Determination of LD‚‚ for Streptococcus agalactiae and Staphylococcus aureus infections in tilapia

Sabri M. Y., . and M. Firdaus Nawi, . and Siti Zahrah A., . and M. Zamri Saad, . and Nur Nazifah M., . Determination of LD‚‚ for Streptococcus agalactiae and Staphylococcus aureus infections in tilapia. pp. 22-27. ISSN 9128-2506

One hundred and sixty fingerlings and 80 adult tilapias were experimentally infected with Streptococcus agalactiae and Stapylococcus aureus to determine their LD50. Four concentrations of Streptococcus agalactiae (10� 10� 10�· 10� CFU/mL) were used in this experimental infection. This tilapia were divided into 4 groups of 40 fingerlings and 20 adults per group. Groups 1 2 3 and 4 of the fingerlings were exposed to 10� 10� 10�· 10� CFU/mL of S. agalactiae by immersion in 2 L inoculum solution for 20 min. Similarly the adult groups were exposed to the same concentrations of S. agalactiae but by intraperitoneal injection at the rate of 1 mL of the inoculum per gram. Similar procedures were repeated using exposure to Staphylococcus aureus alone or a combination of S. agalactiae and S. aureus. All test groups were observed for signs of infections. On Day 7 post-infection (pi) all fish that were still alive were humanely killed. The LD50 of the adult tilapia that were exposed to S. agalactiae S. aureus or mixed infection was 2.3884 10�· 2.8151 10� and 4.2409 10� respectively. For the fingerling groups the LD‚‚ for S. agalactiae S. aureus and mixed infection was 2.9242 10� 2.8665 10�· and 4.9748 10 respectively. Experimental infection in adults could be established within 12 h post-injection to 6.3 10� CFU per mL and 9.7 10� CFU per mL of S. agalactiae and S. aureus respectively. For fingerlings infection could be established within 72 h following bath immersion to 6.3 10� CFU per mL and 9.7 10� CFU per mL of S. agalactiae and S. aureus respectively.

Full text available from: Official URL: https://www.mavma.org.my/2011-volume-23-issue-no-2...

Abstract

One hundred and sixty fingerlings and 80 adult tilapias were experimentally infected with Streptococcus agalactiae and Stapylococcus aureus to determine their LD50. Four concentrations of Streptococcus agalactiae (10� 10� 10�· 10� CFU/mL) were used in this experimental infection. This tilapia were divided into 4 groups of 40 fingerlings and 20 adults per group. Groups 1 2 3 and 4 of the fingerlings were exposed to 10� 10� 10�· 10� CFU/mL of S. agalactiae by immersion in 2 L inoculum solution for 20 min. Similarly the adult groups were exposed to the same concentrations of S. agalactiae but by intraperitoneal injection at the rate of 1 mL of the inoculum per gram. Similar procedures were repeated using exposure to Staphylococcus aureus alone or a combination of S. agalactiae and S. aureus. All test groups were observed for signs of infections. On Day 7 post-infection (pi) all fish that were still alive were humanely killed. The LD50 of the adult tilapia that were exposed to S. agalactiae S. aureus or mixed infection was 2.3884 10�· 2.8151 10� and 4.2409 10� respectively. For the fingerling groups the LD‚‚ for S. agalactiae S. aureus and mixed infection was 2.9242 10� 2.8665 10�· and 4.9748 10 respectively. Experimental infection in adults could be established within 12 h post-injection to 6.3 10� CFU per mL and 9.7 10� CFU per mL of S. agalactiae and S. aureus respectively. For fingerlings infection could be established within 72 h following bath immersion to 6.3 10� CFU per mL and 9.7 10� CFU per mL of S. agalactiae and S. aureus respectively.

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Item Type:	Article
AGROVOC Term:	Streptococcus agalactiae
AGROVOC Term:	Staphylococcus aureus
AGROVOC Term:	Tilapia
AGROVOC Term:	Fingerlings
AGROVOC Term:	Pathogenicity
AGROVOC Term:	Oreochromis
AGROVOC Term:	Water quality
AGROVOC Term:	Bacteria
AGROVOC Term:	Mortality
AGROVOC Term:	Exotoxins
Depositing User:	Mr. AFANDI ABDUL MALEK
Last Modified:	24 Apr 2025 00:54
URI:	http://webagris.upm.edu.my/id/eprint/8396

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