The toothbrush in vitro model

Teresa Semedo-Lemsaddek was financially supported by national funds through the FCT—Foundation for Science and Technology, I.P. under the Transitional Standard—DL57/2016/ CP1438/CT0004. Publisher Copyright: © 2020 by the authors. Licensee MDPI, Basel, Switzerland.The present investigation intended to evaluate the bacteriostatic and bactericidal abilities of clove, oregano and thyme essential oils against oral bacteria in planktonic and biofilm states. Furthermore, aiming to mimic everyday conditions, a toothbrush in vitro model was developed. Determination of the minimum inhibitory concentration, minimum bactericidal concentration, minimum biofilm inhibitory concentration and minimum biofilm eradication concentration were achieved using the microdilution procedure. To simulate the toothbrush environment, nylon fibers were inocu-lated with oral bacteria, which, after incubation to allow biofilm development, were submitted to contact with the essential oils under study. Thyme and oregano essential oils revealed promising antimicrobial effects, both in growth inhibition and the destruction of cells in planktonic and biofilm states, while clove essential oil showed a weaker potential. Regarding the toothbrush in vitro model, observation of the nylon fibers under a magnifying glass proved the essential oil anti-biofilm proper-ties. Considering the effects observed using the in vitro toothbrush model, a realistic approximation to oral biofilm establishment in an everyday use object, a putative application of essential oils as toothbrush sanitizers to help prevent the establishment of bacterial biofilm can be verified.publishersversionpublishe

Enterococcus spp. from Azeitao and Nisa PDO-cheeses: surveillance for antimicrobial drug resistance

Research Areas: Food Science & TechnologyABSTRACT - Enterococcus spp. were isolated from PDO-cheese of Azeitão and Nisa at six cheesemaking units (Azeitão: A1, A2, A3, A4; and Nisa: N9, N10), over four years (2016–2019). Genomic typing was performed using RAPD and distinct enterococci (n = 145) were identified at the species level by multiplex-PCR and evaluated regarding antimicrobial drug resistance (AMR). Antibiotics from nine distinct classes (aminoglycosides, macrolides, oxazolidinones, chloramphenicol, streptogramins, tetracyclines, glycopeptides, β-lactams, and quinolones) were selected for AMR surveillance and breakpoint criteria defined by EUCAST and CLSI were considered and compared. Regarding species allocation, 78 enterococci were identified as E. faecium, 37 confirmed as E. faecalis and 30 as E. durans. High levels of resistance to quinupristin-dalfopristin, tetracycline and teicoplanin were observed. Some resistances to clinically relevant antimicrobials were also detected, including β-lactams, aminoglycosides, and glycopeptides. Two isolates were considered multidrug-resistant, one according to EUCAST and the other to CLSI breakpoint criteria. Overall, considering the absence of reports regarding enterococcalrelated toxinfections or infections resulting from the consumption of PDO-cheeses, traditional foods harbouring these bacteria should be considered safe. However, the possibility of horizontal gene transfer events associated with antibiotic resistance determinants further highlights the importance for AMR surveillance along the food chain.info:eu-repo/semantics/publishedVersio

Dynamics of bovine intramammary infections due to coagulase-negative staphylococci on four farms

The objectives of this study were to compare the impact of different coagulase-negative species (CNS) on udder health measured in terms of individual quarter milk somatic cell count (SCC) and duration of intramammary infection, and to get some insight into most likely routes of infection for different CNS species. This longitudinal observational study was performed on four farms that were sampled at 4-week intervals for a total of 12 visits each. Quarters infected with CNS were followed through time with milk samples being submitted for bacteriological culture and SCC determination. PCR amplification of the internal transcribed spacer region and sequencing of the sodA and rpoB genes were used for species allocation. Pulsed-field gel electrophoresis (PFGE) was performed to assess strain identity. The percentage of quarters affected per farm varied between 6 and 35%, with the most frequently isolated CNS species being Staphylococcus epidermidis, followed by Staph. simulans, Staph. chromogenes and Staph. haemolyticus. It was possible to follow 111 intramammary infections due to CNS through time. Duration of infection had a mean of 188 d and was not significantly different between CNS species. Geometric mean quarter SCC overall was 132 000 cells/ml and was also not significantly different between CNS species. Despite the possibility of a different epidemiology of infection, the impact in terms of udder health seems to be similar for different CNS species

