bita bakhshi

Mesenchymal Stem Cells (MSCs) can repair gastrointestinal tract damage. The Secretome of MSCs has a high capacity to inhibit bacterial colonization and the subsequent inflammatory responses of Vibrio cholerae.

The Caco-2 cells were treated with adipose-derived MSCs (AD-MSCs) secretome and then in- fected with V. cholerae. Subsequently, the bacterial attachment and invasion, cholera toxin gene expression, PGE2 and IL-6 secretion, TNF-α, IL-1β, and IL-8 expression, and apoptosis of Caco-2 cells were evaluated.

The secretome of AD-MSCs significantly reduced the V. cholerae attachment and internalization on Caco-2 epithe- lial cells (P<0.0001). The cholera toxin (Ctx-B) gene expression (FR=4.56 ± 0.66) and PGE2 production (P=0.0007) were also significantly reduced. The production of NO and TNF-α, IL-1β, and IL-8 pro-inflammatory cytokines were significantly (P<0.05) reduced in exposure to the secretome of AD-MSCs. Secretome also improved a significant 81.33% increase in IL-6 production (128.1 ± 37.6 pg/mL) and showed a 12.36% significant decrease in epithelial cell apoptosis (P< 0.0001) after exposure to V. cholerae.

The secretome of AD-MSCs can play a critical role in inhibiting bacterial colonization, and subsequent inflam- matory responses, and maintaining the integrity of the epithelial barrier. The secretome may be effective in the prevention of hypovolemic shock.

Macrolide antibiotics are important for the treatment of Campylobacter jejuni infections. Resistance to this class of antibiotics in Campylobacter is a complex process with dynamic molecular changes that are not well defined. In the present study, to fill the gap related to antibiotic resistance to Erythromycin treatment, the transcriptomic response of Campylobacter jejuni strain NCTC11168 to Erythromycin (ERY) treatment was determined by microarray method. The obtained data were identified, extracted and analyzed with GEO2R online tools and R software. Genes with the highest differential expression were identified by using parameters P<0.05 and LogFC |>1|. Then, the expression of the related genes was separated and for the genes that had an increase in expression, the protein network was predicted through the STRING database and visualized with the Cytoscape software. By identifying different genes that had a significant decrease or increase in expression, it was found that a set of flaA, flaB, flgB, CmeC, sdhA, sdhB genes can play a role in the antibiotic resistance of Campylobacter jejuni to the treatment with Erythromycin antibiotic. In this study by examining the goals, effectiveness and functional analysis of these genes, suitable solutions to curb the resistance were presented.

 Clinical strains of Pseudomonas aeruginosa possess a wide diversity of antibiotic resistance and genetic characteristics.

 This study aimed to determine the antibiotic susceptibility patterns and genotypes of P. aeruginosa isolated from patients with nosocomial infections.

 We tested 149 samples for P. aeruginosa isolation, confirmed by PCR. The Multi, Extensively, and Pan-drug resistant strains were detected through CLSI guidelines. All isolates were subjected to ERIC-PCR genotyping using specific primers. The antibiotic patterns and ERIC types were analyzed statistically using specific software.

 Seventy-six (51%) isolates were confirmed as P. aeruginosa. Among them, 86.8% were determined as MDR, 81.5% as XDR, and 5.3% as PDR. Eight E-types were detected, which belonged to two main clusters with a similarity rate of over 70%. Cluster B, composed of E-types G and H, was a dominant cluster. Interestingly all of these cluster members were isolated from the internal ICU, and we can claim that at least two different colons had been colonized in the internal ICU. Moreover, four PDR strains were detected in this study, three of which possessed E-type G, and the remaining belonged to E-type H.

 Some unique E-types were dominant in ICUs with high diversity in antibiotic resistance patterns, which can be assumed as causative agents for nosocomial infection. The main threat here is regarding the PDR strains. They could be considered nosocomial pathogens and should be deliberated as a critical threat in an emerging hospital outbreak.

Enteropathogenic Escherichia coli (EPEC) strains cause a gastrointestinal disease in the developing countries. Over the years, antimicrobial resistance of EPEC have been a major issue. Bacteriophages have been a therapeutic option for bacterial infection. Our aim was to assay lytic activity of a siphophage on an EPEC strain.

