Distribution of phenotypic and genotypic antimicrobial resistance and virulence genes in Vibrio parahaemolyticus isolated from cultivated oysters and estuarine water

A total of 594 Vibrio parahaemolyticus isolates from cultivated oysters (n = 361) and estuarine water (n = 233) were examined for antimicrobial resistance (AMR) phenotype and genotype and virulence genes. Four hundred forty isolates (74.1%) exhibited resistance to at least one antimicrobial agent and 13.5% of the isolates were multidrug-resistant strains. Most of the V. parahaemolyticus isolates were resistant to erythromycin (54.2%), followed by sulfamethoxazole (34.7%) and trimethoprim (27.9%). The most common resistance genes were qnr (77.8%), strB (27.4%) and tet(A) (22.1%), whereas blaTEM (0.8%) was rarely found. Four isolates (0.7%) from oysters (n = 2) and estuarine water (n = 2) were positive to tdh, whereas no trh-positive isolates were observed. Significantly positive associations among AMR genes were observed. The SXT elements and class 1, 2 and 3 integrons were absent in all isolates. The results indicated that V. parahaemolyticus isolates from oysters and estuarine water were potential reservoirs of resistance determinants in the environment. This increasing threat of resistant bacteria in the environment potentially affects human health. A 'One Health' approach involved in multidisciplinary collaborations must be implemented to effectively manage antimicrobial resistance.

Vibrio and major commercially important vibriosis diseases in decapod crustaceans

Bacteria fromthe Vibriogenus are autochthonous to aquatic environments and ubiquitous in aquaculture production systems. Many Vibrio species are non-pathogenic and can be commonly found in healthy farmed aquatic animals. However, some Vibrio species and strains are pathogenic leading to a variety of 'vibriosis' diseases. These diseases can have a significant negative impact on animal production, including farmed crustaceans such as shrimps, lobsters, and crabs. As such, vibriosis can pose a threat to meeting growing food demand and global food security. Preventive management is essential to avoid the onset of vibriosis. This includes a robust health management plan, the use of prophylaxis and treatment measures, and enhancing animal health through nutrition. Furthermore, the use of probiotics, prebiotics, synbiotics, quorum sensing disruption, green water, biofloc, bacteriophages, and immune priming could also play a role in preventing and controlling a vibriosis outbreak. This review aims to inform and update the reader about the current state of knowledge about Vibrio and associated vibriosis in farmed crustaceans (i.e. shrimp, lobster, and crabs). Furthermore, the review will identify potential knowledge gaps in the literature, which serves as a basis for future research priorities.

Isolation, Molecular Characterization and Antibiotic Susceptibility Pattern of Vibrio parahaemolyticus from Aquatic Products in the Southern Fujian Coast, China

Vibrio parahaemolyticus is a major gastroenteritis-causing pathogen in many Asian countries. Antimicrobial resistance in V. parahaemolyticus has been recognized as a critical threat to food safety. In this study, we determined the prevalence and incidence of antimicrobial resistance in V. parahaemolyticus in the southern Fujian coast, China. A total of 62 isolates were confirmed in retail aquatic products from June to October of 2018. The serotype O3:K6 strains, the virulence genes tdh and trh, antibiotic susceptibility and molecular typing were investigated. Then plasmid profiling analysis and curing experiment were performed for multidrug-resistant strains. The results showed that the total occurrence of V. parahaemolyticus was 31% out of 200 samples. Five strains (8.1%) out of 62 isolates were identified as the V. parahaemolyticus O3:K6 pandemic clone. A large majority of isolates exhibited higher resistance to penicillin (77.4%), oxacillin (71%), ampicillin (66.1%) and vancomycin (59.7%). Seventy-one percent (44/62) of the isolates exhibited multiple antimicrobial resistance. All 62 isolates were grouped into 7 clusters by randomly amplified polymorphic DNA, and most of the isolates (80.6%) were distributed within cluster A. Plasmids were detected in approximately 75% of the isolates, and seven different profiles were observed. Seventy-six percent (25/33) of the isolates carrying the plasmids were eliminated by 0.006% SDS incubated at 42°C, a sublethal condition. The occurrence of multidrug-resistant strains could be an indication of the excessive use of antibiotics in aquaculture farming. The rational use of antimicrobial agents and the surveillance of antibiotic administration may reduce the acquisition of resistance by microorganisms in aquatic ecosystems.

