UNIVERSITY OF PENNSYLVANIA MEDICAL CENTER GUIDELINES FOR ANTIBIOTIC USE
GASTROINTESTINAL INFECTIONS
Recommendations are for empiric therapy. |
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Directed therapy should be based upon culture and sensitivity results. |
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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***
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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)
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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. |
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Severe C. difficile
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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. |
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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:
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 |
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Giardia lamblia |
metronidazole 250mg PO three times daily |
Duration = 5 days |
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| 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)
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cefepime 1g IV q12h
β-lactam allergy vancomycin (see nomogram) + aztreonam 1g IV q8h |
Duration = 5 days |
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SBP prophylaxis during an active GI bleed (in patients with ESLD)
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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. |
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SBP prophylaxis in patients with prior SBP episode and ESLD
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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. |
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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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