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- Evaluation of antimicrobial susceptibility among Campylobacter jejuniPublication . Camilo, Rute; Mena, Cristina; Silva, Joana; Teixeira, Paula
- Evaluation of antibiotic resistance patterns of food and clinical Listeria monocytogenes isolates in PortugalPublication . Barbosa, Joana; Magalhães, Rui; Santos, Isabel; Ferreira, Vânia; Brandão, Teresa R. S.; Silva, Joana; Almeida, Gonçalo; Teixeira, PaulaThe aim of this study was to characterize a broad collection of isolates of Listeria monocytogenes, of different serotypes, recovered in Portugal between 2003 and 2007 from foods (n = 353) and from clinical cases of human listeriosis (n = 95), in terms of antimicrobial susceptibility. All the isolates were susceptible to ampicillin, the preferred agent to treat listeriosis. Resistances to nitrofurantoin (n = 99), to ciprofloxacin (n = 18), to erythromycin (n = 10), to tetracycline (n = 2), to gentamicin (n = 1) and to rifampicin (n = 1) were observed. One hundred (28.3%) and 20 (21.0%) food and clinical isolates, respectively, were resistant to at least one antibiotic. Eight isolates (1.8%) were resistant to two or more antimicrobials of different classes, and all were collected from foods. Serogroup IVb included the highest percentage of isolates resistant to erythromycin. The highest percentages of isolates resistant to nitrofurantoin were of serogroup IVb and IIc. It was demonstrated that the incidence of antibiotic-resistant isolates of L. monocytogenes, during the period 2003 to 2007, was low in Portugal but still higher than that observed in other countries. Given the increasing population at greater risk of listeriosis, namely, the elderly, the high mortality rate of the infection and the detection of resistant isolates, monitoring for antibiotic resistance in strains of L. monocytogenes on a large scale, and assessing the risk of infection by these strains, is highly recommended.
- Characterisation of alheiras, traditional sausages produced in the North of Portugal, with respect to their microbiological safetyPublication . Ferreira, Vânia; Barbosa, Joana; Silva, Joana; Felício, Maria Teresa; Mena, Cristina; Hogg, Tim; Gibbs, Paul; Teixeira, PaulaThe objective of this study was the characterisation of alheiras, traditional Portuguese sausages, with respect to their microbiological safety. Thirty-eight lots from 17 producers were analysed. The microbiological status of the analysed product can be considered of concern in terms of food safety. Although Campylobacter spp. and Escherichia coli O157 were not detected in any sample,and Clostridium perfringens when present was not at levels of concern with reference to public health, Salmonella spp. were detected in 2 lots of industrially produced alheiras, and more than 60% of the lots analysed were contaminated with Listeria monocytogenes in concentrations higher than 100 cfu/g.
- Characterization of a bacteriocin of pediococcus pentosaceus SB83 and its potential for vaginal applicationPublication . Borges, Sandra; Barbosa, Joana; Silva, Joana; Teixeira, PaulaListeria monocytogenes, the responsible agent for listeriosis, is one of several microorganisms which can be transmitted from mother to fetus/neonate by vertical transmission. The aim of this study was to characterize a bacteriocin produced by Pediococcus pentosaceus SB83 for vaginal application, to prevent colonization of pregnant women with L. monocytogenes. Bacteriocin SB83 showed inhibitory activity against L. monocytogenes (serotypes 1/2a 1/2b and 4b) but did not inhibit vaginal lactic acid bacteria. Additionally, bacteriocin SB83 inhibited the growth of Enterococcus faecalis, Enterococcus faecium and Bacillus subtilis. Bacteriocin SB83 was produced at maximum levels between 24 h and 36 h of growth (6400 AU/mL against serotype 1/2b and 4b, 3200 AU/mL against serotype 1/2a). Significant reduction in antimicrobial activity was observed after treatment of cell-free supernatants with proteinase K, pepsin, papain and trypsin. Bacteriocin SB83 was resistant to treatments with Tween 80, Tween 20, Triton X-100, SDS and EDTA. This bacteriocin was stable at pH values between 4 and 6.5; a decrease in activity was observed at pH 2 and above 8. A decrease in antibacterial activity was recorded at 100 °C and 121 °C. In the range 4 °C to 80 °C, antimicrobial activity was not affected. The activity of bacteriocin did not change in simulated vaginal fluid (pH 4.2, 5.5 and 6.5). The molecular size of bacteriocin SB83 was between 3.5 and 6.5 kDa.In conclusion, the bacteriocin produced by P. pentosaceus SB83 has been proved to be resistant to several conditions, including conditions in the vaginal tract (pH and components of vaginal fluid).