An improved recombinase polymerase amplification assay for visual detection of Vibrio parahaemolyticus with lateral flow strips

Vibrio parahaemolyticus is an important pathogenic bacterium in both food safety management and mariculture. Rapid and accurate detection technologies are critical for effective control of its outbreak and spreading. Conventional technologies and polymerase chain reaction (PCR)-based approaches have limited usage because of the requirement of laboratory instruments and trained personnel. Using the isothermal recombinase polymerase amplification (RPA) technology, several detection assays have been developed with added convenience. Combining the lateral flow strip (LFS) test with RPA can further simplify the detection. In this study, an improved RPA assay using LFS for visual detection of V. parahaemolyticus was developed. Primers were designed targeting the virulence genes and screened for amplification efficiency, nonspecific amplification, and primer-dimer formation. Probes were designed for the best primer pairs, and the weakness of LFS tests, being easily affected by primer-dependent artifacts, was overcome by sequence modifications on primers and probe. The RPA-LFS assay took 25 min at 35 to 45 °C, and showed excellent specificity. It detected as low as one colony forming unit (CFU) of V. parahaemolyticus per reaction without DNA purification, or 10 CFU/10 g spiked food samples with 2 hr of enrichment. The detection limit was better than the currently available RPA-based detection methods. Application of the RPA-LFS assay for simulated samples or real clinical samples showed accurate and consistent detection results compared to bioassay and quantitative PCR. The RPA-LFS assay provided a rapid, accurate, and convenient V. parahaemolyticus detection method suitable for on-site detection in resource-limited conditions. PRACTICAL APPLICATION: This research developed a rapid and visual detection technology for Vibrio parahaemolyticus that is not dependent on complicated equipment. The detection process takes 25 min and the result is read with the naked eye. A detection kit can be developed based on this technology for on-site detection of V. parahaemolyticus in resource-limited regions for food safety management and mariculture.

Ocorrência de bactérias patogênicas e deteriorantes em sashimi de salmão: avaliação de histamina e de susceptibilidade a antimicrobianos

Resumo O estudo das condições higiênico sanitárias de alimentos cárneos consumidos crus, como o sashimi, é necessário para definir sua qualidade e possíveis consequências para a saúde humana. Foram coletadas 60 amostras de sashimi de salmão (Salmo salar), de dez restaurantes na cidade de São Luís, Maranhão - Brasil, sendo seis de cada local. As amostras foram analisadas para contagem de coliformes a 35 °C, coliformes a 45 °C e Staphylococcus coagulase positiva e negativa, identificação da presença de Escherichia coli, Salmonella sp., Vibrio parahaemolyticus e Aeromonas spp, teste de suscetibilidade a antimicrobianos dos isolados e quantificação de histamina nas amostras. Os resultados mostraram elevadas contagens de coliformes a 35 °C e 12 amostras com >102 NMP/g de coliformes a 45 °C, presença de E. coli e de Salmonella sp. em 3 amostras cada, ausência de V. parahaemolyticus e Staphylococcus coagulase positiva e contagem de Staphylococcus coagulase negativa entre <20 e 5,0x104 UFC/g, presença de Aeromonas spp. em 95% das amostras, sendo 60 isolados A. hydrophila e 6 A. caviae. Para suscetibilidade aos antimicrobianos, os isolados de E. coli foram sensíveis a CPM, CTX, LVX, PPT e SUT, dois resistentes a AMP; um resistente a GEN, um a AMI e um a AMC. Os isolados de Salmonella foram sensíveis a AMC, CPM, CFO, CRX, GEN, LVX e PPT, um resistente a AMI e um a AMP e SUT. Os isolados de Aeromonas foram resistentes em média a cinco dos antimicrobianos, sendo a AMP (97%), a CRX (90,9%) e a AMC (77,3%), e 81,8% foram sensíveis ao CPM. Os níveis de histamina variaram de 44,06 ± 0,74 a 505,46 ± 8,83 mg/kg, sendo 21 das amostras com níveis superiores a 100 mg/kg. As amostras apresentaram condições higiênicos sanitárias insatisfatórias e riscos para a saúde pública, por identificação de bactérias patogênicas e elevadas concentrações de histamina capazes de causar intoxicação escombróide, e ainda, isolados com multirresistência aos antimicrobianos testados.

