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- Occurrence, genetic diversity and antibiotic resistance of Arcobacter sp. in a dairy plantPublication . Ferreira, Susana; Oleastro, Mónica; Domingues, F.C.Aims The aim of this study was to evaluate the occurrence, diversity and resistance to antibiotics of Arcobacter sp. in a dairy plant samples. Methods and Results A total of 75 samples from dairy plant surfaces and materials and several food products collected in different steps of the cheese production process were analysed by culture, under aerobic and microaerobic atmospheric conditions, and by enrichment molecular detection. Isolates were identified and genotyped by ERIC‐PCR, and their susceptibility to nine antibiotics was evaluated by agar dilution. Global prevalence of Arcobacter sp. was 42·7%, where 20 of the 42 food samples analysed were positive for A. butzleri by both culture and molecular detection, one for A. marinus by culture and one for A. cryaerophilus by molecular detection only; 10 of the 30 analysed materials and plant surfaces were positive for A. butzleri. All A. butzleri isolates were resistant to nalidixic acid and showed high resistance rates to ampicillin (56·2%) and cefotaxime (97·9%), being all strains susceptible to gentamicin and erythromycin. Conclusions Contamination of dairy plant environment with A. butzleri and its progression along cheese production process were observed, however, the cheese ripening process may have a relevant role in the reduction of the contamination. Significance and Impact of the Study This study showed the presence of Arcobacter sp. in a dairy plant, displaying its high prevalence and genetic diversity and highlighting its high resistance rates. The data obtained could contribute to further acknowledge the Arcobacter food contamination as a potential health hazard.
- Optimization of Whey Protein-Based Films Incorporating Foeniculum vulgare Mill: Essential OilPublication . Pedro, Salomé; Pereira, L.; Domingues, F.C.; Ramos, Ana; Luís, ÂngeloPetroleum-based plastics used in food packaging are not biodegradable. They accumulate in the environment in large amounts, causing a decrease in soil fertility, jeopardizing marine habitats, and causing serious problems to human health. Whey protein has been studied for applications in food packaging, either because of its abundant availability or because it confers transparency, flexibility, and good barrier properties to packaging materials. Taking advantage of whey protein to produce new food packaging materials is a clear example of the so-called circular economy. The present work focuses on optimizing the formulation of whey protein concentrate-based films to enhance their general mechanical properties applying the Box–Behnken experimental design. Foeniculum vulgare Mill. (fennel) essential oil (EO) was incorporated into the optimized films, which were then further characterized. The incorporation of fennel EO in the films leads to a significant increase (p < 0.05) in peak elongation (from 14.03 to 31.61%) and tensile index (from 0.40 to 0.50 N.m/g). The optimized whey protein films were yellowish and very transparent (>90%). The results of the bioactive activities of the optimized films showed their ability to be applied as active materials for food packaging to improve the shelf-life of food products and also to prevent foodborne diseases associated with the growth of pathogenic microorganisms.
- Metabolic changes after licorice consumption: A systematic review with meta-analysis and trial sequential analysis of clinical trialsPublication . Luís, Ângelo; Domingues, F.C.; Pereira, L.Background: Licorice, also known as liquorice, refers to the root of Glycyrrhiza glabra L., a product widely available in the market in the form of licorice flavonoid oil (LFO), which is a concentrate of licorice flavonoids, being a dietary ingredient for functional foods with potential benefits for overweight subjects. Purpose: To summarize the results of the numerous clinical trials, and to clarify the metabolic changes after licorice consumption, through a systematic review with meta-analysis and Trial Sequential Analysis (TSA) of clinical trials. Methods: This review was designed according to the PRISMA (Preferred Reported Items for Systematic Reviews and Meta-Analysis) recommendations. Several electronic databases were searched to identify the clinical trials. A meta-analysis approach was then developed to statistically analyze the results, followed by TSA and meta-regression analyses. Results: A total 26 clinical trials were considered for the quantitative synthesis of the data, totalizing 985 patients enrolled. Overall, it was possible to verify that the licorice consumption significantly reduces the body weight (WMD: -0.433 kg; 95% CI: -0.683 to -0.183; p-value = 0.001) and consequently the body mass index (BMI) of patients (WMD: -0.150 kg/m2; 95% CI: -0.241 to -0.058; p-value = 0.001). Another result with statistical significance was the increase in the diastolic blood pressure (DBP) (1.737 mmHg; 95% CI: 0.835 to 2.621; p-value < 0.0001) observed for the group subjected to licorice consumption, which is related to the hypernatremia also caused by licorice. Conclusion: The present meta-analysis demonstrated the positive effects of licorice consumption on the reduction of body weight and BMI of patients. However, the results also show the increase in blood pressure of patients associated with the hypernatremia caused by licorice. Consequently, licorice consumption should be avoided by hypertensive patients.