Resistance and virulence distribution in enterococci isolated from broilers reared in two farming systems

Research Areas: Veterinary SciencesBackground: The impact of enterococci in human health has been growing for the last decades, mainly due to their resistance to several antimicrobial agents. Human consumption of contaminated meat, especially poultry, has been identified as a possible route of transmission. The aim of the present study was to evaluate and compare the antimicrobial resistance profiles and virulence genes of enterococci isolated from Portuguese conventional and free-range broiler farms. Results: Antibiotic susceptibility testing showed high frequencies of resistance to tetracycline in both farming systems. Resistance to erythromycin and gentamicin were detected in about half of the isolates. Resistance to penicillin was the less frequently observed and no vancomycin resistant isolates were identified. The majority of the enterococcal isolates, from either farming systems, were resistant to more than one antibiotic, and no statistical associations were found, except for penicillin resistance which associated with the genetic clusters. No differences were found between farming systems regarding the prevalence of tet(M), erm(B), aac (6′)-Ie-aph (2″)-Ia and pbp5 genes, nevertheless pbp5 prevalence was associated with the different genetic clusters. Hemolytic activity was identified in 26.47% of all isolates and gelatinase activity in 50%. The gelE gene was identified in the majority of the isolates, whereas esp and agg genes were rarely detected. The cylA determinant was not detected in any of the isolates. Conclusions: Overall, results suggest that similar resistance patterns and virulence genes can be found in both farming systems, though enterococci in free-range conditions should be less prone to acquire further resistance genes.info:eu-repo/semantics/publishedVersio

Advantages and disadvantages of non-starter lactic acid bacteria from traditional fermented foods: potential use as starters or probiotics

Research Areas: Food Science & TechnologyTraditional fermented foods are a significant source of starter and/or non-starter lactic acid bacteria (nsLAB). Moreover, these microorganisms are also known for their role as probiotics. The potential of nsLAB is huge; however, there are still challenges to be overcome with respect to characterization and application. In the present review, the most important steps that autochthonous lactic acid bacteria isolated from fermented foods need to overcome, to qualify as novel starter cultures, or as probiotics, in food technology and biotechnology, are considered. These different characterization steps include precise identification, detection of health-promoting properties, and safety evaluation. Each of these features is strain specific and needs to be accurately determined. This review highlights the advantages and disadvantages of nsLAB, isolated from traditional fermented foods, discussing safety aspects and sensory impact.info:eu-repo/semantics/publishedVersio

Duvan chvarci : product characterization and comparison between traditional and industrial production

Research Areas: Food Science & TechnologyThis research aimed to investigate and compare traditional products called “duvan chvarci” produced using pork meat and fat, originated from local households and industries. Physical and chemical analysis demonstrated differences among the examined products, mostly in total chloride content and TBARS values. Samples collected at local households showed finer color (higher lightness and yellowness) and sensory properties (rated as “extremely acceptable”), while industrial products were rated between “very acceptable” and “extremely acceptable“. Microbiological analysis exhibited that enterobacteria, coagulase-positive staphylococci, Salmonella spp., Shigella spp., and fungi were absent from all meat products. Dominant microbiota was identified as Lactobacillus spp. and Staphylococcus spp. All tested isolates showed γ-haemolysis on blood agar plates. Tested Staphylococcus spp. were sensitive to novobiocin while Lactobacillus isolates demonstrated sensitivity to ampicillin, chloramphenicol, clindamycin, erythromycin, tetracycline, gentamycin, and streptomycin. None of the tested isolates showed full resistance to antibiotics. Overall, results indicated that duvan chvarci is a microbiologically safe product and provided the initial evidence regarding the physical, chemical, technological, and sensory properties of this widely consumed product in the Balkans.info:eu-repo/semantics/publishedVersio

