Investigation of rpoS and dps genes in sodium hypochlorite resistance of Salmonella Enteritidis SE86 isolated from foodborne illness outbreaks in southern Brazil.

In Rio Grande do Sul, southern Brazil, Salmonella Enteritidis is one of the principal microorganisms responsible for foodborne disease. The present study was conducted to compare the sodium hypochlorite resistance of Salmonella Enteritidis SE86 with that of other strains of Salmonella Enteritidis isolated from different regions of the world and to investigate the involvement of the rpoS and dps genes in resistance to this disinfectant. We tested five Salmonella Enteritidis wild-type (WT) strains isolated from different countries, two mutant strains of Salmonella Enteritidis SE86, and two tagged (3XFLAG) strains of Salmonella Enteritidis SE86 for their resistance to sodium hypochlorite (200 ppm). The survival of the WT and attenuated strains was determined based on bacterial counts, and tagged proteins (Dps and RpoS) were detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting with anti-FLAG antibodies. None of the WT strains of Salmonella Enteritidis were totally inactivated after 20 min. The SE86 strain lacking dps was more sensitive to sodium hypochlorite than was the WT SE86 strain, with a 2-log reduction in counts after 1 min. The RpoS and Dps proteins were actively expressed under the conditions tested, indicating that in Salmonella Enteritidis SE86 these genes, which are expressed when in contact with sodium hypochlorite, are related to oxidative stress

Qualitative exposure assessment for Salmonella spp. in shell eggs produced on the island of Ireland

A qualitative exposure assessment for Salmonella in eggs produced on the island of Ireland was developed. The assessment was divided into three main modules (production and packing, distribution and storage, and preparation and consumption), and each of these stages into defined steps in the exposure pathway. In the production and packing stage the initial prevalences of Salmonella in the contents and on the shell of eggs were estimated to be negligible and low respectively. Numbers of Salmonella both in and on eggs were estimated to be low. At each subsequent step in the pathway, qualitative assessments were made of the impact of events on the probability and level of Salmonella contamination on the shells and in the contents of eggs. At the end of each module assessments were combined to give an overall probability and level of Salmonella contamination. In the first two modules the assessment focused on the effect of the duration and temperature of storage on yolk membrane integrity and the likelihood of shell penetration. During the final stage the influence of factors such as safe handling procedures, pooling practices, consumption patterns and the effectiveness of cooking, on the prevalence and level of Salmonella contamination in a food item at time of consumption was assessed. The outcome of this assessment was an estimate of a low probability and level of Salmonella contamination of egg containing foods, prepared with eggs produced on the island of Ireland

Application of molecular epidemiological methods to investigate strains of salmonella enterica serovar enteritidis in South Africa

A dissertation submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa, in fulfillment of the requirements for the degree of Master of Science in Medicine Johannesburg, 2017In South Africa, Salmonella Enteritidis has become a significant pathogen and the numbers of cases reported to the Centre for Enteric Diseases (CED) have increased. Pulsed-field gel electrophoresis (PFGE) is a primary for molecular subtyping of Salmonella. However, this technique has poor discrimination for serotypes with high homogeneity such as Salmonella Enteritidis. Multi-locus variable-number tandem-repeats analysis (MLVA) has shown higher discriminatory power for Salmonella Enteritidis compared to PFGE. In this study, MLVA was used to investigate the molecular epidemiology and relatedness of human Salmonella Enteritidis strains from Gauteng and Western Cape, South Africa. Furthermore, MLVA was also used to investigate the relatedness of human and non-human Salmonella Enteritidis strains. MLVA included analysis of five VNTR loci, with varying degrees of diversity. A total of 1221 human isolates and 43 non-human isolates were included in the study. Eighty-six MLVA profiles were obtained; MLVA profiles 7, 21, 22 and 28 were the predominant MLVA profiles. MLVA profile 28 was the most common MLVA profile amongst both the human and non-human isolates. Isolates had low prevalence of antimicrobial resistance, however sulfamethoxazole resistance was notable amongst both the human (348; 29%) and non-human (10; 23%) isolates. During the study period, seven Salmonella Enteritidis outbreaks were investigated from six provinces and isolates from each individual outbreak showed an identical MLVA profile. MLVA was shown to be a successful molecular subtyping tool for Salmonella Enteritidis, for both surveillance purposes and outbreak investigations. Salmonella Enteritidis strains circulating within the human and non-human population were clonal. The study emphasizes the need for the one health approach, in order to curb the spread of Salmonella Enteritidis in South Africa.MT201

