First Things First (assess & treat for the following)

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History and Physical (assess for the following):

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Diagnostic Tests

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General Management Principles

• This section is intended to provide recommendations for empiric (initial) parenteral antibiotic choices for infections seen in immunocompetent, critically ill adult pts.
• Subsequent antibiotic choices should be guided by Gram stain & culture results.
• This section is not intended for use in the mgt of AIDS pts.
• Use local antimicrobial resistance patterns & other specific clinical circumstances (eg, underlying medical problems, acuity of illness, age, setting) to guide empiric antibiotic choices.
• Drug doses assume normal renal function.
• Other empiric strategies exist. More detailed information regarding antibiotic selection can be found in multiple sources.
• Many of these recommendations represent the opinions of the authors.
  

Specific Treatment

• Offending microorganisms are usually normal aerobic & anaerobic flora of the GI tract.
• Empiric antibiotic therapy is aimed at a mixed population of organisms.

Cholecystitis

• Surgical consultation is mandatory.
• Cholecystectomy remains the treatment of choice.
• External drainage is an alternative for pts too unstable to undergo surgery.
• Timing of surgery is individualized.
• Empiric therapy: cholecystitis
  • Piperacillin-tazobactam: 4.5 g IV q8h
  • Imipenem-cilastatin: 500 mg IV q6-12h
  • Ampicillin-sulbactam: 1.5-3.0 g IV q6h

Acute acalculous cholecystitis

• Risk factors include mechanical ventilation, SIRS/sepsis, multiple transfusions, dehydration, TPN, major non-biliary surgery, diabetes mellitus, trauma, burn injury.
• Should remain in the differential diagnosis of any critically ill pt who experiences sepsis w/out a known source of infection
• Mortality rate is high, particularly if diagnosis is delayed.
• Cholecystectomy remains the treatment of choice.
• External drainage is an alternative for pts too unstable to undergo surgery.
• Empiric therapy: acute acalculous cholecystitis
  • Piperacillin-tazobactam: 4.5 g IV q8h + an aminoglycoside
  • Imipenem-cilastatin: 500 mg IV q6h + an aminoglycoside

Acute cholangitis

• Caused by a bacterial infection within partially or totally obstructed biliary ducts
• Biliary decompression & broad-spectrum antibiotics are the mainstays of therapy.
• Gastroenterology or surgical consultation is imperative.
• Empiric therapy: acute cholangitis
  • Piperacillin-tazobactam: 4.5 g IV q8h
  • Imipenem-cilastatin: 500 mg IV q6h

Infected acute pancreatitis

• The diagnosis of superimposed infection associated w/ acute pancreatitis can be difficult.
• Diagnosis based upon clinical & radiographic evidence
• CT-guided fine-needle aspiration is highly sensitive & specific.
• Surgical consultation & mgt is imperative.
• Common pathogens include Enterobacteriaceae, enterococci, S. aureus, S. epidermidis, anaerobes & Candida spp.
• Empiric therapy: infected acute pancreatitis
  • Imipenem-cilastatin: 500 mg IV q6h
  • Piperacillin-tazobactam: 4.5 g IV q8h

Intra-abdominal abscess

• Drainage & empiric broad-spectrum antibiotics are essential.
• Antimicrobial therapy should be directed towards common GI flora.
• Monotherapy is not recommended for severe or hospital-acquired infections.
• Consider Pseudomonas spp., enterococci & resistant gram-negative rods in the setting of prolonged hospitalization. Add yeasts to this list when persistent generalized peritonitis (uncontained persistent infection) develops.
• Surgical consultation mandatory. However, percutaneous drainage (interventional radiology) may be adequate.
• Empiric therapy: intra-abdominal abscess
• Consider adding an aminoglycoside for hospital-acquired infections:
  • Piperacillin-tazobactam: 4.5 g IV qh8
  • Ampicillin-sulbactam: 3 g IV q6h
  • Imipenem-cilastatin: 500 mg IV q6h
  • Ciprofloxacin: 400 mg IV q12h + metronidazole 15 mg/kg IV x 1, then 7.5 mg/kg IV q6h

