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Publication
Intrinsic antibiotic resistance in cyanobacteria: the case of trimethoprim
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Abstract(s)
Antibiotic residues poses an increasing concern both at environmental and public health levels. Besides affecting the structure/functioning/diversity of aquatic communities, antibiotic pollution is responsible for one of the most serious threat to the global health: the emergence/dissemination of antibiotic resistance. Cyanobacteria have been recommended as test organisms in the assessment of environmental contaminants such as antibiotics [1]. However, the species sensitivity should be carefully characterized, since cyanobacteria may present intrinsic resistance to some antibiotics, which can seriously compromise the risk assessment results. We have been studied the putative role of cyanobacteria in aquatic resistome and our studies have demonstrated that strains of Microcystis and Planktothrix genus are not susceptible to some antibiotics, namely trimethoprim (up to 1.6 mg/L) [2,3]. In order to understand the cause of the reduced susceptibility of cyanobacteria to several antibiotics, we performed and analyzed the whole genome sequencing of cyanobacteria strains that exhibits a non-susceptible phenotype. Preliminary results revealed that a M. aeruginosa strain possesses the gene that codifies thymidylate synthase (thyX), an alternative enzyme to dihydrofolate redutase (FolA) in the folate metabolism, which is essential for bacteria replication and survival. As the mechanism of action of trimethoprim in bacteria is the inhibition of FolA, our results strongly suggests that the presence of an alternative pathway to FolA may underlie the intrinsic resistance to trimethoprim in cyanobacteria. The identification of intrinsic antibiotic resistance in cyanobacteria is an important tool for identifying which species should not be included as indicator organisms in environmental risk assessment purposes.
References:
[1] Le Page G, Gunnarsson L, Snape J, Tyler CR (2017) Integrating human and environmental health in antibiotic risk assessment: A critical analysis of protection goals, species sensitivity and antimicrobial resistance. Environm. Int. 109:155–169.
[2] Dias E, Oliveira M, Jones-Dias D, Vasconcelos V, Ferreira E, Manageiro V, Caniça M (2015) Assessing the antibiotic susceptibility of freshwater cyanobacteria spp. Front. Microbiol. 6:799.
[3] Dias E, Oliveira M, Manageiro V, Vasconcelos V, Caniça M (2019) Deciphering the role of cyanobacteria in water resistome: Hypothesis justifying the antibiotic resistance (phenotype and genotype) in Planktothrix genus. Sci. Total Environm. 20: 447-454.
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Keywords
Cyanobacteria Intrinsic Antibiotic Resistance Trimethoprim Risk Assessment Resistência aos Antimicrobianos Agentes Microbianos e Ambiente Água e Solo Avaliação do Risco
Pedagogical Context
Citation
Dias E., Manageiro V., Caniça M. Intrinsic antibiotic resistance in cyanobacteria – the case of trimethoprim. 11th International conference on toxic cyanobacteria. Cracóvia, Polónia, 5-10 Maio 2019.