جستجوی مقالات مرتبط با کلیدواژه « escherichia coli » در نشریات گروه « زیست شناسی »

One of the most important hosts used for production of recombinant proteins is Escherichia Coli. For example, the most therapeutic proteins approved by FDA are produced in Escherichia Coli. Comprehensive knowledge about biologic nature of Escherichia Coli had made this microorganism to a favorable factory for production of recombinant proteins. Accessibility of this information have led to rational manipulation for changing of this small factory to intelligent system can make different recombinant proteins easier. So that, many engineered and useful strains were obtained from wild type and parental strains can produce high amount of diverse and stable recombinant proteins in lab and industrial scale. In this review, we will present some of these strains that are more widely used.

Nanocomposites are prepared from various materials that may have antibacterial activity. This study aimed to investigate antibacterial and antifungal activityies of nanocomposites of bohemite-gold and bohemite-gold-chitosan by help of aqeous extract of peppermint.

In the current study, the nanocomposites were prepared by exextracellular biosynthesis and antibacterial properties were investigated by minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and killing-time curve by classic method of consecutive dilutions by Clinical & Laboratory Standards Institute.

The results showed that MIC and MBC were 10 µg/mL and 20 µg/mL for bohemite group, respectively. The results also showed that MIC and MBC were 2.50 µg/mL and 5 µg/mL against Acinetobacter baumannii and 5 µg/mL and 10 µg/mL against Escherichia coli, respectively. The greatest antibacterial activity for of bohemite-gold and bohemite-gold-chitosan was observed for a period of 6 to 24 h. Based on ourfindings, bohemite showed lower antibacterial activity compared with bohemite-gold and bohemite-gold-chitosan against the mentioned bacteria.

The prepared nanocomposites did not show any antifungal activity. Thus, bohemite-gold and bohemite-gold-chitosan nanocomposites have antibacterial activities against bacteria inducing infection in wound.

Integrons play an essential role in spreading antibiotic resistance genes among Escherichia coli isolates. The aim of this study was to determine the prevalence of class 1 and 2 integrons amongst Escherichia coli isolates producing broad-spectrum beta-lactamases (ESBLs) in patients with urinary tract infections referred to Ahvaz teaching Hospital in 2017-2018. In this cross-sectional descriptive study, isolates were determined using conventional methods. Antibiotic susceptibility was measured by agar disc diffusion method. Production of ESBLs enzymes was measured via double disc method. Finally, presence of genes related to class 1 and 2 integrons was done using specific primers and Polymerase chain reaction method. Amongst 123 Escherichia coli ESBLs producing isolates the highest resistance was related to Cefotaxime, Ceftazidime, Cotrimoxazole and, Nalidixic acid, respectively, and the least resistance was related to Imipenem. About 84 (68.29%) isolates had multiple drug resistance (MDR). Additionally, 93 (75.60 %) isolates had class 1 integron and 11 (8.94 %) isolates had class 2 integron. There were no significant relationships between the presence of integrons and resistance to different antibiotics (p > 0.05). High prevalence of class 1 integron amongst Escherichia coli isolates producing broad-spectrum β-lactamase may contribute to resistance to common antibiotics. Therefore, identifying frequency of integrons and their relationship with drug resistance patterns seems to be necessary.

Escherichia coli is an important indicator in the quality control of pharmaceutical and real samples. This study compares the detection of this bacterium by regular method and a biosensor based on Multi-Walled Carbon Nanotubes (MWCNTs) on glassy carbon electrodes (GCE) in pharmaceutical and water as real sample.

In this experimental study, the conventional culture method (pour plate) and modified biosensor based on Multi-Walled Carbon Nanotubes on glassy carbon electrode with the arrangement of GC/MWCNTs/AuNPs/Ab/BSA were used for the detection of E. coli. Dilutions of E. coli between (1 ×101–1×108 CFU/ml) were used in pharmaceutical and water samples, prepared in 0.1 M PBS (pH 7.4), mixed with 0.5mM acetaminophen. The efficiency of the designed biosensor was investigated using SEM, Cyclic Voltammetry, and Square-Wave Voltammetry electrochemical techniques, as well as interfering bacteria.

The results of E. coli detection using the conventional culture and designed biosensor were not statistically significant. The designed biosensor had a high sensitivity with accuracy in 3 minutes and LOD 3.02 CFU/ml for Escherichia coli.

