Effects of azithromycin on tilapia (Oreochromis niloticus): health status evaluation using biochemical, physiological and morphological biomarkers

Abstract

Bacterial diseases cause tilapia's high‐mortality outbreak. This study investigated the toxicity of azithromycin (AZT), a macrolide antibiotic that has been considered a possible therapeutic drug for tilapia aquacultural use. The 48‐h acute toxicity (50% lethal concentration, LC50; 48 h) of AZT was determined for Oreochromis niloticus. Thereafter, fish were exposed to 0, 1, 50 and 100 mg L−1 AZT during 14 days (chronic exposure) and measured the haematological variables, the activity of superoxide dismutase, catalase, glutathione peroxidase, glutathione‐S‐transferase (GST) and the concentration of glutathione (GSH), protein carbonyl and lipid peroxidation in the liver; histopathology was analysed the liver, gills and kidneys. The LC50; 48 h was >100 mg L−1. No fish died during chronic exposure. Haematocrit and haemoglobin concentration increased in fish exposed to 50 and 100 mg L−1, and the total number of leucocyte and thrombocyte increased after exposure to 100 mg L−1 AZT, suggesting a stimulation of defence cell production. In the liver, the antioxidant enzyme activities did not change, but GST activity and the GSH level increased in fish exposed to 100 mg L−1 AZT. Oxidative stress did not occur. Histopathological index (HIL) indicates moderate liver damage; minor histological changes in the gill and no change in the kidneys. AZT was considered non‐toxic for O. niloticus after acute exposure and, although it causes moderated histopathology in the liver after chronic exposure, this antibiotic may be an alternative against bacterial infections, depending on its efficacy to control bacterial disease in fish.

Accumulation and clearance of tissue residues and health status of Nile tilapia Oreochromis niloticus (L.) juveniles as influenced by the extended oral oxytetracycline-dosing

“…A perusal of literature on the histopathological changes in the kidney of sh treated with various antibiotics at varied concentrations through different routes of administration indicated con icting results. For example, several earlier studies reported no changes in the kidney of sh (Fairgrieve et al 2005;Straus et al 2012;Shiogiri et al 2016); while others demonstrated histopathological alterations in the kidney (Reimschuessel and Ferguson 2006;Gaikowski et al 2013). Our observation on the progressive increase in the renal changes with the duration of treatment validated earlier studies (Reimschuessel and Ferguson 2006;Gaikowski et al 2013;Yang et al 2020;Limbu et al 2020).…”

Responses of Cirrhinus mrigala to second‐generation fluoroquinolone (ciprofloxacin) toxicity: Assessment of antioxidants, tissue morphology, and inorganic ions

“…Epithelium lifting in gills, glycogen depletion in hepatocytes, and necrosis of endothelial cells in the renal corpuscles in fish ( Danio rerio ) exposed to diclofenac might be due to the interference of this drug with biochemical functions which indicate tissue damage 62 . Likewise, Azithromycin caused cellular deformation, lipid accumulation, and nuclear degeneration in fish ( Oreochromis niloticus ) 63 . The antibiotic drug tetracycline caused necrosis in the gill and liver tissues of Gambusia holbrook 64 .…”

Dietary therapeutic dose of oxytetracycline influences histopathological alterations in Nile tilapia Oreochromis niloticus (L.)

“…In contrast, no alteration of the kidney tissues upon oral administration of OTC in Piaractus mesopotamicus (Carraschi et al, 2012) and azithromycin in O . niloticus (Shiogiri et al, 2016) were documented. A perusal of literature, as reviewed by Limbu et al (2020), also indicated conflicting results on the histopathological changes in the kidney of fish treated with various antibiotics at varied concentrations through different routes of administration.…”

“…Also, the intramuscularly administered OTC on Tinca tinca caused the tubular epithelial necrosis, which became severe in the haematopoietic renal tissue on day 7 (Soler et al, 1996). In contrast, no alteration of the kidney tissues upon oral administration of OTC in Piaractus mesopotamicus (Carraschi et al, 2012) and azithromycin in O. niloticus (Shiogiri et al, 2016) were documented. A perusal of literature, as reviewed by Limbu et al (2020), also indicated conflicting results…”