2024_Detection, Characterization and Bacteriophage Control of Salmonella from selected salad vegetables
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| country | Malaysia |
| date | 2024-10-18 11:46 |
| format | General Document |
| id | 16814 |
| institution | UniSZA |
| originalfilename | DETECTION, CHARACTERIZATION AND BACTERIOPHAGE CONTROL OF Salmonella FROM SELECTED SALAD VEGETABLES (PHD_2024).pdf |
| person | Haslinda Binti Wan Hamat |
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| resourceurl | https://intelek.unisza.edu.my/intelek/pages/view.php?ref=16814 |
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| spelling | 16814 https://intelek.unisza.edu.my/intelek/pages/view.php?ref=16814 https://intelek.unisza.edu.my/intelek/pages/search.php?search=!collection3 General Document Malaysia Library Staff (Top Management) Library Staff (Management) Library Staff (Support) Terengganu Faculty of Bio-resources & Food Industry English application/pdf 1.7 192 Microsoft® Word 2019 Server storage Scanned document Universiti Sultan Zainal Abidin UniSZA Private Access Universiti Sultan Zainal Abidin Food Safety Copyright©PWB2025 Dissertations, Academic 2024_Detection, Characterization and Bacteriophage Control of Salmonella from selected salad vegetables Haslinda Binti Wan Hamat Several foodborne outbreaks related to raw vegetable consumption due to Salmonella have been reported worldwide. Multiple antibiotic resistant Salmonella poses greater risk of infection in consumer. Thus, this study aimed to determine the occurrence of Salmonella in salad vegetables with their antimicrobial susceptibility profiles, virulence genes and also their genetic relatedness. This study also aimed to isolate and characterize lytic bacteriophages to control Salmonella. Samples of salad vegetables and environmental were collected from farms (n = 270), wet markets (n = 216) and supermarkets (n = 180) in Kuala Terengganu and Kuala Nerus, Terengganu.The samples were analyzed for the presence of Salmonella according to International Standard protocol ISO 6579:2002(E) and serotyping was performed by Ipoh Public Health Laboratory. The isolated Salmonella were tested for susceptibility against 20 antibiotics. Multiplex PCR assay was done to detect the presence of 15 virulence genes in Salmonella isolates. The genetic relatedness of Salmonella isolates was characterized using ERIC-PCR and BOX-PCR typing methods. Lytic Salmonella bacteriophages were isolated using the double agar overlay plaque assay and characterized for stability, morphology, anti-Salmonella and anti-biofilm activities.Out of 666 salad vegetables, 8.71% were Salmonella positive with 2.96% from farms, 20.37% from wet markets and 3.33% from supermarkets. Among the isolates, 23 Salmonella serovars were identified, the most predominant was Salmonella Weltevreden (20.69%), followed by Salmonella Albany (10.34%) and Salmonella Hvittingfoss (8.62%). Within the isolates, 34.48% exhibited resistance to at least one antibiotic tested. Resistances among isolates were in the highest rate for ampicillin (20.69%), followed by tetracycline (18.97%), doxycycline (17.24%) and trimethoprim-sulfamethoxazole (17.24%). Multidrug resistance (MDR) was identified in 11 isolates (18.67%). Results showed that 91.38% Salmonella isolates carried more than 11 virulence genes.Major clusters of Salmonella were observed at a genetic distance percentage of 90% for both ERIC- and BOX-PCR with discriminatory index of 0.92 and 0.87, respectively. Two Salmonella bacteriophage isolates, SH1 and SH2 were double-stranded DNA phages which belonged to the family Siphoviridae. Both bacteriophages have broad host with capability of inhibiting 17 and 16 different serovars of Salmonella, respectively. The optimal multiplicity of infection of both bacteriophages was 1 with good pH tolerance (pH 5–11) and thermal stability (4–50°C). SH1 and SH2 bacteriophages have the latent periods of 20 min and 10 min with average burst sizes of 59 and 52 PFU/cell, respectively.A total of 0.31 ± 0.01 and 0.32 ± 0.04 log CFU/ml viable cell of Salmonella were significantly reduced from initial count after treatment with SH1 and SH2 for 24 h, respectively. Furthermore, SH1 and SH2 were found capable to reduce Salmonella biofilm of 100% and 89.40% after 24 h treatment, respectively. MDR and virulent Salmonella were found to contaminate salad vegetables, particularly from wet markets. Bacteriophages SH1 and SH2 were identified as potential biocontrol agents for Salmonella in food with good stability and broad-spectrum features. 2024-10-18 11:46 uuid:13B07C68-C1C5-4668-912D-01845056E092 DETECTION, CHARACTERIZATION AND BACTERIOPHAGE CONTROL OF Salmonella FROM SELECTED SALAD VEGETABLES (PHD_2024).pdf Antibiotic Resistance Foodborne Pathogens Salad Vegetables Multiplex PCR Antimicrobial Resistance ERIC-PCR BOX-PCR Lytic Bacteriophage Salmonella Salmonella — Malaysia Bacteriophages — Therapeutic use Drug resistance in microorganisms Foodborne diseases — Malaysia Salmonella infections — Prevention Vegetables — Microbiology Thesis |