EPEC strain ATCC 43887 was used for phage isolation using by double layer agar method. Bacteriophage morphology was visualized by transmission electron microscope.

a siphophage was detected by transmission electron microscope images. The phage formed small clear circular plaques. The results of lytic activity of siphophage on reference EPEC strain showed the phage could lyse the strain.

the phage had lytic activity on reference EPEC strain. The phage belonged to siphoviridae family. It look the phage can lyse clinical EPEC strains.

Acinetobacter baumannii (A. baumannii), an opportunistic pathogen, has been isolated from sewage, soil, and hospital wards. The prevalence of multidrug-resistance A. baumannii has seriously caused a health crisis in hospital settings. Bacteriophages have been used as an alternative therapy for control carbapenem-resistant bacteria-caused infections. We aimed to assay lytic effect of a filamentous phage on clinical bacterial strains.

500-ml water samples was collected from sewage in Tehran. Sewage samples were precipitated at 6000 rpm for 10 minutes and filtered using 0.45-µm syringe filters. Bacteriophage was isolated using double-layer agar assay and evaluated its stability at various pH and temperature ranges. In addition, the stability of the phage was assayed at chloroform 0.1%.

Transmission electron microscopy imagine showed phage is filamentous called vB-AbaI-TMU2. The phage affected on its own host so that could not effect on any Pseudomonas aeruginosa and Klebsiella pneumoniae strains. vB-AbaI-TMU2 phage was stable at pH 5 and 7 and also temperatures 25 and 37°C. vB-AbaI-TMU2 was stable at chloroform 0.1%. vB-AbaI-TMU2 phage infected carbapenem-resistant A. baumannii strains while other bacterial strains were resistant to.

The present study indicated the isolated phage had a narrow host range and is susceptible to various pH values and temperatures.

Segregation of Escherichia coli (E. coli) into the phylogenetic groups was observed in the experiments so that group B2 contained the enteropathogenic E. coli (EPEC) strains and extraintestinal pathogenic E. coli (ExPEC).

This study aimed to identify B2 phylogenetic groups in the extended-spectrum Cephalosporins resistant E. coli isolated from the stool of healthy children under 10 years old.

One hundred E. coli resistant to broad-spectrum Cephalosporins were collected from the feces of healthy children under 10. Subsequently, we grouped phylogenetic via PCR based on the genes yjaA, chuA, arpA, as well, as TspE4.C2. Then, according to Clermont et al.’s study, we used two individual multiplex PCRs for identifying B2 sub-groups (I-X subgroups). Serogroup typing with the 12 O-antigen was analyzed via PCR, and finally, 10 virulence genes (cnf1, papG, ibeA, malX, usp, cdt, eae, bfp, and afa-Dr) were identified with PCR.

The age range of the healthy children was between 1 and 10 years. The B2 and unknown phylogroups were the most common strains in this study. The most common B2 subgroups were I (2%), IX (1%), V (8%), IV, V, VII (1%), IX, V (3%), IX, V, III, I (1%), IX, V, III, VII, I (%1), V, I (6%), V, III, I (3%), and V, III, VII (1%), with each subgroup carrying distinctive sets of ExPEC virulence markers. The results also showed that 29% of E. coli in the healthy children had malX and 23% had papGII. It was also found that 32% of the strains isolated from the healthy children had antigens O2 and 36% were unknown.

In this study, 27% of the strains belonged to B2 phylogroup and 6% to B1 phylogroup. Moreover, serogroups O2, O16, and O25 were predominant and belonged to B2 phylogroup. Moreover, malX, papGII, usp, papGIII, aggR, and eae virulence genes also had the highest to lowest supply among the tested strains, respectively. Moreover, B2 isolates were shown to have further virulence-related genes in comparison to the non B2 isolates.

Gastrointestinal colonization with resistant pathogens is significant because they could be easily transmitted to other hosts or spread to different microbiota through mobile genetic elements.

This study assessed the prevalence of fecal carriage of extended-spectrum β-lactamase-producing and carbapenemaseproducing Enterobacteriaceae (ESBL-E and CPE, respectively) among hemodialysis patients and the factors affecting its occurrence in a hospital in Tehran.