Considering the time-consuming and influenced by environmental factors in the microbial monitoring of pharmaceuticals for E. coli detection in conventional methods and the risk of losing pharmaceutical products, the biosensor has good efficiency in detection with low cost and no need for enrichment in a small volume of samples.

Integrons are mobile genetic elements capable of carrying resistance genes to various antibiotics. These elements have been found in different places of plasmid and chromosome. The aim of this present study was determine the prevalence of class 1, 2 and 3 integrons in Escherichia coli isolates isolated from urinary tract infection in Shahrekord. In this research, the number of 64 isolates of Escherichia coli were investigated. The antibiotic resistance of the investigated isolates was evaluated using a simple disking method in Mueller Hinton agar medium. In order to determine the frequency of class 1, 2 and 3 integrons, specific primer pairs were used. After the antibiogram test, the highest resistance to ampicillin (75%) and the lowest resistance to imipenem (12.5%) were observed. The frequency of class 1, 2 and 3 integron genes was observed as 12.5%, 6.25% and 3.12%, respectively. None of the integron genes were observed in 52 isolates. In the statistical analysis with chi-square test, a statistically significant relationship was observed between class 1 integron and resistance to the antibiotic ampicillin (p = 0.02 < 0.05). Due to the fact that resistance genes are located on integrons and can be transferred from one strain to another strain and spread resistance in the hospital or other environments, this has doubled the importance of identifying this type of antibiotic resistance genes. Key words: Escherichia coli, integron, antibiotic resistance, urinary infection

The savory(Satureja macrantha) belongs to the mint family, it is an annual or multi-year plant, Iran has 12 annual or multi-year grass species. In many studies, antimicrobial, antiviral, antifungal, antispasmodic, stomach strengthening and digestion facilitating properties of this genus have been reported. Nisome is a important surfactant-based non-ionic vesicle. Niosomes offer several advantages for drug delivery systems, including osmotically active, chemical stability and long retention time compared to liposomes. In the present study, niosomes extracted from as a drug are dynamically evaluated by calorimetric method (Folin's method). In this study niosomes formulation containing Satureja macrantha extract, in order to achieve the optimal formulation, different formulations were prepared based on the molar ratio of Span 60/Tween 60, cholesterol and with a sonication time of 7 minutes. The niosomes extracted from the savory plant significantly inhibited the activity of the two bacteria(Staphylococcus aureus ) and (Escherichia coli) tested in the present study.

Due to the importance of disinfection and prevention of diseases caused by Escherichia coli, sometimes the companies producing these disinfectants have exaggerated and it causes the employees of health centers and hospitals to use these products as sterilizers to sterilize surfaces and places without conducting tests. If these products do not have the recommended efficiency and effectiveness mentioned in the instructions of the manufacturer, it will cause irreparable losses. This study was carried out in 1400 with the aim of evaluating the effect of three disinfectants Microten, Benzalkonium Chloride, and Savlon with recommended dilutions on Escherichia coli isolates from general hospital wards. In this study, 50 samples were collected from the general departments of the hospital, and E.coli were analyzed using biochemical and molecular methods. E.coli (G4S45) was used as a control. Bacteria were cultured using the pour plate method using the pharma dilution method according to the American USP standard. Finally, the effect of the mentioned disinfectants on E.coli was investigated. 19 samples were positive for the presence of E.coli and three disinfectants were in 5, 10, and 15 minutes after incubation, and performing the pour plate method caused a 100% lack of growth.  the efficiency of the three tested disinfectants was 100% effective according to the manufacturer's instructions.

Urinary tract infections are one of the medical and health problems. This type of infection is more common in women than in men due to the anatomy of the urinary tract and lack of hygiene. The aim of the present study is to investigate the drug resistance of urinary pathogens in women with urinary tract infection in Savojbolagh city.

The current study is descriptive-cross-sectional, which was collected by examining 5100 urine samples from women suffering from and suspected of urinary tract infection, and after culturing in general-pourpose media and selective media and biochemical tests, the type of pathogenic microorganism was determined; then, the level of resistance in the strains was reported with antibiogram. Microsoft Excel 2022 software was used to draw graphs.

Out of a total of 5100 urine samples, 302 samples were considered positive, and the most infectious pathogens were Escherichia coli (%60.93) and group B streptococcus (%16.56). The age group of 31-40 years (%17.55) was recognized as the high-risk group, and the highest frequency of drug resistance in Escherichia coli to cefazolin (%60.87) and in group B streptococci to tetracycline (%88) was observed.

