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The aim of this study was to evaluate the resistance and virulence characteristics of Yersinia enterocolitica strains of clinical and environmental origins over a 5-year period in Iran and to determine the genetic diversity of strains using pulsed-field gel electrophoresis (PFGE) method. A total of 20 Y. enterocolitica strains were collected from 850 stool samples of patients with diarrhea, and 18 Y e rsinia spp. including 10 Y. enterocolitica were collected from water, food, and vegetable samples. The most frequently isolated Y. enterocolitica strains belonged to biotype (BT) 1A (83.33%). No Y. enterocolitica BT4 was detected that can be attributed to the absence of pig animal reservoir in Iranian food chain. The most frequent chromosomal virulence genes among the Y. enterocolitica isolates were inv (100%), ys tA (67%), ystB (83%), tccC (20%), and ail (17%). The most frequent chromosomal virulence genes among non- enterocolitica Yersinia spp. isolates were ystB (87.5%), ystA (37.5%), and inv (37.5%). None of the Y. enterocolitica isolates harbored plasmid origin virulence genes. None of the isolates was resistant to ciprofloxacin, gentamicin, tetracycline, cotrimoxazole, and chloramphenicol, whereas 90% of the Y. enterocolitica and 62.5% of the Yersinia spp. strains were resistant to ampicillin. PFGE genotyping showed a heterogeneous population of highly susceptible Yersinia spp. in both clinical and environmental samples, putting forward a good prognosis in the treatment of patients with yersiniosis. The occurrence of biotype 1A with inv + ystA + ystB + genotype in clinical strains implies the significance of inv , ystA , and ystB gene products in turning of naturally nonpathogenic biotype 1A strains into clinically important pathogens.

Background: Salmonellosis is a major food-borne disease worldwide. The increasing prevalence of antimicrobial resistance among food-borne pathogens such as Salmonella spp. is concerning., Objective: The main objective of this study is to identify class 1 integron genes and to determine antibiotic resistance patterns among Salmonella isolates from children with diarrhea., Methods: A total of 30 Salmonella isolates were recovered from children with diarrhea. The isolates were characterized for antimicrobial susceptibility and screened for the presence of class 1 integron genes (i.e. intI1, sulI1, and qacEΔ1)., Results: The most prevalent serotype was Enteritidis 36.7%, followed by Paratyphi C (30%), and Typhimurium (16.7%). The highest rates of antibiotic resistance were obtained for nalidixic acid (53.3%), followed by streptomycin (40%), and tetracycline (36.7%). Regarding class 1 integrons, 36.7%, 26.7%, and 33.3% of the isolates carried intI1, SulI, and qacEΔ1, respectively, most of which (81.8%) were multidrug-resistant (MDR). Statistical analysis revealed that the presence of class 1 integron was significantly associated with resistance to streptomycin and tetracycline (p = 0.042). However, there was no association between class 1 integron and other antibiotics used in this study (p > 0.05)., Conclusion: The high frequency of integron class 1 gene in MDR Salmonella strains indicates that these mobile genetic elements are versatile among different Salmonella serotypes, and associated with reduced susceptibility to many antimicrobials., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

The study sought a possible pathogenic role for Aeromonas spp in Tehranian children presenting with diarrhoea. During a 10-month period (February to October 2001), 310 children <10 years of age with diarrhoea and a group of 310 age- and sex-matched controls were selected. Both groups were investigated for diarrhoeal pathogens. Of 310 children who presented with acute diarrhoea, Aeromonas spp was isolated from 14 (4.5%) (A. veronii biovar sobria 8, A. caviae 5 and A. hydrophila 1). The isolation rate was significantly higher than in the controls (p<0.001). Other enteropathogens were also more commonly isolated in children with diarrhoea: 57 (18.4%) Shigella spp (p<0.0001), 8 (2.6%) Salmonella spp (p<0.01), 7 (2.3%) enteropathogenic E. coli (p<0.05) and 8 (2.6%) Giardia lamblia (p<0.01). No enteropathogens were isolated in the control group. Dysentery was the dominant clinical feature in children positive for Aeromonas spp.

This study determined the frequency of Yersinia enterocolitica infection in 300 children with acute diarrhoea aged 0-12 years who were attending a paediatric hospital in Tehran. Over the 5-month study (May-September 2002), Yersinia species and other organisms were cultured and serotyped from stool samples or swabs. Yersinia spp. were found in 8 cases (2.7%). Enteropathogenic Escherichia coli was isolated in 5.7% of cases, Shigella spp. in 3.0% and Salmonella spp. in 2.0%. None of the Y. enterocolitica belonged to the common serotypes of O:3 and O:9. Atypical Yersinia spp. (Y. intermedia and Y. frederiksenii) were isolated. All Y. enterocolitica isolates had a similar pattern of antimicrobial resistance. Yersinia spp. infections are not common in the summer months in Tehran.

