مسعود آل بویه

Contaminated foods with Shiga toxigenic serotypes of Escherichia coli (STEC) can cause diarrhea and severe diseases in consumers. The aim of this study was to investigate frequency of Shiga toxigenic Escherichia coli serotypes and their antibiotic resistance patterns in vegetable samples from Tehran, Iran.

In this study, a total of 97 vegetable samples from 22 urban areas of Tehran, Iran, were investigated, July 2018 to March 2019. To identify Shiga toxigenic Escherichia coli strains, standard method of enrichment and culture in selective media and polymerase chain reaction for verifying presence of stx1 and stx2 genes were used. Presence of eae and ehxA genes was investigated in Shiga toxigenic Escherichia coli isolates. Antibiotic resistance was assessed using disk diffusion method for 15 antibiotics and the multidrug resistance phenotype was assessed.

Shiga toxigenic Escherichia coli strains were isolated in 14/4% of vegetable samples (stx1, stx2, stx1/stx2 of 8, 1 and 5%, respectively). Presence of eae and ehxA genes was shown in 1 and 2% of Shiga toxigenic Escherichia coli isolates, respectively. The highest resistance was detected to trimethoprim-sulfamethoxazole (100%), erythromycin (73.33%) and tetracycline (85.7%) and the lowest against meropenem (0%) and imipenem/ceftazidime (7/7%).

In this study, contamination of vegetables with multidrug resistant Shiga toxigenic Escherichia coli was verified in Tehran, Iran. Further studies on human samples can clarify this contamination.

Identification of rotavirus genotypes in children is clinically important. This study aimed to determine the spectrum of rotavirus genotypes and assess their correlation with demographic variables and clinical manifestations in hospitalized children.

To determine rotavirus genotypes, rotavirus positive stool samples of symptomatic children were included in the study between December 2019 and March 2020. RNA extraction and cDNA synthesis for VP7 and VP4 genes were performed following standard protocols. Genotypes were determined using specific primers. Validation of results was done through sequencing and bioinformatic analysis. Data were statistically analyzed using SPSS version 20 and GraphPad version 9.5.0.

Among the infected patients, three genotypes emerged as dominant in the studied population. The study demonstrated a significant correlation between genotype frequency and seasonal variations (p-value=0.0077), as well as between genotypes, hospitalization, and severity of diarrhea. While significantly more types of rotavirus group A were identified with increasing age, no correlation was observed between the genotypes and gender (p-value=0.473). Furthermore, there was no significant association between genotype, dehydration rates, and the presence or absence of fever.

This study revealed a relatively high diversity of rotavirus genotypes in children. The findings suggest the need for further research to validate the identified correlations between certain genotypes and age groups, seasonal variations, clinical symptoms, and the efficacy of available vaccines.

Acute gastroenteritis is a typical disorder that accounts for 8-12% of pediatric outpatient visits. Campylobacter and Salmonella infections account for about 8.4% and 11% of global diarrhea cases. Due to the importance of these bacteria in pediatric diseases, the aim of this study was to determine the infectious rate of Salmonella and Campylobacter species and also the frequency of the gene encoding Cytholethal distending toxin in children with community-acquired diarrhea.

Stool samples of children under 5 years of age with diarrhea were collected. The samples were related to children referred to hospitals in Hamadan, Ardabil, Bandar Abbas and two hospitals in Tehran. DNA was extracted from the samples using a DNA extraction kit from stool. The presence of Campylobacter in the studied samples was detected by polymerase chain reaction using specific primers. A control stool sample was spiked with 10-fold dilution of C. jejuni suspension for LOD (detection limit determination) measurement.

In this study, PCR results showed a LOD of 100 CFU per gram in the spiked feces sample. Accordingly, out of 144 fecal samples of children with acute diarrhea, one case was positive for Campylobacter jejuni; this sample was also positive for the presence of cdtB gene. Presence of Salmonella was confirmed in two samples of the patients (1.4%).

Low prevalence of Campylobacter and Salmonella was detected in symptomatic children under 5 years of age during the Covid-19 pandemic. Examination of these samples for viruses and other microbial agents can clarify the etiology of diarrhea in children referred to the hospitals.

