Antimicrobial resistance survey in a river receiving effluents from freshwater fish farms

Abstract

Aims: The aims of this study were: (i) to determine the proportions of Aeromonas spp. resistant to florfenicol (FC), oxolinic acid (OA) and oxytetracycline (OTC) along a river receiving effluents from fish farms, and (ii) to assess the relevance of using this bacterial group as an indicator for studying the consequences of the use and release of these aquacultural antimicrobials in the freshwater environment, as compared with performing antimicrobial measurements in sediments. Methods and results: Sediment interstitial waters sampled along a river during two distinct climatic seasons were plated on an Aeromonas‐selective medium supplemented or not with OA, OTC or FC. The October 2004 campaign showed an enrichment of OA‐ and OTC‐resistant Aeromonas immediately downstream of the fish farms and a wastewater treatment plant. Two fish farms showed similar results in March 2005. In contrast, only 10 FC‐resistant Aeromonas strains could be isolated, which revealed that minimum inhibitory concentrations of FC were greater than 64 μg ml−1 and multiple antimicrobial resistances. Contamination of sediments by antimicrobials was detected but was not always co‐localized with resistance peaks or known point sources of contamination. Conclusions: Aeromonas could be valuable indicators of OA, OTC and FC resistance in the freshwater environment. Fish farms contribute to the contamination of the river by antimicrobials and resistant bacteria. Significance and Impact of the Study: Considering the still very low proportion of FC‐resistant Aeromonas, this study can be considered as a reference for further studies about this recently introduced veterinary antimicrobial agent.

Antibiotic Use And Practices In Selected Fish Farms In The Ashanti Region Of Ghana

“…Though this study did not investigate the levels of bacteria at the receiving water bodies, the high numbers of resistant bacteria isolated from the fish pond environment could be transferred to receiving water bodies as observed in a study of water from fish ponds and receiving streams from selected farms in the Ashanti Region, significant levels of bacteria upstream, downstream and reference locations of the streams receiving effluents from the fish ponds [27]. Gordon et al [28] reported a high number of resistant bacteria isolates from a river receiving effluents from fish ponds indicating the transfer of antibiotic resistant isolates to adjoining water bodies.…”

Antimicrobial Susceptibilities of Vibrio parahaemolyticus and Vibrio vulnificus Isolates from Louisiana Gulf and Retail Raw Oysters

“…Aquatic bacteria, including vibrios, live in the coastal and estuarine waters, an open area particularly subject to environmental contaminations by agricultural runoff or wastewater treatment plants, which may contain various levels of antimicrobials and heavy metals and act as selective pressure for antimicrobial-resistant aquatic bacteria (16,27). Despite their public-health significance, strains of V. parahaemolyticus and V. vulnificus have not been extensively monitored for antimicrobial resistance, in contrast to enteric pathogens such as Salmonella or Campylobacter.…”

Entericidin Is Required for a Probiotic Treatment (Enterobacter sp. Strain C6-6) To Protect Trout from Cold-Water Disease Challenge

“…Improved rearing conditions (e.g., stress reduction, reduced stocking densities, cleaner raceways, adjusted feeding strategies, and improved disinfection protocols) and antimicrobials are the only practical control measures. In the United States, oxytetracycline and florfenicol are approved for treatment of BCWD, but drug resistance may be emerging, and concerns about the environmental impact of these treatments make it imperative to find new strategies (19)(20)(21)(22).A probiotic strain, Enterobacter sp. strain C6-6, was recently isolated from trout intestines and was shown to inhibit F. psychrophilum on agar diffusion plates (23) while reducing mortality during F. psychrophilum challenge studies (24).…”