Diverticulitis Medication

Updated: Aug 06, 2019
  • Author: Elie M Ghoulam, MD, MS; Chief Editor: BS Anand, MD  more...
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Medication Summary

Diverticulosis is treated with lifelong dietary modification. However, antibiotics have been the mainstay of therapy for most patients with acute diverticulitis, but more recently, their necessity has been questioned, especially in mild, uncomplicated disease. [4, 31] It appears that antimicrobial use in acute uncomplicated diverticulitis increases patients' stay in the hospital without lowering the overall or individual complication rates. [32] Other studies have shown that the effectiveness of single- or multiple-agent antibiotic regimens for outpatient therapy are essentially the same when they provide both anaerobic and aerobic coverage. [6, 7]

Empiric therapy requires broad-spectrum antibiotics effective against known enteric pathogens. For complicated cases of diverticulitis in hospitalized patients, carbapenems are the most effective empiric therapy because of increasing bacterial resistance to other regimens.

Potential regimens include the following:

  • Ciprofloxacin plus metronidazole

  • Trimethoprim-sulfamethoxazole plus metronidazole

  • Amoxicillin-clavulanate

  • Moxifloxacin (use in patients intolerant of both metronidazole and beta lactam agents)



Class Summary

Empiric antimicrobial therapy is essential and should cover all pathogens likely to cause diverticulitis.

Metronidazole (Flagyl, Medro)

Active against various anaerobic bacteria. Enters cell, binds DNA, and inhibits protein synthesis, causing cell death.

Ciprofloxacin (Cipro)

Bactericidal antibiotic that inhibits bacterial DNA synthesis. Used for infections due to E coli, K pneumoniae, E cloacae, P mirabilis, P vulgaris, P aeruginosa, H influenzae, M catarrhalis, S pneumoniae, S aureus (methicillin susceptible), S epidermidis, S pyogenes, Campylobacter jejuni, Shigella species, and Salmonella typhi.

Amoxicillin/clavulanate (Augmentin, Amoclan)

Amoxicillin inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins. The addition of clavulanate inhibits beta-lactamase–producing bacteria.

This agent is a good alternative antibiotic for patients allergic or intolerant to the macrolide class. It is usually well tolerated and provides good coverage to most infectious agents, but it is not effective against Mycoplasma and Legionella species. The half-life of an oral dosage form is 1-1.3 h. It has good tissue penetration but does not enter the cerebrospinal fluid.

For children >3 months, base the dosing protocol on amoxicillin content. Because of different amoxicillin/clavulanic acid ratios in 250-mg tab (250/125) vs 250-mg chewable tab (250/62.5), do not use 250-mg tab until child weighs >40 kg.

Sulfamethoxazole and Trimethoprim (Bactrim, Bactrim DS, Septra DS)

Inhibits bacterial growth by inhibiting the synthesis of dihydrofolic acid.

Antibacterial activity of TMP-SMZ includes the common urinary tract pathogens, except Pseudomonas aeruginosa.

Ceftriaxone (Rocephin)

Third-generation cephalosporin with broad-spectrum, gram-negative activity; lower efficacy against gram-positive organisms; higher efficacy against resistant organisms. Bactericidal activity results from inhibiting cell wall synthesis by binding to one or more penicillin binding proteins. Exerts antimicrobial effect by interfering with the synthesis of peptidoglycan, a major structural component of bacterial cell wall. Bacteria eventually lyse due to the ongoing activity of cell wall autolytic enzymes while cell wall assembly is arrested.

Highly stable in the presence of beta-lactamases, both penicillinase and cephalosporinase, of gram-negative and gram-positive bacteria. Approximately 33-67% of dose is excreted unchanged in urine, and the remainder is secreted in bile and ultimately in feces as microbiologically inactive compounds. Reversibly binds to human plasma proteins, and binding have been reported to decrease from 95% bound at plasma concentrations < 25 mcg/mL to 85% bound at 300 mcg/mL.