Understanding the bacterial community composition of gastric microbes and the relationship between its differences in the development and progression of gastritis can be of great help in the perception of the mechanism of this disease and designing preventive treatment pathways for its progression. We aimed to investigate the simultaneous colonization of bacterial agents in patients with chronic gastritis.

The study was performed on 168 gastric biopsy specimens of patients with gastric complaints who were referred to the endoscopic ward of Firoozgar hospital in Tehran. Biopsy specimens in the pathology department were examined histologically by the hematoxylin-eosin staining method and in the specific culture medium of Helicobacter under microaerophilic growth conditions and in general culture medium under aerobic conditions for the presence of Helicobacter and other bacteria. Identification of Helicobacter pylori (H. pylori) isolates was performed by analyzing colony morphology, gram staining, positive reactions of oxidase and catalase, rapid urease test, and polymerase chain reaction (PCR). Other bacteria were identified by biochemical and phenotypical analysis.

In our study, the recovery rate of H. pylori infection was 27.4 %. The mean age of patients in the two groups with and without H. pylori infection was almost the same. 87.5% of all patients had chronic gastritis, which showed significant associations with H. pylori infection (p-value: 0.00). We identified 140 bacterial colonies that belonged to 12 genera and 3 phyla. At the genus level, Streptococcus and Staphylococcus were predominant followed by Micrococcus, Escherichia coli, Bacillus, Enterococcus, Klebsiella, Pseudomonas, Enterobacter, Citrobacter, and Providencia. The predominant phyla were Proteobacteria and Firmicutes while Actinobacteria was less frequent. Co-infection of H. pylori with other isolated bacteria, especially Streptococcus and Staphylococcus was observed.

The presence of different bacterial genera in the gastric tissue of patients with gastritis in the absence of H. pylori suggests their possible role in the occurrence or progression of this disease. Additional studies to determine the association of the persistence of these bacteria with the use of drugs that modulate gastric acidity and pathological changes can be useful in the prevention and treatment of gastritis.

The objective of this study was to determine the seroepidemiological history of SARS-CoV-2 infection among asymptomatic children in Tehran.

Blood samples of children younger than 14 years old were collected during the period autumn-winter 2020 and spring 2021 and tested for SARS-CoV-2 IgG antibody using the EUROIMMUN ELISA kit. In addition, questionnaires were used to collect demographic and infection status information in the participants. Data were analyzed using the SPSS software.

Out of the 1142 children collected from the children with no COVID-19 symptoms, 33.3% (381/1142) were found to have had a history of SARS-CoV-2. The positive samples in girls and boys were 34.1% and 33.03%, respectively. Analysis of the data showed no statistically significant differences between the infection rate on the one hand and age, family size, underlying diseases, gender or occupations of the family members on the other hand. In addition, the infection rate was significantly lower in autumn 2020 than in winter 2020 and spring 2021.

SARS-CoV-2 infection can occur in children with no clinical symptoms. In addition, the infection rate is in direct correlation with an increase in age of the children.

Hepatitis B vaccination is necessary to prevent infection with this virus and to prevent the development of chronic hepatocellular carcinoma.

Assessing the immunization status after receiving the vaccine and identifying non-respondents, especially among health care workers and physicians, is important because of the higher risk of contact with infected patients and their body fluids. In this study, the vaccination status of health and medical staff of a children's hospital was investigated to measure the anti-HBs antibody titer and its relationship with body mass index, smoking, and drugs used in individuals with underlying diseases. In this study HBsAb kit, DIA.PRO; Italy was used to measure the antibody titers. Statistical analysis was done using SPSS software version 26.

The results of this study showed that a proper antibody titer is present in 66.6% of the participants. Reduced antibody titers to unsafe levels were measured among the employees older than 50 years, smokers, and employees with low or very high body mass index.

In this study, the decrease in antibody titer did not show any association with underlying diseases and related medications. The presence of an unsafe antibody titer among young vaccinated staff suggested additional studies to identify non-responders after receiving a booster dose of the vaccine.