- Assessment of temperament at 13 and 24 months using maternal report: validation of the Portuguese version of infant characteristics questionnairePublication . Carneiro, Alexandra; Dias, Pedro; Magalhães, Carla; Soares, Isabel; Rangel-Henriques, Margarida; Silva, Joana; Marques, Sofia; Baptista, JoanaTemperament is a set of individual traits that has his origins in biology that is demonstrated from earlychildhood, and has some kind of continuity over time. So, and since the assessment of temperament allows us to understand further the child’s functioning, it becomes relevant validate instruments to collect this type of data. The studies presented here are part of a broader research project that aims to understand the development of children aged from 0 to 60 months. More specifically, the two studies generally aim to validate the Infant Characteristics Questionnaire (ICQ1) for 13 and 24 months of age for the Portuguese population, using mothers as informants. The first sample consists in 289 infants aged between 11 and 20months (Study 1) and the second sample comprised 398 children aged between 21 and 32 months (Study2). The two samples were collected in nurseries and day-care area of †northern Portugal, and are convenience samples. In collecting data, in addition to completing the ICQ1, the mother was asked to complete a questionnaire with demographic information about her, child and pregnancy. The specific objectives of this study were to evaluate the psychometric properties of the two versions of this instrument such as construct validity and internal consistency. The results show that factorial solutions achieved were both appropriate for these versions of ICQ1 to 13 months and to 24 months. In addition, levels of internal consistency of the dimensions obtained are generally adequate.
- Study of Biological Hazards Present on the Surfaces of Selected Fruits and VegetablesPublication . Noronha, Lúcia; Castro, Ana; Ferreira, Vânia; Magalhães, Rui; Almeida, Gonçalo; Mena, Cristina; Silva, Joana; Teixeira, PaulaThis study evaluated the microbial load on the surface of fruits with rough and very pronounced textured peels, namely pineapples and melons (cantaloupe), and investigated the presence of foodborne pathogens in these products since they are usually eaten raw. Similarly, lettuce is one of the most common salad vegetables consumed raw in Portugal, it therefore being important to study the microbial status of lettuce leaves. Enumerations of aerobic mesophilic counts, Enterobacteriaceae, Escherichia coli and coagulase-positive staphylococci, as well as detection of Listeria monocytogenes and Salmonella spp., were performed for all samples. Only in melon samples were E. coli and coagulase-positive staphylococci not detected. Contamination with L. monocytogenes varied from 2.5% and 15% in pineapple/melon and lettuce samples, respectively. Salmonella spp. were not detected. All coagulase-positive staphylococci had similar characteristics and none exhibited multidrug resistance. L. monocytogenes isolates belonged to serogroups II (1/2c or 3c), or to serogroup IV (4b, 4d and 4e). None were found to be resistant to antibiotics commonly used in therapy of listeriosis.
- Protein extraction and comparison of stain protocols for analysis of two-dimensional electrophoresis gelsPublication . Silva, Joana; Carvalho, Ana Sofia; Votorino, Rui; Domingues, Pedro; Teixeira, Paula; Gibbs, paulProtein extraction and the proteome of Lactobacillus delbrueckii subsp. bulgaricus were studied using different stains. The reversible silver staining technique was shown to be more sensitive than the irreversible silver stain. Coomassie colloidal was demonstrated to be as sensitive as reversible silver stain; however, the Coomassie colloidal blue solution developed a higher background and for sample preparation was more time-consuming.
- Effect of various protecting compounds added to the growth medium upon survival of lactobacillus sakei to heating, freezing, freeze-drying and storage in the dried statePublication . Ferreira, Vânia; Soares, Vânia; Santos, Cristina; Silva, Joana; Gibbs, Paul A.; Teixeira, PaulaThe aim of the present study was to investigate if the presence of sorbitol, myoinositol, xylose, mannose and Tween 80 in the growth medium increased the survival of L. sakei during heating, freezing, freeze drying and storage of freeze dried cells. Survival during freezing was enhanced by ca. 8% when glycerol was present in the growth medium. Viability during freeze-drying and storage in the dried state was improved by the presence of xylose in the growth medium. In addition to xylose, the presence of mannose and myoinositol protected cells during storage but not during drying. Cells grown in the presence myoinositol presented the highest D value at 55?C, 1.4 folder higher than control cells. In comparison with cells grown in MRS, total amino acids concentrations were the same order of magnitude for cells grown in the presence of mannose and myoinositol but were lower for cells grown in the presence of the other compounds.
- Study of Biological Hazards Present on the Surfaces of Selected Fruits and VegetablesPublication . Noronha, Lúcia; Magalhães, Rui; Silva, Joana; Teixeira, Paula
- Food safety and quality profile of Alheira de Vitela, Chouriço de Carne and Salpicão Serra D’Arga: traditional Portuguese sausages produced in the North of PortugalPublication . Noronha, Lúcia; Almeida, Ana Luísa; Freixo, Ricardo; Jácome, Samuel; Fonseca, Susana; Vaz-Velho, Manuela; Almeida, Gonçalo; Silva, Cristina L. M.; Morais, Alcina M. M. B.; Silva, Joana; Teixeira, Paula