From the Guidelines
Shigella species detected in a stool sample should be treated with azithromycin or ciprofloxacin as the first-line antibiotic therapy. According to the 2017 Infectious Diseases Society of America clinical practice guidelines for the diagnosis and management of infectious diarrhea 1, the recommended treatment for Shigella species is azithromycin or ciprofloxacin.
Key Considerations
- The choice of antibiotic should be based on susceptibility patterns, and clinicians should avoid prescribing fluoroquinolones if the ciprofloxacin MIC is 0.12 μg/mL or higher, even if the laboratory report identifies the isolate as susceptible 1.
- Alternative options include trimethoprim-sulfamethoxazole (TMP-SMX) or ampicillin if the isolate is susceptible 1.
- Patients with Shigella species infection should increase fluid intake to prevent dehydration, practice strict hand hygiene to prevent transmission to others, and avoid preparing food for others while symptomatic.
- Symptoms of Shigellosis typically include bloody diarrhea, abdominal cramps, fever, and tenesmus, and usually resolve within 5-7 days with appropriate treatment.
Treatment Options
- Azithromycin: 500mg on day one followed by 250mg daily for 4 days
- Ciprofloxacin: 500mg twice daily for 3-5 days
- TMP-SMX: 160/800mg twice daily for 5 days (if susceptible) It is essential to note that Shigellosis is highly contagious, spread through the fecal-oral route, and requires only a small number of organisms to cause infection 1. Most patients recover completely, but those with severe symptoms, persistent fever, or signs of dehydration should seek immediate medical attention.
From the FDA Drug Label
Infectious Diarrhea caused by Escherichia coli (enterotoxigenic strains), Campylobacter jejuni, Shigella boydii†, Shigella dysenteriae, Shigella flexneri or Shigella sonnei† when antibacterial therapy is indicated.
The ciprofloxacin (PO) 2 is indicated for the treatment of infections caused by Shigella species.
- Shigella boydii,
- Shigella dysenteriae,
- Shigella flexneri,
- Shigella sonnei are all susceptible to ciprofloxacin.
Additionally, trimethoprim-sulfamethoxazole (PO) 3 is also indicated for the treatment of Shigellosis caused by susceptible strains of Shigella flexneri and Shigella sonnei.
It is essential to note that the treatment should be based on the results of culture and susceptibility tests, and local epidemiology and susceptibility patterns should be considered in selecting or modifying antibacterial therapy.
From the Research
Treatment Options for Shigella Species
- Azithromycin is effective in the treatment of moderate to severe shigellosis caused by multidrug-resistant Shigella strains 4.
- The American Academy of Pediatrics (AAP) recommends cefixime, ceftriaxone, azithromycin, and fluoroquinolones as alternative antibiotics for the treatment of Shigella species infections in children 5.
- Azithromycin represents an alternative option to treat bacterial diarrhea when antibiotic therapy is indicated, with most Shigella isolates showing susceptibility to azithromycin 6.
Antibiotic Resistance Mechanisms
- Drug resistance in Shigella spp. can result from various mechanisms, including decreased cellular permeability, extrusion of drugs by active efflux pumps, and overexpression of drug-modifying and -inactivating enzymes or target modification by mutation 7.
- There is an increasing need for identification and evolution of alternative therapeutic strategies against Shigella infections due to the global rise in broad-spectrum resistance to many antibiotics 7.
Antimicrobial Susceptibility Patterns
- Among Shigella isolates, 86.9% were susceptible to azithromycin, 65.0% to ciprofloxacin, and 23.7% to co-trimoxazole in a study conducted in New South Wales, Australia 8.
- Ciprofloxacin resistance was more common in infections acquired in Australia compared to those acquired overseas, while azithromycin resistance was more common in males 8.
- Ongoing reconsideration of guidelines for the treatment of shigellosis is recommended based on emerging resistance patterns, with first-line therapy potentially needing to be reconsidered due to common resistance to co-trimoxazole and ciprofloxacin 8.