Investigating the Effect of an Oxytetracycline Treatment on the Gut Microbiome and Antimicrobial Resistance Gene Dynamics in Nile Tilapia (Oreochromis niloticus)

Abstract

Antibiotics play a vital role in aquaculture where they are commonly used to treat bacterial diseases. However, the impact of antibiotic treatment on the gut microbiome and the development of antimicrobial resistance in Nile tilapia (Oreochromis niloticus) over time remains to be fully understood. In this study, fish were fed a single treatment of oxytetracycline (100 mg/kg/day) for eight days, followed by a 14-day withdrawal period. Changes in the distal gut microbiome were measured using 16S rRNA sequencing. In addition, the abundance of antimicrobial resistance genes was quantified using real-time qPCR methods. Overall, the gut microbiome community diversity and structure of Nile tilapia was resilient to oxytetracycline treatment. However, antibiotic treatment was associated with an enrichment in Plesiomonas, accompanied by a decline in other bacteria taxa. Oxytetracycline treatment increased the proportion of tetA in the distal gut of fish and tank biofilms of the treated group. Furthermore, the abundance of tetA along with other tetracycline resistance genes was strongly correlated with a number of microbiome members, including Plesiomonas. The findings from this study demonstrate that antibiotic treatment can exert selective pressures on the gut microbiome of fish in favour of resistant populations, which may have long-term impacts on fish health.

Dysbiosis and Restoration Dynamics of the Gut Microbiome Following Therapeutic Exposure to Florfenicol in Snubnose Pompano (Trachinotus blochii) to Aid in Sustainable Aquaculture Production Strategies

“…In short, the results showed that FFC treatment caused a reduction in all the gut microbial counts but there was a clear shift in the gut microbiome toward well-known putative pathogens. In support of our findings, the shifts in the gut microbiome toward well-known putative pathogens following different antibiotic treatments were reported in the earlier studies on freshwater fish ( Zhou et al, 2018 ; Sáenz et al, 2019 ; Payne et al, 2021 ). Simultaneously, the observed reduction in the bacterial count on TCBS agar showed that FFC has good antagonistic activity against the major marine fish pathogens (belonging to Vibrionacetheae family).…”

“…Contrariwise, cutting-edge research in terrestrial animals has amply demonstrated the adverse effect of antibiotic treatment in disrupting the healthy gut microbiome of the host ( Holman et al, 2019 ). As the gut microbiome serves several vital biological and physiological functions for the host, understanding the intended and unintended consequences of antibiotic treatment on the gut microbiome is vital to support the overall health and welfare of the farmed animals ( Payne et al, 2021 ). The antibiotic treatment can also cause the emergence of antimicrobial resistance (AMR) in gut microbes, raising additional concerns about consumer and environmental safety ( Cabello et al, 2013 ).…”

Exposure to Oxy-Tetracycline Changes Gut Bacterial Community Composition in Rainbow Trout: A Preliminary Study

“…The decrease in Proteobacteria can be attributed to the abundance of fish pathogens that belong to the particular phylum [ 22 , 23 , 24 ]. Additionally, the decrease in the abundance of Fusobacteria can demonstrate the unregulated effect of OTC in targeting other bacterial groups [ 25 ]. However, the abundance of Tenericutes and Firmicutes was higher in OTC-treated fish.…”

Tilapia aquaculture, emerging diseases, and the roles of the skin microbiomes in health and disease

“…In fish, antibiotic exposure has also been experimentally shown to exert selective pressures on skin, gill, and gut microbiomes. Dietary doses of oxytetracycline (100 mg/kg) (Payne et al 2021) and sulfamonomethoxine (200 and 300 mg/kg) (Ming et al 2020) given to Nile tilapia were found to cause minimal changes to alpha and beta diversity metrics of gut microbial communities; however, these exposures were not found to cause altered abundance in taxa for genera containing reputed pathogens. Further experimental evidence, however, has shown perturbation of skin and gut microbiomes, with enrichment of potentially opportunistic pathogens, following oral exposure of yellowtail kingfish Seriola lalandi to an antibiotic cocktail of oxytetracycline (200 mg/kg), erythromycin (50 mg/kg), and metronidazole (50 mg/kg).…”