GI antibiotics

Appendicitis

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

Adult Simple Appendicitis

Antibiotic prophylaxis should be coordinated with surgical consult

Options:

• Cefoxitin 2g IV q6 hours OR
• Cefotetan 2g IV q12 hours OR
• Moxifloxacin 400mg IV once daily OR
• Ertapenem 1g IV once daily

Pediatric Simple Appendicitis

Options:

• Cefoxitin 40mg/kg IV q6 hours
• Cefotetan 40mg/kg IV q12 hours
• Gentamicin 2.5mg/kg IV q8hrs +
  • Metronidazole 7.5mg/kg IV 16hrs OR
  • Clindamycin 10mg/kg IV q8hrs

Complicated Appendicitis

Defined as perforation, abscess, or phlegmon

Options:

• Metronidazole 50mg IV q8hrs +
  • Cefepime 50mg/kg IV q12hrs OR
  • Ciprofloxacin 400mg IV q12hrs OR
  • Levofloxacin 750mg IV q24hrs OR
  • Aztreonam 30mg/kg IV q8hrs
• Imipenem/Cilastatin 25mg/kg IV q6hrs (max 500mg)
• Meropenem 20mg/kg IV q8hrs (max 1g)
• Piperacillin/Tazobactam 100mg/kg (max 4.5g) IV q8hrs

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

Cholecystitis

Coverage is targeted at E. coli, Enterococcus, Bacteroides, and Clostridium (anerobic)

Uncomplicated Cholecystitis

• Ertapenem 1g IV once daily OR
• Metronidazole 500mg IV q8hrs PLUS
  • Ciprofloxacin 400mg IV q12 hrs OR
  • Levofloxacin 750mg IV q24hrs OR
  • Ceftriaxone 1g IV q24hrs

Complicated

Complicated disease such as severe sepsis or hemodynamic instability

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

Options:

• Metronidazole 500mg IV q8hrs PLUS Ciprofloxacin 400mg IV q12hrs
• Piperacillin/Tazobactam 4.5g IV q8hrs
• Imipenem/Cilastin 500mg IV q6hrs
• Doripenem 500mg IV q8hrs
• Meropenem 1g IV q8hrs

Clostridium Difficile

Moderate Infection

• Metronidazole 500mg PO or IV q6hr x10-14d

Serous Infection

• Vancomycin 125-250mg PO q6hr x10d (IV form is not effective)
• Add Metronidazole 500mg IV q6hr if ileus or patient cannot tolerate PO

Diverticulitis

Uncomplicated

Options:

• Metronidazole 500mg PO Q8hrs AND Ciprofloxacin 500mg PO BID x10-14d
• Amoxicillin/Clavulanate 875/125 PO BID x10-14d
• Trimethoprim/Sulfamethoxazole, one double-strength tablet bid, and Metronidazole 500 mg Q8h

Complicated

Options:

• Ticarcillin/Clavulanate 3.1 g IV Q6h or
• Piperacillin/Tazobactam 3.375 g IV q6 hours x 7-10 days
• Ciprofloxacin 400 mg IV q12h and metronidazole 1 g IV Q12h
• Ampicillin 2 g IV Q6h and Metronidazole 500 mg IV q6h Plus (Gentamicin 7 mg/kg Q24h or Ciprofloxacin 400 mg IV Q12h)
• Imipenem 500 mg IV Q6h

General Sick

Intra-Abdominal Sepsis/Peritonitis

	Harbor-UCLA	Santa Monica-UCLA	Other
Primary	Metronidazole 500mg IV q8hrs Plus one of the following: Ceftriaxone 1g IV once daily Ciprofloxacin 400mg IV q12hrs Cefazolin 1g (30mg/kg) IV q8hrs Levofloxacin 750mg IV once daily	Metronidazole 500mg IV q8h + Vancomycin 15mg/kg/dose IV q12h (Max dose = 1500mg) Plus one of the following: Piperacillin/tazobactam 4.5g IV q6h Ertapenem 1g IV q24h Ceftriaxone 1g IV q24h	One of the following: Piperacillin-tazobactam Ticarcillin-clavulanate 3.1 g IV every 6 hours Ertapenem 1 g every 24 hours Moxifloxacin 400 mg IV every 24 hours
Allergy or prior exposure	Piperacillin/Tazobactam 4.5g (80mg/kg) IV q8hrs OR Metronidazole 500mg IV q8hrs PLUS Cefepime 2g IV once daily OR Ciprofloxacin 400mg IV q12hrs OR Levofloxacin 750mg IV once daily Meropenem 1g (20mg/kg) IV q8hrs OR Doripenem 500mg IV q8hrs OR Aztreonam 2g (30mg/kg) IV q8hrs + Metronidazole 500mg IV q8hrs	aztreonam 2g IV q8h + metronidazole 500mg IV q8h +/- vancomycin 15mg/kg/dose IV q12h (Max dose = 1500mg)

