Tania Ribeiro - Academia.edu (original) (raw)

Papers by Tania Ribeiro

International Journal of Food Microbiology, 2007

A total of 109 enterococcal isolates from dairy food products and from human and dog infections, ... more A total of 109 enterococcal isolates from dairy food products and from human and dog infections, isolated in Portugal, and 26 type and reference strains of the genus Enterococcus were screened for vancomycin resistance. MIC values, both for vancomycin and teicoplanin, were determined. The genetic relatedness of isolates carrying either vanA and/or vanB was determined using Pulsed Field Gel Electrophoresis. For vanA carrying isolates, transposon Tn1546 was partially mapped using PCR. None of the 59 dairy isolates was resistant to vancomycin. Among the 50 clinical isolates, only one, carrying vanB, behaved as resistant, with a MIC value of 256 μg/mL. The type and reference strains used were susceptible both to vancomycin and teicoplanin. vanA was found in 37% of the dairy isolates and 40% of the clinical isolates. vanB was only detected in 18% of the clinical, both human and dog, isolates. PCR partial mapping of Tn1546 revealed 23 different patterns among 42 isolates. Some patterns were shared between dairy and clinical isolates. Using Pulsed Field Gel Electrophoresis six groups of isolates were found to be genetically undistinguishable and grouping was found to be geographically and location specific/related. No genetic relatedness was found between isolates from dairy, human and veterinary sources. These results show that an incomplete and/or unfunctional Tn1546 element may explain the absence of resistant behaviour in the studied isolates, even when vanA gene is present. Moreover, the work reported shows that both clinical (human and animal) and dairy isolates have been in contact with VanA genotype of resistance and suggest that dissemination of vanA gene has been through transposable elements, like Tn1546, and not by clonal dissemination of a resistant strain. Therefore, a national strategy should be implemented to survey both vancomycin resistance and its genetic dissemination.

International Journal of Antimicrobial Agents, 2011

Subinhibitory concentrations of vancomycin are known to induce a cell-wall stimulon in some Gramp... more Subinhibitory concentrations of vancomycin are known to induce a cell-wall stimulon in some Grampositive pathogens, but this has never been studied in the genus Enterococcus. In this study, Enterococcus faecalis V583 strain was submitted to a subinhibitory concentration of vancomycin. DNA microarray technology was used to analyse the transcriptomic changes induced by this antibiotic. EF2292, annotated as a hypothetical protein in the E. faecalis V583 genome, was highly induced in response to vancomycin exposure, to similar levels as the vanB operon genes. We investigated further and provide evidence for co-transcription of ef2292 with vanY B WH B BX B genes. It was also demonstrated that expression of ef2292 is under the control of vanR B S B and it is proposed to name it vanV. This gene was found not to be required for vancomycin resistance under the conditions tested, thus coding for another accessory protein in the vanB operon. vanV was detected in some, but not all, E. faecalis carrying the vanB operon, suggesting that this operon can have different composition amongst E. faecalis isolates.

International Journal of Food Microbiology, 2005

The susceptibility to 30 antimicrobial agents was determined by the disk diffusion method for a c... more The susceptibility to 30 antimicrobial agents was determined by the disk diffusion method for a collection of 172 enterococcal strains, including 96 isolates from dairy sources, 50 isolates of human and veterinary origin, and 26 reference strains from 24 different enterococcal species. Results were analysed by hierarchic numerical methods to cluster strains and to group antimicrobials according to similarity profiles. Resistance to 17 of the 30 antimicrobials showed to be correlated, leading to four groups reflecting the mode of action: quinolones (ofloxacin, enrofloxacin, ciprofloxacin and norfloxacin); macrolides (erythromycin, spiramycin), phenicols (cloramphenicol) and tetracyclins (tetracycline, oxytetracyclin); aminoglycosides (gentamicin, kanamycin) and lincosamides (clindamycin); penicillins (amoxicillin, ampicillin, penicillin G, piperacillin) and carbapenems (imipenem). Overall, the genus Enterococcus behaved as resistant to lincomycin, colistin, polimixin B and, with a few exceptions in dairy isolates, to methicillin. In general, all isolates were susceptible to vancomycin, cloramphenicol and fusidic acid. Clusters containing only dairy isolates were susceptible to the majority of antimicrobials tested, as opposed to clusters constituted only by clinical enterococcal isolates. Among the clinical isolates, 62% were highly multiresistant. Low level gentamicin resistance was found to be associated with clinical enterococci. Among dairy isolates, those that clustered with clinical isolates were both resistant to gentamicin and identified as Enterococcus faecalis. Resistance to macrolides, quinolones, penicillins and imipenem was found to be associated also with clinical environments, mainly with multiresistant isolates, contrary to what is generally agreed as a characteristic of the genus. Veterinary clinical isolates were mainly grouped with the multiresistant clinical human isolates. The 26 reference 0168-1605/$ -see front matter D enterococcal strains were distributed in clusters with different antibiotic resistance profiles and were mainly clustered with dairy isolates. D

Enterococci isolated from Portuguese dairy products (milk and cheese) and clinical settings (hosp... more Enterococci isolated from Portuguese dairy products (milk and cheese) and clinical settings (hospitals and veterinary clinics), together with reference strains from the genus Enterococcus, were screened for low-and high-level gentamicin resistance using the standard disc diffusion method (10 and 120 µg gentamicin discs).

Empresas como Nestlé, Bauducco, Vivo, Claro, Trident e Estrela reforçam investimento nas regiões ... more Empresas como Nestlé, Bauducco, Vivo, Claro, Trident e Estrela reforçam investimento nas regiões e customizam produtos e ofertas para consumidores locais.