Delineating the origins of the multidrug-resistant pathogens in ornamental fish farms by multilocus sequence typing and identification of a novel multidrug-resistant plasmid

To evaluate the overuse of antibiotics and to identify the origin of pathogens in the ornamental fish industry, we conducted a field investigation of three representative fish farms in Liaoning province, China. Drug-resistant pathogens in the fishponds and groundwater were isolated and subtyped by multilocus sequence typing (MLST). In total, 33 pathogenic strains, including Aeromonas veronii and five other pathogens, were isolated from diseased fish and from groundwater. MLST revealed that A. veronii obtained from diseased fish in three fish farms can be subtyped into four sequence types, which were also identified in the corresponding groundwater. All of the isolates obtained from diseased fish showed resistance to at least four antibiotics. Notably, Citrobacter freundii JY-17 exhibited resistance to the majority of the antibiotics and was a carrier of a megaplasmid with 15 drug resistance genes. PCR assays targeting β-lactam, kanamycin, macrolide, phenicol, sulfonamide, and trimethoprim resistance genes in the pathogens from the diseased fish and groundwater were also conducted. The results revealed strong correlations between antibiotic treatment and increased antimicrobial resistance in fish pathogens. The results suggested that groundwater is the origin of the pathogens in ornamental fish. Antibiotic treatment of ornamental fish promoted the emergence of resistant pathogens.

Rapid subtyping of pathogenic and nonpathogenic Vibrio parahaemolyticus by fourier transform infrared spectroscopy with chemometric analysis

Vibrio parahaemolyticus which naturally inhabits marine and estuarine environment represents pathogenic strains (virulence genes tdh or trh positive) and non-pathogenic strains (virulence genes negative). In this study, a rapid method for subtyping pathogenic and non-pathogenic V. parahaemolyticus was established using fourier transform infrared (FTIR) spectroscopy with chemometric analysis. This method targeted three strains of genotypes of V. parahaemolyticus including tdh positive, trh positive and virulence gene-negative (nonpathogenic) V. parahaemolyticus. The FTIR absorption spectra between 1800 and 900 cm^-1 highlighted the most distinctive variations and were the most useful for characterizing the three bacteria. The successful differentiation and identification of the three bacteria could be accomplished in less than 1 h by FTIR using principal component analysis (PCA), or another cluster model of hierarchical cluster analysis (HCA). The method was verified by analyzing spiked V. parahaemolyticus fish samples. Furthermore, all of ten clinical isolates of V. parahaemolyticus were identified as tdh-positive, none of the clinical isolates were trh-positive, and all of ten environmental isolates were identified as non-pathogenic by the subtyping method, which were confirmed by PCR assays. All data demonstrated that the newly established subtyping method by FTIR is practical, time-saving, labor-saving, specific and cost-effective, especially suitable for the basic laboratories of CDC and port quarantine departments to perform suiveillance and epidemiological traceability of pathogenic V. parahaemolyticus.

Isolation, molecular characterization, and antibiotic resistance patterns of Vibrio parahaemolyticus isolated from coastal water in the Eastern Province of Saudi Arabia

