Evaluation of health and environmental risks for juvenile tilapia (Oreochromis niloticus) exposed to florfenicol

Abstract

Intensive fish cultivation has a high incidence of infection, which is often controlled by administering antibiotics. Florfenicol (FF) is one of the two antimicrobial drugs permitted for aquaculture in Brazil. Due to their intensive use, potentially harmful effects on aquatic organisms are of great concern. In this sense, we investigated whether the presence of FF in cultivation water could change the health parameters of Nile tilapia. For this, we evaluated hemoglobin, hematocrit, mean corpuscular hemoglobin (MCHC) concentration, mean corpuscular volume (MCV), total plasma protein (TPP), number of circulating red blood cells and leukocytes, as lipid peroxidation levels, catalase activity and glutathione S-transferase activity of fish exposed to 11.72 mg L −1 of FF in water for 48 h. The fish were divided into two groups: Nile tilapia in water with FF or without FF (control). Exposure to FF in cultivation water for a short period didn't change the hematological variables analyzed, but caused changes in liver ROS (Reactive oxygen species) markers of the Nile tilapia, which was revealed by lipid peroxidation levels, catalase activity, and glutathione S-transferase. The 48h exposure period was enough to induce oxidative stress in hepatocytes, causing cellular oxidative damage. Therefore, the antibiotic florfenicol may cause toxicity to organisms and aquatic ecosystems, even at a sublethal concentrations near 1/100 LC50-48h for fish species.

Impacts of Oral Florfenicol Medication and Residues on the Kidney and Liver of Nile Tilapia Oreochromis niloticus (L.)

“…The inability to produce an antioxidant defence system leads to the expression of oxidative stress [ 5 ]. The earlier studies asserted the ability of FFC to inflict oxidative stress on O. niloticus juveniles [ 5 , 11 ]. Oxidative stress participates in the liver fibrogenic response and often results in fibrosis.…”

“…The kidney has a high capacity for the uptake of lipid-binding proteins and lipid-regulating hormones [ 32 ], and peroxidation of lipids persists in the kidney tissues. As renal injury upon oxidative stress has been documented in several animals [ 5 , 32 ], the documentation of glomerulopathy and degeneration of renal tubules upon dietary FFC administration in O. niloticus was considered befitting. The observations on the increase in MDA levels and decreased GST activity due to the drug sulfasalazine in rat liver and kidney tissues were concomitant with the present study, implying considerable hepatic and renal toxicity [ 33 ].…”

“…Nevertheless, as evinced by the higher MDA levels and histopathological alterations of the present study, the cells that collected lipid peroxidation byproducts were less likely to function properly. The increased levels of MDA in the liver and kidney tissues of O. niloticus destroyed the antioxidant enzymes and their substrates, thus reducing the antioxidant capacity [ 5 , 18 , 36 ]. Further, with the suspension of dosing, the MDA levels of the lower-dosed (1×–3×) groups recouped in the liver tissues.…”

“…The toxicological effects of antibiotics on different organs of the host fish are still not fully understood or evaluated [ 4 ]. In intensive tilapia cultivation, FFC has often been recommended as a therapeutic agent to control several bacterial diseases [ 5 ]. It is one of the most commonly used antibiotics in major aquaculture-producing countries, such as Chile, China, Vietnam, South Korea, Norway, Egypt and Brazil [ 2 ].…”

Aeromonas veroniidetection in Egyptian fish farms with summer tilapia mortality outbreaks and the role of formic acid in limiting its spread

“…A study has proven that florfenicol has a suppressive effect on humoral and cellular immune responses and lymphoid organ destruction and haematopoietic tissue IgM immunoreactive cells (Lunden et al, 1999; Reda et al, 2013). Furthermore, Shiroma et al (2020) have found that florfenicol causes lipid peroxidation and DNA damage because of antioxidant depletion and increased reactive oxygen species (ROS) accumulation even at low concentrations, posing health risks to exposed tilapia. High levels of ROS can harm the immune system by disrupting the periphery immune system and activating leukocytes (Tavassolifar et al, 2020).…”