Utilize este identificador para referenciar este registo: http://hdl.handle.net/10400.18/3740
Título: Minimum inhibitory concentrations and antibiotic resistant genes in the freshwater cyanobacteria Planktothirx agardhii
Autor: Dias, Elsa
Oliveira, Micaela
Dias-Jones, Daniela
Manageiro, Vera
Churro, Catarina
Vasconcelos, Vitor
Ferreira, Eugénia
Caniça, Manuela
Palavras-chave: Cyanobacteria
Resistência aos Antimicrobianos
Água e Solo
Data: 2015
Resumo: Planktothrix agardhii is one of the most common cyanobacteria species in Portuguese freshwater reservoirs, often exhibiting long residence time in those reservoirs. This work aimed to evaluate the antibiotic susceptibility patterns and resistance genes in P. agardhii in order to assess their putative contribution to the global pool of resistance determinants in freshwater. We investigated 9 strains of P. agardhii, previously isolated from different freshwater reservoirs. Antibiotic susceptibility was evaluated by a microdilution method previously adapted for cyanobacteria against β-lactams, aminoglycosides, quinolones, trimethoprim and tetracycline. Minimum inhibitory concentrations (MIC) were determined according to cyanobacterial cell dentisty (DO 450nm) and microscopic examination of cultures integrity. All strains were subjected to the search and identification of antibiotic resistance genes and class 1, 2 and 3 integrons by PCR and sequencing. Preliminary results showed that P. agardhii is not susceptible to trimethoprim and nalidixic acid within the tested concentration range (0.0015-1.6 mg/L). Moreover, the cell growth was strongly inhibited by amoxicillin for the majority of the strains (0.003 mg/L≤MIC≤0.1). The other β-lactams, kanamycine, gentamicine, tetracycline and norfloxacine presented MICs above 0.1 mg/L. Strain LMECYA 260 harboured the sul1 gene, and a 3-type integron was also detected in LMECYA 260 and 257. These strains were isolated from the same freshwater reservoir, which has a persistent bloom of Planktothrix spp. for several years. This study suggests that the presence of a common antibiotic resistant determinant in P. agardhii might be a result from a selective pressure within this reservoir. The presence of antibiotic resistance genes and integrons, as well as the reduced susceptibility to antibiotics detected in these strains, suggest that specific cyanobacteria may play a role on freshwater resistome and eventually contribute to the dissemination of antibiotic resistance in freshwater environments.
Peer review: yes
URI: http://hdl.handle.net/10400.18/3740
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