GI antibiotics


Coverage should extend to E. coli, Klebsiella, Proteus, and Bacteroides (an anaerobe)

Adult Simple Appendicitis

Antibiotic prophylaxis should be coordinated with surgical consult


Pediatric Simple Appendicitis


Complicated Appendicitis

Defined as perforation, abscess, or phlegmon


Cautious use should be applied to use of fluoroquinolones in complicated pediatric appendicitis due to the risk of tendon injury


Most often isolated organisms are Escherichia coli, Klebsiella pneumonia, and anaerobes, especially Bacteroides fragilis


Pathogenicity of Enterococci remains unclear and specific coverage is not routinely suggested for community-acquired infections[1]

Complicated or Healthcare Associated

Examples of complication include severe sepsis or hemodynamic instability

  • Vancomycin 15-20mg/kg PLUS any of the following options


Clostridium Difficile

Mild/Moderate Infection

  • Vancomycin 125 mg PO four times daily for 10 days
  • Fidaxomicin 200 mg PO two times daily for 10 days
  • Metronidazole 500mg PO or IV four times daily for 10 days (third line therapy)

Serious Infection






General Sick

Intra-Abdominal Sepsis/Peritonitis

Harbor-UCLA Santa Monica-UCLA Other
Allergy or prior exposure

Infectious Diarrhea

Campylobacter jejuni

Entamoeba Histolytica

Giardia lamblia



Salmonella (non typhoid)

  • Treatment is not recommended routinely but should be considered if:
  • Immunocompromised
  • Age<6 mo or >50yo
  • Has any prostheses
  • Valvular heart disease
  • Severe Atherosclerosis
  • Active Malignancy
  • Uremic

Options: Immunocompromised patients should have 14 days of therapy


Treatment extended for 10 days if immunocompromised'

Vibrio Cholerae

Yersinia enterocolitica

Antibiotics are not required unless patient is immunocompromised or systemically ill

Peritoneal Dialysis Associated Peritonitis

Empiric Therapy (IP)

10- to 14-day course of intraperitoneal (IP) antibiotics that are administered by the patient on an outpatient basis or IV antibiotics and intraperitoneal for admitted patients
  • Vancomycin 30mg/kg loading followed by 0.6 mg/kg IP daily PLUS[5]
  • Ceftazidime 1g IP daily OR
  • Gentamycin 0.6mg/kg daily
  • Catheter removal/exchange is usually only done if IP antibiotics fail (fungal, pseudomonal), and should be done in consultation with a nephrologist[6]

Empiric Tharapy (IV)

Although IP antibiotics are preferred IV antibiotics can be considered with coordination with nephrology for dosing. Coverage should be the same as IP antibiotics [7][8]

Traveler's Diarrhea

Options for Adults:

Typhoid Fever

Oral therapy with Quinolone Susceptibility

Parenteral Therapy with Quinolone Susceptibility

Parenteral Therapy with Quinolone Resistance

if nalidixic acid resistant, assume fluoroquinolone resistant
  • Cefixime 10-15 mg/kg IV q 12 hrs x 8 days

Oral Therapy with Quinolone Resistance

See Also

Antibiotics by diagnosis

For antibiotics by organism see Microbiology (Main)


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  2. Balasubramanian I et al. Out-Patient Management of Mild or Uncomplicated Diverticulitis: A Systematic Review. Dig Surg. 2017;34(2):151-160.
  3. The STAND trial: Jaung R, Nisbet S, Gosselink MP, Di Re A, Keane C, Lin A, Milne T, Su’a B, Rajaratnam S, Ctercteko G, Hsee L, Rowbotham D, Hill A, Bissett I. Antibiotics Do Not Reduce Length of Hospital Stay for Uncomplicated Diverticulitis in a Pragmatic Double-Blind Randomized Trial. Clin Gastroenterol Hepatol. 2020 Mar 30:S1542-3565(20)30426-2. doi: 10.1016/j.cgh.2020.03.049. PMID: 32240832
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