Epidemiology and genetic characterization of Shigella flexneri strains isolated from three paediatric populations in

S F Ahmed1, M S Riddle, T F Wierzba

  • 1United States Naval Medical Research Unit - 3, Cairo, Egypt.

Insights

Shigella flexneri serotype 1c is emerging in Egypt, with high resistance to common antibiotics like ampicillin and tetracycline. This finding is crucial for developing effective Shigella vaccines.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Public Health

Background:

  • Shigella flexneri is a leading cause of bacterial dysentery worldwide.
  • Understanding regional serotype prevalence and antimicrobial resistance is vital for disease control.

Purpose of the Study:

  • To characterize Shigella flexneri isolates from Egyptian children.
  • To determine serotype distribution and antimicrobial resistance patterns.
  • To inform Shigella vaccine development strategies.

Main Methods:

  • Isolation and serotyping of Shigella flexneri from 97 children in Egypt.
  • Antimicrobial susceptibility testing.
  • Pulsed-field gel electrophoresis (PFGE) for genetic relatedness.
  • Detection of specific virulence genes (set and sen).

Main Results:

  • Serotypes 2a, 1b, 1c, and 6 accounted for over 88.7% of isolates.
  • Shigella flexneri serotype 1c showed increased prevalence.
  • High resistance rates observed for ampicillin (87.6%), tetracycline (84.5%), and trimethoprim-sulfamethoxazole (63.9%).
  • PFGE demonstrated distinct clustering by serotype.
  • The sen gene was universally present; the set gene was specific to serogroup 2a.

Conclusions:

  • Shigella flexneri serotype 1c has emerged as a dominant serotype in Egypt.
  • High antimicrobial resistance necessitates careful treatment choices.
  • Future Shigella vaccine development must account for regional serotype diversity.

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