The amount of drug resistance of microorganisms is increasing day by day, and this issue is a threat to all humans and animals. In this study, the highest rate of drug resistance to cefazolin and tetracycline was observed in two pathogens, which are main causes of urinary tract infection.

CRISPR  system (clustered regularly interspaced short palindromic repeats) and Cas portions is a part of the immune system in microorganisms. The cas genes could be involved in reducing antibiotic resistance in bacteria. The aim of the study was to investigate the frequency of cas genes of the CRISPR/Cas system in Extended Spectrum        Beta-Lactamase (ESBL) producing Escherichia coli isolated from urine culture of patients with urinary tract infection.

In this cross-sectional study, 437 positive urine culture samples were collected from Chalus hospitals. Escherichia coli strains were isolated based on standard biochemical tests and Enterobacteriaceae commercial diagnostic kit, as well as antibiotic sensitivity using disc diffusion method (Kerby Baer). Combined disk test was conducted for isolates that were resistant to at least one of the third-generation cephalosporins in the foregoing antibiotic susceptibility test. Molecular identification of cas1,cas2,cas3,cas7 and cas5 genes was performed using the PCR method.

Out of 437 urin culture samples, 106 samples (24.3%) had E.coli infection. The highest antibiotic resistance was associated with ampicillin (99%). Among the resistant isolates, thirty isolates (88.3%) were ESBL producing. cas1 gene had the highest frequency (96.2%) and other cas genes had almost the same frequency.

The results of the present study showed that a significant percentage of E. coli isolates had ESBL phenotype, which may be due to the presence of broad-spectrum beta-lactamase genes in these samples. Besides,  it was shown that there is no relationship between the presence of ESBL phenotype and the distribution of cas genes.

Cervical cancer is the leading cause of morbidity and cancer mortality in women throughout the world and persistent infection with human papillomavirus (HPV) is the main etiology for the development of this cancer. Peptide vaccines derived from E6 and E7 oncogenes are promising candidates for HPV vaccine production due to their safety, high stability, and ease of production. In the current study, expression strains such as Escherichia coli BL21 (DE3), BL21 (DE3)-AI, Rosetta, C41 (DE3), and BL21 (DE3)-pLysS were applied for poly epitopic E6 expression and the effects of temperature, induction time, and inducer concentration on the expression level of recombinant HPV16-E6 polypeptide protein were examined in the mentioned strains.

In the present study, the optimized gene of E6 recombinant protein was cloned into pET28a vector under the control of T7 promoter and the resulting plasmid was successfully transformed into Escherichia coli strains BL21 (DE3), BL21 (DE3)-AI, Rosetta, C41 (DE3), and BL21 (DE3)-pLysS. Then, the ability of these strains to express the desired recombinant protein in different conditions was compared.  Two temperatures of 25 ° C and 37 ° C, IPTG concentrations between 0.1 and 1.0 mM, and different incubation times were selected to examine the expression level of recombinant E6 protein in these strains.

The highest level of expression was obtained in Escherichia coli BL21 (DE3) -AI strain inducing at Optical Density (OD) of 0.9, 0.1 mM IPTG, and 16 hours induction at 25 °C.

The results of this study can be used to produce E6 protein as a vaccine candidate in the treatment of HPV-related cancers.

Extra-intestinal strains of the pathogenic Escherichia coli APEC are one of the most serious threats to the poultry industry in the world and in Iran, with extensive economic losses due to the high mortality rate in broiler herds. Molecular studies and determination of the frequency of virulence factors of APEC strains provide very useful information for designing and manufacturing vaccines against diseases caused by these strains. The aim of this study was to molecular detection of virulence genes iss and fimC in Escherichia coli Isolates from Poultry with Colibacillosis in Ilam City.

This descriptive cross-sectional study was performed on one hundred and fifty APEC isolates collected from general cases of poultry Colibacillosis in the year 1399. First, isolates were identified using selective and ‎differential culture media and standard biochemical tests. PCR test was used to determine the ‎presence of virulence genes iss and fimC among Escherichia coli isolates using a specific primer.

Results of PCR test on one hundred and fifty APEC isolates obtained from Colibacillosis cases ‎using specific primers to detect the genes encoding fimbriae type 1 fimC and the gene ‎Increased serum survival ‎iss showed that 139 isolates (92.66%) had fimC gene. Also, the results ‎showed that among the total isolates, 126 isolates (84%) have the increased serum survival iss gene.‎

The results of this study indicate the high presence of virulence genes iss and fimC in Escherichia coli isolates isolated from avian Colibacillosis in the study area. Detection of these genes can be used as diagnostic markers of pathogenic Escherichia coli in poultry.