From January 2018 to May 2019, 150 hemodialysis patients referred to a hospital in Tehran were sampled in this study. Stool samples of the patients were diluted in saline and cultured on MacConkey agar plates containing cefotaxime, ceftazidime, imipenem, and meropenem discs. The clinical data were analyzed to identify the risk factors using a logistic regression model.

The colonization rate of ESBL-E was 48.6%, while only 2% of patients were identified as the carriers of CPE (3 of 150). A higher prevalence rate was obtained for intestinal carriage of ESBL-E among hemodialysis patients aged 18 to 42 years using multivariate analysis. The prevalence rate of multidrug-resistant isolates was 73.8%. The blaCTX-M1 gene was identified as the most prevalent ESBL gene. Among carbapenemase-encoding genes, blaKPC and blaoxa-48 were found in 12 and two isolates, respectively.

These results demonstrated a high prevalence rate of ESBLs among hemodialysis patients, although this rate was low for carbapenemases. Therefore, more control measures should be taken in hospitals to prevent the spread of antibiotic resistance genes in healthcare settings.

currently TB diagnosis is limited by some major limitations in low-income and less experienced hospitals. Recently, it has been proposed that the ku gene of mycobacterial strains has the potential to be a highly specific and sensitive candidate biomarker for molecular detection of Mycobacterium tuberculosis (Mtb). This study was aimed to evaluate the specificity and sensitivity of a real-time PCR assay for detection of ku gene in Mtb complex to determine its applicability for Mtb identification.

The identification of Mtb was confirmed using GeneXpert assay. Specific primers for ku gene were designed and the cycle threshold (Ct) value from the real-time PCR was used as a proxy measure of the cut-off point. Receiver operating characteristic (ROC) curve analysis was conducted to determine the diagnostic performance of ku gene in detecting Mtb directly from clinical specimens.

ku amplification was interpreted as positive and negative based on Ct values, in which a value <38 was considered positive and a value >40 was considered negative. Our findings revealed that the ku gene was found to be distributed in all Mtb-positive samples. Of note, none of the Mtb-negative exhibited a specific signal in a maximum of 40 cycles.

The ku gene amplification using real-time PCR indicated high sensitivity and specificity for the detection of Mtb complex in sputum samples.

Vibrio cholerae, the causative agent of cholera, has attracted a great deal of attention as one of the major causes of morbidity and mortality worldwide, especially in developing countries. In most laboratories, biochemical assays are primarily performed for possible detection of these strains, which are then followed by a PCR (polymerase chain reaction) test to verify their identity. This study aimed to optimize dot blot technique to detect Vibrio cholerae bacteria for V. cholera as an easy-to-use and beneficial method.

 A dot blot hybridization test was developed in this study to identify V. cholerae isolates as well as to assess the sensitivity and specificity of this test compared whit biochemical and PCR tests routinely performed for V. cholerae screening and detection in clinical specimens.

Herein, the dot blot hybridization test was optimized to detect V. cholerae. A combination of three biochemical assays and PCR test confirmed the results of dot blot hybridization test. This test was able to identify V. cholerae strains with a high sensitivity and specificity of 100%. Using the newly developed method, a set of 26 V. cholerae isolates collected from clinical samples were accurately identified.

This study optimized dot blot technique as a simple and useful assay that could be employed in V. cholerae monitoring programs and strategies to effectively detect V. cholerae strains in surface water and fecal specimens.

Inflammation-induced by the interaction of the Vibrio cholerae with the epithelial cells is considered as a main cause of bacteria spreading through the gastrointestinal tract and its consequences. Because of the immunomodulatory and antibacterial properties of adipose-derived mesenchymal stem cells (AD-MSCs), this study aimed to investigate the effect of AD-MSCs on the interaction of the bacterial-epithelial cell. Caco-2 differentiated to intestinal epithelial cells co-cultured with AD-MSCs in a 1:1 ratio of the surface area of six-well plates, for 48 hours. After exposure to Vibrio cholerae, bacterial attachment and internalization were evaluated. Secretions of interleukin (IL) -6, prostaglandin E2 (PGE2), and nitric oxide (NO) were also measured using ELISA, and Griess assay, respectively. In addition, the expression of chloratoxin (Ctx-β) and inflammatory cytokines such as TNF-α, IL-1β, and IL-8 were evaluated by real-time polymerase chain reaction (RT-PCR). The rate of apoptosis was also evaluated by Annexin V-PI flow cytometry. Bacterial attachment and Ctx-β expression were significantly reduced in the co-culture group compared to the Vibrio cholerae-exposed Caco-2. IL-6 and PGE2 secretion increased in the co-culture group. NO, was also slightly reduced in exposure to Vibrio cholerae. An elevated level of bacterial internalization was observed in the co-culture group compared to the Caco-2 cells leading to an increase in the expression of pro-inflammatory cytokines. The rate of apoptosis was also increased significantly. Cell-to-cell contact of AD-MSCs and Caco-2 promoted inflammatory responses and disruption of the epithelium barrier by enhancing bacterial invasion. This may be due to the high expression of surface matrix metalloproteinases on MSCs.

