UNIVERSITY OF PENNSYLVANIA MEDICAL CENTER GUIDELINES FOR ANTIBIOTIC USE

GASTROINTESTINAL INFECTIONS

Recommendations are for empiric therapy.
Directed therapy should be based upon culture and sensitivity results.
Clinical Setting
Likely Pathogens
Empiric Treatment Options (normal renal function - see dosing in renal impairment page for adjustments for renal insufficiency)
Duration/Comments
Uncomplicated intra-abdominal infections (e.g. community-acquired infections such as diverticulitis, peritonitis, and cholecystitis/cholangitis without abscess)

Enterobacteriaceae

Enterococcus spp.

anaerobes

Option 1

cefazolin 500mg IV q8h + metronidazole 500mg IV or PO q12h

Option 2

ampicillin/sulbactam 1.5g IV q6h

β-lactam allergy option 1

trimethoprim/sulfamethoxazole 8-10mg/kg/day IV or PO in 2-4 divided doses + metronidazole 500mg IV or PO q12h

β-lactam allergy option 2

levofloxacin 500mg IV or PO q24h + metronidazole 500mg IV or PO q12h

Duration ~ 7 days (until resolution of signs and symptoms)

If the patient is able to take oral medications, use cephalexin 500mg PO q6h (or cefadroxil 500mg PO q12h) instead of cefazolin and amoxicillin/clavulanate 875mg PO q12h instead of ampicillin/sulbactam.

Complicated intra-abdominal infections (e.g. hospital-acquired infection, cholecystitis/cholangitis with abscess or recent biliary instrumentation, secondary peritonitis, immunocompromised patients)

Enterobacteriaceae

P. aeruginosa

Enterococcus spp.

anaerobes

Option 1

piperacillin/tazobactam 4.5g IV q8h

Option 2

cefepime 1g IV q12h + metronidazole 500mg IV q12h

β-lactam allergy

levofloxacin 750mg IV q24h + metronidazole 500mg IV q12h

Duration depends on clinical setting

P. aeruginosa infections require increased dosing of cefepime (2g IV q12h) and piperacillin/tazobactam (3.375g IV q4h).

Necrotizing pancreatitis

Use of antibiotic therapy is controversial, but can be considered if there is > 30% necrosis on CT scan

Enterobacteriaceae

Enterococcus spp.

anaerobes

Option 1

cefepime 1g IV q12h + metronidazole 500mg IV q12h

Option 2

piperacillin/tazobactam 4.5g IV q8h

β-lactam allergy

levofloxacin 500mg IV q24h + metronidazole 500mg IV q12h

Duration ~ 10-14 days

Therapeutic pancreatic tissue levels have been shown with the use of fluoroquinolones, 3rd generation cephalosporins, imipenem, piperacillin, and metronidazole in human and animal studies.

Infected pancreatic necrosis

***Surgical management required***

 

Enterobacteriaceae

Enterococcus spp.

anaerobes

Option 1

cefepime 1g IV q12h + metronidazole 500mg IV q12h

Option 2

piperacillin/tazobactam 4.5g IV q8h

β-lactam allergy

levofloxacin 750mg IV q24h + metronidazole 500mg IV q12h

Duration of therapy depends on clinical setting

Therapeutic pancreatic tissue levels have been shown with the use of fluoroquinolones, 3rd generation cephalosporins, imipenem, piperacillin, and metronidazole in human and animal studies.

C. difficile colitis
Mild to moderate C. difficile (Do not treat asymptomatic C. difficile carriers)

metronidazole 500mg PO q8h

 

If not tolerating oral medications

metronidazole 500mg IV q8h

Duration = 10 days

IV metronidazole may NOT be as effective as oral therapy.

Severe C. difficile

  • WBC ≥ 25,000/uL
  • Hypotension
  • ICU patients
  • Severe abdominal pain
  • Second recurrence
  • No improvement after 5 days of metronidazole
vancomycin 125mg PO q6h

Duration = 10 days

For markedly severe cases, consider combination therapy, surgery consult, and ID consult.

Vancomycin IV is ineffective for the treatment of C. difficile.

Bacterial gastroenteritis and/or traveler's diarrhea

Salmonella spp.

Shigella spp.

Campylobacter spp.

E. coli

Antibiotics should not be prescribed routinely as antibacterial treatment may worsen outcomes.

Treatment should be considered in:

  1. Returning travelers with moderate to severe diarrhea
  2. Immunocompromised patients
  3. Fever and signs of invasive disease

Option 1

azithromycin 500mg PO q24h

Option 2 (for traveler's diarrhea)

rifaximin 200mg PO three times daily

Duration = 3 days

Antibiotics should NOT be given in cases of suspected enterohemorrhagic E. coli 0157:H7.

Bacteremic salmonella infections require longer treatment duration. ID consult should be considered.

Cryptosporidium parvum
nitazoxanide 500mg PO twice daily
Duration = 3 days
Giardia lamblia
metronidazole 250mg PO three times daily
Duration = 5 days
Spontaneous bacterial peritonitis (SBP)
SBP without recent antibiotic exposure (no recent antibiotic exposure or hospitalizations, not currently on SBP prophylaxis)

Enterobacteriaceae

S. pneumoniae

group A streptococcus

S. aureus

ampicillin/sulbactam 1.5g IV q6h

 

β-lactam allergy

levofloxacin 500mg IV or PO q24h

Duration = 5 days

If patient is able to take oral medications, use amoxicillin/clavulanate 875mg PO q12h instead of ampicillin/sulbactam.

SBP with recent antibiotic exposure (recent antibiotic exposure or on a fluoroquinolone for SBP prophylaxis)

cefepime 1g IV q12h

 

β-lactam allergy

vancomycin (see nomogram) + aztreonam 1g IV q8h

Duration = 5 days
SBP prophylaxis during an active GI bleed (in patients with ESLD)

norfloxacin 400mg PO q12h

 

If unable to take oral medications

levofloxacin 500mg IV q24h

Duration = 7 days

After a 7 day course, patient may receive prophylaxis with norfloxacin 400mg PO q24h.

SBP prophylaxis in patients with prior SBP episode and ESLD

Option 1

norfloxacin 400mg PO q24h

Option 2

trimethoprim/sulfamethoxazole 1 DS (160mg/800mg) tablet PO five times per week

Duration = chronic

Short term (while inpatient) or long term outpatient prophylaxis can also be considered in all patients with cirrhosis and ascites when the ascitic fluid total protein is ≤ 1g/dL or serum bilirubin is > 2.5 mg/dL.

H. pylori-associated disease
H. pylori

clarithromycin 500mg PO q12h + amoxicillin 1g PO q12h + lansoprazole 30mg PO q12h

 

β-lactam allergy

clarithromycin 500mg PO q12h + metronidazole 500mg PO q12h + lansoprazole 30mg PO q12h

Duration = 10 days

If the patient is allergic to or intolerant of clarithromycin, substitute metronidazole 500mg PO q12h; however, this reduces efficacy by 10%.

For treatment failure or recurrent disease, consider GI consult.

Updated on 10/14/08 by Shawn Binkley, PharmD

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