Browsing by Author "Vasconcelos, Vítor"
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- Descrição de um surto de intoxicação por cianobactérias (algas verdes-azuis) em bovinos no AlentejoPublication . Menezes, Carina; Nova, Rita; Vale, Micaela; Azevedo, Joana; Vasconcelos, Vítor; Pinto, CarlosSuspeita de hepatoxicidade provocada por cianotoxinas, num surto de morte súbita em 25 bovinos numa exploração com 54 vacas de carne em Almodôvar, Alentejo.
- Description of an outbreak of cattle intoxication by cyanobacteria (blue-green algae) in the South of PortugalPublication . Menezes, Carina; Nova, Rita; Vale, Micaela; Azevedo, Joana; Vasconcelos, Vítor; Pinto, CarlosIn 2017, 25 cows from a beef herd consisting of 54 healthy animals, with ages between 1.5 to 4 years old, from Aberdeen Angus breed x Charolais were found dead in Almodôvar, Alentejo, in the South of Portugal. They were grazing on a field of stubble for about 3 weeks when they broke the electric fence that bordered the field and had access to stagnant water from a small stream (Ribeira de Oeiras) that run across the herd. All the animals were seen healthy, by the keeper, until 12 a.m. of Sunday August 27th. When they were last observed before the occurrence, they were resting at the shade of trees and bushes surrounding the Oeiras stream. At this time of the year, this is a normal behaviour due to the high temperatures, and it is common for them to engage in grazing activities in the evening, when the temperature begins to decrease. On the next day (the 28th August), at 7 a.m., the keeper encountered 20 cadavers scattered throughout the land and 5 sick cows. The other 29 animals of the group did not show any clinical signs during the following weeks after the occurrence. In the same period, was reported the death of a heron in the Oeiras stream.
- First description of an outbreak of cattle intoxication by cyanobacteria (blue-green algae) in the South of PortugalPublication . Menezes, Carina; Nova, Rita; Vale, Micaela; Azevedo, Joana; Vasconcelos, Vítor; Pinto, CarlosA herd of 53 Angus x Charolais crossbred cows and 1 herd bull grazing a stubble field broke through an electric fence, and gained access to stagnant water from a small river (Ribeira de Oeiras). In less than 19 hours, 20 cows died and 5 were sick with clinical signs of ataxia, recumbence, abdominal distension, opisthotonus, paddling and masticatory movements, frothing at the mouth, and bloody diarrhea. The 5 sick cows later died, and the remaining 29 animals remained healthy. Clinical and pathological findings revealed the presence of hepatic and renal necrosis. In the water samples, several cyanobacterial species were identified, predominantly belonging to the toxic genera Microcystis. Altogether, these observations led to a tentative diagnosis of acute hepatoxicity caused by cyanotoxins. The diagnosis was confirmed by detection of microcystin-LR in the kidney from 1 animal. To our knowledge, this is the first report of microcystin-LR animal poisoning in Portugal.
- Intoxicação por cianobactérias em bovinos: caracterização de um surtoPublication . Menezes, Carina; Nova, Rita; Azevedo, Joana; Vasconcelos, Vítor; Pinto, CarlosSuspeita de hepatoxicidade provocada por cianotoxinas, num surto de morte súbita em 25 bovinos numa exploração com 54 vacas de carne em Almodôvar, Alentejo.