Infectious Diarrhea

Campylobacter jejuni

• Erythromycin 500mg PO BID x 5 days
• Ciprofloxacin 500mg PO BID x 5 days OR
• Azithromycin 500mg PO once daily x 5 days

Entamoeba Histolytica

• Metronidazole 750mg PO three times daily for 5-10 days PLUS
  • Paromomycin 500mg q8hrs for 7 days OR
  • Iodoquinol 650mg q 8hrs daily 20 days

Giardia lamblia

• Metronidazole 250mg PO q8hrs for 7-10days
• Tinidazole 2g PO once

Microsporidium

• Albendazole 400mg PO BID x 21 days + HAART therapy if HIV positive

Cryptosporidium

• Paromomycin 500mg PO q8hrs x 14-28days +HAART therapy if HIV positive

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

• TMP/SMX 1 DS tab PO BID x 5 days
• Ceftriaxone 2g IV once daily x 5 days
• Levofloxacin 500mg PO once daily x 5 days
• Ciprofloxacin 500mg PO BID x 5 days

Shigella

Treatment extended for 10 days if immunocompromised'

• Ciprofloxacin 500mg PO BID x 5 days
• TMP/SMX 1 DS tab PO BID x 5 days
• Levofloxacin 500mg PO once daily x 5 days
• Azithromycin 500mg PO daily x 5 days

Vibrio Cholerae

• Doxycycline 300mg PO as single dose
• TMP/SMX 1 tablet (5mg/kg) PO BID daily x 3 daily
• Azithromycin 20mg/kg (1g) PO once

Yersinia enterocolitica

Antibiotics are not required unless patient is immunocompromised or systemically ill

• Ciprofloxacin 500mg PO BID daily
• Levofloxacin 500mg PO once daily
• TMP/SMX 1 DS tab (5mg/kg) PO BID

Traveler's Diarrhea

Options for Adults:

• Ciprofloxacin 750mg PO once daily x 1-3 days
  • First choice for use except in South and Southeast Asia
• Azithromycin 500mg PO q24h x 3 days OR 1000mg PO x 1
  • Nausea is a frequent adverse event
  • First choice for use in South and Southeast Asia
• Rifaximin 200mg PO TID x 3 days
  • Ineffective against mucosally invasive pathogens (Shigella, Salmonella, Campylobacter)
  • Considered very safe as it is not absorbed

Typhoid Fever

Oral therapy with Quinolone Susceptibility

• Ciprofloxacin 500-750 mg PO q 12 hrs x 14 days

Parenteral Therapy with Quinolone Susceptibility

• Ciprofloxacin 400 mg IV q 12 hrs x 10 days

Parenteral Therapy with Quinolone Resistance

if nalidixic acid resistant, assume fluoroquinolone resistant

• Ceftriaxone 2mg IV q 24 hrs x 14 days

OR

• Cefixime 10-15 mg/kg IV q 12 hrs x 8 days

Oral Therapy with Quinolone Resistance

• Azithromycin 1 g PO daily x 5 days

See Also

Antibiotics by diagnosis

• Bone and joint antibiotics
• Cardiovascular antibiotics
• ENT antibiotics
• Eye antibiotics
• GI antibiotics
• GU antibiotics
• Neuro antibiotics
• OB/GYN antibiotics
• Pulmonary antibiotics
• Skin and soft tissue antibiotics
• Bioterrorism antibiotics
• Environmental exposure antibiotics
• Immunocompromised antibiotics
• Post exposure prophylaxis antibiotics
• Pediatric antibiotics
• Sepsis antibiotics
• Arthropod and parasitic antibiotics

For antibiotics by organism see Microbiology (Main)

References

Authors

Ross Donaldson, Daniel Ostermayer