Browsing by Author "Oleastro, Mónica"
Now showing 1 - 10 of 116
Results Per Page
Sort Options
- Acute gastroenteritis outbreak associated to norovirus GI.9 in a Portuguese army basePublication . Lopes-João, António; Mesquita, João R.; de Sousa, Rita; Oleastro, Mónica; Penha-Gonçalves, Carlos; Nascimento, Maria São JoséGastroenteritis is considered a major illness within the military settings being caused by foodborne enteric pathogens that are particularly easily spread in the crowded conditions of military camps. Gastroenteritis outbreaks caused by norovirus usually affect a great number of soldiers due to the low infectious dose, copious viral shedding, and environmental stability. The present study describes the investigation of an outbreak of acute gastroenteritis that occurred in April 2015 in a Portuguese army base, focusing on the study of the epidemiological curve, symptoms experienced by the affected soldiers, and results of food, water, and stool microbiological analysis. From a total of 938 military personnel stationed on the base 46 soldiers developed acute gastroenteritis. Stool analysis of seven cases showed to be positive for norovirus GI.9 that was the probable cause of the outbreak. This report shows that genogroup I norovirus can also cause considerable morbidity in healthy young soldiers, affecting the operational effectiveness on the military forces. J. Med. Virol. 89:922-925, 2017. © 2016 Wiley Periodicals, Inc.
- Acute gastroenteritis outbreak associated to norovirus GI.9 in a Portuguese army basePublication . Lopes-João, António; Mesquita, João R.; de Sousa, Rita; Oleastro, Mónica; Penha-Gonçalves, Carlos; Nascimento, Maria Sao JoséGastroenteritis is considered a major illness within the military settings being caused by foodborne enteric pathogens that are particularly easily spread in the crowded conditions of military camps. Gastroenteritis outbreaks caused by norovirus usually affect a great number of soldiers due to the low infectious dose, copious viral shedding, and environmental stability. The present study describes the investigation of an outbreak of acute gastroenteritis that occurred in April 2015 in a Portuguese army base, focusing on the study of the epidemiological curve, symptoms experienced by the affected soldiers, and results of food, water, and stool microbiological analysis. From a total of 938 military personnel stationed on the base 46 soldiers developed acute gastroenteritis. Stool analysis of seven cases showed to be positive for norovirus GI.9 that was the probable cause of the outbreak. This report shows that genogroup I norovirus can also cause considerable morbidity in healthy young soldiers, affecting the operational effectiveness on the military forces. J. Med. Virol. © 2016 Wiley Periodicals, Inc.
- Aetiology of Acute Gastroenteritis in Hospitalized Children from Lisbon AreaPublication . Costa, Inês; Júlio, Cláudia; Rodrigues, João; Machado, Jorge; Correia, Cristina; Oliveira, Maria Marisa; Escobar, Carlos; Costa, Beatriz; Brito, Maria João; Correia, Paula; Ferreira, Gonçalo Cordeiro; Simões, Maria João; Oleastro, MónicaGastroenteritis is a major cause of morbidity and mortality worlwide. Aim: Determine the etiology of gastroenteritis in a cohort of children hospitalized Methods: From May 2011 to January 2012, stool samples were collected from children (4.2 ± 4.8 years). Viral agents (enteric and enterovirus) were detected by RT-PCR. Stool specimens were also tested for bacteria and parasites, by conventional methods. Results: From the 82 stool samples, 42(51.2%) were positive for virus, 22 (26.8%) for bacteria and 35.6% (26/73) for parasites. An association between viral infection and age<3 years (OR=4.92, p<0.01) was observed. Distribution of viral agents was NorovirusII (33.3%), Enterovirus (31%), Rotavirus (23.8%), Adenovirus (9.5%), NorovirusI (2.4%). Simultaneous detection of two viral agents was observed in seven cases (16.7%) - NorovirusII and Enterovirus was the most frequent (57.1%); association with another agent was detected in 33.3% samples. Eight of 22 samples (36.4%) were positive for Campylobacter jejuni, 5 (22.7%) for Salmonella spp, 7 (31.8%) for E. coli, although always in co-infection with another agent, and 1 (4.5%) for Shigella spp. 38.5% of the samples were positive for Cryptosporidium spp., 23.1% for Giardia sp. and 3.8% for Entamoeba histolytica. 69.2% of the parasites were co-detected with other agents. Conclusion: Results suggest that viral agents are the most common among children with acute gastroenteritis, although co-infections with bacteria and parasites are frequent. The most common viral agent associated with acute diarrhea was NorovirusII. An important percentage of cases with no infectious aetiology identified, suggesting that other emergent agents are probably implicated.