Gastritis is one of the most common diseases affecting the stomach. Helicobacter pylori infection could lead to DNA damage in gastric epithelial cells, followed by error-prone DNA repair pathways that increase the accumulation of damage at the site of DNA double-stranded breaks, exacerbate genome instability, and facilitate the emergence of gastric cancer. This study aimed to examine the expression level of ATM, POLM, and TP53 genes involving in the DNA Damage Response and the cell cycle arrest in the gastric precancerous stage.

Among 180 gastric biopsy specimens, 30 samples taken from patients with moderate chronic gastritis infected by H. Pylori were regarded as the case group, and 30 other samples taken from non-infected patients with mild chronic gastritis were regarded as control. Following that, RNA extraction and cDNA synthesis was performed. Afterward, the expression levels of ATM, POLM, and TP53 genes were evaluated by the Real-Time PCR method. Ethics code: 98-02-27-43392

The ATM, POLM, and TP53 genes in the cases showed a 4.07, 3.35, and 5.13 increase in the gene expression at the transcriptional level, compared to the controls.

In general, ATM, POLM, and TP53 genes showed a higher increased expression level in the case group, compared to the controls, which might indicate the activation of noted genes after H. pylori infection. This may subsequently activate the error-prone DNA repair and non-homologous recombination pathways.

Gastritis is one of the most common diseases of human stomach. Most of the time, it is asymptomatic and if not treated, can cause atrophy in gastric tissue. Gastritis seems to be a consequence of Helicobacter pylori infection. H. pylori can induce DNA double strand breaks in DNA and activates the error-prone DNA repair pathways that result in accumulation of mutations and genomic instability which may mediate gastric carcinogenesis. In this study, we assessed expression of CHEK2, DCLRE1C and XRCC4 genes which are involved in cell cycle arrest and DNA double strand break repair systems happening with Gastritis. One hundred and eighty biopsy specimens were collected from patients who were referred for endoscopic examination. 60 samples including 30 cases (H. pylori positive Moderate chronic gastritis) and 30 controls (H. pylori negative Mild chronic gastritis) were selected for RNA extraction. Later cDNA was synthesized and Real-Time PCR was used to assess expression of CHEK2, DCLRE1C, XRCC4 and B2M genes. CHEK2, DCLRE1C and XRCC genes showed 5.88, 6.7 and 3.4 up-regulation respectively in comparison to the controls. Increasing level of CHEK2, DCLRE1C and XRCC4 genes might be related to activation of these genes after H. pylori infection.

Salmonella is one of the most important bacteria that causes gastroenteritis in humans and the spread of Salmonella strains with multidrug resistance is an acute global problem. Integrons are one of the most important factors responsible for transfering of drug resistance genes among Salmonella serotypes. In the present study, the frequency of class 1 and class 2 integrons as well as their relationship with drug resistance patterns in patients with gastrointestinal symptoms were investigated.

In this cross-sectional study, 400 human fecal samples with gastrointestinal symptoms were collected from 4 hospitals in Tehran. All the samples were analyzed by standard method for microbial culture and the results were confirmed by biochemical and PCR tests. Antimicrobial susceptibility testing was performed by disk diffusion method. After DNA extraction, the presence of class 1 and 2 integrons was investigated by PCR. Statistical analysis for detection of correlation between the presence of integrons and resistance patterns was done using SPSS software and Fisherʼs exact test.

The results showed that Salmonella was present in 5.5% (22.400) of the stool specimens. The prevalence rates of class 1 and 2 integrons for human stool specimens were 40.9% (9/22) and 27.2% (6/22), respectively. MDR phenotype was detected in 4.5% (1.22) of the Salmonella isolates from patients with gastroenteritis.

In this study, high levels of integrons 1 and 2 were observed in the patients' Salmonella isolates with gastroenteritis. The observed relationship between drug resistance patterns and the integrons indicated a possible increased risk of drug resistance genes in Salmonella isolates with human gastroenteritis.

Salmonella is considered as a main cause of community-acquired diarrhea in humans, however, sources of the multi-drug resistant (MDR) strains and their link with the disease are not well known.