| spellingShingle | 2024_Detection, Characterization and Bacteriophage Control of Salmonella from selected salad vegetables |
| state | Terengganu |
| subject | Dissertations, Academic Salmonella — Malaysia Bacteriophages — Therapeutic use Drug resistance in microorganisms Foodborne diseases — Malaysia Salmonella infections — Prevention Vegetables — Microbiology |
| summary | Several foodborne outbreaks related to raw vegetable consumption due to Salmonella have been reported worldwide. Multiple antibiotic resistant Salmonella poses greater risk of infection in consumer. Thus, this study aimed to determine the occurrence of Salmonella in salad vegetables with their antimicrobial susceptibility profiles, virulence genes and also their genetic relatedness. This study also aimed to isolate and characterize lytic bacteriophages to control Salmonella. Samples of salad vegetables and environmental were collected from farms (n = 270), wet markets (n = 216) and supermarkets (n = 180) in Kuala Terengganu and Kuala Nerus, Terengganu.The samples were analyzed for the presence of Salmonella according to International Standard protocol ISO 6579:2002(E) and serotyping was performed by Ipoh Public Health Laboratory. The isolated Salmonella were tested for susceptibility against 20 antibiotics. Multiplex PCR assay was done to detect the presence of 15 virulence genes in Salmonella isolates. The genetic relatedness of Salmonella isolates was characterized using ERIC-PCR and BOX-PCR typing methods. Lytic Salmonella bacteriophages were isolated using the double agar overlay plaque assay and characterized for stability, morphology, anti-Salmonella and anti-biofilm activities.Out of 666 salad vegetables, 8.71% were Salmonella positive with 2.96% from farms, 20.37% from wet markets and 3.33% from supermarkets. Among the isolates, 23 Salmonella serovars were identified, the most predominant was Salmonella Weltevreden (20.69%), followed by Salmonella Albany (10.34%) and Salmonella Hvittingfoss (8.62%). Within the isolates, 34.48% exhibited resistance to at least one antibiotic tested. Resistances among isolates were in the highest rate for ampicillin (20.69%), followed by tetracycline (18.97%), doxycycline (17.24%) and trimethoprim-sulfamethoxazole (17.24%). Multidrug resistance (MDR) was identified in 11 isolates (18.67%). Results showed that 91.38% Salmonella isolates carried more than 11 virulence genes.Major clusters of Salmonella were observed at a genetic distance percentage of 90% for both ERIC- and BOX-PCR with discriminatory index of 0.92 and 0.87, respectively. Two Salmonella bacteriophage isolates, SH1 and SH2 were double-stranded DNA phages which belonged to the family Siphoviridae. Both bacteriophages have broad host with capability of inhibiting 17 and 16 different serovars of Salmonella, respectively. The optimal multiplicity of infection of both bacteriophages was 1 with good pH tolerance (pH 5–11) and thermal stability (4–50°C). SH1 and SH2 bacteriophages have the latent periods of 20 min and 10 min with average burst sizes of 59 and 52 PFU/cell, respectively.A total of 0.31 ± 0.01 and 0.32 ± 0.04 log CFU/ml viable cell of Salmonella were significantly reduced from initial count after treatment with SH1 and SH2 for 24 h, respectively. Furthermore, SH1 and SH2 were found capable to reduce Salmonella biofilm of 100% and 89.40% after 24 h treatment, respectively. MDR and virulent Salmonella were found to contaminate salad vegetables, particularly from wet markets. Bacteriophages SH1 and SH2 were identified as potential biocontrol agents for Salmonella in food with good stability and broad-spectrum features. |
| title | 2024_Detection, Characterization and Bacteriophage Control of Salmonella from selected salad vegetables |
| title_full | 2024_Detection, Characterization and Bacteriophage Control of Salmonella from selected salad vegetables |
| title_fullStr | 2024_Detection, Characterization and Bacteriophage Control of Salmonella from selected salad vegetables |
| title_full_unstemmed | 2024_Detection, Characterization and Bacteriophage Control of Salmonella from selected salad vegetables |
| title_short | 2024_Detection, Characterization and Bacteriophage Control of Salmonella from selected salad vegetables |
| title_sort | 2024_detection, characterization and bacteriophage control of salmonella from selected salad vegetables |