Abstract Background and Objectives: gasterointertidis is one of the most common forms of Salmonellosis, which is a worldwide problem. The invasive characteristic of intestinal bacteria is one of their pathogenicity Mechanisms , which can be easily investigated by cell culture technique. In this study ,the invasive characteristic of some Salmonella serogroup were investigated by using HEP-2 cell. Methods and Material: The rectals soap were prepared from 280 diarrhea patients referred to Imam Khomeyni and children medical centres , 140 with bloody diarrhea and 140 with watery diarrhea as a comparison group. The rectal soap was taken before patients taking any antibiotics, and 140 rectal specimens were taken from healthy people as a control group. All the samples were inoculated in differential and selective media, like Hektoen enteric agar and Xylose lysine deoxycholate (XLD) agar .After incubation at 37C for 24 hours, the colonies were examined and identified by conventional biochemical and serological tests. Using HEP-2, cellular invasion characteristic of Salmonella serogroups was assessed. Moreover, the antibiotic resistance patterns were performed according to Clinical and Laboratory Standards Institute (CLSI). Results: Of all tested samples, 35(8.3%) are Salmonella strains. The frequency of Salmonella is reported for bloody diarrhea (5.2%) , watery diarrhea ( 1.7%) and control group( 1.4%) .The most abundant serogroups with invasive characteristic, using HEP-2 cell culture, are serogroup B ( 62.9%) and D (17.2%). Conclusion The results obtained in this study show that the majority of Salmonella isolates are without invasive characteristic. Key words: Salmonella, Diarrhea, Cell invasion, Cell culture

Background and Aim: Enteroinvasive Escherichia coli (EIEC) strains include a group of diarrheagenic Escherichia coli (DEC) and are known to cause shigellosis-like symptoms in both adults and children. They belong to a limited number of serotypes and their somatic (O) antigens are identical with, or related to, certain Shigella antigens. EIEC strains are confirmed by demonstration of invasiveness by polymerase chain reaction (PCR) for detection of the ipaH (invasive plasmid antigen H) gene that is specific for these strains among DEC.Since in our country,Iran study for detection of these strains. hasnot been carried out therefore the aim of this study was detection of EIEC in diarrheal under 5 year old children in Tehran.Materials and Methods: During the descriptive study,300stool samples were collected from children with diarrhea in Ali Asghar Hospital and children medicinal center of Tehran during 4 months (April-Jul 2008). E.coli species were isolated by standard bacteriological and biochemical tests. Presence of invasive plasmid antigen H (ipaH) gene in confirmed colonies was investigated by PCR technique.Results: Among 300 stool specimens studied using culture method and biochemical tests,39(13%) E.coli species were isolated. Among these 39 strains,7(2.3%) strains containing ipaH gene (EIEC) were detected by PCR technique.Conclusions: Enteroinvasive Escherichia coli (EIEC) in our country, Iran, may be as bacterial pathogen causing childhood diarrhea. Therefore we should apply new techniques for investigation of these strains.

Background and Aim: Enteroinvasive Escherichia coli (EIEC) strains include a group of diarrheagenic Escherichia coli (DEC) and are known to cause shigellosis-like symptoms in both adults and children. They belong to a limited number of serotypes and their somatic (O) antigens are identical with, or related to, certain Shigella antigens. EIEC strains are confirmed by demonstration of invasiveness by polymerase chain reaction (PCR) for detection of the ipaH (invasive plasmid antigen H) gene that is specific for these strains among DEC.Since in our country,Iran study for detection of these strains. hasnot been carried out therefore the aim of this study was detection of EIEC in diarrheal under 5 year old children in Tehran. Materials and Methods: During the descriptive study,300stool samples were collected from children with diarrhea in Ali Asghar Hospital and children medicinal center of Tehran during 4 months (April-Jul 2008). E.coli species were isolated by standard bacteriological and biochemical tests. Presence of invasive plasmid antigen H (ipaH) gene in confirmed colonies was investigated by PCR technique. Results: Among 300 stool specimens studied using culture method and biochemical tests,39(13%) E.coli species were isolated. Among these 39 strains,7(2.3%) strains containing ipaH gene (EIEC) were detected by PCR technique. Conclusions: Enteroinvasive Escherichia coli (EIEC) in our country, Iran, may be as bacterial pathogen causing childhood diarrhea. Therefore we should apply new techniques for investigation of these strains.

Introduction: Shiga toxin- producing Escherichia coli (STEC) is an emerging bacterial pathogen in developing countries that causes several diseases such as diarrhea, hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS), particularly in children. Aim of the research was detection of STEC in diarrheal specimens from under 5 year olds and study of the patterns of antibiotic resistance of these strains. Methods: In the study,300 fecal samples were collected from children with diarrhea referring to Ali Asghar Hospital. E.coli species were isolated by standard bacteriological and biochemical tests. Presence of shiga toxin genes (stx1/2) was investigated by PCR technique (Qiagen). Antibiogram test for strains containing the toxin gene was performed using 16 different antibiotic discs (MAST) by disc diffusion agar (Kirby-Bauer) method. Results: From 39 E.coli isolates, 9(23.1%) strains were detected by PCR to contain stx1/2 gene. One strain was resistant to all 16 antibiotics. All the STEC strains were sensitive to meropenem (MRP), imipenem (IMI), gentamycin (GEN) and nitrofurantoin (NI). 4(44.44%) strains showed multi-drug resistant pattern. All these 4strains were resistant to cotrimoxazole(SxT). Also, 6(66.66%) strains were resistant to at least one antibiotic. Conclusion: In Iran, shiga toxin- producing Escherichia coli (STEC) may be a commonly bacterial pathogen causing diarrhea, particularly in children. Therefore, we should use new techniques for investigation of these strains. Increase in number of emerging and new strains that could be resistant to classic antibiotics such as cotrimoxazole may be foreseen. It is suggested that antibiotics prescription programs in treatment of diarrhea causing E.coli strains be updated.