Resumo

MARTINS, ML. et al. Haematological changes in Nile tilapia experimentally infected with Enterococcus sp.. Braz. J. Biol. [online]. 2008, vol.68, n.3, pp. 657-661. ISSN 1519-6984.  http://dx.doi.org/10.1590/S1519-69842008000300025.

This study evaluated the haematological changes in Nile tilapia experimentally infected with 1 x 10³ and 1 x 10⁶ colony-forming units (CFU)/mL of Enterococcus sp. in the swim bladder. The experiment consisted of four treatments in triplicates: non-injected fish (NI); fish injected with 1 mL of sterile saline solution 0.65% (SAL); fish injected with 1 x 10³ and 1 x 10⁶ CFU/mL of Enterococcus diluted in 1 mL sterile saline. Twenty-four hours after injection, the fish were anesthetized and the blood collected. The haematological tests included red blood cell (RBC) and white blood cell (WBC) counts, hematocrit, number of total thrombocytes, and differential counting of WBC. Fish injected with 1 x 10⁶ CFU/mL of Enterococcus showed a higher number of thrombocytes than the other treatments. White blood cell and lymphocyte numbers increased significantly in fish injected with 1 x 10⁶ CFU/mL of Enterococcus when compared to non-injected control. There was significant increase in the number of neutrophils in saline injected fish and reduced number of monocytes after injections with 1 x 10⁶ CFU/mL of Enterococcus. Hematocrit increased in fish injected with 1 x 10³ and 1 x 10⁶ CFU/mL of Enterococcus.

Palavras-chave : tilapia; Enterococcus; infection; haematology.