Biofouling of stainless steel surfaces by four common pathogens: the effects of glucose concentration, temperature and surface roughness.

There is a wide range of factors affecting bacterial adhesion and biofilm formation. However, in both food processing and medical settings, it is very hard to obtain suitably controlled conditions so that the factors that reduce surface colonisation and biofouling can be studied. The aim of this study was to evaluate the effect of glucose concentration, temperature and stainless steel (SS) surface roughness on biofouling by four common pathogens (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and L. monocytogenes). Among the tested variables, the untreated SS surface (3C) was shown to be fouled more than 3D polished, brushed or electropolished SS surfaces. Although an array of parameters influenced biofouling, the most promising control measure was the influence of low temperature (4 °C) that reduced biofouling even in the case of the psychrophilic Listeria monocytogenes. The study findings could significantly contribute to the prevention of SS surface contamination and consequential biofouling by food and healthcare associated pathogens.

Attenuation of Adhesion, Biofilm Formation and Quorum Sensing of Campylobacter jejuni by Euodia ruticarpa.

Thermophilic campylobacters are a major cause of bacterial food-borne diarrhoeal disease. Adherence and biofilm formation are key elements of Campylobacter jejuni persistence in unfavourable environmental conditions. The phytochemical analysis of Euodia ruticarpa fruit ethanol solution extract (EREE) indicated that the major compounds were evodiamine (1), rutaecarpine (2) and evocarpine (9). E. ruticarpa fruit ethanol solution extract, compounds 1 and 2 as well as a mixture of quinolinone alkaloids with 41.7% of 9 were tested for antibacterial, antibiofilm and antiquorum sensing activities against C. jejuni. Minimal inhibitory concentrations varied from 64 to 1024 µg/mL. A mutant strain that lacks the functional gene coding for the CmeB efflux pump protein was the most susceptible. Interestingly, in addition to the wild-type (NCTC 11168) and cmeB mutant, also a mutant that lacks autoinducer-2 production (luxS) was able to adhere (1 h) and to produce a biofilm (24, 48 and 72 h). The subinhibitory concentrations of all preparations at least partly inhibited C. jejuni adhesion and biofilm formation with the most visible effect of the quinolinone alkaloid fraction. Using a Vibrio harveyi luminescence assay, the inhibition of autoinducer-2 production was observed in the wild-type and cmeB mutant after 48 h with the most visible effect of EREE and its fraction Q. Copyright © 2016 John Wiley & Sons, Ltd.

Parents' Perspective on Probiotics in Preschool Children: A Cross-sectional Survey.

Introduction: The composition of the human gut microbiota, which can also be regulated by the consumption of probiotics, has a significant impact on host health. The main source of probiotics can be foods such as fermented foods, yogurts, fermented drinks and/or probiotic supplements. While parents play a critical role in ensuring the well-being of their children, this cross-sectional study is focused on parents' perspectives regarding the use of probiotics in the preschool period. Methods: The self-administered online survey consisted of 24 questions arranged across two thematic sections. The final data analysis included 102 parents (96% F; 4% M), aged between 22 and 47. Their children were aged up to 6 years. Results: The majority (52%) of the parents were familiar with the term 'probiotics' and 86.3% were including probiotics in their children's diet at the time of the survey. The main source was probiotic food (36.3%), of which yoghurt was the most commonly consumed (87.2%). The inclusion of probiotic supplements in a child's diet was positively correlated with parents' consumption and level of knowledge about the term 'probiotics'. Digestive tract-related disorders were the most frequently reported motive for the initial introduction of probiotics into children's diet. Conclusions: Based on our study results, parents are familiar with probiotics and include them in their children's diet. However, an attempt should be made to close the gaps in parents' knowledge that our research identified. Further studies are needed to determine the recommended amount of probiotic foods, as well as strategies to educate parents about the benefits of including probiotic foods in their children's diet.

Antimicrobial and Antibiofilm Effect of Commonly Used Disinfectants on Salmonella Infantis Isolates.

Salmonella enterica subsp. enterica serovar Infantis is the most prevalent serovar in broilers and broiler meat in the European Union. The aim of our study was to test the biofilm formation and antimicrobial effect of disinfectants on genetically characterized S. Infantis isolates from poultry, food, and humans. For the biofilm formation under various temperature conditions (8 °C, 20 °C, and 28 °C) and incubation times (72 h and 168 h), the crystal violet staining method was used. The evaluation of the in vitro antimicrobial effect of Ecocid® S, ethanol, and hydrogen peroxide was determined using the broth microdilution method. The antibiofilm effect of subinhibitory concentration (1/8 MIC) of disinfectants was then tested on S. Infantis 323/19 strain that had the highest biofilm formation potential. Our results showed that the biofilm formation was strain-specific; however, it was higher at 20 °C and prolonged incubation time. Moreover, strains carrying a pESI plasmid showed higher biofilm formation potential. The antibiofilm potential of disinfectants on S. Infantis 323/19 strain at 20 °C was effective after a shorter incubation time. As shown in our study, more effective precautionary measures should be implemented to ensure biofilm prevention and removal in order to control the S. Infantis occurrence.