International Journal of Food Microbiology, 2007

A total of 109 enterococcal isolates from dairy food products and from human and dog infections, ... more A total of 109 enterococcal isolates from dairy food products and from human and dog infections, isolated in Portugal, and 26 type and reference strains of the genus Enterococcus were screened for vancomycin resistance. MIC values, both for vancomycin and teicoplanin, were determined. The genetic relatedness of isolates carrying either vanA and/or vanB was determined using Pulsed Field Gel Electrophoresis. For vanA carrying isolates, transposon Tn1546 was partially mapped using PCR. None of the 59 dairy isolates was resistant to vancomycin. Among the 50 clinical isolates, only one, carrying vanB, behaved as resistant, with a MIC value of 256 μg/mL. The type and reference strains used were susceptible both to vancomycin and teicoplanin. vanA was found in 37% of the dairy isolates and 40% of the clinical isolates. vanB was only detected in 18% of the clinical, both human and dog, isolates. PCR partial mapping of Tn1546 revealed 23 different patterns among 42 isolates. Some patterns were shared between dairy and clinical isolates. Using Pulsed Field Gel Electrophoresis six groups of isolates were found to be genetically undistinguishable and grouping was found to be geographically and location specific/related. No genetic relatedness was found between isolates from dairy, human and veterinary sources. These results show that an incomplete and/or unfunctional Tn1546 element may explain the absence of resistant behaviour in the studied isolates, even when vanA gene is present. Moreover, the work reported shows that both clinical (human and animal) and dairy isolates have been in contact with VanA genotype of resistance and suggest that dissemination of vanA gene has been through transposable elements, like Tn1546, and not by clonal dissemination of a resistant strain. Therefore, a national strategy should be implemented to survey both vancomycin resistance and its genetic dissemination.

International Journal of Antimicrobial Agents, 2011

Subinhibitory concentrations of vancomycin are known to induce a cell-wall stimulon in some Gramp... more Subinhibitory concentrations of vancomycin are known to induce a cell-wall stimulon in some Grampositive pathogens, but this has never been studied in the genus Enterococcus. In this study, Enterococcus faecalis V583 strain was submitted to a subinhibitory concentration of vancomycin. DNA microarray technology was used to analyse the transcriptomic changes induced by this antibiotic. EF2292, annotated as a hypothetical protein in the E. faecalis V583 genome, was highly induced in response to vancomycin exposure, to similar levels as the vanB operon genes. We investigated further and provide evidence for co-transcription of ef2292 with vanY B WH B BX B genes. It was also demonstrated that expression of ef2292 is under the control of vanR B S B and it is proposed to name it vanV. This gene was found not to be required for vancomycin resistance under the conditions tested, thus coding for another accessory protein in the vanB operon. vanV was detected in some, but not all, E. faecalis carrying the vanB operon, suggesting that this operon can have different composition amongst E. faecalis isolates.

International Journal of Food Microbiology, 2005

The susceptibility to 30 antimicrobial agents was determined by the disk diffusion method for a c... more The susceptibility to 30 antimicrobial agents was determined by the disk diffusion method for a collection of 172 enterococcal strains, including 96 isolates from dairy sources, 50 isolates of human and veterinary origin, and 26 reference strains from 24 different enterococcal species. Results were analysed by hierarchic numerical methods to cluster strains and to group antimicrobials according to similarity profiles. Resistance to 17 of the 30 antimicrobials showed to be correlated, leading to four groups reflecting the mode of action: quinolones (ofloxacin, enrofloxacin, ciprofloxacin and norfloxacin); macrolides (erythromycin, spiramycin), phenicols (cloramphenicol) and tetracyclins (tetracycline, oxytetracyclin); aminoglycosides (gentamicin, kanamycin) and lincosamides (clindamycin); penicillins (amoxicillin, ampicillin, penicillin G, piperacillin) and carbapenems (imipenem). Overall, the genus Enterococcus behaved as resistant to lincomycin, colistin, polimixin B and, with a few exceptions in dairy isolates, to methicillin. In general, all isolates were susceptible to vancomycin, cloramphenicol and fusidic acid. Clusters containing only dairy isolates were susceptible to the majority of antimicrobials tested, as opposed to clusters constituted only by clinical enterococcal isolates. Among the clinical isolates, 62% were highly multiresistant. Low level gentamicin resistance was found to be associated with clinical enterococci. Among dairy isolates, those that clustered with clinical isolates were both resistant to gentamicin and identified as Enterococcus faecalis. Resistance to macrolides, quinolones, penicillins and imipenem was found to be associated also with clinical environments, mainly with multiresistant isolates, contrary to what is generally agreed as a characteristic of the genus. Veterinary clinical isolates were mainly grouped with the multiresistant clinical human isolates. The 26 reference 0168-1605/$ -see front matter D enterococcal strains were distributed in clusters with different antibiotic resistance profiles and were mainly clustered with dairy isolates. D

Enterococci isolated from Portuguese dairy products (milk and cheese) and clinical settings (hosp... more Enterococci isolated from Portuguese dairy products (milk and cheese) and clinical settings (hospitals and veterinary clinics), together with reference strains from the genus Enterococcus, were screened for low-and high-level gentamicin resistance using the standard disc diffusion method (10 and 120 µg gentamicin discs).

Empresas como Nestlé, Bauducco, Vivo, Claro, Trident e Estrela reforçam investimento nas regiões ... more Empresas como Nestlé, Bauducco, Vivo, Claro, Trident e Estrela reforçam investimento nas regiões e customizam produtos e ofertas para consumidores locais.