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Abstract Background and objectives: Water-born diseases are typically caused by pathogens transmitted by orofecal way. Because it is no practical and no economical and also it is time-consuming to find water-born pathogens in water reservoirs, the laboratory studies are performed on the basis of indicator microorganism. Escherichia coli is considered as the most important indicator bacterium for water monitoring. The aim of this study was to evaluate the three methods of Pour Plate (PP), Most Probable Number (MPN) and Membrane Filter (MF) in isolation of Escherichia coli in well water of Parks. Material and Methods: One hundred and sixty five samples of well water, from five geographical zones of north, south, east, west and center of Tehran, were taken in a sterile condition and sent to microbiology department of health faculty to assess with three methods of PP, MPN and MF. The results were analyzed by chi-square. Results: The results indicate that 90 water samples (54.5%) aren’t health. The samples taken from south of Tehran are most contaminant than other zones. The highest contaminated Samples (54.5%) are related to membrane filtration method in comparison with MPN (34.5%) and PP (27.3%). Conclusion: Since the MF method can recognize the contaminants quickly and effectively, we recommend it more. Based on these results, it is essential to educate children not to drink well water in parks. Keywords: well water contamination, Escherichia coli, Tehran's parks

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Abstract Bachground and objectives: Salmonella is one of the most important agents of gastrointestinal infection and diarrhea in our country. Misdiagnosis of these bacteria leads to cure failure. The aim of this study was to make a comparison between PCR and the API-20E and conventional biochemical tests carried out for the identification of Salmonella. Material and Methods: In this study 470 specimens taken from children, with acute gastroenteritis, referred to teaching hospitals called Imam, Shariati and children medical centre. The specimens were transferred to microbiology laboratory in public health school for identification of Salmonella with PCR and API-20E methods. Results: Of 470 specimens, 65(13.8%) are positive for salmonella in hospital laboratory, while 37 (7.9%) for API-20E and 39 (8.3%) for PCR are positive. The results of antibiotic sensitivity tests on 39 salmonella isolated from diarrhea specimens show that 73.3% of them are resistance to at least one of the sixteen antibiotics tested. Conclusion: Based on the the results, there is significant difference (P<0.05) between conventional method, API-20E and PCR Key words: Salmonella, conventional identification, molecular identification

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Abstract Background and objectives: Helicobacter pylori is a helical gram negative bacterium with polar flagella, discovered by Warren and Marshall in 1983. Helicobacter pylori exist in the stomach mucus tissue of less than 20% of people under 30 years old, but this amount would increase up to 40% and 60% in 60- year- old people. The aim of this study was to compare three methods of culture media, direct slide staining and the urease test for the rapid diagnosis of bacterium in case of peptic or duodenal ulcer. Material and Methods: In This descriptive study, duplicate biopsy specimens were taken from 82 clients referring to four different Hospitals .In endoscopy room of the Hospitals, a rapid urease test were carried out on one of duplicate specimens for the presence or non-presence of Helicobacter pylori. In order to see the Helicobacter pylori in the tissues, three slides using foushin, giemsa, and gram staining were prepared from the second specimens. Then, the specimens were incubated into selective culture media and incubated for 4-6 days in micoraerophilic condition. Results: Of 82 tested specimens 70(85.5%) and 66(80.5%) are identified as Helicobacter pylori by positive urease and culture medium, respectively. The frequency of foushin, giemsa, and gram staining are 67 (81.7%), 66 (80.5%), and 61 (74.4%), respectively. The foushin staining is the best with 100% sensitivity among the other methods. Conclusion: Based on difference between proportions, There is no significant difference between staining methods (foshin, giemsa, gram staining) and culture media in all cases. Key words: Helicobacter pylori, microscopic methods, urease test, culture media, identification

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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

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Abstract Background and Objective: Cream, a rich dairy product, with a neutral PH and low preservation time is a suitable medium for microbial growth. Salmonella is one of the most important pathogens in causing food poisoning and human gastroenteritis. This study aimed at investigating the quality of traditional cream for the bacterial contamination. Material and Methods: In this cross-sectional study, 196 non-pasteurized cream samples were collected from 5 regions of Hamedan, Iran. After dilution in phosphate buffer and serial dilution preparation, Salmonella was transferred to Rappaport-Vassiliadis (RV) enrichment medium according to CDC guidelines. After 24 h incubation at 37 ° C, a loop was inoculated in MacConkey and Hektoen Enteric (HE) Agar. The suspected colony phenotype was examined and their identification confirmed by API-20 E. Results: The samples (29%) were contaminated with at least one kind of bacteria, Salmonella Spp (4.59%) and Yersinia Spp (2.55%). The other bacteria like Escherichia, Enterobacter, Klebsiella, and Citrobacter were also isolated. Nine samples were contaminated with two kinds of bacteria. Conclusion: The presence of bacteria such as Salmonella and Yersinia in unpasteurized cream indicates that more quality control needs to be applied to the traditional crème produced in the city by health control office of food products. Keywords: Cream, Salmonella SPP, Coliform, Yersinia Enterocolitica, Hamedan

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Abstract Background and Objective: Cystic fibrosis (CF) is an autosomal recessive genetic disease and Pseudomonas aeruginosa is one of the most common bacteria colonized in CF patients. Growing resistance of this bacterium to antibiotics now a day is a challenge of controlling infection in CF patient. In this study colonization of CF patients with Pseudomonas aeruginosa and antibiotic susceptibility pattern of isolated strains were examined. Material and Methods: From 100 CF patients, during a year, sputum and bronchial swabs were collected. After culturing the samples, some of them were reported as Pseudomonas aeruginosa using biochemical tests. Mucoid strains of Pseudomonas aeruginosa were identified the same as non-producing alginate strains while for catching single pure colony, repeated passage was used. For determining antibiotic resistance of Pseudomonas aeruginosa to some antimicrobial agents Kirby-Bauer method based on CLSI was used. Results: Of 100 samples, 40 (40%) were positive for Pseudompnas aeruginosa. The prevalence of P. aeruginosa was 23.8, 36.84 and 80% at the age of 1-3, 4-12 and 13, respectively. Conclusion: Statistically, there is a significant difference between age and contracting with Pseudomonas aeruginosa in that the higher the age the more colonization with Pseudomonas aeruginosa. Key words: Pseudomonas Aeruginosa, Cystic Fibrosis, Drug Resistance

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