Hematological examination
Hematological parameters in fish have been widely used as good indicators for analysing the harmful effects of antibiotics, an environmental pollutant PCBs and fish physiological status
(Kumar et al., 2011).
The results of hematology parameters of
Oreochromis niloticus treated with antibiotics at therapeutic dose and maximum residue limit (MRL) level are presented in the Table 3. There were no major alterations in the values of hemoglobin and packed cell volume between the control group and experimental group. The data were subjected to statistical analysis by ANOVA and found a significant difference at 1% level (P<0.01) between groups. The present study confirmed that the hematological parameters were not influenced in the fish exposed to antibiotics.
Kondera et al., (2020) reported that there were no crucial changes in the values of hematological parameters of carp which was fed with 75 mg/g of OTC for every two days/4 times. Consistent with the results of the present study,
(El-Adawy et al., 2018) also demonstrated that there were no changes in the values of hematology and thrombocytes in
Oreochromis niloticus fed with OTC at 500mg/kg for 60 days.
Reda et al., (2016) reported that there were no changes in values of hematology however, a decrease in hematocrit and thrombocyte count in
Oreochromis niloticus fed with OTC at 500 mg/kg for 2 weeks.
Karadeniz et al., (2007) also noticed that there were no changes in the values of hematological parameters of fish following the administration of florfenicol at 100 and 300 mg/kg body weight.
Iftikhar and Hashmi (2021) reported that sulfamethoxazole exposed to
Cyprinus carpio reduced the level of hemoglobin, platelet and erythrocyte and increased the value of leukocyte which was contrary to the findings in the present study and it might be due to long term exposure of SMX to fish
i.e., 28 days.
Most of the studies done in fish to demonstrate hematology parameters were not comparable to our findings which might be due to the differences in the fish species studied, environmental differences and the aligned stress factors apart from the type and dosage of the antibiotics.
The dosage of antibiotics and the sensitivity of fish play a major role in causing changes in the blood parameters. The changes in the hematology parameters mainly depend on the concentration of the antibiotics. In our study, concentration of the drug administered to fish and the duration of exposure of fish to the drug did not pose any changes in the hematological parameters.
Biochemical profile
Biochemical parameters are one of the important parameters for toxicity studies and are also used to evaluate the physiological systems of an organism
(Vutukuru, 2003). The results of biochemical parameters for
Oreochromis niloticus treated with antibiotics at therapeutic dose and maximum residue limit (MRL) level are presented in Table 4. All the parameters expressed some changes in their values between the control and experimental groups.
Oreochromis niloticus exposed to antibiotics showed elevation of the values for all the parameters and the statistical analysis revealed a significant difference between the groups studied.
The present study revealed that there was an increase in the values of alanine aminotransaminase (ALT), aspartate aminotransferase (AST), albumin, total protein (TP), cholesterol, phosphorus and a decrease in the values of calcium and glucose for all the antibiotic treated groups which indicated damage to the liver and kidney tissues.
Similar to the present study,
(El-Adawy et al., 2018) found that when Nile tilapia (
Oreochromis niloticus) treated with 500 mg OTC/kg, there was an increase in total protein and globulin level.
Soltan et al., (2013) stated that
Oreochromis niloticus exposed to 40 mg OTC/kg increased the level of alanine aminotransaminase (ALT) and aspartate aminotransferase (AST). In addition,
Nakano et al., (2018) demonstrated that the exposure of Coho salmon (
Oncorhynchus kisutch)
to 100 mg OTC/kg/day for two weeks increased the activity of alanine aminotransaminase (ALT) accompanied by increase in the hepatosomatic index,
Ambili et al. (2013) illustrated that OTC treatment for
Labeo rohita increased the activity of hepatic ALT and AST which were similar to the findings of this study.
The outcome of the present study was similar to the results of
KuHua et al., (2009), who reported that there was an increase in the alanine aminotransaminase (ALT) activity following the exposure of sea bass to 30, 60, 120 mg FF/kg body weight for seven days.
Abdolhossein et al., (2016) studied the effect of florfenicol on biochemical parameters. Common carp
(Cyprinus carpio) received florfenicol for 10 days at 5 mg/l and 10 mg/kg concentration. The results revealed that there was an increase in the activity of alanine aminotransaminase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) with respect to the control group.
Iftikhar and Hashmi (2021) observed that sulfamethoxazole exposed to
Cyprinus carpio increased the level of alanine aminotransaminase (ALT) which was similar to the present findings. In this trial, common carp (
Cyprinus carpio)
were exposed to sulfamethoxazole for 28 days at a concentration of 25, 50, 100 and 200 µg/l.
The increase in the activity of alanine aminotra nsaminase (ALT) and aspartate aminotransferase (AST) indicated liver damage and a decrease in calcium level reflected kidney damage
(Mikulikova et al., 2013). The rise in the level of ALT and AST and the decrease in the level of calcium were due to stress conditions caused by antibiotics. Irregular metabolism of protein and carbohydrates was the reason for the high levels of transaminase activity when exposed to antibiotics
(Akrami et al., 2013; Sampaio et al., 2016).
Histopathology of liver
The histopathological results of liver collected at the end of treatment with antibiotics at therapeutic dose and maximum residue limit (MRL) level from
Oreochromis niloticus are depicted in Fig 1-7.
The control group (C1) showed normal features of the liver, whereas, the A1 (OTC-200 mg/l) and A2 (OTC-0.1 mg/l) groups showed multifocal moderate hydropic degeneration. The A3 (FF-10 mg/l) group showed multifocal mild to moderate vacuolar degeneration and the A4 (FF-1 mg/l) group showed multifocal mild hydropic degeneration. The A5 (Sm and O-50 mg/l) group showed hydropic degeneration and the A6 (Sm and O-0.1 mg/l) group showed mild hydropic degeneration of hepatocytes.
The result of the present study was similar to
Reda et al., (2013) who reported that the OTC fed at 100 mg/kg for 12 weeks to
Oreochromis niloticus led to congestion, vacuolations in the hepatocytes and fatty changes in the liver and in kidney. Similar to the results obtained in this study,
Dey et al., (2022) also reported that when monosex
Oreochromis niloticus fries exposed to OTC at 350, 700, 2100, 3500 and 7000 mg/l for 30 days at 3 h/day showed dilatation of vascular duct, diffuse necrotized hepatic parenchyma, fatty changes and vacuolation in hepatocytes and necrosis, dissolution of the nephritic tubule and glomerulonephritis.
Florfenicol administered to tilapia via the feed at 15, 45, 75 mg/kg BW for twenty days caused hepatocellular vacuolation and tubular epithelial cell degeneration and necrosis
(Gaikowski et al., 2012).
Iftikhar et al., (2022) reported that the fresh water fish exposed to sulfamethoxazole at 25-200 µg/l concentration for 28 days caused stagnation of bile, vacuolization of hepatocytes and congestion of liver parenchyma, which were similar to the present research findings.
Hentschel et al., (2005) stated that the long-term exposure with high dosage of antibiotics leads to hepatoxicity (liver damage) and nephrotoxicity (kidney damage). The histological changes and elevated activity of ALT and AST were due to the stress caused by antibiotics which in turn led to the damage of liver and kidney.