metabolic panel
- PT/PTT
- LFTs (including albumin)
- Blood cultures
- UA and culture
Imaging
- Abdominal ultrasound:
- Confirms presence of ascites
- Helps guide paracentesis
- CXR
- Abdominal radiographs: Flat-plate and upright to evaluate for perforation or obstruction
- Water-soluble contrast CT if suspect secondary bacterial peritonitis
Diagnostic Procedures/Surgery
Surgery consultation to consider exploratory laparotomy if free air on x-ray or extravasation of contrast on CT
Differential Diagnosis
- Secondary bacterial peritonitis:
- Surgically treatable intra-abdominal infection
- Due to perforation or abscess
- Cell count/differential with PMNs >250/mm3 and polymicrobial Gram stain or 2 of the following:
- Ascites total protein >1 g/dL
- Ascites glucose <50 mg/dL
- Ascites LDH >1/2 upper limit of normal serum LDH or LDH>225
- Orange ascites with bilirubin >6 mg/dL suggests ruptured gallbladder
- Acute hepatitis:
- Fever, leukocytosis, abdominal pain ± ascites
- Ascites PMNs <250/mm3
- Culture-negative neutrocytic ascites:
- Ascites PMNs >250/mL, culture negative
- Monomicrobial nonneutrocytic bacterascites:
- Due to colonization phase of SBP
- Ascites PMNs <250/mm3, monomicrobial culture
- Treated like SBP if symptomatic
- Polymicrobial bacterascites:
- Due to accidental gut perforation (1 in 1,000 paracenteses)
- Ascites PMNs <250/mm3, polymicrobial culture
- Pancreatitis:
- Peritoneal carcinomatosis or tuberculous peritonitis:
- Secondary bacterial peritonitis criteria with non-PMN predominance and lack of fever
Prehospital
- IV fluids for hypotension
- Blood glucose measurement
- Supplemental oxygen for respiratory complaints
Initial Stabilization/Therapy
- ABCs
- Prompt antibiotic treatment and IV fluids for septic shock
ED Treatment/Procedures
- Administer platelets before paracentesis only if platelet count is <20,000/mm3
- Give empiric antibiotics immediately after paracentesis for:
- Ascites PMNs >250/mm3 or
- Temperature >37.8°C or
- Altered mental status or
- Abdominal pain/tenderness or
- Clinical features most consistent with SBP
- Antibiotic options:
- Cefotaxime
- Alternatives:
- Avoid aminoglycosides, fluoroquinolones
- Add metronidazole for secondary bacterial peritonitis
- IV albumin is helpful in preventing renal impairment and reducing mortality in diagnosed SBP
- Discontinue any concomitant use of any β-blockers as this increases patient's mortality
Prognosis
- In-hospital noninfection-related mortality is 20%
- Can be precursor to hepatorenal syndrome
- 1- and 6-mo mortality rates after an episode of SBP are 32% and 69%, respectively
Medication
First Line
- Cefotaxime: 2 g IV q8h
- Albumin for high-risk patients: 1.5 g/kg IV on day 1 and 1 g/kg IV on day 3
Second Line
- Ceftriaxone: 2 g IV q8h
- Piperacillin-tazobactam: 3.375 g IV q6h
- Ampicillin-sulbactam: 1.5-3 g IM/IV q6h
- Aztreonam: 0.5-2 g IM/IV q6-12h
Disposition
Admission Criteria
- Admit all patients for IV antibiotics and gastroenterology consultation
- ICU admission for septic shock or severe hepatic encephalopathy
Discharge Criteria
All patients with suspected or known SBP should be admitted
Issues for Referral
- Hepatology and gastroenterology referral may be indicated
- Prophylaxis with a fluoroquinolone or trimethoprim/sulfamethoxazole
ALERT |
Infections related to continuous abdominal peritoneal dialysis:- Symptoms: Cloudy peritoneal fluid (90%), abdominal pain (80%), and fever (50%)
- Signs: Abdominal tenderness 70%
- Diagnosis: Peritoneal WBCs >100/mL with >50% PMNs and positive Gram stain or culture:
- Fluid should be accessed by trained personnel
- Microbiology:
- >50% of cases are due to gram-positives, most commonly staphylococci
- E. coli is an uncommon cause of peritonitis in patients with chronic ambulant peritoneal dialysis
- Treatment:
- Antibiotics are given through the intraperitoneal (IP) route
- First choice: Cefazolin (1 g IP per day) + ceftazidime (1 g IP per day)
- Vancomycin (2 g IP every week) is an alternative to cefazolin
- Amikacin 2 mg/kg/d IP
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Follow-up Recommendations
- Gastroenterology or PCP follow-up for patients with SBP
- No need to repeat paracentesis to document improvement or cure
- GrabauCM, CragoSF, HoffLK, et al. Performance stand ards for therapeutic abdominal paracentesis . Hepatology. 2004;40:484-488.
- GreenbergerNJ, BlumbergRS, BurakoffR. Current Diagnosis & Treatment: Gastroenterology, Hepatology, & Endoscopy. 2nd ed.McGraw-Hill; 2012.
- McHutchisoneJG, RunyonBA. Spontaneous bacterial peritonitis. In: SurawiczCM, OwenRK, eds. Gastrointestinal and Hepatic Infection. Philadelphia, PA: WB Saunders Company; 1994:455.
- SuchJ, RunyonBA. Spontaneous bacterial peritonitis . Clin Infect Dis. 1998;27:669-674.
- WiestR, KragA, GerbesA. Spontaneous bacterial peritonitis: Recent guidelines and beyond . Gut. 2012;61(2):297-310.
- WongCL, Holroyd-LeducJ, ThorpeKE, et al. Does this patient have bacterial peritonitis or portal hypertension? How do I perform a paracentesis and analyze the results ? JAMA. 2008;299:1166-1178.
See Also (Topic, Algorithm, Electronic Media Element)
The authors gratefully acknowledge Michael Schmidt, Amer Aldeen and Lucas Roseire for their contribution to the previous edition of this chapter.
ICD9
567.23 Spontaneous bacterial peritonitis
ICD10
K65.2 Spontaneous bacterial peritonitis
SNOMED