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  • ItemAcesso Restrito
    Diversity of serine-ß-lactamase genes among Aeromonas isolates from pigs slaughtered for consumption
    2010 - Fontes, M. C.; Martínez-Murcia, A.; Martins, C.; Saavedra, M. J.
    Introduction: Antimicrobial resistance in foodborne pathogens has become a public health issue. The intense and indiscriminate use of antibiotics is undoubtedly the major force associated with the high bacteria resistance worldwide. Some Aeromonas species cause both gastrointestinal and extraintestinal infectious diseases in humans. Many studies suggest members of Aeromonas developed multiple antibiotic resistances which constitutes a limitation to the treatment of infections associated to these bacteria. Rationale: The aim of this work was to evaluate the susceptibility patterns of the isolates obtained from pigs slaughtered for consumption and to assess the occurrence and diversity of ß-lactamase genes. Results: A total of 106 Aeromonas strains were isolated from 50 (73%) of the 69 samples of pig carcasses and diaphragm muscle analysed. The strains, identified by gyrB gene sequencing, belong to eight different species (A. hydrophila, A. bestiarum, A. salmonicida, A.caviae, A. media, A. veronii, A. allosaccharophila and A. aquariorum) and were tested against 8 families of antibiotics (27 antimicrobial agents). The β-Lactamases encoding genes blaTEM, blaSHV, blaCTX-M, blaOXA, blaFOX and blaMOX were detected by PCR. The susceptibilities profiles revealed a high level of resistance to several groups of antibiotics. The genes blaOXA-B (1) and blaOXA-C (1) were detected in strains of A. hydrophila and the gene blaCTX-M (1) was presented in A. media. In A. aquariorum and in one A. caviae the gene blaMOX was presented. The genes blaFOX and blaOXA-aer were detected in 71% and 49% respectively of the strains tested. There was no evidence for the presence of blaTEM and blaSHV genes. Conclusion: In the present work we verified multiresistance mainly to the cephalotin (ß-lactam) and erythromycin (macrolide) in different Aeromonas strains. In several strains, the presence of more than one β-Lactamase gene, from different classes, was detected. The genes blaFOX and blaOXA-aer showed a high dispersal in some species of the Aeromonas genus.
  • ItemAcesso Restrito
    Detection of Metallo-ß-lactamases in Aeromonas isolated from alheira: a tradicional portuguese meat product
    2010 - Fontes, M. C.; Martínez-Murcia, A.; Martins, C.; Saavedra, M. J.
    Introduction: Members of the genus Aeromonas are facultative anaerobic gram-negative rods, oxidase-positive that are widely distributed in aquatic environments and have also been isolated from different kinds of food. Gastroenteritis is considered the most common Aeromonas clinical presentation. Susceptibility patterns of these species revealed an increase in resistance to ß-lactam antibiotics, which is attributed to the presence of ß-lactamases. Zinc-dependent class B metallo-ß-lactamases (MBLs), chromosomally mediated and those encoded by transferable genes, are of special importance because display an extremely wide spectrum of hydrolysis that includes also carbapenems. Rationale: The aim of this study was to determine the susceptibility patterns, to ß-lactam antibiotics, of Aeromonas strains isolated from alheira, a traditional Portuguese meat sausage and the occurrence of CphA, a chromosomally mediated MBL, and VIM, an acquired MBL. Results: Thirty-two samples purchased in different local markets were analysed. A total of 84 presumptive Aeromonas spp. were obtained and subjected to genotyping ERIC-PCR analysis. The 20 strains showing differences in the ERIC-pattern were identified by gyrB gene sequencing and tested against 15 ß-lactam antibiotics. Metallo-beta-lactamases encoding genes were detected by PCR and positive results were confirmed by sequencing. All the strains studied belonged to the species A. hydrophila (5), A. caviae (6), A. media (6), A. salmonicida (2) and A. allosaccharophila (1). Tested antibiotic susceptibilities in these strains indicated a noticeable level of multiresistance. blaCphA gene was detected in 8 strains (40%). There was no evidence for the presence of blaVIM genes in any isolate. Conclusion: In this study a high percentage of resistance to cephalotin and ticarcillin and low percentage to other ß-lactam antibiotics have been detected in Aeromonas spp. from alheira. Despite blaCphA gene was detected in all strains of the species A. hydrophila, A. salmonicida and A. allosaccharophila, only one strain of A. salmonicida showed resistence to imipenem.
  • ItemAcesso Aberto
    Ovulation parameters in nulliparous and multiparous Serrana goats
    2007 - Simões, João; Azevedo, Jorge Manuel Teixeira de; Almeida, José Carlos; Fontes, Paulo J.; Mascarenhas, Ramiro
    The aim of this study was to characterize the ovulation parameters in nulliparous (n=24) and multiparous (n=14) Serrana goats during the breeding season. Oestrus was synchronised with two cloprostenol injections (50 µg, 10 days apart). Transrectal ovarian ultrasonographic scanning was performed daily, during 2 consecutive oestrous cycles. Day of ovulation was considered when large follicles disappeared and the number of ovulations was confirmed by posterior corpora lutea counting. The mean ovulation rate was 1.47 ± 0.06 (n=91); no differences were observed between induced and natural oestrus. However, ovulation rate was lower in nulliparous goats than in multiparous goats, either after induced oestrus (1.25 ± 0.09, n=24 versus 2.00 ± 0.18, n=14, P<0.001) or natural oestrus (1.19 ± 0.07, n=32 versus 1.81 ± 0.09, n=21, P<0.001). 44.8% (64/134) of total ovulations were observed in left ovary and 55.2% (70/134) in the right ovary (P>0.05). Single ovulations were observed in 78.6% (44/56) of the oestrous cycles in nulliparous goats and in 20% (7/35) of the oestrous cycles in multiparous goats (P<0.01). Double ovulations occurred in both ovaries (73%; 27/37), only in the right ovary (24.3%; 9/37) or in the left ovary (2.7%; 1/37). Ovulations observed in two consecutive oestrous cycles were both single in 36.5% (19/52) of the cycles, alternatively single and multiple in 34.6% (18/52) and both multiple in 28.9% (15/52). The correlation coefficient between the number of ovulations in two consecutive oestrus was very low (r=0.31, P<0.05, n=52). In conclusion, nulliparous goats have lower ovulation rates, due mainly to a higher number of single ovulations, when compared with multiparous goats.