Citation
Wan Omar, Wan Haifa Haryani
(2024)
Distribution, virulence factors and antimicrobial resistance of Vibrio species isolated from cultured shrimp in Peninsular Malaysia.
Doctoral thesis, Universiti Putra Malaysia.
Abstract
Vibrio, the most common bacterium associated with crustacean diseases,
poses a significant threat to shrimp farming due to outbreaks of vibriosis.
Therefore, the study aims to provide a comprehensive database on the
distribution of Vibrio spp. as well as virulence genes and antimicrobial
resistance profiling in Malaysian shrimp farms. Briefly, a total of 210 cultured
shrimp were collected from seven farms in Peninsular Malaysia. The findings
revealed that 225 presumptive Vibrio isolates were isolated from cultured
shrimp which were then subjected to biochemical test and molecular
detection using pyrH gene analysis. Eventually, 13 different Vibrio spp. were
successfully isolated and characterized including Vibrio parahaemolyticus
(55%), V. communis (9%), V. campbellii (8%), V. owensii (7%), V. rotiferianus
(5%), Vibrio spp. (4%), V. alginolyticus (3%), V. brasiliensis (2%), V.
natriegens (2%), V. xuii (1%), V. harveyi (1%), V. hepatarius (0.4%) and P.
damselae (3%). Based on virulence genes assessment, eight of the eleven
virulence genes in this study were detected, including chiA (89%), flaC
(74%), tlh (72%), toxR (70%), luxR (40%), pirA (11%), pirB (11%) and hlyA
(0.4%). Other virulence genes, such as tdh, trh and ctxA, were not detected
in any isolates (0%). From the virulence gene assessment, three Vibrio
isolates were chosen for the pathogenicity test based on highest number
present in each of the species. The isolates including V. parahaemolyticus
S12-3, V. campbellii S10-4, and V. rotiferianus S24-4 were tested by
immersion challenge test against postlarvae (PL) Penaeus monodon
approximately PL-20 with three different concentrations of 1 × 106 CFU/mL, 1
× 107 CFU/mL, and 1 × 108 CFU/mL. The LC50 result revealed that the lowest
were V. parahaemolyticus S12-3 (1 × 105 CFU/mL) followed by V.
rotiferianus S24-4 (1 × 1011 CFU/mL) and V. campbellii S10-4 (1 × 1013
CFU/mL). Moreover, histopathological analysis showed sloughing of
epithelial cells in hepatopancreatic tubule, haemocytic infiltration, massive
vacuolation and loss of hepatopancreatic tubule structure. Meanwhile, the
majority of the species tested were resistant to penicillin G (100%), but
susceptible to norfloxacin (96%). According to the multiple antibiotic
resistance (MAR) index, 84% of Vibrio spp. exhibited a MAR index value of
more than 0.2. Thus, the findings suggested that a large number of Vibrio
spp. were resistant to several antibiotics and had been exposed to antibiotics
on a regular basis at the farms. Plasmid profiling revealed that 125 isolates
from a total 225 of Vibrio isolates harboured plasmid with the size ranging
from 1 kb and above 10 kb, separating the isolates into 23 plasmid profiles.
After plasmid curing, Vibrio-positive plasmid was lost resistance to antibiotics.
The findings revealed that the resistance to antibiotics in isolated Vibrio spp.
were either chromosomal or plasmid mediated. In conclusion, ongoing monitoring of antibiotic-resistant microorganisms as well as understanding
the genetic basis of resistance are essential to implement a strategy for
minimizing AMR strain yet to improve shrimp farming management in
Malaysia.
Download File
Additional Metadata
Item Type: |
Thesis
(Doctoral)
|
Subject: |
Vibrio |
Subject: |
Shrimp - Diseases |
Subject: |
Antibiotic resistance |
Call Number: |
IB 2024 4 |
Chairman Supervisor: |
Ina Salwany Md Yasin, PhD |
Divisions: |
Institute of Bioscience |
Keywords: |
Antimicrobial resistance, Peninsular Malaysia, shrimp, Vibrio
spp., virulence |
Depositing User: |
Ms. Rohana Alias
|
Date Deposited: |
04 Aug 2025 02:21 |
Last Modified: |
04 Aug 2025 02:21 |
URI: |
http://psasir.upm.edu.my/id/eprint/118170 |
Statistic Details: |
View Download Statistic |
Actions (login required)
 |
View Item |