Spontaneous Bacterial Peritonitis secondary to… Acinetobacter? 11/14/2018

Our doctor-in-training Jacqueline presented a middle man with infrequent medical care, with a history of heavy alcohol use, who presents with generalized swelling and anorexia. He was septic on presentation with a distended abdomen. Ascitic fluid anlysis was concerning for bacterial peritonitis, and blood cultures (4/4 bottles) were positive for acinetobacter with OXA resistance marker!


Spontaneous bacterial peritonitis

Important to distinguish between Spontaneous bacterial peritonitis (SBP) vs Secondary bacterial peritonitis (also SBP but for the sake of clarity, SBP from this point on will refer to spontaneous bacterial peritonitis)

  • Secondary: Bacterial peritonitis secondary to something else besides spontaneous, i.e. bowel perforation, surgery.
    • 100% mortality without surgical intervention. Surgical risk is high but patient mortality is almost guaranteed without surgery!
    • If Spontaneous BP, mortality can approach 80% with abdominal surgery.
  • Diagnosis: history, fluid analysis
  • Cultures from peritoneal fluid usually polymicrobial (gut flora)
  • Tertiary bacterial peritonitis: Persistence of peritonitis or abscess following adequate treatment of primary or secondary peritonitis

Epidemiology

  • Pts with cirrhotic ascites, suspect SBP in all these patients, and also pts with ascites suffering from a GIB.
  • Organisms: E.coli, Klebsiella, strep pneumo are most common, usually single organism
  • Less common: Acinetobacter, pseudomonas, proteus
  • If polymicrobial of anaerobes, suspect secondary bacterial peritonitis
  • Rarely fungal but they have been described, poor prognosis.

Presentation

  • S/S of ascites
  • May have fever, malaise, encephalopathy, decompensated liver cirrhosis, peritoneal signs sometimes.
  • Frequently an instigator for hepatorenal syndrome in cirrhotic patients.

Diagnosis:

  • PMN > 250 cells/mL
  • Positive cultures/Gram-stain
  • Absence of secondary causes

Management:

  • Antibiotics:
    • Cefotaxime 2g Q8H
    • Ceftriaxone once daily is an alterative with some evidence trending toward improved survival and less ICU stay with 2g daily dosing vs 1g.
    • Cefepime 1-2g Q8H is an alternative as well esp for resistant pathogens.
    • Fluoroquinolones: Consider alternative if pt already on a quinolone for prophylaxis prior to developing SBP. Can use Cipro, Levo, or Moxi.
    • Carbapenems
    • Beta lactam/Beta lactamase inhibitors i.e. Zosyn
    • Duration: At least 5 days
  • Albumin: Recommended, RCT published in NEJM in 1999 established the administration of albumin decreases the incidence of renal failure with albumin + antibiotics as well as decrease in mortality.
    • Patients in the study who were most likely to benefit from albumin had:
      • Bili > 4
      • Cr > 1
      • BUN > 30
    • 1.5g albumin /kg on day 1, the 1.0g/kg on day 3. Dose limited to max of 100g
  • HRS (Hepatorenal syndrome): 1.0g/kg albumin days 1 & 2 and see if renal function improves (albumin challenge)

Prognosis

  • Renal failure can be seen in 30-40% of patients with SBP
  • Prognosis tends to be poor once HRS sets in
  • HRS
    • Type 1: Rapid progressive decline, 50% 1 month mortality
    • Type 2: More subacute/chronic, not associated with an inciting event, median survival 6 months

 Prophylaxis

  • Primary
    • Cirrhotics presenting with GIB should get primary prophylaxis, total duration of therapy x 7 days
    • Ascitic protein < 1.0 g/dL can also be considered (RCT published in Journal of Hepatology in 2008)
    • Ascitic protein <1 and Childs Pugh > 9 or T.bili > 3 or renal dysfunction: can also consider long-term primary prophylaxis, based on an RCT from Gastroenterology in 2007, drug of study was norfloxacin.
  • Secondary
    • Indicated after first episode of SBP, one year recurrence rate of 40-70%, mortality rate of 50-70%
    • Meds: Norfloxacin or cipro daily, Bactrim also an equivocal alternative
    • Life-long or until transplant

Please refer to this article for an overview of SBP.


Acinetobacter

Epidemiology:

  • Nosocomial, ICU
  • Tropical/humid environments
  • Water and soil
  • Certain strains can survive in a desiccated environment for weeks.

Presentation

  • Most commonly in ventilator associated pneumonia and blood stream infection (1.5% – 2.4%)
  • Others: Central line, catheters, surgical site infection
  • Can be contamination, pts and health care workers can be colonized
  • Can also present as endocarditis or meningitis or ocular infection (contact lens)
  • Peritonitis secondary to acinetobacter usually more common in peritoneal dialysis patients.

Risk Factors

  • Prior antibiotics, especially beta lactams, carbapenems, fluoroquinolones
  • Presence of catheters, ICU
  • PD (especially in setting of peritonitis secondary to actinobacteria)
  • Trauma, burn, immunosuppression

Resistance

  • Increasingly resistant, both acquired and inherent
  • ESBL phenotype also emerging

Management

  • 1st line: cephalosporin (ceftaz, cefepime), beta-lactam/beta lactamase inhibitor, carbapenems are highly effective, ampicillin0sulbactam is also very effective.
  • Sometimes combination therapy is used i.e. with a fluoroquinolone or aminoglycoside due to concerns of emerging and acquired resistance but limited data on combo therapy vs emergences of resistance or whether clinical outcome is improved.
  • Other possible options: minocycline, tigecycline, polymyxins

Prognosis

  • 2x more likely to die from a carbapenem resistant strain

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