Pathogenecity and antimicrobial susceptibility of bacteria isolated from kidney, liver, and brain of Nile tilapia (oreochromis niloticus) stocked in intensive cage farming systems in Taal Lake, Batangas

Tilapia disease outbreak and fish kills have been ever pressing problems of tilapia farmers in Taal lake, but the bacterial etiology of the disease is still unknown. In the Philippines, limited studies have been conducted on the pathogenecity and antimicrobial susceptibility of bacterial isolates in...

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Main Author: Limbauan, Jaryna O.
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Published: Animo Repository 2018
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Online Access:https://animorepository.dlsu.edu.ph/etd_masteral/5536
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spelling oai:animorepository.dlsu.edu.ph:etd_masteral-123742020-10-10T02:18:03Z Pathogenecity and antimicrobial susceptibility of bacteria isolated from kidney, liver, and brain of Nile tilapia (oreochromis niloticus) stocked in intensive cage farming systems in Taal Lake, Batangas Limbauan, Jaryna O. Tilapia disease outbreak and fish kills have been ever pressing problems of tilapia farmers in Taal lake, but the bacterial etiology of the disease is still unknown. In the Philippines, limited studies have been conducted on the pathogenecity and antimicrobial susceptibility of bacterial isolates in aquaculture. Hence this study was undertaken to identify the bacteria of diseased tilapia in Taal Lake and determine their antimicrobial susceptibility and pathogenicity. A total of 181 bacteria were isolated from diseased Nile tilapia in Taal Lake. The commonly isolated bacteria were aeromonas hydrophila/caviae (41.99%), streptococcus agalactiae (19.89%), plesiomonas shigelloides (5.52%), aeromonas sobria (3.78%) and vibro cholerae (2.76%). Aermonas spp. and plesiomonas shigelloides isolates were chosen and tested against 11 antimicrobials. The antimicrobial susceptibility patterns of the isolates revealed resistance to at least one antimicrobial. All isolates showed susceptibility to ceftriaxone and chloramphenicol, while 50 (80%) of the isolates were found resistant to cefoxitin. A multyiple antibiotic resistance (MAR) index value of <0.2 was found on 97.14% of the bacterial isolates, which indicated that Taal Lake has low risk of antibiotic contamination. Two bacterial isolates, streptococcus agalactiae and aeromonas hydrophila, were tested for their pathogenicity in juvenile Nile tilapia. Pathogenicity test results proved that S. agalactiae and A. hydrophila were pathogenic to tilapia, and suggested that the gross clinical signs and internal abnormalities observed in the diseased Nile tilapia in Taal Lake were caused by S. agalactiae and/or A. hydrophila infection. At 96 h post infection, the median lethal dose (LD50) of S. agalactiae and A. hydrophila in juvenile Nile tilapia were 2.27 x 102 CFU/fish and 1.34 x 102 CFU/fish, respectively. Results of this study highlights the importance of antimicrobial susceptibility testing and pathogenicity test in the surveillance of pathogenic and antibiotic resistant bact 2018-01-01T08:00:00Z text https://animorepository.dlsu.edu.ph/etd_masteral/5536 Master's Theses Animo Repository Tilapia -- Philippines
institution De La Salle University
building De La Salle University Library
continent Asia
country Philippines
Philippines
content_provider De La Salle University Library
collection DLSU Institutional Repository
topic Tilapia -- Philippines
spellingShingle Tilapia -- Philippines
Limbauan, Jaryna O.
Pathogenecity and antimicrobial susceptibility of bacteria isolated from kidney, liver, and brain of Nile tilapia (oreochromis niloticus) stocked in intensive cage farming systems in Taal Lake, Batangas
description Tilapia disease outbreak and fish kills have been ever pressing problems of tilapia farmers in Taal lake, but the bacterial etiology of the disease is still unknown. In the Philippines, limited studies have been conducted on the pathogenecity and antimicrobial susceptibility of bacterial isolates in aquaculture. Hence this study was undertaken to identify the bacteria of diseased tilapia in Taal Lake and determine their antimicrobial susceptibility and pathogenicity. A total of 181 bacteria were isolated from diseased Nile tilapia in Taal Lake. The commonly isolated bacteria were aeromonas hydrophila/caviae (41.99%), streptococcus agalactiae (19.89%), plesiomonas shigelloides (5.52%), aeromonas sobria (3.78%) and vibro cholerae (2.76%). Aermonas spp. and plesiomonas shigelloides isolates were chosen and tested against 11 antimicrobials. The antimicrobial susceptibility patterns of the isolates revealed resistance to at least one antimicrobial. All isolates showed susceptibility to ceftriaxone and chloramphenicol, while 50 (80%) of the isolates were found resistant to cefoxitin. A multyiple antibiotic resistance (MAR) index value of <0.2 was found on 97.14% of the bacterial isolates, which indicated that Taal Lake has low risk of antibiotic contamination. Two bacterial isolates, streptococcus agalactiae and aeromonas hydrophila, were tested for their pathogenicity in juvenile Nile tilapia. Pathogenicity test results proved that S. agalactiae and A. hydrophila were pathogenic to tilapia, and suggested that the gross clinical signs and internal abnormalities observed in the diseased Nile tilapia in Taal Lake were caused by S. agalactiae and/or A. hydrophila infection. At 96 h post infection, the median lethal dose (LD50) of S. agalactiae and A. hydrophila in juvenile Nile tilapia were 2.27 x 102 CFU/fish and 1.34 x 102 CFU/fish, respectively. Results of this study highlights the importance of antimicrobial susceptibility testing and pathogenicity test in the surveillance of pathogenic and antibiotic resistant bact
format text
author Limbauan, Jaryna O.
author_facet Limbauan, Jaryna O.
author_sort Limbauan, Jaryna O.
title Pathogenecity and antimicrobial susceptibility of bacteria isolated from kidney, liver, and brain of Nile tilapia (oreochromis niloticus) stocked in intensive cage farming systems in Taal Lake, Batangas
title_short Pathogenecity and antimicrobial susceptibility of bacteria isolated from kidney, liver, and brain of Nile tilapia (oreochromis niloticus) stocked in intensive cage farming systems in Taal Lake, Batangas
title_full Pathogenecity and antimicrobial susceptibility of bacteria isolated from kidney, liver, and brain of Nile tilapia (oreochromis niloticus) stocked in intensive cage farming systems in Taal Lake, Batangas
title_fullStr Pathogenecity and antimicrobial susceptibility of bacteria isolated from kidney, liver, and brain of Nile tilapia (oreochromis niloticus) stocked in intensive cage farming systems in Taal Lake, Batangas
title_full_unstemmed Pathogenecity and antimicrobial susceptibility of bacteria isolated from kidney, liver, and brain of Nile tilapia (oreochromis niloticus) stocked in intensive cage farming systems in Taal Lake, Batangas
title_sort pathogenecity and antimicrobial susceptibility of bacteria isolated from kidney, liver, and brain of nile tilapia (oreochromis niloticus) stocked in intensive cage farming systems in taal lake, batangas
publisher Animo Repository
publishDate 2018
url https://animorepository.dlsu.edu.ph/etd_masteral/5536
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