Journal Article

Multidrug-resistant Aeromonas bacteria prevalence in Nile tilapia broodstock

Sherif, Ahmed H., Kassab, Amina S.

2023

Overview

Background Aeromonas hydrophila is an opportunistic pathogen. Thus, it has received significant attention mainly in the fish sectors with high production scales. Nile tilapia broodstock confined in the environment of fish hatcheries can be stressed. Hence, they are vulnerable to A. hydrophila. Results Sequencing of the gyr B gene revealed the presence of 18 different A. hydrophila strains (kdy 10,620–10,637), which were deposited in the NCBI under accession numbers ON745861–ON745878. The median lethal doses of the isolates ranged from 2.62 × 10 4 to 3.02 × 10 6  CFU/mL. Antibiotic resistant genes, sulfonamide (sul1) and tetracycline (tetA) were found in the eighteen isolates . Approximately 83.3% of A. hydrophila strains were sensitive to ciprofloxacin and florfenicol. Further, eight A. hydrophila strains had high MDR indices at 0.27–0.45. All isolates presented with hemolysin activity. However, only 72.22% of them had proteolytic activity, and only 61.11% could form biofilms. Bacterial isolates harbored different pattern virulence genes, the heat-stable cytotonic enterotoxin (ast), cytotoxic enterotoxin (act), and hemolysin (hly) genes were the most prevalent. Also, a trial to inhibit bacterial growth was conducted using titanium dioxide nanoparticles (TiO 2 NPs) with three sizes (13, 32, and 123 nm). If A. hydrophila strains with a high MDR index were tested against TiO 2 NPs (20 µg/mL) for 1, 12, and 24 h, those with a small size had a greater bactericidal action than large ones. Bacterial strains were inhibited at different percentages in response to TiO 2 NP treatment. Conclusions Nile tilapia broodstock, mortality is associated with different A. hydrophila strains , which harbored virulent and MDR genes. Furthermore, TiO 2 NPs had bactericidal activity, thereby resulting in a considerable reduction in bacterial load.

• Publisher: BioMed Central,BioMed Central Ltd,Springer Nature B.V,BMC
• Subject: Aeromonas / Aeromonas hydrophila - genetics / Analysis / Animals / Anti-Bacterial Agents - pharmacology / Antibiotic resistance / Antibiotics / Aquaculture / Aquaculture industry / Bacteria / Bacterial infections / Bactericidal activity / Biofilms / Biological Microscopy / Biomedical and Life Sciences / Brain research / Cichlids - microbiology / Ciprofloxacin / Composition / Contamination / Cytotoxicity / Disease / Diseases / Drug resistance / Drug resistance in microorganisms / Enterotoxins - genetics / Fish / Fish Diseases - microbiology / Fish hatcheries / Florfenicol / Fresh water / Genes / Genetic aspects / Gram-Negative Bacterial Infections - microbiology / Gram-Negative Bacterial Infections - veterinary / Gram-positive bacteria / Growth / Hatcheries / Health aspects / Hemolysin Proteins / Life Sciences / Microbiology / Multidrug resistance / Multidrug resistant organisms / Mycology / Nanoparticles / Nile tilapia; Multidrug resistant; Aeromonas bacteria; Hatcheries / Opportunist infection / Oreochromis niloticus / Parasitology / Pathogens / Phylogenetics / Prevalence / Prevention / Proteolysis / Scales / Seafood industry / Strains (organisms) / Sulfonamides / Tetracycline / Tetracyclines / Thermal stability / Tilapia / Titanium dioxide / Virology / Virulence / Virulence (Microbiology)