This study aims to produce drinkable flavored milk using berry juice (as a source of functional compounds), cacao and various hydrocolloids such as inulin, guar gum and gelatin as stabilizing in both low and high fatty formulation. The stabilizers included inulin, guar and gelatin (at levels of 0.25 and 0.5%). In all samples, the amount of berry juice was the same. The results showed that application of stabilizers significantly (P< 0.05) decreased pH and increased acidity. Studies also showed that the viscosity and sedimentation rate of the samples were completely dependent on the presence of hydrocolloids and fat in their formulation. So that, increasing the amount of hydrocolloids and fat in the formulation significantly increased the viscosity of the samples and reduced the deposition of the particles in the product, thereby stabilizing the final product. High-fat formulation with high levels of sustainability yielded higher overall acceptance in the study of sensory properties, too. In general, the treatment containing 0.5% inulin, 0.5% guar and 0.5% gelatin as a stabilizer resulted in improvement of the physical and sensory properties of the functional drinkable milk.

Concrete is one of the most used materials in the world. Cracking in concrete is a common problem that occurs due to its relatively low tensile strength. The cracks created in concrete are the main reason for the reduced durability and useful life of concrete structures. Proper and timely repair of primary cracking is necessary in order to prevent its expansion in concrete and reduce the high cost of maintenance. For this purpose, self-healing methods have been developed. Adding microorganisms to concrete mixing and bio-concrete production is an intelligent and environmentally friendly strategy for the repair of concrete cracks. Bacterial species resistant to hard and rough concrete environment such as bacillus, with the production of calcium carbonate precipitation, can be repaired in a continuous hydration process by filling freshly formed fine cracks. The aim of this study was to identify the effective bacterial species and its effect on the strength properties of concrete as a restorative agent.The results show that the changes in the strength properties of bio-concrete by adding Bacillus subtelius at a concentration of 〖10〗^8 (Cells⁄ml), increase the compressive strength by 24.24% and also improve the durability of concrete by bacterial self-healing process.

Toxigenic Clostridium difficile is one of the prevalent diarrheagenic pathogens in hospitalized patients.

The study assessed the ability of three diagnosticmethods in identifyingC. difficile strains. The genotyping of the isolates was done, as well.

Stool samples were subjected to three different diagnostic methods including direct stool culture, glutamate dehydrogenase enzyme immunoassay (GDH-EIA), and direct stool PCR for the detection of the tcdA andtcdB genes. The sensitivity and specificity of the tests were evaluated. The genotyping was done by the PFGE method.

Of 120 samples, 20 (16%) were positive for C. difficile based on PCR, while 15 (12.5%) and 12 (10%) were positive according to GDH-EIA and direct stool culture. Among patients with C. difficile-associated diseases (CDAD), 11 (61%) were more than 65-years-old. The specificity of PCR, GDH-EIA, and direct culture was almost similar and equal to 100%, but their sensitivity was 90%, 70%, and 60%, respectively. The positive predictive value (PPV) was lower for GDH-EIA than for the other two methods, and the highest negative predictive value (NPV) was related to the PCR method. The results showed a high similarity between the isolates, and only were three pulsotypes differentiated among the isolates.

The specificity and sensitivity of the direct stool PCR method were higher than those of the other two methods. Although PCR inhibitors may reduce its ability for the correct diagnosis of negative samples, it seems to be a reliable method for the detection of C. difficile infection. The weakness of the GDH-EIA method was its lower PPV, which can cause false-positive results. Toxin patterns and pulsotypes of C. difficile isolates revealed a high similarity between the strains isolated from the same units.

