Antibiotic contamination in the marine environment forms an emerging threat to marine ecosystems. This study aimed to compare the gut and coelomic microbiota of Stichopus ocellatus with sediments between two coastal districts of Pahang, which potentially conferring as putative biomarkers for sediment pollution monitoring. The composition of the bacteria communities was determined using 16S rRNA V3-region gene amplicon sequencing, while hybrid whole-genome sequencing was employed to analyze the genome of Vibrio parahaemolyticus. The trace elements and antibiotic compositions were access using high-throughput spectrometry. The alpha- and beta-diversity of bacteria in gut and sediment samples from Kuantan differed substantially within (p-value = 0.017604) and between samples (p-value <0.007), respectively. Vibrio genera predominated in Kuantan samples, while Flavobacterium and Synechococcus_E genera predominated in Pekan samples. Vibrio parahaemolyticus revealed the presence of tet(35) and blaCARB₋₃₃ genes that conceived resistance towards tetracycline and beta-lactam antibiotics, respectively, which were detected in sediment and gut samples.

To examine the influence of anthropogenic activities on the marine ecosystem around the Andaman and Nicobar Islands, a study was conducted to investigate the abundance of heterotrophic, indicator and pathogenic bacteria during the monsoon season. We noticed the higher abundance of heterotrophic, indicator (Escherichia coli and Enterococcus faecalis) and pathogenic bacterial counts (Aeromonas hydrophila, Enterobacter aerogens, Escherichia coli strain O157:H7, Shigella dysenteriae and Vibrio parahaemolyticus) near the 10ᵒ channel, which is the principal route to reach Andaman mainland. Most of the stations are offshore (chosen to cover shipping tracks) at a distance ranging from 41 to 266 km from the coast. The nearest station to the coast was at 21 km away. Apart from those mentioned above, several other pathogenic bacteria were also detected such as Klebsiella pneumoniae, Salmonella paratyphi, Vibrio cholera and Vibrio vulnificus but they are sparsely detected at few stations only.

In characterization of food borne pathogens from the environment, assessment of virulence, genetic diversity and AMR are essential preludes to formulate preventive strategies and to combat the spread. This study aimed to identify and characterize pathogenic Vibrio parahaemolyticus in the coastal aquaculture farms of Kerala, India. Twenty-seven β-haemolytic V. parahaemolyticus were isolated from 7 out of 40 farms studied. Among the 27 isolates, 15 possessed the tdh gene and 4 had trh. ERIC PCR and PFGE illustrated the presence of pathogenic isolates that shared genetic similarity with clinical strains. One pathogenic isolate was identified to be multidrug resistant (MDR) and 59% exhibited a MAR index of 0.2 or above. Seventy four percent of the pathogenic isolates were ESBL producers and 3.7% of them were carbapenemase producers phenotypically. This asks for adoption of control measures during farming to prevent the transmission of pathogenic V. parahaemolyticus to the environment and food chain.

Vibrio parahaemolyticus can cause severe gastroenteritis, septicaemia and even death in humans. Continuous monitoring of V. parahaemolyticus contamination in aquatic products is imperative for ensuring food safety. In this study, we isolated and characterized 561 V. parahaemolyticus strains recovered from 23 species of commonly consumed shellfish, crustaceans, and fish collected in July and August of 2017 in Shanghai, China. The bacterium was not isolated from two fish species Carassius auratus and Parabramis pekinensis. The results revealed a very low occurrence of pathogenic V. parahaemolyticus carrying the toxin genes trh (0.2%) and tdh (0.0%). However, high percentages of resistance to the antimicrobial agents ampicillin (93.0%), rifampin (82.9%), streptomycin (75.4%) and kanamycin (50.1%) were found. A high incidence of tolerance to the heavy metals Hg²⁺ (74.7%) and Zn²⁺ (56.2%) was also observed in the isolates. ERIC-PCR-based fingerprinting of MDR isolates (77.5%) revealed 428 ERIC-genotypes, demonstrating remarkable genetic variation among the isolates. The results of this study support the urgent need for food safety risk assessment of aquatic products.

The aquatic environment can represent a reservoir of antimicrobial resistance genes. In the present study, phenotypical, biochemical and molecular techniques were used to screen a collection of marine strains isolated in Italian aquaculture farms to investigate their beta-lactam resistance profiles. The genome of 12 carbapenemase and/or beta-lactamase producing strains was sequenced and a phylogenetic analysis of the beta-lactamases found in their chromosomes was performed. Gene annotation and prediction revealed the presence of blaAₘₚC and blaOXA₋₅₅₋ₗᵢₖₑ in all the Shewanella algae isolates whereas in Vibrio anguillarum and Vibrio parahaemolyticus strains, blaAₘₚC and blaCARB₋₁₉ were found, respectively. Multiple alignments of OXA-55-like and AmpC protein sequences showed different point mutations. Finally, comparisons between enzyme phylogeny and strain clusterization based on sampling sites and dates indicate the diffusion of specific Multi Drug Resistant (MDR) Shewanella algae clones along the Italian Adriatic coast.