Antioxidant and Antimicrobial Properties of Helichrysum italicum (Roth) G. Don Hydrosol.

(1) Background: According to the emergence and spread of antibiotic resistance, there is an urge for new promising substances. The purpose of the study was to test the antioxidant, cytotoxic and antimicrobial properties of the Helichrysum italicum (Roth) G. Don essential oil (EO) and hydrosol. (2) Methods: The antioxidant potential was determined using the DPPH (2,2-diphenyl-1-picrylhydrazyl) method. The cytotoxicity for human skin and intestinal cells was tested using primary and immortalized cell line models. The minimum inhibitory concentration (MIC) of hydrosol was then determined for six bacterial strains covering four commonly reported food pathogens. Further on, the hydrosol at a concentration of 1/8 MIC was used to test the antiadhesive effect by the crystal violet (CV) staining method. (3) Results: the EO showed a 100-times higher antioxidant and 180- to 25.000-times higher cytotoxic activity, when compared to hydrosol. Nevertheless, all bacterial strains, with the exception of Staphylococcus aureus, were sensitive to hydrosol in the range of 12.5% (V/V) for Campylobacter jejuni, to MIC values of 100% (V/V) for Escherichia coli and Pseudomonas aeruginosa. The antiadhesive potential of hydrosol was also shown. (4) Conclusions: Even though hydrosols are a by-product of the EO distillation process, they possess valuable biological activities.

Comparison of Campylobacter jejuni Slaughterhouse and Surface-Water Isolates Indicates Better Adaptation of Slaughterhouse Isolates to the Chicken Host Environment.

Campylobacter jejuni is an emerging food-borne pathogen that poses a high risk to human health. Knowledge of the strain source can contribute significantly to an understanding of this pathogen, and can lead to improved control measures in the food-processing industry. In this study, slaughterhouse and surface-water isolates of C. jejuni were characterized and compared in terms of their antimicrobial resistance profiles and adhesion to stainless steel and chicken skin. Resistance of C. jejuni biofilm cells to benzalkonium chloride and Satureja montana ethanolic extract was also tested. The data show that the slaughterhouse isolates are more resistant to ciprofloxacin, and adhere better to stainless steel at 42 °C, and at 37 °C in 50% chicken juice. Additionally, biofilm cells of the isolate with the greatest adhesion potential (C. jejuni S6) were harvested and tested for resistance to S. montana ethanolic extract, benzalkonium chloride, and erythromycin; and for efflux-pump activity, as compared to their planktonic cells. The biofilm cells showed increased resistance to both S. montana ethanolic extract and erythromycin, and increased efflux-pump activity. These data indicate adaptation of C. jejuni slaughterhouse isolates to the chicken host, as well as increased biofilm cell resistance due to increased efflux-pump activity.

Obesity Measures and Dietary Parameters as Predictors of Gut Microbiota Phyla in Healthy Individuals.

The dynamics and diversity of human gut microbiota that can remarkably influence the wellbeing and health of the host are constantly changing through the host's lifetime in response to various factors. The aim of the present study was to determine a set of parameters that could have a major impact on classifying subjects into a single cluster regarding gut bacteria composition. Therefore, a set of demographical, environmental, and clinical data of healthy adults aged 25-50 years (117 female and 83 men) was collected. Fecal microbiota composition was characterized using Illumina MiSeq 16S rRNA gene amplicon sequencing. Hierarchical clustering was performed to analyze the microbiota data set, and a supervised machine learning model (SVM; Support Vector Machines) was applied for classification. Seventy variables from collected data were included in machine learning analysis. The agglomerative clustering algorithm suggested the presence of four distinct community types of most abundant bacterial phyla. Each cluster harbored a statistically significant different proportion of bacterial phyla. Regarding prediction, the most important features classifying subjects into clusters were measures of obesity (waist to hip ratio, BMI, and visceral fat index), total body water, blood pressure, energy intake, total fat, olive oil intake, total fiber intake, and water intake. In conclusion, the SVM model was shown as a valuable tool to classify healthy individuals based on their gut microbiota composition.

Bacterial adhesion rate on food grade ceramics and Teflon as kitchen worktop surfaces.

Here we present a research of bacterial adhesion to two most often used materials in modern kitchens, namely food grade ceramics and Teflon. To test the bacterial adhesion on kitchen worktops Escherichia coli, Pseudomonas aeruginosa and Campylobacter jejuni were used as the most common foodborne contaminants. Contact angle, roughness and streaming potential measurements were used for surface characterization. Crystal violet staining and scanning electron microscopy were applied for bacterial adhesion analysis. We showed that the adhesion of tested bacteria strains was lower on the Teflon surface compared to the ceramics. The hydrophobicity of the surface substantially contributed to the bacterial adhesion rate. On the other hand, the surface roughness and charge did not play a crucial role in the adhesion process.