Bactericidal effect of water-washing methods on Vibrio vulnificus contaminated in a raw fish Konosirus punctatus: water type, temperature, and pH

This study aimed to evaluate a method for effectively reducing Vibrio vulnificus contamination in fish based on the type of washing water and method. Texture profiles and sensory evaluations were performed to determine the effect of the developed method on the quality and preference of the samples. The selected fish sample was Konosirus punctatus, which is mainly consumed in Asian countries. Various factors that could affect the survival rate of V. vulnificus were reviewed, including water type, temperature, exposure time, organic acids, pH, and washing methods. As a result, immersion and washing with filtered water with pH adjusted to 4.0 using acetic acid showed a high bactericidal effect of 2.5 log MPN/100 g. Furthermore, this method showed no statistically significant effect on the texture and sensory characteristics of fish. The results of the present study suggest a simple and effective method for preventing V. vulnificus infection in raw fish.

Fulminant necrotizing fasciitis by Edwardsiella tarda in a patient with alcoholic liver cirrhosis: A case report

We herein present a unique and extremely rare fulminant case of Edwardsiella tarda infection-related necrotizing fasciitis. The patient had alcoholic cirrhosis and preferred to consume raw fish. He experienced painful swelling of the right forearm one day after he got a minor injury when falling from the ladder, and visited our hospital. His accompanied symptoms were diarrhea and general fatigue. His consciousness got deteriorated after the admission. The lesion of the right forearm had spread and the color had deteriorated with epidermolysis in a few hours. Necrotizing soft-tissue infection was suspected, and emergency debridement of the swollen forearm was performed 4 hours after the admission. However, unfortunately, he died of sepsis approximately 5 hours later. Histological examination of the biopsy specimen revealed features consistent with those of necrotizing fasciitis. The bacterial cultures of blood and the wound identified E. tarda. Since this microorganism is usually isolated from aquatic environments and can cause intestinal infection, sometimes followed by bacteremia especially in immunocompromised hosts, two possible infection routes were suspected. One route was from the skin injury, leading to bacteremia. Another possible route was per oral: orally taken E. tarda invaded deeper tissues from the intestine and reach the bloodstream, leading to extraintestinal infections, although direct evidence remains elusive. Raw fish eaten 1 week prior is considered to be the most possible contaminated food. Overall mortality rate of E. tarda bacteremia is very high and the clinician should pay attention on characteristic clinical findings of E. tarda infection on cirrhotic patients.

Characterization of ready-to-eat fish surface as a potential source of contamination of Vibrio parahaemolyticus biofilms

The worldwide consumption of ready-to-eat seafood products has steadily increased due to a range of health benefits. However, depending on the handling or cutting process of raw fish, ready-to-eat sashimi can be exposed to microbiological risks that can lead to foodborne infection by marine pathogens. Since surface characteristics are key factors for microbial adhesion and biofilm formation, the present study aims to determine the correlation between raw fish skin properties and Vibrio parahaemolyticus biofilm formation. We analyzed V. parahaemolyticus biofilms (ATCC 17802; initially inoculated ca. 2 or 4 log CFU/cm²) on fish skin (gizzard shad, pomfret, red snapper, and mackerel; fish species served as sashimi without peeling the skin) formed under simulated marine environments (incubating in artificial seawater with rocking motion at 30 °C, the maximum temperature of seasonal seawater) for 24 h. The characteristics of fish skin were determined using confocal laser scanning microscopy/scanning electron microscopy. V. parahaemolyticus showed higher biofilm counts on fish skins than on stainless steel, which was used as a control (P < 0.05). In particular, V. parahaemolyticus formed biofilms with significantly higher levels of bacterial populations on gizzard shad and pomfret (ca. 5 log CFU/cm²; P < 0.05), highlighting the relationship between the biofilm formation level and the characteristics of gizzard shad and pomfret skins. The surface roughness of fish skins, including the main roughness parameters (Ra, Rq, and Rz), influenced the attachment of V. parahaemolyticus (P < 0.05). Additionally, images of V. parahaemolyticus biofilms suggested that different topographical profiles of fish species (e.g., mucus, unique structural features, etc.) could cause V. parahaemolyticus to exhibit different biofilm phenotypes, such as sticking to or entangling on the fish skin surface. The major findings of this study provide various phenotypic adhesions of V. parahaemolyticus to fish skin in considerations of the potential hazard for the consumption of ready-to-eat sashimi served with its skin.

A case of Shewanella algae-induced bacteremia in Japan: Case report and literature review

Shewanella algae (S. algae) is a rare bacterium that causes infectious diseases in humans. Herein, we present a case of an 84-year-old man with S. algae-induced bacteremia and performed a review of 12 cases identified via a literature search and this case. Literature review of previous reports in Japan have revealed that 69.2% of patients with S. algae-induced bacteremia had a history of contact with fresh fish. Appropriate interviews of patients, especially in the hot season, and the accurate identification of the causative bacterium, by using techniques such as MALDI-TOF-MS and genetic testing, are necessary if S. algae or other bacteria from the genus Shewanella are detected in blood-culture tests.