Escherichiacoli is an opportunistic pathogenic bacterium that causes numerous diseases in humans and animals.Because of increased resistance to antibiotics, this bacterium has raised many concerns in the livestock industry as well as in medicine. The aim of this study was to determine the resistance to fluoroquinolones, to identify plasmid-mediated quinolone resistance (PMQR) genes and to determine the biofilm formation ability of E. coli strains isolated from human and bovine samples in Hamadan.In this descriptive study, 40 isolates of E. coli(20 human isolates, 20 bovine isolates) were studied. First, the resistance of the isolates to ciprofloxacin and levofloxacin was measured by microdilution broth method, and then the identification of fluoroquinolone resistance genes (qnrA, qnrB, qnrC, qnrD, qnrS and acc) was performed by PCR method. In the following, the ability of E. coli isolates to produce biofilm was evaluated by microtiter plate method and the results were analyzed by chi-square test using SPSS software (version 19). Microdilution results showed of 40 E.coli isolates, 26 (65%) were resistant to ciprofloxacin and 23 (57.5%) were found to be resistant to levofloxacin.In PMQR genes frequency analysis by PCR,the qnrA, qnrB, qnrC,qnrD, qnrS and aac genes were detected in 45%, 47.5%, 67.5%, 27.5%, 60% and 55% of the isolates, respectively. Also microtiter plate test results showed that 40% of the isolates were capable of forming strong biofilm and only 4% did not form biofilm.The results of the present study showed that the main mechanism of resistance to fluoroquinolones is related to PMQR genes and possibly excessive use of fluoroquinolones in human infections leads to the development of resistance to these drugs.Biofilm formation has also been shown to be effective in creating fluoroquinolone resistance.

Due to the widespread use of antimicrobials in veterinary medicine and the increase in livestock production, it seems that the risk of spreading antibiotic resistance in human societies is more related to animals and the veterinary field. In this study, antibiotic resistance and frequency of fimH, papC and sfa-foc virulence genes among Escherichia coli isolated from Caspian horse feces in Guilan were studied. In this cross- sectional study, E. coli isolates were isolated from the feces of 157 apparently healthy Caspian horses by culture method and biochemical tests. Resistance patterns against 17 different antibiotics were determined by disk diffusion method and frequency of virulence genes were assessed by PCR in isolates. In phenotypic assay of antibiotic resistance, the isolates showed the most resistance to streptomycin and sulfamethoxazole-trimetoprim antibiotics. Imipenem and gentamicin were the most effective antibiotics and 51.59 percent of isolates showed multi drug resistance pattern. The frequency of fimH, papC and sfa-foc virulence genes in isolates were 91%, 56.6% and 33.3%, respectively. Frequency of all of three investigated genes were significantly higher in MDR isolates (P< 0.05). The results of the present study indicate that Escherichia coli isolated from the feces of horses in Guilan has the potential to transmit antibiotic resistance and endanger public health.

 

High metabolism occurs in the presence of oxygen with rapid growth rate in a wide range of organisms including bacteria, yeasts or cancer cells. The ability to grow at high yields plays an important role in biotechnology, especially during the production of proteins (preferably recombinant) or metabolic compounds such as organic acids and secondary metabolites. Increasing the growth efficiency of bacteria, especially Escherichia coli, which is the engine of research and industrial activities, is a noble goal in microbial biotechnology. In this study, we sought to find a solution to reduce the amount of CO2 produced and thus increase the production efficiency of cell mass from organic matter in the process of growth and proliferation by examining the metabolic pathways of E. coli.

Metabolic pathways documented on the KEGG site were examined with a view to reducing the CO2 production efficiency of formic acid. Two strains of knockout bacteria of K12 origin were obtained from Keio microbial bank. Then, selected strains were cultured in complex (LB) and simple (M9 + Glycerol) media. Cell mass production in different treatments were compared with the standard BL21 strain based on optical absorption at 600 nm.

In the LB complex medium, Escherichia coli mutants (W3866 and W4040) grew faster than BL21 (approximately 5-fold at 8 and 10 h and 3 times at 12 h compared to samples with the dehydrogenase formate gene). However, this difference was more pronounced in the simple M9 medium, as we observed more than 6-fold growth in 24 hours of incubation in mutant samples lacking the FDH gene compared to the BL21 maternal strain.

