Prevalence, Antimicrobial Resistance Pattern of <i>Shigella</i> Spp. and Assessed Their Pathogenic Potential Using the <i>Caenorhabditis elegans</i> Infection Model Associated with Acute Diarrheal Patients in Tangail, Bangladesh

<i>Shigella</i> infection is a leading cause of diarrheal diseases, especially in developing countries like Bangladesh, contributing significantly to morbidity and mortality. Despite its importance, data on <i>Shigella</i> prevalence, serotype distribution, and antimicrobial resistance (AMR) patterns remained limited. This study aimed to explore the prevalence of <i>Shigella</i> among patients with acute diarrhea at Tangail Medical College and Hospital, Tangail, Bangladesh, and to analyze the serogroup distribution and AMR profiles of the isolated strains. Stool samples from 96 patients with diarrhea were collected from May 2018 to December 2018 and tested for <i>Shigella</i> using biochemical, molecular, and serotyping methods. The isolates were further examined for antibiotic resistance. In addition, pathogenicity of <i>Shigella</i> spp. was assessed using <i>Caenorhabditis elegans</i> in a solid agar infection assay. Of the total participants, 28.1% were <i>Shigella</i>-positive by culture, while 5.2% and 4.15% were positive by molecular and serotyping methods, respectively. All <i>Shigella</i> isolates exhibited varying degrees of resistance to common antibiotics. <i>Shigella flexneri</i> isolates exhibited high resistance for nalidixic acid only among the tested antibiotics. <i>Shigella dysenteriae</i> was resistant to amoxicillin-clavulanic acid, erythromycin, gentamicin, and nalidixic acid, while <i>Shigella boydii</i> showed resistance to ampicillin, amoxicillin-clavulanic acid, and nalidixic acid. However, no resistance was observed to azithromycin, tetracycline, levofloxacin, or ciprofloxacin. In the pathogenicity assay, a significant difference in survival was observed in <i>C. elegans</i> infected with <i>Shigella</i> spp. compared with the control group. <i>S. dysenteriae</i> exhibited the highest pathogenicity, with only 21.6% survival of <i>C. elegans</i> after 12 h postinfection, while <i>S. boydii</i> and <i>S. flexneri</i> exhibited 27.47% and 35.55% survival, respectively. This study highlights the importance of regular surveillance of <i>Shigella</i> prevalence and AMR patterns in Bangladesh. Furthermore, exploring genomic epidemiology and alternative treatments for <i>Shigella</i> infections is crucial in combating its spread and resistance in Bangladesh.