This study aimed to investigate the frequency, serogroup diversity, and antimicrobial susceptibility patterns of Salmonella strains in poultry meat and stool samples of patients with community acquired diarrhea in Tehran.

We compared the frequency of non-typhoidal Salmonella serogroups, the similarities of their resistance patterns to 10 antimicrobial compounds, the prevalence of extended spectrum β-lactamase (ESBL) and ampicillinase C (AmpC) genetic determinants, and class 1 and 2 integrons in 100 chicken meat and 400 stool samples of symptomatic patients in Tehran during June 2018 to March 2019.

Salmonella was isolated from 75% and 5.5% of the chicken meats and human stool samples, respectively. The chicken meat isolates mainly belonged to serogroup C (88%, 66/75), while the human stool isolates were mainly related to serogroup D (59.1%, 13/22). The MDR phenotype and the most common rates of resistance to antibiotics, including tetracycline, trimethoprim/sulfamethoxazole (TS) and azithromycin, were detected in 4.5% and 45.3%, 59% and 13.6%, 43% and 9.1%, 42% and 9.1% of the human stool and chicken meat samples, respectively. Carriage of blaCTX, blaSHV, and blaPER genes in the meat isolate with ESBL resistance phenotype and blaACC, blaFOX, and blaCMY-2 among the 7 meat strains with AmpC resistance phenotype was not confirmed using polymerase chain reaction (PCR). High prevalence of class 1 and 2 integrons was characterized and showed a correlation with resistance to TS and chloramphenicol.

These findings showed a lack of association between chicken meats and human isolates due to discrepancy between the characterized serogroups and resistance phenotypes.

Campylobacter species are among foodborne pathogens that are known as the main cause of inflammatory diarrhea in humans. In this cross-sectional study, we investigated the prevalence of Campylobacter spp. and their drug resistance status in fecal samples of patients with community-acquired gastroenteritis in Tehran.

In this survey, infection with Campylobacter spp. was evaluated in 400 stool samples of patients with diarrhea. Accordingly, microscopic examination to show the presence of exudative diarrhea, rejection of fungi and parasitic infections, enrichment and culture in a specific medium under microaerophilic conditions, determination of biochemical identity, and molecular confirmation at genus and species levels for C. jejuni, C. coli, C. lari, and C. upsaliensis were performed. Antibiotic resistance patterns were determined by E-test and disk diffusion methods, and the presence of the dominant gyrA gene mutations in the quinolone-resistance domain of C. jejuni isolates was determined by using Mismatch Amplification Mutation Assay-polymerase chain reaction (MAMA-PCR)[1].

A total of 28 strains of Campylobacter were isolated from the samples obtained from the patients with diarrhea. The most common species were C. jejuni (6%), C. coli (0.5%), C. lari (0.25%), and other unknown species (0.25%). The highest antibiotic resistance rate was observed against tetracycline and ampicillin (53.5% and 50%, respectively), and the lowest rate was detected for nalidixic acid and ciprofloxacin (28.5% and 28.5%). Multiple drug resistance (MDR) phenotype was detected among 51.8% of the strains.

Results of this study indicated C. jejuni as the main Campylobacter species responsible for community-acquired diarrhea among the studied patients. The high rate of resistance to antibiotics and MDR phenotype in these strains compared with other countries is considered a risk, especially in the treatment of invasive infections.

Pathogenic species of Campylobacter, in addition to diarrhea and gastrointestinal diseases, could cause debilitating auto-immune and chronic diseases in humans. Investigation of the existence of this bacterium in food sources and clinical samples, and detection of antibiotic resistance could be helpful in the control of its spread and treatment procedures. The aim of this study was to evaluate the frequency and antibiotic resistance of Campylobacter isolates isolated from poultry meat.

In this study, a total of 100 poultry meat samples were collected from 22 districts of Tehran from July 2018 until March 2019. Accordingly, standard enrichment of the collected samples and their culture in selective medium was done. The isolates were characterized biochemically and by polymerase chain reaction for genus and species specific primers for C. jejuni, C. coli, C. upsaliensis, and C. lari. Antimicrobial susceptibility of the isolates to 7 antibiotics were done using E-test and disk diffusion methods. Moreover, resistance to three or greater classes of antibiotics was determined as multiple drug resistance phenotype (MDR) and the results were statistically analyzed using SPSS16 software.