- Agentes infecciosos e cancroPublication . Oleastro, Mónica; Verdasca, Nuno
- Airborne spores’ dissemination of a swine associated Clostridioides difficile clonePublication . Alves, Frederico; Cano, Manuela; Brondani, Greice; Nunes, Alexandra; Oleastro, MónicaThis study supports the airborne dissemination of Clostridioides difficile spores. Of the sieve impaction samples collected at a swine production unit, 66.7% were positive and all belonged to the predominantly established clone. Spores' density varied according to the characteristics of the animal population, suggesting the possibility of airborne transmission.
- Allelic Diversity among Helicobacter pylori Outer Membrane Protein Genes homB and homA Generated by RecombinationPublication . Oleastro, Mónica; Cordeiro, Rita; Ménard, Armelle; Gomes, João PauloRecombination is one of the main mechanisms contributing to Helicobacter pylori genomic variability. homB and homA are paralogous genes coding for H. pylori outer membrane proteins (OMPs). Both genes display allelic variation yielded by polymorphisms of the genes’ middle regions, with six different alleles. This study used bioinformatic and statistical analyses to evaluate whether the allelic diversity of homB and homA is generated by recombination. A detailed molecular analysis of the most prevalent homB allelic variant was also performed to establish its molecular profile. The two most prevalent homB and homA allelic variants resulted from interallelic homologous recombination between the rarest allelic variants of each gene, with a crossover point localized in the middle of the genes, containing the allelic region. Molecular analysis of the most prevalent homB allele revealed a geographic partition among Western and East Asian strains, more noticeable for the 5 and 3 homB regions than for the middle allelic regions. In conclusion, the diversity of the 5 and 3 homB regions reflect the strains’ geographical origin, and variants likely occur via the accumulation of single nucleotide polymorphisms. On the other hand, homologous recombination seems to play an important role in the diversification of the highly polymorphic homB and homA allele-defining regions, where the most prevalent alleles worldwide result from genomic exchange between the rarest variants of each gene, suggesting that the resulting combinations confer biological advantages to H. pylori. This phenomenon illustrates an evolutionary scenario in which recombination appears to be associated with ecological success.
- Anti-Helicobacter pylori and urease inhibitory activities of resveratrol and red winePublication . Paulo, Luísa; Oleastro, Mónica; Gallardo, Eugenia; Queiroz, João António; Domingues, FernandaThere is considerable interest in alternative approaches for the eradication of Helicobacter pylori using biologically active compounds including antioxidants from a wide range of natural sources. In this work we have investigated the antibacterial properties of resveratrol towards different H. pylori strains. In addition we studied the inhibition of H. pylori urease by resveratrol and red wine. In those assays, resveratrol inhibited the growth of all the 17 H. pylori strains tested, with inhibition diameters ranging from 16 to 28 mm and minimum inhibitory concentration values varying from 25 to 100 mu g/mL, confirming its antimicrobial properties. Moreover, resveratrol and red wines showed an inhibitory effect on H. pylori urease activity, which is considered a virulence factor of this organism and essential for colonization and establishment of the infection. Further kinetic analysis revealed that inhibition occurred in a non-competitive and concentration-dependent manner. Overall, the results suggest that resveratrol and red wine may have potential for new therapy schemes that include natural products as an alternative therapeutic approach.
