جستجوی مقالات مرتبط با کلیدواژه "ژن های بیماری زا" در نشریات گروه "پزشکی"

The importance of the health of red meat, poultry and eggs in human nutrition is very high. One of the factors that jeopardize the health of poultry food products is the bacterial family of Enterobacteriaceae, especially Salmonella. The aim of this study was to detect pathogenic genes in Salmonella infectious bacteria isolated from stool specimens using the multiple PCR assay.
Selective and specific media for isolation of Salmonella were used. Primary isolation was carried out using Peptone water, Rapaport, selenite cysteine, MacConky agar and xylose-lysine deoxycholate agar. To confirm the diagnosis, biochemical tests including TSI, urea, endodontic, and citrate were used. The Salmonella Polyvalent Kit was used to determine Salmonella groups and mgtC, spi4R, agfA, invE/A and ttrC genes were studied in 60 samples by the multiple PCR method.
The results showed that all samples had 2 genes mgtC and ttrC, and none of the samples showed resistance to cefepime. Of the 60 samples of Salmonella, none were resistant to cefepime and ceftriaxone; 38.8% of the samples were resistant to amoxicillin, 53% to erythromycin and 38.3% to sulfamethoxazole.
It can be concluded that cefepime is the best selective drug for the treatment of Salmonella infections. Identification and validation of genes in the region's bacteria can play a role in the broad epidemiological examination, antibiotic resistance, vaccine production, level of virulence, prevention and treatment. Also, evaluation of these genes in the samples for their virulence index is very important.

Helicobacter pylori (H. pylori) is the causative agent in development of gastroduode-nal diseases، such as chronic atrophic gastritis، peptic ulcers، mucosa associated lym-phoid tissue (MALT) lymphoma، and gastric cancer. H. pylori has been associated with inflammation in cardia، showing the fact that infection with this bacterium could also be a risk factor for gastric cardia cancer. Gastric cancer is the fourth most common cancer worldwide. This is the second leading cause of cancer-related deaths، and ap-proximately 700،000 people succumb each year to gastric adenocarcinoma. It has been estimated that 69% of the Iranian population currently harbor H. pylori infection. The prevalence of duodenal ulcer and gastric cancer is high in Iranian populations. However، this has been largely influenced by geographic and/or ethnic origin. Epidemi-ology studies have shown that host، environmental، and bacterial factors determine the outcome of H. pylori infection. The bacterium contains allelic diversity and high genet-ic variability into core- and virulence-genes and that this diversity is geographically and ethnically structured. The genetic diversity within H. pylori is greater than within most other bacteria، and its diversity is more than 50-fold higher than that of human DNA. The maintenance of high diversification makes this bacterium to cope with particular challenges in individual hosts. It has been reported that the recombination contributed to the creation of new genes and gene family. Furthermore، the microevolution in cagA and vacA genes is a common event، leading to a change in the virulence phenotype. These factors contribute to the bacterial survival in acidic conditions in stomach and protect it from host immune system، causing tissue damage and clinical disease. In this review article، we discussed the correlation between H. pylori virulence factors and clin-ical outcomes، microevolution of H. pylori virulence genes in a single host، microevolu-tion of H. pylori during primary infection and progression of atrophic gastritis to ade-nocarcinoma، and H. pylori infection status in Iran. Finally، we put forward the hy-pothesis that if the pattern of nucleotide sequence evolution shifts from recombination (r) to mutation (m) and the r/m ratio is reduced، bacterial pathogenicity may be re-duced while maintaining the bacterial life. However، this hypothesis should be further studied with future experiments.

Enterohemorrhagic Escherichia coli (EHEC) strains are one of the most important enteric pathogens which cause of the food-borne disease in humans. The purpose of this study was to survey the prevalence of diarrhea arising from this bacteria and infection source and antibiotic resistance of isolated strains in children under 5 years old in Marvdasht. In this descriptive study, Stool samples of under 5 years old children in Marvdasht were collected. After enrichment in specific culture media and evaluation sorbitol fermentation and their β-glucoronidase activity (MUG test) with specific antisera, the isolation of EHEC O157:H7 strain was confirmed. Then, virulence genes verotoxin, intimin and hemolysin with multiplex PCR and antibiotic resistance strains with disk diffusion method were tested. Also, getting infection with water, food and animal contact was evaluated. Out of 615 cases, 89 sorbitol negative colonies isolated which 7 strains O157 (1.14%) confirmed with antisera. Of virulence genes, only 1 of the isolated strains (0.16%) had stx1 and eaeA genes. All isolated bacteria had resistance to penicillin, ampicillin and erythromycin. There was no significant relation between isolated EHEC strains and the different seasons of the year. Hospital based surveillance to estimate the burden of EHEC strains in clinical centers in all less than 5 years old children with acute gastroenteritis and studies on etiology and genotyping of this bacterium in other parts of the country are recommended.

Introduction & Different studies show that the reasons for clinically diverse outcomes of infections caused by H. pylori may include host and environmental factors as well as differences in the prevalence or expression of bacterial virulence factors. The aim of this study was to study the distribution of different genotypes of major virulence factors cagA, vacA and ureAB among H. pylori strains isolated from patients with gastric ulcer (ulcerative disease) and patients with gastritis (non ulcerative disease). In this cross sectional study 65 H. pylori strains, 30 from patients with gastric ulcer and 35 from patients with non ulcerative gastritis disease were investigated by RFLP-PCR. The prevalence of vacA-positive strains in ulcerative patients was significantly more than that in non ulcerative patients (P<0.05). RFLP analysis revealed two different patterns for cagA gene. The prevalence of pattern β with three bands was significantly higher in both groups of patients. Enzymatic digestion resulted in a strictly homogeneous pattern for 83.33% of the vacA+ strains isolated from the patients with ulcer. This pattern was significantly associated with ulcerative status (P<0.05). ureAB polymorphism analysis revealed 10 distinguishable DNA banding patterns among them the pattern named ureAB 5a was the most prevalent (47.61%) in all isolates. No association between a specific DNA pattern and clinical disease was observed for cagA and ureAB (P>0.05). It seems that in the patients under our study the presence of cagA gene may not necessarily be a risk factor for ulcer disease, while a homologous genotype of vacA appears to be associated with an increase risk of ulcer development. Lastly, despite the existence of a high degree of genomic variability within ureAB, conserved DNA banding profiles are distributed in our areas.