Campylobacter was isolated from 35% of the poultry meat samples. C. jejuni (23%), C. coli (1%), and C. lari (1%) were among the Campylobacter isolates from these samples. Highest resistance phenotype and the lowest ones were detected against tetracycline (62.8%), and ampicillin and clindamycin (17.1%, each one), respectively. The MDR phenotype was detected among 42.8% of the isolates.

Our results showed high level of contamination with Campylobacter in the poultry meat samples which proposed increased risk of the infection with MDR strains among the consumers in Tehran. Further studies on human clinical samples could better determine this correlation.

Listeria monocytogenes, as a foodborne pathogenic bacterium, is considered as major causative agent responsible for serious diseases in both humans and animals. Milk and dairy products are among the main sources of energy supply in the human, therefore contamination of these products with Listeria spp., especially L. monocytogenes, could lead to life threatening infections in a large population of people. Rapid and accurate detection of L. monocytogenes in milk and dairy products, vegetables, meat, poultry, and seafood products is needed to prevent its dissemination through the food chain. Upon contamination of food materials with this pathogen, increase in its antibiotic resistance rate can occur after exposure to preservatives, antibiotics, and stress conditions, which has now become another major public health concern emphasizing the need for special attention on its control along the food chain and management of the disease in the patients. This review provides an overview of researches with respect to the prevalence of Listeria spp., especially L. monocytogenes, in milk and dairy products, methods of their detection and typing, and current status of resistance rates to the antibiotics used for treatment of listeriosis.

Salmonella is one of the leading causes of foodborne illnesses worldwide which has become an important issue today due to the increasing drug resistance. This study was aimed to detect the frequency and diversity of Salmonella serogroups and drug resistance patterns among poultry meat samples distributed in Tehran, Iran.
 
In this cross-sectional study, 100 samples of poultry meat were prepared from authorized distributors of meat products from 22 districts of Tehran. All samples were analyzed by standard method and characterization of the isolates were done using biochemical, polymerase chain reaction, and serogrouping methods. Antibiogram was done using disk diffusion method.
 
The results showed that Salmonella was present in 75% (75/100) of the chicken meat samples. Chicken meat isolates were predominantly belonged to serogroup C (88%, 66/75), while other isolates belonged to serogroup B (2.6%, 2/75), serogroup D (5.3%, 4/75), and non-group A–D Salmonella isolates (5.3%, 4.75). While resistance to tetracycline (59%) was the most common resistance phenotype in these isolates, concurrent resistance to 3 classes of antibiotics (3DR) was the most common type of multidrug resistance (MDR) phenotype among them.
 
In this study, high rate of contamination with Salmonella was observed in the chicken meat samples. Dominance of antibiotic resistance in these isolates showed their possible risk for transmission of resistance gene markers to the human gut microbiota through food chain.

Cytolethal distending toxin (CDT) is one of the bacterial toxins that present in a variety of Gram-negative human pathogens, such as E. coli, Salmonella spp. and Campylobacter spp. CDT consist of three subunits encoded by three adjacent genes, including cdtA, cdtB and cdtC. It is approved thet cdtB had toxic activity and caused DNA damage of the host cell. Despite its presence in different bacterial species, role of CDT in acute and chronic infections, such as gastroenteritis and irritable bowel syndrome (IBS) is unclear. To clear this correlation, we studied the prevalence of cdtB gene among different enteropathogenic bacteria in patients with gastroenteritis and IBS compared with healthy people. This study was conducted on stool samples that obtained from patients with gastroenteritis, IBS and healthy people (as control). All the samples were subjected to DNA extraction. cdtB of Campylobacter spp., Yersinia entercolitica, Providencia alkalifacience, Salmonella enterica and E. coli was analyzed by PCR using specific primers. CdtB encoding Campylobacter spp. was found in 7.5% (5/80) and 34.6% (52/150) of patients with IBS and gastroenteritis, respectively. Also, the PCR results showed that 14% (14/150) of the patients with gastroenteritis and 5% (8/80) of IBS patients carried CdtB encoding Salmonellaenterica. None of the samples were infected with CdtB -encoding E. coli and Providensia spp. Finally, all results were confirmed by sequencing. Our results showed the presence of CdtB encoding pathogenic bacteria in IBS patients and those with gastroenteritis. Regarding the high frequency of CdtB encoding Salmonella and Campylobacterspp., it was proposed that infection to these bacterias could be considered as a risk factor for the development of post-infectious IBS in Iranian patients. Further studies are needed to establish this relationship.

