Extended spectrum β-lactamase and integron genes among Shigella flexneri and Shigella sonnei isolated from children with diarrhea in shiraz, Southwest Iran

Shigellosis, a bacterial infection marked by dysentery, is typically a self-limiting disease and can be effectively managed with oral rehydration. However, antibiotics may help reduce the severity and duration of Shigellosis despite rising antimicrobial resistance. This study examines the prevalence of ESBL-producing isolates and the presence of bla_TEM, bla_CTX-M, bla_SHV, intI1, and intI2 genes among Shigella sonnei and Shigella flexneri isolates from children with diarrhea in Shiraz, southwest Iran. From October 2019 to March 2020, 50 S. flexneri and 50 S. sonnei were isolated from children under 13 years old with diarrhea. Antimicrobial susceptibility and ESBL production were assessed, and the presence of ESBL-mediated genes, also intI1 and intI2 genes, was investigated using polymerase chain reaction methods. Resistance rates of 100% were observed against cefotaxime, ceftriaxone, streptomycin, and trimethoprim/sulfamethoxazole in all S. flexneri and S. sonnei isolates, with all isolates exhibiting multidrug resistance (MDR). ESBL positivity was found in (68%) of S. flexneri and (64%) of S. sonnei isolates. The bla_CTX-M gene was prevalent in (56%) of S. flexneri and (70%) of S. sonnei isolates. Remarkably, intI1 and intI2 were detected in (80%) and (86%) of S. flexneri isolates and (18%) and (90%) of S. sonnei isolates, respectively. In conclusion, the increasing resistance to first- and second-line antibiotics for treating shigellosis in Iran is a significant concern. The high prevalence of MDR Shigella spp. isolates in our region underscores the critical need to address the spread of antibiotic resistance and integrons in Shigella spp., making it an urgent priority.