Peritonitis

• Causes of primary infectious peritonitis include spontaneous bacterial peritonitis (SBP), infections caused by peritoneal dialysis catheters, TB & other granulomatous peritonitis. Primary peritonitis usually responds to medical therapy.
• Secondary infectious peritonitis is a localized (abscess) or diffuse infectious process resulting from a defect (spontaneous, post-traumatic or postop) in an abdominal viscus. Timely surgical intervention is imperative.
• Tertiary peritonitis is a peritonitis-like syndrome due to an altered immune response by the host (peritonitis w/out pathogens, peritonitis w/ fungi, peritonitis w/ low-grade bacteria).
  • Empiric therapy for spontaneous bacterial peritonitis
    • Cefotaxime: 2 g IV q8h
    • Ceftriaxone: 1-2 g IV q24h
    • Imipenem-cilastatin: 500 mg IV q6h
    • Ciprofloxacin: 400 mg IV q12h
• Empiric therapy for secondary peritonitis
• Consider adding an aminoglycoside for hospital-acquired infections.
  • Piperacillin-tazobactam: 4.5 g IV qh8
  • Ampicillin-sulbactam: 3 g IV q6h
  • Imipenem-cilastatin: 500 mg IV q6h
  • Ciprofloxacin: 400 mg IV q12h + metronidazole: 15 mg/kg IV x 1, then 7.5 mg/kg IV q6h

Diverticulitis

• Surgical consultation advised.
• Indications for emergent surgical intervention in immunocompetent pts include generalized peritonitis, uncontrolled sepsis, visceral perforation, obstruction & acute clinical deterioration.
• Empiric inpatient therapy: diverticulitis
  • Piperacillin-tazobactam: 4.5 g IV q8h
  • Ampicillin-sulbactam: 3.0 g IV q6h
  • Ciprofloxacin: 400 mg IV q12h + metronidazole: 15 mg/kg IV x 1, then 7.5 mg/kg IV q6h
  • Imipenem-cilastatin: 500 mg IV q6h

Peptic ulcer disease (H. pylori)

• NIH recommends testing & treating all pts w/ symptomatic peptic ulcer disease.
• Therapy: peptic ulcer disease
  • Proton pump inhibitor + clarithromycin 500 mg PO bid + amoxicillin 1 g PO bid
  • Alternate 3-drug & 4-drug strategies exist.

Acute community-acquired diarrhea

• Causes of acute community-acquired diarrhea include bacteria and/or their toxins, viruses & parasites.
• Most cases are treated w/ supportive care only.
• Empiric antibiotic therapy for community-acquired diarrhea must be carefully weighed against its potentially harmful consequences:
• Diarrhea caused by C. difficile can be seen in outpatients who have recently taken antibiotics.
• Circumstances where empiric antibiotic therapy is considered include:
  • Traveler’s diarrhea
  • Moderate to severe, febrile diarrheal illnesses
• Empiric therapy: community-acquired diarrhea
  • Ciprofloxacin: 500 mg PO bid x 3-5 days
  • Trimethoprim/sulfamethoxazole: 1 DS tab PO bid x 5 days
    • See Nosocomial Diarrhea for toxigenic C. difficile treatment recommendations.

Nosocomial diarrhea

• Causes of nosocomial diarrhea include antibiotics & other drugs, enteral feeding, infection & GI bleeding or ischemia.
• Nearly all cases of infectious diarrhea in the ICU are caused by C. difficile.
• Only rarely do community-acquired infections (eg, Salmonella, Shigella, Campylobacter, others) cause diarrhea in pts after they have been admitted for several days to an ICU.
• Repeat C. difficile assays are usually obtained because their sensitivity is incomplete.
  • Therapy: C. difficile enterocolitis
    • Metronidazole: 500 po qid
    • Vancomycin: 125-250 mg PO q12h
    • Metronidazole: 500 mg IV q8h (least preferred)

Ongoing Assessment

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Complications

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Author

• Robert O’Connell, MD & Steven A. Venticinque, MD