Effects of Oxytetracycline and Gentamicin Therapeutic Doses on Hematological, Biochemical and Hematopoietic Parameters in Cyprinus carpio Juveniles.

Elżbieta Kondera,Małgorzata Witeska,Barbara Kot,Katarzyna Ługowska,Bartosz Bojarski

doi:10.3390/ani10122278

Abstract

Hematological, biochemical and hematopoietic effects of therapeutic doses of two antibiotics, oxytetracycline (OTC) and gentamicin (GEN), in clinically healthy common carp juveniles were studied. The fish were divided into four groups: controls 1 and 2 (untreated or injected with 0.6% NaCl solution), and two groups treated with antibiotics (orally with 75 mg/kg OTC four times every two days or injected with a single dose (4 mg/kg) of GEN dissolved in 0.6% NaCl). Blood and head kidneys were sampled from all fish 3 days post-treatments for hematological, biochemical and hematopoietic tissue analyses. No major alterations in the values of hematological and serum biochemical parameters occurred following administration of OTC or GEN. Glucose concentrations were significantly lower in both groups of fish subjected to injections (Control 2 and GEN), while the oxidative metabolic activity of phagocytes increased in the antibiotic-treated groups (significantly in OTC). More alterations were observed in hematopoietic tissue. Immunocytochemical analysis revealed that G caused a significant increase in the rate of cell proliferation (PCNA-positive cells) and an increase in the frequency of apoptotic cells (caspase-positive). The frequency of lymphoid lineage decreased, which was related to a decrease in the abundance of mature lymphocytes in GEN-treated fish. Percentages of neutrophilic lineage were significantly elevated in OTC and GEN groups compared to controls. The obtained results showed no considerable hematotoxicity or hepatotoxicity of therapeutic doses of OTC and GEN to carp.

Highlights

Fish rearing under high stocking densities is accompanied by increased risk of infectious bacterial diseases that are treated mainly with antibiotics
Antibiotics at significant concentrations in aquatic environments are the principal source of selective pressure for antimicrobial resistance in bacteria because susceptible bacteria in the sediment and water are replaced by resistant ones [7], while antibiotics at subinhibitory concentrations may stimulate mutagenesis and horizontal transfer of antibiotic resistance genes (ARGs) for human pathogens, which may result in decreased efficacy of different antibiotic groups and severely limits the therapeutic options in human infections [8,9]
Antibiotics did not significantly alter the activities of hepatic aminotransferases ALT and AST; in groups exposed to antibiotics the results were much more variable and the mean values were higher compared to the controls

Summary

Introduction

Fish rearing under high stocking densities is accompanied by increased risk of infectious bacterial diseases that are treated mainly with antibiotics. Oxytetracycline (OTC) is often employed in fish farms to treat or prevent bacterial infections [1] and is one of the most used antibiotics in aquaculture [2]. Gentamicin (GEN) is an aminoglycoside antibiotic commonly used in veterinary medicine against a variety of infections caused by Gram-positive and Gram-negative aerobic bacteria and sometimes applied in fishery practice [3]. The presence of aminoglycosides in fresh water and sediments was reported in Polish rivers and lakes [5]. Antibiotics at significant concentrations in aquatic environments are the principal source of selective pressure for antimicrobial resistance in bacteria because susceptible bacteria in the sediment and water are replaced by resistant ones [7], while antibiotics at subinhibitory concentrations may stimulate mutagenesis and horizontal transfer of antibiotic resistance genes (ARGs) for human pathogens, which may result in decreased efficacy of different antibiotic groups and severely limits the therapeutic options in human infections [8,9].

Methods

Results

Conclusion