- The antimicrobial action of resveratrol against Listeria monocytogenes in food-based models and its antibiofilm propertiesPublication . Ferreira, Susana; Domingues, F.C.BACKGROUND Resveratrol (3,5,4′‐trihydroxy‐trans‐stilbene) is a natural phytoalexin synthesized by plants in response to stress. This compound has several beneficial documented properties, namely anti‐inflammatory, antioxidant, neuroprotective and antimicrobial activities. In this study the antimicrobial activity of resveratrol against Listeria monocytogenes and Listeria innocua was investigated. RESULTS Resveratrol had a minimum inhibitory concentration of 200 µg mL−1 for the tested strains, with time‐kill curves demonstrating bacteriostatic activity. Inhibition of biofilm formation was also assessed, with resveratrol strongly inhibiting biofilm formation by both species even at subinhibitory concentrations. Overall, resveratrol showed antimicrobial properties on planktonic cells and on biofilm formation ability. Considering the potential use of resveratrol as a food preservative, the antimicrobial efficacy of resveratrol in food was studied in milk, lettuce leaf model and chicken juice. Resveratrol retained greater efficacy in both lettuce leaf model and chicken juice, but milk had a negative impact on its antilisterial activity, indicating a possible reduction of resveratrol availability in milk. CONCLUSION This study reinforces resveratrol as an antimicrobial agent, pointing out its antibiofilm activity and its potential use as preservative in some food matrices. © 2016 Society of Chemical Industry
- Bark residues valorization potential regarding antioxidant and antimicrobial extractsPublication . Neiva, Duarte; Luís, Ângelo; Gominho, Jorge; Domingues, Fernanda C.; Duarte, Ana Paula; Pereira, HelenaBark residual side streams from industries (Eucalyptus globulus—Eg and Picea abies—Pa) or from control of invasive species in Mediterranean countries (Acacia melanoxylon—Am and Acacia dealbata—Ad) are burned for energy production, although their high content of extractable compounds points to a possible valorization as sources of phytochemicals with antioxidant and antimicrobial activities. Non-polar and polar extracts were obtained, and their phenolic contents, antioxidant activity, antiquorum sensing and antimicrobial potential against several human pathogenic microbes (nine bacteria and two yeasts) were determined. Extraction yield ranged from 0.5 to 37% of barks dry weight varying with species and solvent used, and both water and ethanol extracts presented strong or very strong scavenging antioxidant ability. Eg and Pa non-polar extracts showed the lowest minimum inhibitory concentration for gram-positive bacteria (0.04–1.25 mg/mL), while Ad presented the best results among polar extracts regarding bacteria (0.16 mg/mL for K. pneumoniae) and yeast strains (0.02–0.04 mg/mL). Non-polar extracts showed great response against both Candida species (MIC=0.04–0.63 mg/mL). Each extract had diferent antimicrobial activity showing that species and solvents can be used to tailor compounds to target specifc pathogens. Information regarding these bioactive extracts from residual forest side streams can provide possible utilization routes for natural compounds recovery prior to combustion.