Cefotaxime (Claforan)

Third-generation cephalosporin with broad gram-negative spectrum, lower efficacy against gram-positive organisms, and higher efficacy against resistant organisms. Arrests bacterial cell wall synthesis by binding to one or more of the penicillin-binding proteins, which, in turn, inhibits bacterial growth. Used for septicemia and the treatment of gynecologic infections caused by susceptible organisms.

Third-generation cephalosporin with gram-negative spectrum. Lower efficacy against gram-positive organisms.

Ceftolozane/tazobactam (Zerbaxa)

A cephalosporin antibiotic plus a beta-lactamase inhibitor. Indicated for use in combination with metronidazole for complicated intra-abdominal infections caused by Enterobacter cloacae, Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, Bacteroides fragilis, Streptococcus anginosus, Streptococcus constellatus, and Streptococcus salivarius. Dose must be adjusted for reduced CrCl.

Moxifloxacin (Avelox)

Moxifloxacin is the only fluoroquinolone that is FDA approved as monotherapy for the treatment of complicated intra-abdominal infections. Moxifloxacin, a broad-spectrum antibiotic, exhibits activity against Escherichia coli, Bacteroides fragilis, Streptococcus anginosus, Streptococcus constellatus, Enterococcus faecalis, Proteus mirabilis, Clostridium perfringens, Bacteroides thetaiotaomicron, or Peptostreptococcus species. Moxifloxacin is active against gram-positive organisms and anaerobes but is less active against Enterobacteriaceae and Pseudomonas species.

Levofloxacin (Levaquin)

For pseudomonal infections and infections due to multidrug resistant gram-negative organisms.

Ampicillin/Sulbactam (Unasyn)

Drug combination of beta-lactamase inhibitor with ampicillin. Interferes with bacterial cell wall synthesis during active replication, causing bactericidal activity against susceptible organisms. Alternative to amoxicillin when unable to take medication orally. Covers skin, enteric flora, and anaerobes. Not ideal for nosocomial pathogens.

Piperacillin and Tazobactam sodium (Zosyn)

Anti-pseudomonal penicillin plus beta-lactamase inhibitor. Inhibits biosynthesis of cell wall mucopeptide and is effective during the stage of active multiplication.

Ticarcillin and clavulanate potassium (Timentin)

Inhibits biosynthesis of cell wall mucopeptide and is effective during active replication.

Antipseudomonal penicillin and beta-lactamase inhibitor that provides coverage against most gram-positive and gram-negative bacteria and most anaerobes.

Meropenem (Merrem)

Bactericidal broad-spectrum carbapenem antibiotic that inhibits cell-wall synthesis. Effective against most gram-positive and gram-negative bacteria. Has slightly increased activity against gram-negative organisms and slightly decreased activity against staphylococci and streptococci compared with imipenem. Drugs of this class are a good choice for empiric therapy of GI-based infections in hospitalized patients with complicated conditions.


Aminoglycoside antibiotic used to cover gram-negative organisms.

Not the drug of choice (DOC). Consider if penicillins or other less toxic drugs are contraindicated, when clinically indicated, and in mixed infections caused by susceptible staphylococci and gram-negative organisms.

Dosing regimens are numerous; adjust dose based on CrCl and changes in volume of distribution. May be given IV/IM.

Imipenem and cilastatin (Primaxin)

Used for the treatment of multiple organism infections as in peritonitis when other agents are not appropriate.


Broad-spectrum penicillin. Interferes with bacterial cell wall synthesis during active replication, causing bactericidal activity against susceptible organisms. Alternative to amoxicillin when unable to take medication orally.

Tigecycline (Tygacil)

Tetracycline-type antibiotic with broad coverage. NOTE: Tigecycline has a Black Box Warning. This agent was previously used in patients with a severe penicillin allergy, but owing to an increased risk of all-cause mortality, IV tigecycline is now reserved for use in situations when alternative treatments are not suitable. It is FDA approved for complicated intra-abdominal infections, as well as complicated skin and skin structure infections and community-acquired bacterial pneumonia.