Risks Associated with Fish and Seafood

Evaluation of public health impact risks associated with bacterial antimicrobial resistome in tropical coastal environments

This study investigated antimicrobial resistance genes (ARGs) and microbial communities in Singapore's tropical coastal environments, comparing natural marine waters with aquaculture sites using metagenomic analysis. Results show consistently low ARG levels in natural ecosystems, whereas aquaculture sites exhibit elevated ARG concentrations, particularly those relevant to human pathogens, with considerably temporal fluctuations likely driven by human activities and seasonal factors. Additionally, aquaculture sites were found to host mobile genetic elements (MGEs) that may facilitate ARG spread, identifying aquaculture as a key reservoir of resistance genes with potential public health implications. These findings underscore distinct prevalence of ARG between natural and managed marine environments and highlight the need for continued surveillance to monitor ARG dynamics in coastal areas. By elucidating the potential for ARGs to transfer from aquaculture environments to the human food chain, this research emphasizes the importance of sustainable aquaculture practices and proactive ARG management strategies to mitigate antimicrobial resistance risks posed by tropical coastal ecosystem.

High risk of Vibrio pathogen and antibiotic resistance transfer in live seafood wet markets of Shantou, China

The global demand for seafood necessitates robust food safety practices, particularly within traditional wet markets. This study investigated the microbiomes of live Japanese mantis shrimp (JMS) and their associated environments (water and biofilm) in local wet markets to assess the risk of pathogen and antibiotic resistance gene (ARG) transfer. Metagenomic analysis showed a significant link between microbiome composition and the type of sample (shrimp, biofilm, and water). While several known human pathogens were associated with shrimp samples, water and biofilm samples exhibited higher abundances of ARGs, suggesting a high risk of pathogen and ARG transfer from the market environment. Notably, this study focused on the diversity and characterization of poorly understood Vibrio species associated with JMS. The prevalence of β-lactam resistance genes in Vibrio isolates, combined with a comparative genomic analysis of several species, highlights this concern. Our study emphasizes the need to improve hygiene practices in wet markets to reduce foodborne illness risks and address antibiotic resistance. This work represents, to our knowledge, the first comparative genomic analysis of Vibrio species in the context of JMS and wet market seafood safety.

Cross-sectional analysis of risk factors associated with Mugil cephalus in retail fish markets concerning methicillin-resistant Staphylococcus aureus and Aeromonas hydrophila

Introduction

Aeromonas hydrophila and methicillin-resistant Staphylococcus aureus (MRSA) are potent bacterial pathogens posing major hazards to human health via consuming fish harboring these pathogens or by cross-contamination beyond the contaminated environment. The aim of this study was to determine risk variables associated with the presence of certain pathogenic bacteria from Mugil cephalus fish in retail markets in Egypt. The virulence genes of A. hydrophila and S. aureus were also studied. Furthermore, the antibiotic sensitivity and multidrug resistance of the microorganisms were evaluated.

Methods

In a cross-sectional investigation, 370 samples were collected from mullet skin and muscle samples, washing water, fish handlers, knives, and chopping boards. Furthermore, fish handlers' public health implications were assessed via their response to a descriptive questionnaire.

Results

S. aureus and Aeromonas species dominated the investigated samples with percentages of 26.76% and 30.81%, respectively. Furthermore, A. hydrophila and MRSA were the predominant recovered bacterial pathogens among washing water and knives (53.85% and 46.66%, respectively). The virulence markers aerA and hlyA were found in 90.7% and 46.5% of A. hydrophila isolates, respectively. Moreover, the virulence genes nuc and mec were prevalent in 80% and 60% of S. aureus isolates, respectively. Antimicrobial susceptibility results revealed that all A. hydrophila isolates were resistant to amoxicillin and all MRSA isolates were resistant to amoxicillin and ampicillin. Remarkably, multiple drug resistance (MDR) patterns were detected in high proportions in A. hydrophila (88.37%) and MRSA (100%) isolates. The prevalence of Aeromonas spp. and S. aureus had a positive significant correlation with the frequency of handwashing and use of sanitizer in cleaning of instruments. MRSA showed the highest significant prevalence rate in the oldest age category.

Conclusion

The pathogenic bacteria recovered in this study were virulent and had a significant correlation with risk factors associated with improper fish handling. Furthermore, a high frequency of MDR was detected in these pathogenic bacteria, posing a significant risk to food safety and public health.

Microsporidia in Commercially Harvested Marine Fish: A Potential Health Risk for Consumers

Microsporidia are widely spread obligate intracellular fungal pathogens from vertebrate and invertebrate organisms, mainly transmitted by contaminated food and water. This study aims to detect the presence of major human-pathogenic microsporidia, i.e., Enterocytozoon bieneusi, Encephalitozoon intestinalis, Encephalitozoon hellem, and Encephalitozoon cuniculi, in the gastrointestinal tract of commercially harvested marine fish from Mediterranean coast of the Comunidad Valenciana, Eastern Spain. A total of 251 fish, 138 farmed fish and 113 wild fish from commercial fishing were tested by SYBR Green real-time PCR, enabling the simultaneous detection of the four targeted species. E. intestinalis/hellem was found in 1.45% of farmed fish and 7.96% of wild fish, while Enterocytozoonidae was detected in 2.90% and 18.58% of farmed and wild fish, respectively. E. cuniculi was not detected in any of the analyzed specimens. To the authors' knowledge, this is the first report of E. intestinalis/hellem in fish, particularly in marine fish. Although the role of fish in these species' epidemiology remains unknown, this finding points out a potential public health risk linked to fish consumption. Further studies are necessary to characterize these microsporidia in fish hosts better and to elucidate their epidemiological role.

