What is the recommended treatment for shigellosis in pregnancy?

Treatment of Shigellosis in Pregnancy

For shigellosis in pregnancy, azithromycin is the recommended first-line antibiotic, with ceftriaxone as an alternative, following the same treatment approach as non-pregnant patients while being vigilant for preterm labor complications.

Antibiotic Selection

The 2017 IDSA guidelines recommend azithromycin, ciprofloxacin, or ceftriaxone as first-line agents for shigellosis 1. However, in pregnancy:

• Azithromycin is preferred as it has the best safety profile in pregnancy (FDA Category B) and maintains good efficacy against Shigella
• Ceftriaxone is an excellent alternative, particularly given rising fluoroquinolone resistance 1
• Avoid fluoroquinolones (ciprofloxacin) in pregnancy due to potential fetal cartilage toxicity, despite their effectiveness
• TMP-SMX and ampicillin should only be used if susceptibility testing confirms sensitivity 1, though resistance is increasingly common

Important Caveat on Fluoroquinolone Resistance

Even if laboratory reports indicate susceptibility, avoid fluoroquinolones if the ciprofloxacin MIC is ≥0.12 μg/mL 1. Recent data shows increasing fluoroquinolone resistance and azithromycin non-susceptibility globally 2, making susceptibility testing crucial when possible.

Critical Pregnancy-Specific Complications

Shigellosis in pregnancy carries unique risks that demand aggressive treatment:

• 61% of pregnant women develop preterm uterine contractions before 37 weeks 3
• 82% of those with contractions show cervical changes 3
• 25% of women at risk progress to actual preterm birth 3
• Mother-to-child transmission occurs in documented cases 3

These complications make prompt antibiotic treatment essential—do not withhold antibiotics in pregnant women with confirmed or highly suspected shigellosis.

Treatment Algorithm

1. Initiate empiric azithromycin immediately for pregnant women with bloody diarrhea, fever, and abdominal pain (classic shigellosis presentation)

2. Obtain stool culture before starting antibiotics when possible, but do not delay treatment

3. Monitor closely for:

   • Uterine contractions (even in second trimester)
   • Cervical changes
   • Signs of preterm labor
   • Worsening symptoms despite treatment

4. Switch to ceftriaxone if:

   • Patient fails to improve on azithromycin within 48-72 hours
   • Susceptibility testing reveals azithromycin resistance
   • Patient cannot tolerate macrolides

5. If symptoms worsen on treatment, consider:

   • Antibiotic-associated diarrhea (non-C. difficile)
   • C. difficile superinfection (test for toxin/toxigenic strain)
   • Antimicrobial resistance (obtain susceptibility testing) 1

Common Pitfalls to Avoid

• Do not withhold antibiotics due to pregnancy concerns—untreated shigellosis poses greater fetal risk through preterm labor than antibiotic exposure
• Do not rely solely on bloody diarrhea as a trigger for treatment; 39% of pregnant women with shigellosis may not report this symptom initially
• Do not use ciprofloxacin as first-line in pregnancy despite guideline listing, due to teratogenic concerns
• Do not assume prior antibiotic exposure rules out shigellosis—molecular methods detect Shigella in 30% of culture-negative cases with prior antibiotics 4

Resistance Considerations

Recent surveillance shows concerning trends 2, 5:

• Azithromycin resistance reaching 30% in some populations
• Ceftriaxone resistance increasing from 6% to 42% in recent years
• Ciprofloxacin maintains only 3% resistance but is pregnancy-inappropriate

This makes culture and susceptibility testing valuable when feasible, though empiric treatment should not be delayed while awaiting results.