- Antigenic diversity among Portuguese clinical isolates of Helicobacter pyloriPublication . Vitoriano, Inês; Rocha-Gonçalves, Alexandra; Carvalho, Teresa; Oleastro, Mónica; Calado, Cecília; Roxo-Rosa, MónicaBACKGROUND: The human gastroduodenal pathogen, Helicobacter pylori, is characterized by an unusual extent of genetic heterogeneity. This dictates differences in the antigenic pattern of strains resulting in heterogeneous human humoral immune responses. Here, we examined the antigenic variability among a group of 10 strains isolated from Portuguese patients differing in age, gender, and H. pylori-associated gastric diseases. MATERIAL AND METHODS: Immunoassays were performed on two-dimensional electrophoresis gels obtained for the proteome of each strain, using a commercial pool of antibodies produced in rabbit, against the whole cell lysate of an Australian H. pylori strain. Relevant proteins were identified by mass spectrometry. RESULTS: Immunoproteomes of the Portuguese strains showed no correlation between the number of antigenic proteins or the antigenic profile, and the disease to which each strain was associated. The Heat shock protein B was the unique immunoreactive protein common to all of them. Additionally, seven proteins were found to be antigenic in at least 80% of strains: enoyl-(acyl-carrier-protein) reductase (NADH); Catalase; Flagellin A; 2 isoforms of alkyl hydroperoxide reductase; succinyl-CoA transferase subunit B; and an unidentified protein. These proteins were present in the proteome of all tested strains, suggesting that differences in their antigenicity are related to antigenic variance. CONCLUSIONS: This study showed evidence of the variability of antigenic pattern among H. pylori strains. We believe that this fact contributes to the failure of anti-H. pylori vaccines and the low accuracy of serological tests based on a low number of proteins or antigens of only one strain.
- Antioxidant properties of coriander essential oil and linalool and their potential to control Campylobacter spp.Publication . Duarte, A.; Luís, A.; Oleastro, Mónica; Domingues, F.C.Foodborne diseases remain common around the world with Campylobacteriosis being the most commonly reported zoonosis in the European Union in 2013. Campylobacter jejuni and Campylobacter coli are the main species associated with human illness. Furthermore, Campylobacter can develop biofilms which is becoming a major problem within the food industry. In addition to foodborne pathogens, oxidation is a non-microbial cause of deterioration of food causing loss of quality and safety. Thus, there is an urgent need in the food industry for new and effective strategies that can help prevent food contamination, spoilage and consequently, foodborne illnesses. Essential oils are known for their antimicrobial and antioxidant properties and are already widely used in the food industry. So, the aim of this work was to study the antimicrobial and anti-biofilm activity of coriander essential oil and its major compound linalool against C. jejuni and C. coli strains, as well as their effect in the quorum sensing (QS) system and their potential as antioxidants. Our results, demonstrated that both compounds have anti- Campylobacter activity, inhibited in vitro biofilm formation and promoted biofilm dispersion even at sub-MIC concentrations and interfered with the QS system through the inhibition of violacein production. Moreover, the essential oil and linalool were shown to have radical scavenging properties and lipid peroxidation inhibition ability which could make them potential alternatives to synthetic antioxidants. In sum, our results demonstrated the antibacterial, anti-biofilm, anti-QS and antioxidant potentials of the coriander essential oil and its major compound, linalool, suggesting that they could be used in the food industry to enhance shelf life of food products and increase food safety without requiring chemical additives or preservatives.
- Arcobacter butzleri Ciprofloxacin Resistance: Point Mutations in DNA Gyrase A and Role on Fitness CostPublication . Ferreira, Susana; Correia, Daniela R; Oleastro, Mónica; Domingues, Fernanda CArcobacter butzleri is a widely distributed emerging pathogen resistant to various classes of antimicrobial agents, namely fluoroquinolones. A. butzleri resistance to fluoroquinolones is conferred by point mutations at the antibiotic target. The aim of this study was to evaluate mutations at gyrA associated with ciprofloxacin resistance and evaluate whether acquisition of resistance impacts on fitness and stress tolerance of A. butzleri. A. butzleri ciprofloxacin mutants were generated by laboratory induction. Identification of mutations associated with ciprofloxacin resistance was performed by gyrA sequencing. Growth kinetics, cost of fitness, biofilm formation ability, and stress tolerance were assessed. Two amino acid substitutions in the quinolone resistance-determining region of GyrA were identified in the mutant strains, one previously described (Thr-85-Ile) and a new substitution (Asp-89-Tyr). No differences in growth kinetics were recorded between parental and mutant strains; however, fitness cost was variable, according to the genetic background of the strains, and independently of ciprofloxacin resistance. Overall, the ciprofloxacin resistance development did not significantly affect stress tolerance, motility, or biofilm-forming ability. In conclusion, acquisition of ciprofloxacin resistance in A. butzleri is associated with mutations in gyrA and is likely well compensated, with cost of fitness reflecting the diversity in genetic background of this bacterium.