Toxigenic Clostridium difficile is one of the prevalent diarrheagenic pathogens in hospitalized patients.

The study assessed the ability of three diagnostic methods in identifying C. difficile strains. The genotyping of the isolates was done, as well.

Stool samples were subjected to three different diagnostic methods including direct stool culture, glutamate dehydrogenase enzyme immunoassay (GDH-EIA), and direct stool PCR for the detection of the tcdA and tcdB genes. The sensitivity and specificity of the tests were evaluated. The genotyping was done by the PFGE method.

Of 120 samples, 20 (16%) were positive for C. difficile based on PCR, while 15 (12.5%) and 12 (10%) were positive according to GDH-EIA and direct stool culture. Among patients with C. difficile-associated diseases (CDAD), 11 (61%) were more than 65-years-old. The specificity of PCR, GDH-EIA, and direct culture was almost similar and equal to 100%, but their sensitivity was 90%, 70%, and 60%, respectively. The positive predictive value (PPV) was lower for GDH-EIA than for the other two methods, and the highest negative predictive value (NPV) was related to the PCR method. The results showed a high similarity between the isolates, and only were three pulsotypes differentiated among the isolates.

The specificity and sensitivity of the direct stool PCR method were higher than those of the other two methods. Although PCR inhibitors may reduce its ability for the correct diagnosis of negative samples, it seems to be a reliable method for the detection of C. difficile infection. The weakness of the GDH-EIA method was its lower PPV, which can cause false-positive results. Toxin patterns and pulsotypes of C. difficile isolates revealed a high similarity between the strains isolated from the same units.

Background & Methicillin-resistant Staphylococcus aureus (MRSA) is reported as one of the important bacterial causes of burn wound infections. This study was carried out to investigate molecular characterization of community-associated MRSA (CA-MRSA) isolated from Iranian burn patients. A total of 31 isolates of S. aureus were collected fromthe Motahari Burns Hospital (Tehran, Iran) in 2016. All isolates were collected from outpatients and inpatients within 48 hours of admission. The mecA, pvl, tsst-1, hla-α, and psmα genes detecting, SCCmec, agr and PFGE typing were done. A total of 13 (41.9%) isolates were cefoxitin-resistant and mecA-positive, which were considered as MRSA. The SCCmec typing MRSA strains revealed type II in 1 (7.7%), type III in 9 (69.2%), and other types in 3 isolates (23.7%) cases. The agrtyping of all 31 isolates showed that 14 (45.2%), 1 (3.2%), 6 (19.4%), and 10 (32.3%) strains belonged to agr groups 1, 3, 4, and unknown type, respectively. The pvl, tsst-1, hla-α, and psmα genes were positive in 3 (9.7%), 4 (12.9%), 21 (67.7%), and 31 (100%) isolates, respectively. Considering the cut-off values of ≥50%, 3 groups of related isolates (cluster A1, B1, and C1) in PFGE study were observed. The MRSA strains of this study were initially isolated as Community-associated S. aureus (CA-MRSA); however molecular characterization showed that a significant proportion of them had hospital-associated MRSA (HA-MRSA) features. Therefore, it is likely that the HA-MRSA strains are spread among the community.

The aim of this study was to evaluate the antibacterial and antibiofilm activity of recombinant Azurin from Pseudomonas aeruginosa against different bacterial species. The azurin gene was cloned in the pET21a vector. The pET21a-azurin construct was transformed into Escherichia coli BL21. The recombinant Azurin was expressed and purified using affinity chromatography and confirmed by Western blotting. The cytotoxicity of rAzurin was assessed on peripheral blood mononuclear cells. Antibacterial and antibiofilm activity of rAzurin with different concentrations were determined by micro-broth dilution and crystal violet methods, respectively. The effect of rAzurin on bacterial species was statistically analyzed by t- test and spearman correlation. The identity of purified protein was confirmed by blotting and distinguished as a 14 kDa band on 15% SDS-PAGE. The IC50 of rAzurin on Peripheral Blood Mononuclear Cell (PBMC) was determined as 377.91±0.5 µg/mL in 24 h. Vibrio cholerae and Campilobacter jejuni displayed the most sensitivity to rAzurin (27.5 and 55 μg/mL, respectively) and the highest resistance (220 μg/mL) was displayed by P. aeruginosa and E. coli. The MIC for other species was 110 μg/mL. The Minimum Biofilm Inhibition Concentration (MBIC) was determined as 220 μg/mL for Salmonella enterica and V. cholerae, 300 μg/mL for Shigella sonnei, Shigella flexneri and P. aeruginosa and 440 μg/mL for the other species. The antimicrobial effect of rAzurin on bacterial species were significant (p value<0.05) and correlation coefficient was negative. The rAzurin appears to be an appropriate choice and a new strategy for prevention of bacterial infection. It inhibits bacterial growth and biofilm formation and candidates as antimicrobial peptides.