- Minimum inhibitory concentrations and antibiotic resistant genes in the freshwater cyanobacteria Planktothirx agardhiiPublication . Dias, Elsa; Oliveira, Micaela; Jones-Dias, Daniela; Manageiro, Vera; Churro, Catarina; Vasconcelos, Vítor; Ferreira, Eugénia; Caniça, ManuelaObjectives: Cyanobacteria are ubiquitous prokaryotes in aquatic ecosystems and although they can be exposed to antibiotics and antibiotic resistant bacteria, their role on water resistome was never investigated. Planktothrix agardhii is one of the most common cyanobacteria species in Portuguese freshwater reservoirs, often exhibition long residence time in those reservoirs. This work aimed to evaluate the antibiotic susceptibility patterns and resistance mechanisms in P. agardhii in order to assess their putative contribution to the global pool of resistance determinants in freshwater. Methods: We investigated 8 strains of P. agardhii, previously isolated from different freshwater reservoirs. The antibiotic susceptibility was evaluated by a microdilution method previously adapted for cyanobacteria, against beta-lactams, aminoglycosides, quinolones, trimethoprim and tetracycline. Minimum inhibitory concentrations (MIC) were determined according to cell density (DO, 450nm) and microscopic examination of cultures integrity. All strains were searched for antibiotic resistance genes and class 1, 2 and 3 integrons by PCR/sequencing. Results: The results showed that P. agardhii is not susceptible to trimethoprim and quinolones within the tested concentrations (0.0015-1.6 mg/L). However, the cell growth is strongly inhibited by amoxicillin (median MIC value of 0.1mg/L). The other antibiotics presented the following median MICs: ceftazidime, 1.6 mg/L; ceftriaxone, 0.8 mg/L; tetracycline, 0.4 mg/L; kanamycine, 0.2 mg/L and gentamicine, 0.1mg/L. None of the P. agardhii strains exhibited genes associated with trimethoprim and quinolones resistance, which suggests that these cyanobacteria are intrinsically non susceptible to this antibiotics. Conversely, genes associated with streptomycin (strAstrB) and sulfonamide (sul1) resistance, as well as a 1-type integron, were detected in three of the strains. These strains were isolated from the freshwater reservoirs where Planktothrix blooms are frequent and. This suggests that the presence of a common antibiotic resistant determinant in P. agardhii might be a result from a similar selective pressure within those reservoirs. Conclusions: The presence of antibiotic resistance genes and integrons, as well as the reduced susceptibility to antibiotics, suggest that cyanobacteria may play a role on freshwater resistome and eventually contribute to the dissemination of antibiotic resistance in freshwater environments.
- Reduced antibiotic susceptibility in wastewater Planktothrix sp.: evaluation of minimum inhibitory concentrations by a method designed for cyanobacteria – molecular identification of resistance genesPublication . Dias, Elsa; Oliveira, Micaela; Jones-Dias, Daniela; Manageiro, Vera; Churro, Catarina; Vasconcelos, Vítor; Ferreira, Eugénia; Caniça, ManuelaBackground: Cyanobacteria are ubiquitous in aquatic ecosystems, being Planktothrix spp. one of the most common bloom-forming species in freshwaters worldwide. In these environments, cyanobacteria are exposed to antibiotics and antibiotic resistant bacteria, but their role on water resistome was never investigated. One limitation of testing antibiotic resistance in cyanobacteria is the lack of standardized methods and interpretative guidelines. Based on the standard broth microdilution method, we developed a procedure for testing antibiotic susceptibility in cyanobacteria. This work aimed to test the applicability of that method in Planktothrix mougeotti from a wastewater treatment plant, in order to assess their susceptibility patterns and their putative contribution to the global pool of resistance determinants in freshwater. Material/methods: We investigated 8 strains of Planktothrix mougeotti isolated from a wastewater treatment plant (WWTP) located in the north of Portugal (41º07’05.22’’N, 8º34’015.40’’W) and dimensioned for a population of 80,000 habitants. Antibiotic susceptibility was evaluated by a microdilution method previously adapted for cyanobacteria, against beta-lactams, aminoglycosides, quinolones, trimethoprim and tetracycline. Minimum inhibitory concentrations (MIC) were determined according to cyanobacterial cell dentisty (optical density, 450nm) and microscopic examination of cultures integrity. All strains were subjected to the search of antibiotic resistance genes and class 1, 2 and 3 integrons by PCR/sequencing. Results: The MIC values of P. mougeotti strains varied between 0.2-0.8 mg/L for ceftazidime, ceftriaxone, kanamycine and gentamicine. On the other hand, all of the tested strains were not susceptible to trimethoprim, quinolones (norfloxacin and nalidixic acid), tetracycline and amoxicillin, within the tested concentration range (0.0015-1.6 mg/L). None of the strains exhibited any gene conferring resistance to these antibiotics. On the contrary, a pair of strA-strB-type genes, a sul1-type gene and a class 1-type integron (int1) were detected in four, five and three strains, respectively. Conclusions: The results suggests that the presence of antibiotic resistance genes and integrons in Planktothrix mougeotti, as well as their reduced susceptibility to some antibiotics, might be a result of their exposure to antibiotics and antibiotic resistance genes in the WWTP. This reinforces the hypothesis that cyanobacteria may play a role on freshwater resistome and point out the need to implement standard methodologies and guidelines for susceptibility testing in cyanobacteria.