Development of a Tetraplex qPCR for the Molecular Identification and Quantification of Human Enteric Viruses, NoV and HAV, in Fish Samples

Human enteric viruses such as norovirus (NoV) and hepatitis A virus (HAV) are some of the most important causes of foodborne infections worldwide. Usually, infection via fish consumption is not a concern regarding these viruses, since fish are mainly consumed cooked. However, in the last years, raw fish consumption has become increasingly common, especially involving the use of seabass and gilthead seabream in dishes like sushi, sashimi, poke, and carpaccio. Therefore, the risk for viral infection via the consumption of raw fish has also increased. In this study, a virologic screening was performed in 323 fish specimens captured along the Portuguese coast using a tetraplex qPCR optimised for two templates (plasmid and in vitro transcribed RNA) to detect and quantify NoV GI, NoV GII and HAV genomes. A difference of approximately 1-log was found between the use of plasmid or in vitro transcribed RNA for molecular-based quantifications, showing an underestimation of genome copy-number equivalents using plasmid standard-based curves. Additionally, the presence of NoV genomic RNA in a pool of seabass brains was identified, which was shown to cluster with a major group of human norovirus sequences from genogroup I (GI.1) by phylogenetic analysis. None of the analysed fish revealed the presence of NoV GII or HAV. This result corroborates the hypothesis that enteric viruses circulate in seawater or that fish were contaminated during their transportation/handling, representing a potential risk to humans through raw or undercooked fish consumption.

Synergistic Antimicrobial Effectiveness of Plant Essential Oil and Its Application in Seafood Preservation: A Review

The synergistic potential of plant essential oils (EOs) with other conventional and non-conventional antimicrobial agents is a promising strategy for increasing antimicrobial efficacy and controlling foodborne pathogens. Spoilage microorganisms are one of main concerns of seafood products, while the prevention of seafood spoilage principally requires exclusion or inactivation of microbial activity. This review provides a comprehensive overview of recent studies on the synergistic antimicrobial effect of EOs combined with other available chemicals (such as antibiotics, organic acids, and plant extracts) or physical methods (such as high hydrostatic pressure, irradiation, and vacuum-packaging) utilized to reduce the growth of foodborne pathogens and/or to extend the shelf-life of seafood products. This review highlights the synergistic ability of EOs when used as a seafood preservative, discovering the possible routes of the combined techniques for the development of a novel seafood preservation strategy.

Proteomic Strategies to Evaluate the Impact of Farming Conditions on Food Quality and Safety in Aquaculture Products

This review presents the primary applications of various proteomic strategies to evaluate the impact of farming conditions on food quality and safety in aquaculture products. Aquaculture is a quickly growing sector that represents 47% of total fish production. Food quality, dietary management, fish welfare, the stress response, food safety, and antibiotic resistance, which are covered by this review, are among the primary topics in which proteomic techniques and strategies are being successfully applied. The review concludes by outlining future directions and potential perspectives.

Genome Sequencing and Analysis of Bacillus pumilus ICVB403 Isolated from Acartia tonsa Copepod Eggs Revealed Surfactin and Bacteriocin Production: Insights on Anti-Staphylococcus Activity

Here we show that Bacillus pumilus ICVB403 recently isolated from copepod eggs is able to produce, after 48-72 h of growth in Landy medium, extracellular inhibitory compounds, which are active against Staphylococcus aureus ATCC 25923, methicillin-resistant S. aureus (MRSA) ATCC 43300, MRSA-S1, Staphylococcus epidermidis 11EMB, Staphylococcus warneri 27EMB, and Staphylococcus hominis 13EMB. Moreover, these extracellular inhibitory compound(s) were able to potentiate erythromycin against the aforementioned staphylococci. The minimum inhibitory concentration (MIC) of erythromycin was reduced from 32 μg/mL to 8 μg/mL for MRSA ATCC 43300 and MRSA SA-1 strains, and from 32-64 μg/mL to 4 μg/mL for S. epidermidis 11EMB and S. hominis 13EMB strains.The genome sequencing and analysis of B. pumilus ICVB403 unveiled 3.666.195 nucleotides contained in 22 contigs with a G + C ratio of 42.0%, 3.826 coding sequences, and 73 RNAs. In silico analysis guided identification of two putative genes coding for synthesis of surfactin A, a lipopeptide with 7 amino acids, and for a circular bacteriocin belonging to the circularin A/uberolysin family, respectively.