Purpose: To investigate the prevalence of qnr, intI, and intII genes in extended spectrum betalactamase (ESBL)-producing Escherichia coli isolated from clinical samples in

Background:Enteroaggregative Escherichia coli (EAEC) is commonly associated with pediatric diarrhea, in developing countries. Objectives: In this study, we investigated the distribution of virulence genes, enterotoxin and biofilm formation among EAEC strains isolated from stools of children with diarrhea referred to three hospitals in south east Iran. Patients and Methods: A total of 464 diarrheic stools were screen for the presence of E. coli using conventional tests. Well isolated colonies were then evaluated for the presence of EAEC diagnostic genes (aggR and pCVD432) by duplex polymerase chain reaction (D-PCR). Positive samples were further subjected to three sets of multiplex-PCR for detection of fimbrial subunits (AAF), serine protease autotransporter toxins (SPATE) and at least one enterotoxin gene. Hemolytic activity was observed on sheep blood agar. Biofilm formation was measured by using a microtiter plate assay. Results: Among the 322 E. coli isolated, 23 were identified as EAEC. All EAEC carried a 630-bp fragment of the plasmid (pAA) encoded pCVD432 and aggR genes. Four major EAEC fimbriae variants aggA, agg4A, agg3A and aafA were detected, with the frequencies of 21.7% (n = 5), 26.8% (n = 6), 21.7% (n = 5) and 4.3% (n = 1), respectively. The class I and II virulence toxins pic, sat, sepA, pet and sigA were detected with frequencies of 56.5% (n = 13), 30.4% (n = 7), 26.8% (n = 6), 21.7% (n = 5) and 4.3% (n = 1), respectively. A heat-stable Shigella enterotoxin-1 gene (astA) was detected in 17.3% (n = 4) of the cases. In addition, 56.4% of the EAEC isolates were α-hemolytic. Quantification of the biofilm revealed six isolates with strong biofilm. Conclusions: Overall, except for pCVD432 and aggR, we detected high heterogeneity of virulence factors among EAEC isolates causing diarrhea in children. One set of genes, in the combination, pic-sepA-agg4A, was associated with strong biofilm.

Background: Helicobacter pylori causes dangerous and deadly diseases such as gastric cancer and duodenal ulcers. Eradication and treatment of this bacterium are very important due to the deadly diseases caused by H. pylori and the high cost of treatment for countries. So, we present a complete list of the most important causes of failure in the treatment and eradication of H. pylori, and addresses new therapeutic methods that may be effective in controlling this bacterium in the future. Results: Many efforts have been made to control and eradicate this bacterium over the years, but no success has been achieved since its eradication is a complex process affected by the bacterial properties and host factors. Previous studies have shown that various factors are involved in failure to eradicate H. pylori, such as new genotypes of the bacterium with higher pathogenicity, inappropriate patient cooperation, mutations, biofilm formation and dormant forms that cause antibiotic resistance, acidic stomach pH, high bacterial load, smoking, immunosuppressive features and intracellular occurrence of H. pylori. On the other hand, recent studies reported that the use of probiotics, nanoparticles, antimicrobial peptides, natural product and vaccine can be helpful in the treatment and eradication of H. pylori infections. Conclusion: Eradication of H. pylori is crucial for the treatment of important diseases such as gastric cancer. Therefore, it seems that identifying the failure causes of treating this bacterium can be helpful in controlling the infections. Besides, further studies on new therapeutic strategies may help eradicate H. pylori in the future.

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