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Advisor(s)
Abstract(s)
Freshwater bivalves are widely used as accumulation indicators and monitoring tools for
assessing contaminant effects on different levels of biological integration. This pilot study aimed to
explore the phylogenetic diversity of Escherichia coli isolated from freshwater mussels (Margaritifera
margaritifera and Potomida littoralis) and characterize their phenotypes and antibiotic resistance profiles.
Samples were collected in the Rabaçal and Tua Rivers, in the Douro basin, Portugal—two sites
representing different levels of anthropogenic contamination. Antimicrobial susceptibility testing
was performed via the disk diffusion method with 21 antibiotics. Results showed that 31% of isolates
were multidrug-resistant (MDR). Thus, freshwater mussels provide an effective and time-integrated
approach for identifying/quantifying fecal indicators, including MDR bacteria. PCR-based assays
were designed for assessing phylogenetic E. coli groups. Among the E. coli isolates, the highest
prevalence (44%) was observed in group D or E, followed by group E or Clade I (25%), group A (19%),
and group B1 (13%). E. coli isolated from M. margaritifera predominantly exhibited a higher prevalence
of phylogroups D or E, whereas E. coli from P. littoralis showed associations with phylogroups E
or clade I, B1, A, and D or E. Our results provide new insights into the phylogenetic diversity of E.
coli in freshwater bivalves. Additionally, the findings highlight the possible linkage of phylogroups
with the host species, the geographical location in the water stream, and human activity. Using E.
coli as a bioindicator isolated from freshwater mussels helps us grasp how human activities affect
the environment. This study has important implications for those interested in safeguarding water
resources, especially in tackling antibiotic resistance in aquatic ecosystems.
Description
Keywords
Escherichia coli One Health-EcoHealth Antimicrobial resistance Potomida littoralis Margaritifera margaritífera Ecological integrity
Pedagogical Context
Citation
Varandas, Simone; Fernandes, Conceição; Cabecinha, Edna; Gomes, Sónia; Silva, Gabriela Jorge da; Saavedra, Maria José (2023). Escherichia coli phylogenetic and antimicrobial pattern as an indicator of anthropogenic impact on threatened freshwater mussels. ISSN 2079-6382. Antibiotics. 12:9, p. 1-10
Publisher
MDPI