Molecular characterization of Salmonella Enteritidis : comparison of an optimized multi-locus variable-number of tandem repeat analysis (MLVA) and pulsed-field gel electrophoresis

Salmonella Enteritidis (SE) is a genetically homogenous serovar, which makes optimal subtype discrimination crucial for epidemiological research. This study describes the development and evaluation of an optimized multiple-locus variable number tandem-repeat assay (MLVA) for characterization of SE. The typeability and discriminatory power of this MLVA was determined on a selected collection of 60 SE isolates and compared with pulsed-field gel electrophoresis (PFGE) using restriction enzymes XbaI, NotI, or SfiI. In addition, the estimated Wallace coefficient (W) was calculated to assess the congruence of the typing methods. Selection of epidemiologically unrelated isolates and more related isolates (originating from layer farms) was also based on the given phage type (PT). When targeting six loci, MLVA generated 16 profiles, while PFGE produced 10, 9, and 16 pulsotypes using XbaI, NotI, and SfiI, respectively, for the entire strain collection. For the epidemiologically unrelated isolates, MLVA had the highest discriminatory power and showed good discrimination between isolates from different layer farms and among isolates from the same layer farm. MLVA performed together with PT showed higher discriminatory power compared to PFGE using one restriction enzyme together with PT. Results showed that combining PT with the optimized MLVA presented here provides a rapid typing tool with good discriminatory power for characterizing SE isolates of various origins and isolates originating from the same layer farm

Bacterial contamination of table eggs and the influence of housing systems

With the introduction of alternative housing systems for laying hens in the EU, recent research has focussed on the bacterial contamination of table eggs, e.g. eggshell and egg content contamination. Contamination of eggshells with aerobic bacteria is generally higher for nest eggs from non-cage systems compared to nest eggs from furnished cages or eggs from conventional cages. Studies indicate limited or no systematic differences in eggshell contamination with aerobic bacteria between eggs laid in the nest boxes of furnished cages and eggs laid in conventional cages. The major differences found in experimental studies between cage- and non-cage systems are less pronounced under commercial conditions. The effect of housing system on eggshell contamination with specific groups of bacteria is variable. Limited information is available on the influence of housing system on egg content contamination. Recent research does not indicate large differences in egg content contamination between eggs from cage- and non-cage systems (ignoring outside nest and floor eggs). The microflora of the eggshell is dominated by Gram-positive bacteria, whereas Gram-negative bacteria are best equipped to overcome the antimicrobial defences of the egg content. Much of the research on eggshell and egg content contamination focuses on Salmonella, since infection with Salmonella enteritidis, resulting from the consumption of contaminated eggs or egg products, is still a major health problem. Observed Salmonella prevalence on the eggshell and in the egg content vary, depending on the fact whether investigations were based on randomly sampled table eggs or on eggs from naturally infected hens. The limited information available on other pathogens shows that they are exclusively isolated from the eggshell and not from the internal contents

Efek Ekstrak Kasar Cacing Tanah Pheretima sp. terhadap Morfologi Sel Bakteri Salmonella enteritidis

Abtract. This study was aimed at studying changes in the morphology of Salmonella enteritidis bacterial cells after the crude extract of Pheretima sp. using a scanning electron microscope (SEM). Earthworm extraction uses 96% ethanol, and binds to the appropriate bacteria in the exponential phase with extract concentrations of 5% and 10%. Observations using a microscope scanner were carried out after agreeing to a 6-hour, 12-hour, and 24-hour extract. Obtained from the results showing the crude extract of Pheretima sp. to changes in cell morphology of Salmonella enteritidis bacteria. Salmonella enteritidis bacterial cells are damaged consisting of: formed holes in the surface of bacterial cells, bumps on the surface of bacterial cells, shrinkage of bacterial cells, elongation of bacterial cells, and increase in bacterial cells. In addition, as well as longer contributions and free time, incubation, after being added, crude extract of Pheretima sp. against Salmonella enteritidis bacteria, the greater the damage caused. However, 5% extract concentration is the optimal concentration in the effect of damage to the morphology of the cells of Salmonella enteritidis bacteria.Keywords: Coarse Extract, Earthworms, Pheretima sp., Morphological Cells, Salmonella enteritidis, Scanning Electron Microscope (SEM)