The experiments were completely in line with metabolic predictions and the growth of mutant bacteria was higher than that of BL21. Interestingly, most mutants grew in a simple medium containing glycerol, which showed that glycerol is a very good source for the growth of Escherichia coli bacteria. These results explain the inconsistency of predictions of previous metabolic models that declared glycerol a suitable carbon source for the growth of E. coli, but did not achieve it in practice.

Under normal physiological conditions, E. coli is not able to grow high in glycerol medium. Deletion of formate dehydrogenase gene caused fundamental changes in metabolic process and increased growth rate compared to BL21 strain, which indicates the inhibitory role of this enzyme in increased growth efficiency of E. coli in the presence of glycerol. In addition, the resulting strain can be used to express recombinant proteins with higher efficiency

Antibiotic resistance can complicate the treatment of infectious diseases of livestock and poultry. The aim of this study was to determine the frequency of genes encoding resistance to quinolones and sulfonamides in Escherichia coli (E. coli) isolated from pericarditis and periphepatitis lesions in broilers to provide a suitable background for treatment with these drugs in these lesions.

In this study, for detecting of resistance genes to fluoroquinolones and suvanamides, 50 bacterial strains were isolated from broiler chickens with pericarditis and periphepatitis and E. coli colonies were confirmed by microbial and biochemical tests. Then, the resistance of the strains to the commercial antibiotics (Enrofloxacin and sulfonamide + trimethoprim) was evaluated by the conventional antibiogram method. In addition, the bacterial genome was extracted by boiling method and the qnrA and sul1 genes were amplified with specific primers to evaluate antibiotic resistance against fluoroquinolones and sulfonamides.

In this study, 54% of enrofloxacin-resistant strains possed qnrA gene and 48% of sulfonamide-resistant strains plus trimethoprim contained sul1 gene. In this study, resistant strains without studied resistance genes were also found, which indicates the importance of other resistance genes in the development of resistance against sulfonamides and fluoroquinolones.

Evaluation of antibiotic resistance against enrofloxacin and sulfonamides is not possible with the help of one gene and to accurately determine antibiotic resistance, routine phenotypic tests are more effective than detecting a specific gene.

The aim of this study was to investigate the effects of probiotics isolated from local chickens on the expression of luxS, ctxM genes in resistant Escherichia coli.

Biochemical tests of Escherichia coli samples were isolated and then the presence of luxS and ctxM genes was detected by PCR with specific primers. In order to extract the native strains of Bacillus coagulans and Bacillus subtilis, the intestinal contents of 9 local chickens were cultured, isolated and identified by biochemical and PCR methods.

Commercial strains of Bacillus subtilis and Bacillus coagulans were isolated along with isolates of resistant Escherichia coli strains containing ctxm and luxs genes. Real-time PCR was used to evaluate gene expression. From 300 fecal samples taken, 40 isolates(7.5%) of Escherichia coli were obtained; Four Escherichia coli strains were isolated from patients carrying ctxM and luxS genes. Isolates of Bacillus coagulans and Bacillus subtilis were confirmed by molecular experiments. Decreased by 2.2 times, equal to the control group in Escherichia coli.

The results of statistical analysis showed that there was a significant relationship between the presence of native and commercial probiotics in culture and reduced expression of ctxM and luxS genes.

Urinary tract infection is one of the most common and common bacterial infections, accounting for a significant proportion of hospital admissions (about 30-40%). Silver nanoparticles work by releasing silver ions against various bacteria. The fact that bacteria are not resistant to nanoparticles is very important and therefore will affect a wide range of bacteria.

In this study, 50 specimens of positive cultures with urinary tract infection referred to Imam Reza Hospital Laboratory in Bojnourd were studied. Resistance and susceptibility of the isolates were determined by disk diffusion method. In this study, antibacterial effects of silver nanoparticles were investigated by microdilution method using aqueous extract of Ganoderma leucidum. Vegetative electron microscopy was used to measure the size and shape of silver nanoparticles. In addition, infrared spectroscopy analysis was performed to investigate possible organic compounds involved in the synthesis of nanoparticles.

The highest antibiotic resistance was related to ampicillin (84%). The resulting nanoparticles were 20 to 45 nm in size.

The produced nanoparticles have antimicrobial activity and can be a good alternative in the treatment of antibiotic resistant infectious diseases.