To meet the growing need for food and drugs to improve quality of life, new technologies (e.g. biotechnology and genetic engineering) have attracted politicians and food producers worldwide. Aberrant application of these technologies could cause irreparable consequences that can be life threatening. Changes of genetic entity for improvement and reconstruction of the creation for usage in modern world are main topic under consideration in these technologies. However, there are many controversies for their application in the world. In this study, by reviewing the Quran, Hadiths, and articles, we tried to provide a discussion on limitations, justifiability or illegality of the creation change. The researchers observed all ethical issues in the study and declared no conflict of interests . The provided data showed that change in the creation occurs naturally in the physical dimension, in contrast to the spiritual view, and seems to be allowable provided by the preserve of the entity of the creation. With respect to the ethical issue and nature of the creatures, manipulation of the creation for the sake of their improvement in function and activity toward normal status seems to be allowable.

  The clinical outcome of Helicobacter pylori in the infected patients depends on the genetic diversity of H. pylori strains. Colonization and adherence on cell host is the first step of the bacteria pathogenesis. This study was aimed to understand the role of pathogenesis factors of H. pylori strains and adherence rate of these strains on AGS cell line, as well as exploring the association between these rates with bacteria pathogenesis outcomes.

This study was conducted on genes, including iceA, cagA, babA, vacA, and cag-PAI in clinical strains of H. pylori with different pathogenesis outcomes through polymerase chain reaction (PCR) analysis using specific primers. Moreover, the adherence assay was performed on AGS for exploring the association between adherence rate and pathogenesis outcomes in infected patients.

The analysis of PCR results indicated that in strains with severe diseases outcomes all the investigated genes were present, while in strain with moderate outcome only adherence genes were present. Furthermore, the results of adherence analysis were indicative of the difference among these strains. Accordingly, two strains with severe pathogens outcomes had the highest rate of colonization. Minimum colonization rate and moderate pathogenesis outcome were observed in other strains, although adherence genes present.

Discussion & According to the results of the current study, it can be concluded that different genes are contributing to bacterial adherence on host cells, meaning that the presence or absence of one or two of these genes may not affect its adherence to host cells. Furthermore, adherence genes along with oncogens cause severe clinical outcomes in infected patients.

Clostridium difficile infection in patients with inflammatory bowel disease (IBD) is associated with more severe disease, longer hospital admission, higher treatment costs, higher risk of colectomy, and higher mortality rate. The classic endoscopic view of the disease is adherent whitish-yellowish multifocal membrane, defined as “psudo-membrane”. Using stool polymerase chain reaction (PCR) is the best way for identifying this organism. Patients with mild to moderate infection are treated with oral metronidazole, while severe infections are treated with oral vancomycin for 10 days. The first recurrence of clostridium infection is treated with the same regimen as the initial episode, however the second recurrence is treated with vancomycin pulse therapy. In the third recurrence, fecal microbial transplantation (FMT) is one of the treatment choices. This study is a report of three successful FMT in our patients.

