Sulfamethoxazole (SMX) Alters Immune and Apoptotic Endpoints in Developing Zebrafish (Danio rerio)

Abstract

Sulfamethoxazole (SMX) is a broad-range bacteriostatic antibiotic widely used in animal and fish farming and is also employed in human medicine. These antibiotics can ultimately end up in the aquatic ecosystem and affect non-target organisms such as fish. To discern the effect of SMX on developing zebrafish embryos and larvae, we investigated a broad range of sub-lethal toxicity endpoints. Higher concentrations of SMX affected survivability, caused hatch delay, and induced malformations including edema of the yolk sac, pericardial effusion, bent tail, and curved spine in developing embryos. Lower levels of SMX provoked an inflammatory response in larvae at seven days post fertilization (dpf), as noted by up-regulation of interferon (ifn-γ) and interleukin 1β (il-1β). SMX also increased the expression of genes related to apoptosis, including BCL2-Associated Agonist of Cell Death (bad) and BCL2 Associated X, Apoptosis Regulator (bax) at 50 µg/L and decreased caspase 3 (casp3) expression in a dose-dependent manner. SMX induced hyperactivity in larval fish at 500 and 2500 µg/L based upon the light/dark preference test. Collectively, this study revealed that exposure to SMX can disrupt the immune system by altering host defense mechanisms as well as transcripts related to apoptosis. These data improve understanding of antibiotic chemical toxicity in aquatic organisms and serves as a baseline for in-depth environmental risk assessment of SMX and antibiotics.

Mechanisms of Gills Response to Cadmium Exposure in Greenfin Horse-Faced Filefish (Thamnaconus septentrionalis): Oxidative Stress, Immune Response, and Energy Metabolism

“…It is worth noting that, in contrast to freshwater species, the mechanisms underlying Cd-induced detrimental effects on marine fishes, particularly Cd-induced signaling networks, are still poorly understood. Factors such as the duration and concentration of Cd exposure, as well as the species and life stage of the fish, can all influence the severity of its harmful effects [8].…”

Prevalence, antibiotic susceptibility, and genomic analysis of Vibrio alginolyticus isolated from seafood and freshwater products in China

“…The antibiotic Bactrim, or trimethoprim-sulfamethoxazole, is commonly used in the treatment of UTIs ( DeMasi et al, 2021 ). It operates by sulfamethoxazole inhibiting bacterial folate synthesis ( Iftikhar et al, 2023 ), while trimethoprim blocks the utilization of folate by bacteria ( Janssen et al, 2015 ), collectively halting bacterial proliferation. However, the increasing reports of resistance to Bactrim have raised significant concerns.…”