Detection and characterization of Kudoa thunni from uncooked yellowfin tuna (Thunnus albacares) in Southeast Asia

Myxosporean parasites Kudoa spp. have been reported in several marine fish species worldwide. However, little is known about the contamination of these parasites in raw fish in Southeast Asia, where the consumption demand of uncooked fish is increasing. In 2019, the occurrence of several cases of raw yellowfin tuna (Thunnus albacares) obtained from retail shops with the presence of unknown white, nodular cysts within the musculature have raised public health concerns for the consumption of raw marine fish in Vietnam. Microscopic examination revealed numerous myxospores with the quadratic shape of the Kudoidae. Morphologically, stained spores detected in this study are suspected to Kudoa thunni. To confirm the suspected Kudoa species, further examination of the 18S small-subunit (SSU) was conducted and the results of nucleotide sequence analysis obtained from nodular cysts revealed 99.18-100% identity to that of Kudoa thunni sequences available in GenBank. Detection of K. thunni infection in tuna in Southeast Asia highlights the need for appropriate surveillance and control measures to ensure high quality standards and safety on raw fish production and consumption.

An investigation of Human Clonorchiasis prevalence in an Endemic County in Guangxi Zhuang Autonomous Region, China, 2016

To effectively promote the implementation of interventions, the identification of high-risk groups and the characteristics of Clonorchis sinensis infection in endemic regions are needed. In a clonorchiasis-endemic area, local residents were randomly enrolled for helminth egg examination in June 2016. The prevalence in subpopulations as well as the knowledge, attitudes, and behaviours and the factors influencing clonorchiasis in egg-positive populations were analysed. A total of 2282 local residents participated in the survey; the C. sinensis prevalence was 48.6% (1109 persons). A higher prevalence was found in males (62.6%) than in females (29.7%). People older than 30 years had the highest prevalence (52.7%-57.6%). Among the 888 persons who were infected with C. sinensis and participated the questionnaire investigation, 19.0% (169/888) knew that it could cause cancer. In addition, 60.6% of people reported that they intended to keep eating raw fish despite knowing the risk of infection. The two primary reasons for continuing to eat raw fish were the disease being regarded as not serious (38.3%) and the belief that anti-parasite medications are effective (39.6%). A total of 94.4% (797/844) of responders reported eating raw fish more frequently in the home than outside of the home. Our study revealed a notably high C. sinensis prevalence in the study area. Awareness of clonorchiasis disease severity should be increased among high-risk individuals and families in highly endemic areas.

[New eating habits, new parasitic risks: The example of fish]

Introduction

In the past decades, the massive explosion of "Japanese" restaurants serving raw fish popularised new culinary habits in France. At the same time, consumers have made a habit of preparing raw or pickled fish dishes themselves at home. As a result, the identification of live parasitic worm larvae in raw fish flesh is common and a source of concern for professionals or amateur cooks. Sometimes, these worms are spit out or removed after fibroscopy in patients developing severe epigastric pain quickly after eating raw fish. This paper is aiming at having a quick review of the main parasites transmitted to humans by eating raw fish in France.

Methods

This article is based on the personal experience of the authors, on references preferentially from the French literature and on the results of the Fish Parasites (ANR) research program.

Results

From 2011 to 2014, Fish-Parasites (ANR) assessed the prevalence of parasitism in sea and freshwater fish belonging to 29 species. About 57% of sea fish were parasitised by Anisakidae. Larvae of Dibothriocephalus latus were found in pike, perch, and burbot in Lake Geneva but in none of the fish examined from Annecy or Le Bourget lakes. Concerning human anisakidosis, a retrospective survey was carried out in the years 2010 to 2014 among all medical parasitology laboratories from university hospitals in France. Thirty-seven cases of anisakidosis have been reported, including 18 cases of allergic anisakidosis. Six additional cases of severe Anisakidae allergy were reported to the National Allergovigilance Network over the same period.

Conclusions

Despite the increase in consumption of raw fish, and compared to previous studies, cases of anisakidosis are decreasing, but their allergenic potential is increasing. The incidence of dibothriocephalosis, after some trend of emergence on the shores of Lake Geneva some 20 years ago, is currently decreasing, but sporadic cases of importation are still reported. Actions with professionals (investigation, providing of information) and research programs on management of parasitic risk control are being pursued and have resulted in an update of the technical instruction of the French General Directorate for Food on the control of parasitic risk in fish.