Vibrio parahaemolyticus is a Gram-negative halophilic marine microbe that causes gastroenteritis, wound infections, and septicemia in humans. Since the emergence of the pandemic clone O3:K6, V. parahaemolyticus has become a globally well-known pathogen. In this study, 375 seawater samples collected from the Eastern coast of Saudi Arabia were tested for the presence of V. parahaemolyticus. Three hundred and forty samples were determined positive for V. parahaemolyticus using traditional microbiological techniques. The genes toxR and tlh were detected via polymerase chain reaction (PCR) in 41 isolates from 23 samples (6%). Thermostable direct hemolysin (tdh) and thermostable direct hemolysin-related hemolysin (tdh) are the most common virulence genes associated with V. parahaemolyticus. As such, four isolates were tdh+ (1%) and another four were trh+ (1%). No evidence of pandemic clones was detected using group-specific PCR (GS-PCR). Samples were tested for antibiotic susceptibility against 28 agents. The vast majority of samples exhibited high resistance to carbenicillin (98%), ampicillin (88%), and cephalothin (76%). The multiple antibiotics resistance index was &gt;0.2 for 35% of the isolates. The results of this study confirm the presence of V. parahaemolyticus in the Eastern coast of Saudi Arabia. This is the first report of tdh+ and trh+ isolates from this area.

High flux isothermal assays on pathogenic, virulent and toxic genetics from various pathogens

Toxins, encoding by virulence factors, are significant cause of food-borne illnesses and death in the worldwide. Loop-mediated isothermal amplification (LAMP) is one of the widely used methodologies because of the high sensitivity, specificity and rapidity. Nowadays, LAMP has been regarded as an innovative gene amplification technology and emerged as an alternative to PCR-based methodologies in identification of the pathogenic virulent and toxic genetics. The high sensitivity of LAMP enables detection of the pathogens in sample materials even without time consuming and sample preparation. Therefore, we review the typical characteristics of LAMP assay, recent advance in detection of virulence factors and the application of LAMP assay on detection of four commonly virulence factors. As concluded, with the advantages of rapidity, simplicity, sensitivity, specificity and robustness, LAMP is capable of identification the virulence factors. Moreover, the main purpose of this review is to provide theory support for the application of LAMP assay on the virulence factors identification.

Vibrio Parahaemolyticus: A Review on Distribution, Pathogenesis, Virulence Determinants and Epidemiology

Vibrio parahaemolyticus is a Gram-negative, halophilic bacterium isolated from marine environments globally. After the consumption of contaminated seafood, V. parahaemolyticus causes acute gastroenteritis. To initiate infection, a wide range of virulence factors are required. A complex group of genes is known to participate in the pathogenicity of V. parahaemolyticus; however, to understand the full mechanism of infection, extensive research is yet required. V. parahaemolyticus has become the leading cause of seafood-related gastroenteritis in Japan, the United States and several other parts of the world. In addition, outbreaks caused by the pandemic clone of this organism are escalating and spreading universally. To minimize the risk of V. parahaemolyticus infection and warrant the safety of seafood, collaboration between governments and scientists is required. We herein provide an updated review of the pathogenicity determinants and distribution of V. parahaemolyticus to deliver a better understanding of the significance of V. parahaemolyticus and its host-pathogen interactions.

Microbiological evaluation of fish

Fish meat has a specific composition that positively influences human health. Thanks to this composition, it is an excellent nutritional medium for growth and reproduction of undesirable microorganisms, which may cause spoilage and they can also lead to alimentary illnesses. Microbiota of fish is dominated by Gram negative and psychrophilic bacteria. Microbial contamination causes fish deterioration and leads to the end of its shelf-life when reaches levels between 107 and 109 CFU.g-1. The most appropriate temperature for storage of fish is between -1 °C and 4 °C and the ideal relative air humidity is 80 to 85%. The objective of the work was to evaluate microbiological quality of fresh fish (Rainbow Trout, Atlantic Salmon, Atlantic Cod) bought in various types of stores in the Czech Republic and to evaluate if different storage temperatures have influence on the quantity of microorganisms. The following microorganisms were monitored: the total aerobic count (TAC), coliform bacteria, E. coli, Salmonella spp. and Vibrio parahaemolyticus. Based on the obtained results it is possible to state that difference between individual stores (p >0.05) in the total aerobic count and the quantity of E. coli (except for cod) was not proven. After 2 days of storage there was increase (p ˂0.05) of the total aerobic count in case of all monitored fish species from all stores. In case of coliform bacteria and E. coli there was increase (p ˂0.05) of their quantity in a majority of the analysed samples. Different storage temperature (4 °C and 8 °C) did not have influence (p ˂0.05) on the TAC, the quantity of coliform bacteria (except for cod) and the quantity of E. coli (except for trout).