Antimicrobial resistance genes in aquaculture environments have attracted wide interest, since these genes pose a severe threat to human health. This study aimed to explore the possible mechanisms of the ciprofloxacin resistance of Vibrio parahaemolyticus (V. parahaemolytiucs) in aquaculture environments, which may have been affected by the biofertilizer utilization in China. Plasmid-mediate quinolone resistance (PMQR) genes, representative (fluoro)quinolones (FNQs), and ciprofloxacin-resistance isolates in biofertilizer samples were analyzed. The significantly higher abundance of oqxB was alarming. The transferable experiments and Southern blot analysis indicated that oqxB could spread horizontally from biofertilizers to V. parahaemolyticus, and two (16.7%) trans-conjugants harboring oqxB were provided by 12 isolates that successfully produced OqxB. To the best of our knowledge, this study is the first to report PMQR genes dissipation from biofertilizers to V. parahaemolyticus in aquaculture environments. The surveillance, monitoring and control of PMQR genes in biofertilizers are warranted for seafood safety and human health.

Vibrio parahaemolyticus is a major gastroenteritis-causing pathogen in Korea. Recent studies have reported that heavy metal and antimicrobial resistance in bacteria are related. In this study, we investigated heavy metal and antimicrobial resistance in wild strains of V. parahaemolyticus. First, we isolated and characterized 38 V. parahaemolyticus strains (toxR-positive) from shellfish collected from the West Sea of Korea between May and November 2018. Antibiotic and heavy metal resistance in the 38 strains were tested by disk diffusion assay and broth dilution assay, respectively. Then, we selected seven strains that showed resistance to cobalt (Co²⁺) and copper (Cu²⁺), to examine the relationship between heavy metal resistance and antimicrobial resistance. After heavy metal (Co²⁺ and Cu²⁺) pretreatment, the seven strains exhibited increased resistance to kanamycin, streptomycin, tetracycline, and gentamycin. Likewise, antimicrobial pretreatment resulted in increased heavy metal tolerance.

Environmental antimicrobial resistance (AMR) has drawn increasing attention due to its great risk to human health. The aim of this study was to investigate AMR and genotyping of Vibrio parahaemolyticus isolates (n = 114) recovered from shrimp mariculture environment in China. The isolates exhibited a high rate of resistance to streptomycin (78.9%), ampicillin (64.9%) and gentamicin (53.5%). Furthermore, multi-drug resistance was highly prevalent (61.4%), in which 95.9% of these ampicillin-resistant isolates were primarily mediated by blaCARB-17. Surprisingly, doxycylcine, florfenicol, and trimethoprim/sulfamethoxazole (TMP/SMZ) resistance genes occurred in susceptible isolates. Moreover, 114 isolates were grouped into unique pulsed field gel electrophoresis patterns. These findings suggest the need for the prudent use of antimicrobial agents on mariculture farms, in order to control the dissemination of antimicrobial resistant V. parahaemolyticus.

The influence of environmental parameters on the total and pathogenic Vibrio parahaemolyticus seasonal densities in American oysters (Crassostrea virginica) was evaluated for 1year. Harvesting site A yielded the highest mean densities of V. parahaemolyticus tlh+, tdh+/trh−, tdh−/trh+ and tdh+/trh+ during spring season at 2.57, 1.74, 0.36, and −0.40 log10MPN/g, respectively, and tdh+/orf8+ during winter season (0.90 log10MPN/g). V. parahaemolyticus tlh+ densities were associated to salinity (R2=0.372, P<0.022), tdh+/trh+ to turbidity (R2=0.597, P<0.035), and orf8+ to temperature, salinity, and pH (R2=0.964, P<0.001). The exposure to salinity and temperature conditions during winter and spring seasons regulated the dynamics of V. parahaemolyticus harboring potentially pathogenic genotypes within the oyster. The adaptive response of V. parahaemolyticus to seasonal environmental changes may lead to an increase in survival and virulence, threatening the seafood safety and increasing the risk of illness.

A presumed Vibrio parahaemolyticus isolate from Chesapeake Bay, Maryland, USA was previously reported to grow on phenanthrene, a polyaromatic hydrocarbon (PAH) found in crude oil. Following the Deepwater Horizon oil spill in the Gulf of Mexico, concerns were raised that PAH-degrading V. parahaemolyticus could increase in abundance, leading to elevated risks of disease derived from shellfish consumption. To assess this possibility, we examined responses to naphthalene and phenanthrene of 17 coastal Louisiana environmental V. parahaemolyticus isolates representing five distinct genotypes. Isolates were obtained immediately after the spill began and after oil had reached the Louisiana coast. None of the isolates grew on or oxidized either substrate and a naphthalene degradation product, 1-naphthol, substantially inhibited growth of some isolates. The use of PAH by V. parahaemolyticus is unusual, and an increase in human health risks due to stimulation of V. parahaemolyticus growth by oil-derived PAH under in situ conditions appears unlikely.