Intra-Abdominal Infections

Infections commonly occurring within the peritoneal cavity

  • As you go down the GI tract you go from more gram negative bacteria to more anaerobic bacteria
  • Intra-abdominal infections = those occurring in the peritoneal cavity
    • Primary = spontaneous, unknown cause
      • Occur less frequently than secondary
      • Most often associated w/ diseases of the liver (hepatitis, alcoholic cirrhosis)   (more often seen in adults than children)
      • 30% produce bacteremia
    • Secondary = organ rupture (ex. Acute appendicitis, diverticulitis, trauma, colonic carcinoma, etc)
      • These typically involve more than 1 pathogen & require combo therapy to cover a broad spectrum of pathogens
  • Continuous ambulatory peritoneal dialysis-associated peritonitis
    • Contamination of peritoneal fluid via dialysis ports (80% incidence during the 1st year w/ a cathetar)
    • 20-30% of patients have a recurring infection
  • Cholangitis:  infection of the biliary ductal system
  • Cholecystitis:  infection of the gall bladder

Bacteria frequently responsible for Intra-abdominal infections (IAIs).

  • Primary (spontaneous) peritonitis:
    • **E. Coli**, Strept pneumoniae  (also could be staph or klebsiella)
  • Secondary bacterial peritonitis:  (mainly gram – & anaerobes)
    • Upper small intestine:  lactobaccilli, streptococcus & oral anaerobes (peptostreptococcus, fusobacterium, bacteroides)
    • Biliary tract:  E. Coli, Klebsiella, enterococci
    • Large Bowel:  anaerobes (bacteroides)
  • Continuous ambulatory peritoneal dialysis-associated peritonitis
    • MRSA, coagulase negative staph or gram negatives
  • Acute cholecystitis & cholangitis
    • E. Coli, Klebsiella, enterobacter, proteus, bacteroides, clostridia

Characteristics/signs/symptoms of various IAIs.

  • Primary (spontaneous) peritonitis
    • Bacteria spread via either hematogenous spread, lymphatic or translocation (through the gut wall)
    • Diagnosis:  presence of bacteria is ascitic fluid (pt has ascites), presence of an abscess
    • Signs/symptoms:  fever/chills, abdominal pain, vomiting, cloudy peritoneal fluid, shock, hepatic coma
  • Secondary bacterial peritonitis
    • The dissemination of the infection is dependent upon the patient’s immune system, adjacent structures, presence of adhesions, etc
    • Localization of the bacteria promotes the formation of abscesses
    • Signs/symptoms:  intense abdominal pain, hypoactive bowel sounds, shock, diminished urine output, fever, N/V, tense, rigid, tachycardia, involuntary abdominal guarding
  • Acute cholecystitis & cholangitis
    • Signs/symptoms:  jaundice, fever & abdominal pain (Charcot’s triad)
      • Chills, N/V, right upper quadrant pain, leukocytosis, hyperbilirubinemia, elevated liver enzymes
    • Diagnosis:  ultrasound of the gallbladder or IV choliangiography
    • Complications:  perforation, pancreatitis, bacteremia & shock (the latter 2 are more common in cholangitis)

Antibiotic regimens used to treat these infections.

  • Primary (spontaneous) peritonitis
    • Prophylaxis is not recommended
    • Treatment:  3rd generation cephalosporin (certriaxone (DOC), ceftazadime, cefotaxime) or cefepime
      • 3rd gen cephalosporins are used b/c this is usually caused by E. Coli or strept. Pneumoniae
      • Add an antibiotic w/ anaerobic coverage if there is no response to the above antibiotics after 10-14 days
  • Secondary bacterial peritonitis
    • Treatment:  an antipseudomonal fluoroquinolone (ex. Cipro)        or         clindamycin           or           metronidazole + an aminoglycoside
      • Or any of the following  imipenem/cilastin, piperacillin/tazobactam, meropenem, ertapenem, ampicillin/sulbactam (this one will also need something to cover anaerobes though)
      • With a persistent infection an aminoglycoside or fluoroquinolone should be added
      • Surgical drainage of the abscess is usually required as well
      • Hydration therapy should also be supplied
  • Continuous ambulatory peritoneal dialysis-associated peritonitis
    • Treatment:  Vanco (for gram +), aminoglycosides (ex. Gentamicin) or Cipro for gram negatives
  • Acute cholecystitis & cholangitis
    • Fluids, surgery
    • Aminoglycoside + clindamycin or metronidazole
    • Piperacillin/tazobactam (zosyn)
    • Ceftazadime or cefepime    +     metronidazole or clindamycin

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