- Star anise (Illicium verum Hook. f.) essential oil: Antioxidant properties and antibacterial activity against Acinetobacter baumanniiPublication . Luís, Ângelo; Sousa, Sónia; Wackerlig, Judith; Dobusch, Daniel; Duarte, Ana Paula; Pereira, L.; Domingues, F.C.The increased resistance of pathogenic bacteria to multiple antimicrobial agents is becoming a significant public health threat. For many pathogenic bacteria there are already limited or no effective antimicrobials available to treat the infections caused by them. Acinetobacter baumannii is a Gram‐negative, biofilm‐forming, nonmotile coccobacillus and a major human pathogen causing hospital‐acquired infections, such as ventilator‐associated pneumonia, bacteraemia, meningitis, and urinary tract and wound infections. There is therefore a clear need to discover new compounds and strategies to overcome widespread antimicrobial resistance, with a focus on A. bau-mannii strains. Star anise (Illicium verum Hook. f.) has been widely used as an ingredi‐ent in traditional Chinese cooking, as a flavouring agent, and as a medicine for over 3000 years; however, the essential oil (EO) isolated from star anise has not been fur‐ther characterized in terms of its bioactivities and potential applications. In this work, a screening of the biological properties of star anise EO together with its chemical characterization were performed. Special attention was given to the impact of this EO in the formation of biofilms by A. baumannii. It was demonstrated that star anise EO is able to scavenge free radicals, to inhibit lipid peroxidation, and to inhibit protein denaturation, which is associated with its antioxidant and anti‐inflammatory proper‐ties. Moreover, the effects of the EO on the planktonic and biofilm cells of A. bau-mannii, inhibiting the formation of biofilms, dispersing preformed biofilms, and decreasing the capacity of the bacterial cells to adhere to polystyrene, together with its ability to inhibit quorum sensing, were also demonstrated.
- Molecular diagnosis of Arcobacter and Campylobacter in diarrhoeal samples among Portuguese patientsPublication . Ferreira, Susana; Júlio, Cláudia; Queiroz, João; Domingues, F.C.; Oleastro, MónicaThe present study was conducted to investigate the prevalence and diversity of Arcobacter and Campylobacter spp. in 298 stool samples of patients with diarrhoea, collected from 22 Portuguese hospitals, between September and November 2012. Detection of Arcobacter and Campylobacter spp. was performed using molecular-based detection techniques, such as real-time fluorescence resonance energy transfer PCR, species-specific PCR, and sequencing of amplified PCR products. Overall, 1.3% of the samples were positive for Arcobacter butzleri and 0.3% for Arcobacter cryaerophilus. Campylobacter spp. were found in 31.9% of diarrhoeic faeces. Campylobacter jejuni and Campylobacter concisus were the most prevalent species (13.7% and 8.0%, respectively). The prevalence of Arcobacter and Campylobacter spp. was significantly different between children and adults (39.7% versus 22.8%, P = 0.003). We underline the high prevalence of these pathogens in diarrhoeal samples among Portuguese patients, with particular relevance in the paediatric age group.
- Association between berries intake and cardiovascular diseases risk factors: a systematic review with meta-analysis and trial sequential analysis of randomized controlled trialsPublication . Luís, Ângelo; Domingues, F.C.; Pereira, L.The main goal of this work was to clarify the effects of the consumption of berries on cardiovascular disease (CVD) risk factors by performing a systematic review according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) statement, followed by a meta-analysis and a trial sequential analysis (TSA) of randomized controlled trials (RCTs). The electronic search was conducted in PubMed, Scopus, SciELO, Web of Science and Cochrane Library between April and June 2016. To be included, RCTs had to report 1 or more of the following outcomes: total cholesterol (TC), HDL-cholesterol (HDL), LDL-cholesterol (LDL), triglycerides (TG), blood pressure (BP), C-reactive protein (CRP), tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6), vascular cell adhesion molecule-1 (VCAM), intercellular adhesion molecule-1 (ICAM), glucose, insulin, apolipoprotein A-I (Apo A-I) or apolipoprotein B (Apo B). It was observed that the intake of berries reduces TC, LDL, TG, and BP while increasing the level of HDL, suggesting a beneficial effect on the control of CVDs' risk factors. Thus, the intake of berries as nutraceuticals or functional foods could be suggested for the prevention and control of CVDs.