Probabilistic model for contamination of egg dishes with Salmonella spp. made from shell eggs produced on the island of Ireland

A quantitative model was constructed to estimate the probability that a serving of food containing eggs produced on the island of Ireland is contaminated with Salmonella spp. The model is based on the prevalence of contaminated eggs at the time of lay and a set of parameters which describe the pooling of eggs in the home and in catering situations. Both external and internal contamination of the eggs by Salmonella spp. was considered. The model estimates that there is a 90% chance that the probability of a serving of food being contaminated is between 0.0043% and 0.038%. Sensitivity analysis demonstrated that egg prevalence drives this low probability and that, at the current level of egg prevalence at the time of lay, pooling of eggs has a minor effect. These results indicate the importance of maintaining the low prevalence of contaminated eggs at the time of lay to minimise the risk of human cases of salmonellosis from consumption of eggs

Intestinal epithelial responses to Salmonella enterica serovar Enteritidis: Effects on intestinal permeability and ion transport

Salmonella infection of chickens that leads to potential human foodborne salmonellosis continues to be a major concern. Chickens serve as carriers but, in contrast to humans, rarely show any clinical signs including diarrhea. The present investigations aimed to elucidate whether the absence of diarrhea during acute Salmonella enterica serovar Enteritidis (Salmonella Enteritidis) infection may be linked to specific changes in the electrophysiological properties of the chicken gut. Immediately after slaughter, intestinal pieces of the mid-jejunum and cecum of either commercial broiler or specific pathogen-free (SPF) chickens were mounted in Ussing chambers in 2 separate experimental series. Living Salmonella Enteritidis (3 × 109) or Salmonella Enteritidis endotoxin (20 mg/L), or both, were added to the mucosal side for 1 h. In both experimental series, the Salmonella infection decreased the trans-epithelial ion conductance Gt (P < 0.05). In the jejunum of SPF chickens, there was also a marked decrease in net charge transfer across the epithelium, evidenced by decreased short-circuit current (Isc, P < 0.05). Interestingly, the mucosal application of Salmonella endotoxin to the epithelial preparations from jejunum and cecum of SPF chicken had an effect similar to living bacteria. However, the endotoxin had no additional effect on the intestinal function in the presence of bacteria. The decreasing effect of Salmonella and or its endotoxin on Gt could be partly reversed by serosal addition of histamine. To our knowledge, this is the first study to address the functional response of native intestinal epithelium of chicken to an in vitro Salmonella infection. For the first time, it can be reported that intestinal ion permeability of chicken decreases acutely by the presence of Salmonella. This type of response could counteract ion and fluid secretion and may thus, at least in part, explain why chickens do not develop overt diarrhea after Salmonella infection

Study of the antibacterial activity of total extract and Petroleum ether, chloroform, ethyl acetate and aqueous fractions of aerial parts of heliotropium bacciferum against staphylococcus aureus, Bacillus cereus, Pseudomonas aeruginosa, E.coli, Salmonella enteritidis

Heliotropium bacciferum is One of the plants belonging to the family Boraginaceae , which is Restricted distribution in the south of Iran. It is used for Hypotension, fever, stomach ulcers in traditional medicine. In this study, the antibacterial effects of extracts and fractions of chloroform, ethyl acetate and aqueous, aerial parts of Heliotropium bacciferum Forssk was evaluated against five bacterial strains. The methanol extract were prepared using the percolation method. Fractions of chloroform, Petroleum ether, ethyl acetate, methanol and aqueous respectively by Liquid - Liquid fractionation of the total extract were prepared. The antibacterial activity against two Gram positive bacteria, three Gram negative bacterial using Minimum inhibitory concentration in microplate and well plate method. Results showed that H. bacciferum extracts exhibited a significant activity against strains Staphylococcus aureus, Bacillus cereus,Pseudomonas aeruginosa, E.coli, Salmonella enteritidis. MIC and well plate is between 7.6-125 μg/ml. The results of this study indicate that extracts of the plant H.bacciferum has a antimicrobial effect against strains are listed And among the extracts, aqueous part is that most antibacterial effect of the other fraction and then methanolic extract has the greatest effect