Helicobacter pylori is the main cause of various gastroduodenal diseases. As the diseases caused by H. pylori are associated with severe tissue damage, proteases of bacteria may play an important roles in this process. In current study we investigated diversity of H. pylori protease activity and its association with different pathological lesions of gastric tissue.
The study was performed on 116 gastric biopsy specimens obtained from patients with gastrointestinal disorders referred to Taleghani hospital in Tehran, IR.Iran. Isolates were identified by culture and polymerase chain reaction (PCR). Their protease activity was assessed by spectrophotometric and well diffusion assays using casein as substrate. Variance analysis (One-way ANOVA) was used for statistical analysis.
A prevalence of 43.1% (50/116) of H. pylori infection was detected in the studied patients. Histopathological lesions among 50 H. pylori positive patients were included: chronic gastritis 40% (20/50), intestinal metaplasia 8% (4/50), and severe active gastritis 52% (26/50). Nearly, 4.25% of the strains showed high protease activity, while 91.4% and 4.25% of the strains showed moderate and low protease activities, respectively. Statistical analysis demonstrated significant association between low protease activity of the strains and chronic gastritis (p= 0.044).
Results of this study indicated diversity of protease activity among different strains of H. pylori and significant association between low protease activity of the strains and occurrence of chronic gastritis. Further studies are necessary to investigate this association.

AmpC and ESBLs as mediated-plasmid extended spectrum β-lactabases are the main factors of resistance to extended-spectrum cephalosporins in enterobacteriacea especially E. coli and will follow treatment failure, high costs of treatment in human and economic losses in the poultry industry. The purpose of this study was to screen and study the faecal E. coli isolates producing extended spectrum β-lactamases (ESBLs) and AmpC enzymes and related workers. A total of 500 cloacal swab samples from broiler chickens and 25 rectal swab samples from workers were collected from five poultry houses around Tehran. All samples were seeded on MacConkey agar and identification of E. coli isolates were performed via biochemical tests. Antibiotic susceptibility was determined against 12 antibiotics using the disk diffusion method as recommended by the clinical and laboratory standard institute (CLSI2012). Ceftazidim / ceftazidim-clavolanic acid and cefoxitin / cefoxitin-EDTA disks were used for the detection of ESBL and AmpC phenotypes, respectively. phonetic analysis of the drug resistances was performed via SPSS software and Chi-square test. ESBL- producing E. coli screened by PCR for the presence of genes encoding beta-lactamases of TEM, CTX-M and SHV. A total 467 E. coli isolates were isolated from 88.9% of the samples as 92% and 72.7% of isolates presenting MDR phenotype among chickens and workers respectively. ESBL phenotype detected in 5.5% (26) of poultry isolates while, none of the workers isolates have this phenotype. Six isolates carried both of TEM and CTX-M whereas, five and one isolates were detected only for TEM and CTX-M, respectively. Eighty-eight and nine-tenths percent of ESBL E. coli displayed AmpC phenotype. Since cephalosporins are not used in broilers in Iran, isolation of faecal E. coli isolates producing extended spectrum β-lactamases in broilerchickens can indicate transfer of the resistance genes via plasmids and other mobile genetic elements among Enterobacteriaceae.

Staphylococcus aureus (S. aureus), particularly methicillin- resistant strain (MRSA), is one of the most important pathogens in nosocomial infections that is capable of producing food poisoning and food-borne outbreaks. This study aimed to focus on the contamination status of food handlers, utensils and foodstuffs with this agent in a hospital kitchen as sources of distribution of these strains into hospitals. A total of 220 samples were collected from freshly prepared foods, kitchen utensils and food handlers. The samples were cultured in Blood agar and Mannitol salt agar media and the isolates were evaluated both morphologically and biochemically using specialized tests and consequently were identified via polymerase chain reaction (PCR) using femA and nuc primers. For antibiogram, the standard disk diffusion test was used in accordance with CLSI, 2012 guidelines. To detect MRSA strains, resistance of the S. aureus isolates to cefoxitin (30 µg) in Mueller-Hinton agar was evaluated. Thirty- nine S. aureus isolates from food handlers (50%), 26 from kitchen utensils (48.1%), and 22 from food samples (25%) were detected. MRSA strains were found in 22.7% of the S. aureus isolates of foodstuffs, 23.1% in utensils and 5.1% in food handler samples. Homology of the resistance patterns among these isolates was also observed. This study showed the presence of MRSA strains and homology of resistance patterns among the isolates of the foodstuffs, kitchen utensils and food handlers all of which call for a careful monitoring to prevent their distribution among hospitalized patients.

