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Background: Dysentery accounts for a significant proportion of morbidity and mortality cases, especially in children with diarrhea in developing countries. Shigellosis remains a public health problem in Iran. Objectives: The objectives of this study were to investigate the presence and the frequency of Shigella spp. among children younger than 10 years with diarrhea and to determine the antimicrobial resistance patterns of these isolates in Tehran, Iran. Patients and Methods: This cross-sectional study was conducted in two pediatric hospitals in Tehran, from October, 2013 to October, 2014. Nine hundred and thirty-eight (n = 938) stool samples were collected (one stool per patient) from children less than 10 years of age. The stools were primarily cultured on MacConkey agar and xylose lysine deoxycholate (XLD). (Selenite-F broth is also used as an enrichment medium for the isolation of Shigella spp.) All of the isolates were confirmed as Shigella species by biochemical and serological tests. Molecular confirmation of Shigella isolates was determined by polymerase chain reaction (PCR) using specific primers for the ipaH gene. The antibiotic susceptibility of the Shigella isolates was tested using the Kirby-Bauer disc-diffusion method. Results: Amongst 938 stool samples, 36 were Shigella spp. S. sonnei (61.1%, n = 22), which was the most common, followed by S. flexneri (27.8%, n = 10), S. boydii (8.3%, n = 3), and S. dysenteriae (2.8%, n = 1). Furthermore, most Shigella isolates showed resistance to amoxicillin (83.3%), tetracycline (61.1%), and co-trimoxazole (83.3%). No resistance was found against ciprofloxacin and imipenem. This study showed that S. sonnei is currently the predominant species in Tehran, Iran. Conclusions: Because resistance to antibiotics changes constantly, Shigella strains should be under surveillance in order to monitor local susceptibility and subsequently formulate policies for the use of antimicrobial drugs.

Background: Antibiotic resistance is widespread among diarrheagenic Escherichia coli in developing countries, where the overuse of antibiotics is common. Information regarding β-lactamases, especially Extended-Spectrum β-Lactamases (ESBLs) in diarrheagenic pathogens should be considered in clinical management when an optimal treatment is needed. Objectives: The main objective of this study was to investigate the prevalence of blaCTX-M, blaSHV and blaTEM β-lactamase genes among enteropathogenic E. coli (EPEC) isolates in Tehran, Iran. Materials and Methods: Stool specimens were collected from children with diarrhea during a 17-month period from 2011 to 2013. Routine biochemical tests were performed for identification of E. coli isolates. The isolates were further examined by PCR for the presence of eae, stx1, stx2 and bfp genes. EPEC isolates have been screened for different β-lactamase genes. Genotyping EPEC isolates harboring blaCTX-M15 gene was performed through Multi-Locus VNTR Analysis (MLVA). Results: Of 42 EPEC, eight isolates carried the blaCTX-M1. None of the isolates carried blaCTX-M2 and blaCTX-M9. The blaCTX-M15 variant was identified in all of blaCTX-M1-positive isolates. Furthermore, blaSHV and blaTEM genes were detected in 40.5% (n = 17) and 19% (n = 8) of all EPEC isolates, respectively. No significant association was observed between the existence of bfp gene and presence of those β-lactamase genes (P > 0.05). MLVA analysis revealed high genetic diversity among blaCTX-M15-positive isolates. Conclusions: Our study emphasized the increasing role of ESBL genes, especially blaCTX-M15 in EPEC isolates.