The increased prevalence of extended-spectrum β-lactamases (ESBLs)-producing virulent strains possibly leads to serious outbreaks in hospitals. The aims of the study were to detect ESBLs in Klebsiella pneumoniae isolated from patients in intensive care units (ICUs) of a hospital and to investigate their genetic relationships. A total number of 85 K. pneumoniae isolates were detected in the specimens of ICU patients in a tertiary hospital in the southwest of Tehran, Iran. Antibiotic susceptibility was determined by the disk diffusion method. The rmpA and wcaG virulence genes were detected by polymerase chain reaction (PCR). The ESBL-positive isolates were typed using multilocus variable-number tandem repeat analysis (MLVA) method. Of the 85 K. pneumoniae isolates, 48 (56.5%) produced ESBLs. There were statistically significant differences in the prevalence of virulence genes based on ESBL production. The typing of the 48 ESBL-positive isolates showed a significant genetic relatedness with the identification of nine MLVA types. This study showed a relatively high prevalence of ESBL in K. pneumoniae isolated from ICU patients and a low diversity between these isolates. The selection of ESBL-producing clones was mainly responsible for the spread of K. pneumoniae in the ICUs.

Enterobacter cloacae bacteremia is reported as an important cause of morbidity and mortality. The members of E. cloacae complex are clinically involved in nosocomial infections. The purpose of this study was to investigate the prevalence of E. cloacae complex and its members in blood samples and conduct the hsp60 cluster analysis and genotyping of the isolates. Eight isolates of E. cloacae complex were collected from blood cultures of hospitalized patients during the study period (December 2012 to November 2013). The hsp60 sequencing was done for the genetic classification. Pulsed-field gel electrophoresis (PFGE) was used for genotyping of the isolates. Fifty percent of the isolates belonged to two E. hormaechei subspecies. Three isolates (37.5%) clustered within genotype III while only one isolate fitted cluster XIII genotype (12.5%). Pulsed-field gel electrophoresis analysis revealed four different pulsotypes. Different E. cloacae complex species and subspecies unequally contribute to the pathogenesis of blood infections and the subspecies of E. hormaechei were found to be most prevalent. Moreover, the common E. cloacae pulsotypes were observed to essentially produce identical hsp60 sequence types, indicating the probable clonality of isolates with identical pulsotypes.

Infectious diarrheal diseases are a major cause of death in community, especially in children. Enteropathogenic Escherichia coli (EPEC) are considered as a major cause of children's diarrhea in developing countries. The aim of this study was to evaluate the prevalence of both typical Enteropathogenic (tEPEC) and atypical Enteropathogenic (aEPEC) E. coli isolated from patients admitted to the children's hospital in Tehran by the PCR method.
In this cross-sectional study, a total of 157 children diarrheal samples were collected from February 2016 to August 2017 and were sent to the microbiology department in the School of Public Health in Tehran University of Medical Sciences for testing. The identification of isolates was performed by conventional biochemical tests. The typical and atypical E. coli isolates were identified for the presence of eae, sxt1, sxt2 genes, and bfp A by the PCR method. The drug resistance patterns of isolated EPEC were tested by the agar disk diffusion method. The antibiotics used were amoxicillin-clavulanic, ampicillin, gentamicin, trimethoprim- sulfamethoxazole, ciprofloxacin, cefepim, Nitrofurantoin and imipenem.
Out of 101 E. coli isolates, 7 were identified as EPEC. All the isolated strains carried eae but not stx1, stx2, and bfp A genes. Also, 100% of the isolates were resistant to amoxicillin-clavulanic and ampicillin.
A high prevalence of EPEC in children can be considered as a threat to the children's health. In this study, all the isolates were aEPEC.