There are many techniques to knock out directed genes in bacteria، some of which have been described in Salmonella species. In this study، a combination of SOEing PCR method and the λ Red disruption system were used to disrupt phoP gene in wild type and standard strains of Salmonella typhimurium. Three standards PCR and one fusion PCR reactions were performed to construct a linear DNA including upstream and downstream of phoP gene and Kanamycin cassette. As a template plasmid، we used pKD4 whichcarries kanamycin gene flanked by FRT (FLP recognition target) sites. The resulting construct was electroporated into prepared competent cells of S. typhimurium. The transformants colonies related to the standard strain appeared on the LB-Km-agar plates after incubation، but there was no colony on LB-Km-agar plates corresponding to the wild type strain. The failure in transformation of the wild type strain may be because of inflexibility of the λ Red disruption system in this strain or its unique restriction-modificationsystem. However، by this construct we are able to generate phoP mutant in many of the Salmonella species due to high homology of the phoP gene which exists in different species.

some of predisposing factors for enterococci colonization are hospitalization in ICU, prolonged use of antibiotics and continued bed rest in hospital. In this study antibiotic resistance of enterococcus in hospitalized patients of four hospitals in Tehran were studied. the Clinical samples were taken from patients admitted to the ICU, from September 2011 to April 2012. Enterococci isolates were confirmed by biochemical tests, and Enterococcus faecalis and Enterococcus species by species-specific ddl genes. The disk diffusion and micro agar dilution susceptibility tests were performed according to Clinical and Laboratory Standards Institute (CLSI). of 41 isolates in ICUs, 22 (5.52%) were E. faecium and 19 (5.47%) were E. faecalis. Most of E. faecium was isolated from urine and E. faecalis from trachea specimens. The rate of resistance to vancomycin, ampicillin, gentamicin, chloramphenicol and nitrofurantoin in E. faecium isolates was more than that of E. faecalis and the rate of resistance to tetracycline, ciprofloxacin and erythromycin was the same in both of them. MIC50 in vancomycin and ampicillin resistant E. faecium isolates was greater than 256 microgram and the MIC50 in gentamicin resistant isolates was more than 1024 microgram. The presence of multi-resistant E. faecium strains in ICUs can be a serious warning for physicians and patients.

Helicobacter pylori as an etiological agent of active chronic gastritis and peptic ulcer disease، is now considered to be an important pathogen for gastroduodenal diseases. Resistance to antimicrobial drugs is a major cause of treatment failure and decline in eradication rates in most of countries. The aim of this study was molecular typing of Helicobacter pylori isolates was done throughout MLST (multi locus sequence typing)، the most reliable typing method، which is based on DNA sequencing. H. pylori isolates of gastric biopsies from patient''s ≥ 18 years old were used in this study. Genomic DNA was extracted and used for PCR of glmM، atpA، mutY، efp، trpC، yphC، ppa and ureI. PCR product of 7 latter genes sequenced and analyzed with proper bioinformatics soft wares and compared with other H. pylori isolates from other countries. According to MLST results the isolates were so divers and different from other countries. According to different STs resulted from MLST typing، it can be considered that H. pylori isolates in Iran are very different. It may due to many DNA exchange mechanisms which H. pylori have.

Among all common techniques in sitedirected mutagenesis, λ Red recombinase system has been widely used to knock out chromosomal genes in bacteria. In this method, there is always the risk of DNA Linear digestion by host's restriction enzymes that leads to the low frequency of recombination. To overcome this, we constructed a recombinant vector to disrupt phoP gene in Salmonella typhimurium. The SOEing PCR method and restriction enzymes were used to construct the vector. The resulting plasmid, pTAAZ92, contains a Kanamycin cassette with two long homologous arms flanking of the phoP gene. After electrotransformation of the pTAAZ92 into the Salmonella typhimurium, the phoP gene is replaced by the Kanamycin cassette through homologous recombination. According to the high homology of the phoP gene in many of Salmonella species the pTAAZ92 can be used to disrupt the phoP gene in most of these species.