Impact of fish farming on antibiotic resistome and mobile elements in Baltic Sea sediment

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Sammanfattning

Antibiotic resistance has become a serious threat to the efficacy of antibiotics used in human and veterinary medicine. Understanding the abundance and prevalence of antibiotic resistance genes (ARGs) in the environmental resistome is important for maintaining the efficacy of antibiotics and predicting a risk of the ARGs spreading in the environment and moving into previously non-resistant bacteria, including human pathogens. Fish farms are an environmental reservoir of ARGs due to the treatment of fish with antibiotics that also are important for human medicine.

The two main topics of this thesis are (1) determining the abundance and diversity of ARGs and mobile elements in sediments impacted by fish farming and (2) investigating the major source of ARGs in the farm sediments in the Northern Baltic Sea. In addition, correlations between ARGs and mobile elements were examined to estimate the potential risk of ARG mobilization in the environment. This study employed a high-throughput qPCR array, which permits quantifying hundreds of ARGs and genes associated with mobile elements in the environmental resistome in a single experiment.

Fish farming impacts the composition of ARGs in sediments below fish farms in the Northern Baltic Sea. However, the impact is local and mostly limited to enrichment of ARGs associated with antibiotics used at the farms. In the current conditions, the risk of ARG spread from the farm sediments to the surrounding sediments is low in the Northern Baltic Sea. However, the enriched ARGs persist in the farm sediments during the 6-year observations even when the selection pressure of the antibiotics is negligible. Moreover, significant correlations between mobile elements and ARGs may imply the persistence of certain ARGs in the fish farming environments and their potential for mobilizing the ARGs to other bacteria including pathogens. The persistence of ARGs at the farm facilities is a threat to the efficacy of the antibiotics against fish diseases, potentially leading to fish production losses. We provide indirect evidence suggesting that certain ARGs are being constantly introduced by feces of the farmed fish into the sediments below the fish farms. Further studies could focus on investigating the development of ARGs in juvenile fish before they are introduced into the Baltic Sea open-cage farms. We conclude that a high throughput qPCR array is a powerful tool that provides unprecedented insights into the ARG composition in the environmental resistome associated with fish farming.
Originalspråkengelska
Tilldelande institution
  • Helsingfors universitet
Handledare
  • Virta, Marko, Handledare
  • Tamminen, Manu, Handledare, Extern person
Tilldelningsdatum17 juni 2016
UtgivningsortHelsinki
Förlag
Tryckta ISBN978-951-51-2233-9
Elektroniska ISBN978-951-51-2234-6
StatusPublicerad - 17 juni 2016
MoE-publikationstypG5 Doktorsavhandling (artikel)

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