Profiling of Virulence-associated Factors in Shigella Species Isolated from Acute Pediatric Diarrheal Samples in Tehran, Iran

OBJECTIVES: The genus Shigella comprises the most infectious and diarrheagenic bacteria causing severe diseases, mostly in children under five years of age. This study aimed to detect nine virulence genes (ipaBCD, VirA, sen, set1A, set1B, ial, ipaH, stx, and sat) in Shigella species (spp.) using multiplex polymerase chain reaction (MPCR) and to determine the relation of Shigella spp. from pediatric diarrheal samples with hospitalization and bloody diarrhea in Tehran, Iran. METHODS: Shigella spp. were isolated and identified using standard microbiological and serological methods. The virulence genes were detected using MPCR. RESULTS: Seventy-five Shigella spp. (40 S. sonnei, 33 S. flexneri, 1 S. dysenteriae, and 1 S. boydii) were isolated in this study. The prevalence of ial, sen, sat, set1A, and set1B was 74.7%, 45.4%, 28%, 24%, and 24%, respectively. All S. flexneri isolates, while no S. sonnei, S. dysenteriae, or S. boydii isolates, contained sat, set1A, and set1B. All isolates were positive for ipaH, ipaBCD, and virA, while one (1.4%) of the isolates contained stx. The highest prevalence of virulence determinants was found in S. flexneri serotype IIa. Nineteen (57.6%) of 33 S. flexneri isolates were positive for ipaBCD, ipaH, virA, ial, and sat. The sen determinants were found to be statistically significantly associated with hospitalization and bloody diarrhea (p = 0.001). CONCLUSION: This study revealed a high prevalence of enterotoxin genes in S. flexneri, especially in serotype 2a, and has presented relations between a few clinical features of shigellosis and numerous virulence determinants of clinical isolates of Shigella spp.

[Frequency of babA2 genotype in helicobacter pylori from patient with gastroduodenal diseases in Firoozgar Hospital in Tehran]

Blood group antigen binding adhesin [babA2], is essential for attachment of Helicobacter pylori [H. pylori] to the epithelial cell layer and is the most important adhesin of H. pylori. The prevalence rate of the babA2 gene varies in different geographic areas. The aim of this study is to determine the frequency of the babA2 gene in patients with different clinical outcomes. We obtained two gastric biopsy specimens from each patient who suffered from gastrointestinal disease. Rapid urease test [RUT] was performed using one biopsy and the remaining biopsy was delivered to the laboratory for DNA extraction. Prevalence of the babA2 gene was determined using gene specific primers. A total of 56 strains [68.3%] of H. pylori were babA2 positive. The prevalence of babA2 in gastric cancer patients [84.6%] was higher than seen with gastric ulcer [66.7%], duodenal ulcer [61%], and gastric patients [66.7%]. There was no correlation between the babA2 genotype and clinical outcomes. We found that babA2 gene was more prevalent in gastric cancer but no correlation was demonstrated. However, previous studies have demonstrated a correlation of babA2 with severe H. pylori-associated diseases such as duodenal ulcers and gastric cancer. This discrepancy may be related in part to geographic diversity or sample size.