Aim: The aims of this study were to characterize Iranian Shigella sonnei strains isolated from pediatric cases and evaluate the utility of multilocus variable-number tandem-repeat (VNTR) analysis (MLVA) for genotyping of local S. sonnei strains. Background: S. sonnei has become the dominant species in certain parts of Iran. Although PFGE is still a gold standard for genotyping and source tracking of food-borne pathogens, it is laborious, expensive, time-consuming, and often difficult to interpret. However, MLVA is a PCR-based method, which is rapid, relatively inexpensive and easy to perform. Patients and methods: A total of 47 S. sonnei isolates were obtained from sporadic cases of pediatric shigellosis in Tehran, Iran, during the years 2002-2003 (n=10) and 2008-2010 (n=37). The patients suffered from acute diarrhea and had evidence of more than three episodes of watery, loose, or bloody stools per day. A MLVA scheme based on 7 VNTR loci was established to assess the diversity of 47 S. sonnei isolates. Results: Based on the results, it was clear that the S. sonnei isolates were heterogeneous. Overall, 47 S. sonnei isolates were discriminated into 21 different genotypes. Analysis of the MLVA profiles using a minimum spanning tree (MST) algorithm showed the usefulness of the MLVA assay in discriminating S. sonnei isolates collected over different time periods. However, no correlation was found between the MLVA genotypes and age, gender or clinical symptoms of the patients. Conclusion: It is assumed that our S. sonnei isolates are derived from a limited number of clones that undergo minor genetic changes in the course of time. The present study has provided some valuable insights into the genetic relatedness of S. sonnei in Tehran, Iran.

Patients and Methods: In total, 42 enteropathogenic E. coli strains were isolated from children with diarrhea and examined for the presence of class 1 and 2 integrons. The combined disk method was also performed to detect ESBL production. Statistical analysis was used for the comparison of the categorical data. Results: Class 1 integron was identified in 24 (57.1%) isolates, while only 2 (4.8%) isolates harbored class 2 integron. Integrons were significantly associated with resistance to certain antibiotics, including; co-trimoxazole (P = 0.016) and tetracycline (P = 0.006). Of the 42 enteropathogenic E. coli isolates, 9 (21.4%) isolates were ESBL producers. However, no significant association was observed between the existence of integrons and ESBL production (P = 0.26). Conclusions: Class 1 integrons are prevalent among enteropathogenic E. coli isolates, regardless of whether or not they produce ESBLs. This study emphasizes the alarming role of integrons in antibiotic resistance within diarrheagenic E. coli strains.

Multi-drug-resistant (MDR) diarrheagenic Escherichia coli (DEC) has rapidly spread worldwide and represents the most serious threat to the management of diarrhea in developing countries. During the period from March 2011 to January 2012, a total of 450 stool samples of diarrheal children aged 0-60 months were studied. In order to detect enterotoxigenic E. coli (ETEC) and enterohemorrhagic E. coli (EHEC) simultaneously, a mixture of four primer pairs specific for eltB, estA, vt1, and vt2 genes was used in a multiplex PCR. Antimicrobial susceptibility testing was performed as the Clinical and Laboratory Standards Institute (CLSI) guidelines. A total of 140 (31·1%) DEC were isolated from 450 stool samples. Diarrheagenic E. coli exhibited high-level resistance to aztreonam (80·7%), amoxicillin (74·4%), and tetracycline (69·3%). Also, 86·4% of E. coli isolates were resistant to at least three different classes of antimicrobial agents and considered as MDR. The frequency of ETEC and EHEC pathotypes was 46·4 and 12·1%, respectively and all of these isolates were MDR. In conclusion, MDR ETEC continues to be an important agent associated with diarrhea in children from Tabriz, Iran.

and MIC. CTX-M encoding genes were identified by PCR, and blaCTX-M -carrying isolates were genotyped by rep-PCR. Results: A total of 140(70%) non-duplicate ESBL positive E. coli were determined. Imipenem and Amikacin were effective against 100% and 85% of all tested isolates respectively. Co-resistance of ESBL positive isolates to Erythromycin, Tetracycline, Co-trimoxazole and Ciprofloxacin were found in 93%, 75%, 63% and 43% of the strains, respectively. The rate of cefotaxime and ceftazidime resistant isolates dramatically decreased from 72% to 8.5% and 39% to 4.5% respectively, in the presence of clavulanic acid. Eighty nine (44.5%) E. coli isolates carried the blaCTX-M-1 group alleles. The levels of similarity of the rep-PCR fingerprints of blaCTX-M-1 isolates ranged from 40 to 90%. Conclusions: The rapid dissemination of non clonal multi-resistant CTX-M-1 producing E. coli isolates approved the need for further studies in our medical centers.