Serbian traditional goat cheese : physico-chemical, sensory, hygienic and safety characteristics

Research Areas: MicrobiologyThis research project aimed to investigate the physico-chemical, sensory, hygienic and safety characteristics of raw goat milk, whey, brine and traditional goat cheese during the ripening period of 28 days. Physico-chemical parameters included the determination of dry matter, fat, ash, protein, pH, water activity and NaCl content. The presence of Enterobacteriaceae and fungi was estimated on milk and cheese samples, and a sensory panel evaluated the products’ features and acceptability during ripening. The results show that the cheese under study belongs to the acid full-fat cheese group. A consumer panel attributed high scores to the goat cheese, until the 21st day of ripening. After this period, the overall features altered significantly, including augmented bitterness, odor intensification and the development of molds on the surface. The presence of fungi, associated with Enterobacteriaceae, suggests that the hygiene of the production processes needs to be improved. Regarding microbial safety, the detection of putative pathogens and antibiotic resistances recommend an active surveillance of traditional foods to avoid foodborne infections and/or the dissemination of resistant microorganisms along the food chaininfo:eu-repo/semantics/publishedVersio

Characterization and Technological Features of Autochthonous Coagulase-Negative Staphylococci as Potential Starters for Portuguese Dry Fermented Sausages

The manufacture of dry fermented sausages is an important part of the meat industry in Southern Europeancountries. These products are usually produced in small shops from a mixture of pork, fat, salt, and condiments andare stuffed into natural casings. Meat sausages are slowly cured through spontaneous fermentation by autochthonousmicrobiota present in the raw materials or introduced during manufacturing. The aim of this work was to evaluate thetechnological and safety features of coagulase-negative staphylococci (CNS) isolated from Portuguese dry fermented meatsausages in order to select autochthonous starters. Isolates (n = 104) obtained from 2 small manufacturers were identifiedas Staphylococcus xylosus, Staphylococcus equorum, Staphylococcus saprophyticus,andStaphylococcus carnosus. Genomically diverseisolates (n = 82) were selected for further analysis to determine the ability to produce enzymes (for example, nitrate-reductases, proteases, lipases) and antibiotic susceptibility. Autochthonous CNS producing a wide range of enzymes andshowing low antibioresistance were selected as potential starters for future use in the production of dry fermented meatsausages

Putative probiotic lactic acid bacteria isolated from sauerkraut fermentations

Probiotics are live microorganisms which confer health benefits to the host, and may be isolated from several sources, such as vegetable foodstuffs. Sauerkraut is a cabbage product resulting from fermentation by a lactic acid bacteria microbial succession, and is a potential source for probiotics. The aim of the present study was the isolation and characterization of probiotic microorganisms from sauerkraut fermentations. Four distinct fermentations were performed, from which lactic acid bacteria were recovered. Overall, 114 isolates were obtained, phenotypically and genotypically characterized, identified to the genus level and evaluated regarding safety and probiotic potential. Representative bacteria were selected for further analysis, 52% being Lactobacillus spp. and 33% belonging to Leuconostoc spp. genus. One isolate revealed to be β-hemolytic, 42% possessed potentially mobile antimicrobial resistance, 88% were resistant to bile and 20% to low pH. The six most promising candidates were further characterized and presented antimicrobial activity against Listeria monocytogenes, three being resistant to lower pH values. Thus, global analysis of data gathered during this study highlighted the identification of three Lactobacillus strains with putative probiotic potential, suggesting the applicability of sauerkraut fermentations as a source for probiotic isolation. Due to their origin these strains should be suited for future application in the food industry, namely vegetable products such as sauerkraut itself.publishe