The Stober process is frequently used to prepare silica-coated iron oxide nanoparticles. This is usually achieved by seeding a reaction mixture consisting of water, ethanol and a catalyst with iron oxide particles and adding a silica precursor. The hydrolysis and condensation of precursor monomers results in the deposition of a silica layer on iron oxide particles. However, this process is accompanied by an increase in the ionic strength of the medium which promotes the rapid aggregation of iron oxide particles. A number of methods have been developed to prevent seed aggregation during the coating process. The majority of these methods include a pretreatment step in which the surface of iron oxide particles is modified in a manner that increases their stability in aqueous solutions. Here we suggest that by decreasing the initial concentration of the catalyst for a short period to minimize nucleation by reducing precursor hydrolysis rate and then gradually increasing the concentration to the optimum level to allow silica formation to proceed normally it may be possible to prevent aggregation without surface modification. The properties of the resulting nanoparticles as analyzed by transmission electron microscopy and magnetometry as well as their efficiency at extracting genomic DNA from different bacterial strains compared to that of a commercial extraction kit are also reported.

Cholera is an acute and dangerous intestinal diarrhea that leads to death if hypovolemic shock occures. Vibrio cholera, as a causative agent of cholera, is a noninvasive enteric gram-negative bacteria which exerts its pathological effects by producing cholerae toxin (CT). The first time, the acute inflammatory responses of Cholerae was considered when the development of laboratory techniques in the last years demonstrated that CT can induce lipid mediators synthesis like prostaglandin E2, F2 and leukotrienes and recruit neutrophils, mast cells, macrophages and other immune cells. The recruited cells respond to infection by lactoferrin and myeloperoxidase secretion in the excretory liquid and production of inflammatory cytokines like, TNF-α, IL-1 and IL-6. On the one hand, the formed inflammatory responses, stimulate innate and adaptive immune system and produce antibodies against Vibrio cholerae, but on the other hand, it enhances the excretion of water and salts from the gastrointestinal tract epithelial cells and induces apoptosis and loss of defensive function of epithelial barrier. Although the epithelial cell shedding and excretion of infected fluids from the intestinal tract is the body’s natural defensive mechanism to remove bacteria, but in the case of the failure in bacteria reduction and lost fluid compensation by serum therapy, the disease will lead to death. Therfore the use of antibiotics and anti-inflammatory drugs will be effective besides serum therapy to reduce the number of baceria and fluid loss from the body and repair the epithelial barrier.

Shigella spp. are gram negative bacteria, which are of global public health importance. The growing of multidrug-resistant Shigella isolates are a major problemaround the world.
Overall, 50 isolates of Shigella spp. from children diarrheic stools were studied. The isolates were identified and confirmed using biochemical, serological and molecular methods (ipaH, wbgZ and rfc genes). Antimicrobial susceptibility test was done according to the Clinical and Laboratory Standards Institute (CLSI) guidelines against minocycline, tetracycline, doxycycline, ampicillin, streptomycin, trimethoprim-sulfamethoxazole, nalidixic acid, norfloxacin, ciprofloxacin and levofloxacin. Also, the role of efflux pump in defense of Shigella against tetracycline was investigated by Minimum Inhibitory Concentration (MIC) with and without an efflux pump inhibitor. Detection of tetA, tetB, tetC and tetD genes in Shigella was evaluated by conventional Polymerase Chain Reaction (PCR) and real time PCR.
Molecular identification revealed a prevalence of 14% for Shigella flexneri and 86% for Shigella sonnei. Minimum Inhibitory Concentration (MIC) of 90% of resistant isolates was changed in the presence CCCP.Results of conventional PCR exhibited that 66% of isolates were positive for tetA, while according to real time PCR method, 90% of isolates carried tetA. Positive results for tetB were12% and 18% by conventional and real time PCR methods, respectively. No positive results were detected for tetC and tetD. Also, tetB was detected only in S. flexneri while tetA was detected in both S. flexneri and S. sonnei.
It seems that efflux-mediated tetracycline resistance to tetracycline in S. flexneri can be related to tetB, however resistance in S. sonnei can be related to the expression of tetA.

Extended-spectrum β-lactamase (ESBL)-producing Klebsiella pneumoniae is rapidly spreading worldwide, creating serious problems in clinical settings.