- A meta-analytic perspective on Arcobacter spp. antibiotic resistancePublication . Ferreira, Susana; Luís, Ângelo; Oleastro, Mónica; Pereira, L.; Domingues, F.C.Objectives: Over the years, an increased prevalence of resistant strains of Arcobacter has been observed, which may be due to Arcobacter exposure to antibiotics used both in animal production and human medicine. A systematic review was performed with the objective of summarising the results of the rates of antimicrobial resistance of Arcobacter isolates. Methods: The systematic review was performed according to PRISMA (Preferred Reported Items for Systematic Reviews and Meta-Analysis) recommendations, followed by meta-analysis. Results: It was observed that the resistance rate ranged between 69.3-99.2% for penicillins and 30.5-97.4% for cephalosporins. The overall percentage of resistance to fluoroquinolones ranged from 4.3% to 14.0%, with the highest resistance percentage observed for levofloxacin. Resistance rates ranged between 10.7-39.8% for macrolides, 1.8-12.9% for aminoglycosides and 0.8-7.1% for tetracyclines. Conclusions: These results show that Arcobacter spp. present resistance to various antibiotics commonly used and advocate further studies of the associated resistance mechanisms.
- Resveratrol against Arcobacter butzleri and Arcobacter cryaerophilus: Activity and effect on cellular functionsPublication . Ferreira, Susana; Silva, Filomena; Queiroz, João; Oleastro, Mónica; Domingues, F.C.The frequent isolation of Arcobacter butzleri and Arcobacter cryaerophilus from food samples makes it imperative to search for potential compounds able to inhibit the development of these bacteria. Taking this into consideration, this study focuses on the antimicrobial activity of resveratrol and its mechanism of action against A. butzleri and A. cryaerophilus. The activity of resveratrol was assessed by a microdilution method and time-kill curves. Resveratrol effect on cellular functions was assessed by flow cytometry evaluating intracellular DNA content and metabolic activity. Ethidium bromide (EtBr) accumulation in the presence of resveratrol was also evaluated, as well as the susceptibility to resveratrol in the presence of phenylalanine-arginine β-naphthylamide (PAβN). Scanning electron microscopy (SEM) was used to further evaluate cell damage caused by resveratrol. Resveratrol presented MIC values of 100 and 50μg/mL to A. butzleri and A. cryaerophilus, respectively. Based on the time-kill curves, resveratrol exhibited bactericidal activity, leading to a ≥3log10CFU/mL reduction of initial inoculums, for A. butzleri exponential phase cells incubated for 6h with 1× MIC or with 2× MIC after 24h for stationary phase cells. For A. cryaerophilus cells in exponential growth phase, 99.9% killing was achieved after 24h incubation with 2× MIC, whereas, for stationary phase cells, bactericidal activity was only detected after incubation with 4× MIC. Incubation with resveratrol led to a decrease in both intracellular DNA content and metabolic activity. An increase in the accumulation of EtBr was observed in the presence of resveratrol, and the efflux pump inhibitor PAβN reduced the MIC of resveratrol. SEM analysis revealed disintegration of A. butzleri cells treated with resveratrol, whereas no morphological alteration was observed for A. cryaerophilus cells. Resveratrol has a good anti-Arcobacter activity, and the results obtained suggest that this compound could act through several different mechanisms in the inhibition of this microorganism. The results encourage the use of this compound for the development of potential strategies to control Arcobacter in food products.