The aim of this study was to describe the molecular and epidemiological characteristics of CTX-M-1 group ESBL-producing K. pneumoniae.

Seventeen CTX-M-1 group ESBL-producing K. pneumoniae isolates found among 31 K. pneumoniae isolates in samples collected from three hospitals in Tehran, Iran between May and December 2011 were included in the present study for further characterization and determination of clonal relationships. The genetic environment of blaCTX-M-1 was analyzed by polymerase chain reaction (PCR) mapping and sequencing, and the transferability of blaCTX-M-1 was evaluated through the use of a conjugation assay. PCR-based replicon typing (PBRT) was used to identify plasmid replicons. The isolates were typed using pulsed-field gel electrophoresis (PFGE).

All 17 isolates carried the blaCTX-M-15 gene. IncL/M was the most common replicon type (82.3%). The conjugation experiment showed that blaCTX-M-15 was carried on transferable plasmids. In all of the studied isolates, the mobile element ISEcp1 was found upstream and orf477 downstream of blaCTX-M-15, whereas IS26 was not found. PFGE identified 11 different profiles and one major clone.

The findings of this study suggest that among the K. pneumoniae strains isolated from samples of children, dissemination of the blaCTX-M-15 gene is due to clonal spread and to the dissemination of mobile genetic elements bearing blaCTX-M-15, such as ISEcp1. Genotyping of K. pneumoniae is indispensable for monitoring the spread of ESBL-producing strains, for initiating the implementation of suitable infection control measures, and for general epidemiology purposes.

Strains of Shigella spp. can cause shigellosis, or bacillary dysentery.that is a public health problem worldwide. The aim of this study was to describe the population structure and genetic relatedness of multidrug resistant S. sonnei and S. flexneri isolated during a one year period from children with diarrhea in Tehran, Iran.
A total of 70 Shigella spp. were detected during the study period . Twenty MDR isolates of Shigella spp. were randomly selected and used in this study. Bacterial identification was performed by conventional biochemical and serological and confirmed by molecular method. After antimicrobial susceptibility testing, we used Multilocus sequence typing (MLST) for subtyping isolates.
We found 14 Shigella sonnei and 6 Shigella flexneri isolates. Results of MLST showed five sequence types (ST) (145, 152, 241, 245, 1502) and BURST analysis revealed the largest number of single locus variant (SLV) and highest frequency (FREQ) for ST152. ST 152 with nine members was predicted as the founder by BURST. Frequency for ST 1502 and ST 245 was four isolates and the least frequency was seen for ST 241 and 145 with one and two members, respectively. ST 145 and ST 245 were described as singletons in BURST. All isolates with ST145 and ST245 were identified as Shigella flexneri.
Annual Multi locus sequence typing of MDR Shigella would help us in better understanding of dominant species and comparing our results with the same studies in other countries especially our neighbor countries in source tracking purposes.

Shigella spp. are gram negative bacteria that can cause shigellosis in human. It is important in young children as well as elderly and immunocompromised people. Threatening complications can occur in severe cases with multidrug resistance species. It has been observed that Shigella spp. have become resistant to antibiotics like other bacteria. Investigation of resistance to azithromycin, tetracycline and pattern of resistance are the objectives of this study.
Fifty isolates of Shigella spp. which have been collected from three hospitals in Tehran were studied. Isolates identified and confirmed as Shigella spp. by biochemical, serological and molecular methods (ipaH, wbgz, rfc genes). Antimicrobial susceptibility test was performed for ampicillin, azithromycin, ciprofloxacin, doxycycline, levofloxacin, minocycline, nalidixic acid, norfloxacin, streptomycin, trimethoprim-sulfamethoxazole and tetracycline by disc agar diffusion method. Minimal inhibition concentrations were performed for azithromycin and tetracycline.
From a total of 50 Shigella spp. isolates, 16% of them were Shigella flexneri and 84% Shigella sonnei. The majority of isolates were multidrug resistant. The most resistance was seen to doxycycline, streptomycin, trimethoprim-sulfamethoxazole and tetracycline. Resistance to azithromycin was 6% and all of the isolates were susceptible to norfloxacin and levofloxacin. Nine patterns of resistance were revealed to these isolates.
High resistance to tetracycline was observed and resistance to azithromycin as an alternative treatment choice was also considerable.