Detection of cylindrospermopsin and its decomposition products in raw and cooked fish (Oreochromis niloticus) by analytical pyrolysis (Py-GC/MS)

The presence of the toxin cylindrospermopsin is increasingly frequent in samples from different ecosystems and it is a serious problem both at environmental level and for animal and human health. To be able to prevent CYN exposure risk, it is important to have suitable analytical methods, but also quick and economical ones. Analytical pyrolysis coupled to GC/MS (Py-GC/MS) represents an important alternative for the rapid detection, characterization or "fingerprinting" of different materials. However, it has been less studied with cyanotoxins up to date. The present work aims to investigate: 1) the suitability of Py-GC/MS for detection of CYN and its decomposition products in raw and cooked fish samples before consumption and 2) the influence of the different cooking methods on the presence of different CYN degradation products detected by Py-GC/MS. For first time, these results present that Py-GC/MS could be a rapid and economical alternative for the detection and monitoring of CYN and its degradation products (DP. m/z 290.1, 169.1 and 336.2) in raw or cooked fish. Moreover, the changes induced in CYN and DP by cooking could be amenable and detected by Py-GC/MS.

Bacterial content and characterization of antibiotic resistant Staphylococcus aureus in Danish sushi products and association with food inspector rankings

This study examined the prevalence and phenotypic and genotypic antibiotic resistance patterns of Staphylococcus aureus in sushi from 20 Danish outlets. Microbial quality of sushi products and food inspector ranking of outlets were assessed and results for thirteen of the outlets were compared with findings from a previous study in 2012. Inspector rankings were similar in the two studies. The mesophilic aerobic counts were slightly lower (p = 0.0296) in 2017 than in 2012 with average values of the 13 shops of 5.2 log CFU/g and 5.7 log CFU/g, respectively. In both studies E. coli was only found in the products from outlets that did not have consistently superior rankings. On the other hand prevalence and average counts of Staphylococcus spp. were slightly higher in 2017 (p = 0.0286) but no methicillin-resistant S. aureus (MRSA) were observed in the present study. Methicillin-sensitive S. aureus (MSSA) were, however, isolated from 18.7% of sushi products with an average count below 2 log CFU/g. Based on spa and multilocus sequence typing (MLST), isolates belonged to clonal complex CC7 (t2016), CC20 (t7836), CC45 (t065, t127, t362), CC88 (t1998) and CC398 (t164, t331, t1451). The Panton-Valentine leukocidin (PVL)-encoding gene lukF was detected only in isolates of the t065 spa-type whereas the scn gene from the ΦSa3 prophage was detected in 76.5% of the isolates, supporting that the majority of isolates were of likely human origin. Thirty-six isolates (70.6%) were resistant to at least one of the antibiotic compounds tested. Antibiotic resistance genes that confer resistance to β-lactams (blaZ) and macrolides (ermC) were detected in 33.3% and 9.8% of isolates, respectively. The tet(K) gene that encode tetracycline resistance was only found in a t7836 strain. Overall, this study indicates that S. aureus in sushi products in Denmark do not represent a major food safety hazard due to, firstly, the low temperature and limited time of storage of product may prevent significant growth and production of toxic levels of enterotoxin of this species. Secondly, the S. aureus isolates obtained did not include MRSA variants and none of them encoded PVL that constitute one of the virulence factors in pathogenesis. Several MSSA isolates contained however genes encoding antibiotic resistance, which emphasize the potential role of foods as vehicles for transmission of such variants.

Restaurant Policies and Practices for Serving Raw Fish in Minnesota

The number of restaurants serving sushi within Minnesota is continuously increasing. The practices and protocols of serving raw fish are complex and require detailed planning to ensure that food served to patrons will not cause illness. Although the popularity of sushi is increasing, there is a lack of research on food safety issues pertaining to preparation of raw fish and sushi rice. To address this gap, the Minnesota Department of Health Environmental Health Specialists Network Food program collected descriptive data on restaurant practices and policies concerning the service of raw fish and sushi rice in 40 Minnesota restaurants. At each restaurant, a specialist interviewed a restaurant manager, conducted an observation of the sushi prep areas in the restaurant kitchen, and reviewed parasite destruction letters and invoices from fish supplier(s). Over half of the restaurants (59%) were missing one or more of the parasite destruction letters from their fish supplier(s) guaranteeing that fish had been properly frozen to the time and temperature requirements in the Minnesota Food Code. A total of 42 parasite destruction letters from suppliers were observed; 10% were considered "adequate" letters. The majority of the letters were missing details pertaining to the types of fish frozen, the length of time fish were frozen, or details on what temperatures fish were held frozen or a combination of all three. Most restaurants were using time as a public health control for their sushi rice. For those restaurants using time as a public health control, 26% had a written procedure on-site, and approximately 53% were keeping track of time. Bare hand contact during sushi prep was observed in 17% of restaurants, and in more than 40% of the restaurants, at least one fish was mislabeled on the menu. Findings from this study indicate that many Minnesota restaurants are not complying with the Food Code requirements pertaining to parasite destruction for the service of raw fish or the use of time as a public health control for sushi rice.

The consumption of fish cooked by different methods was related to the risk of hyperuricemia in Japanese adults: A 3-year follow-up study

BACKGROUND AND AIMS

Fish consumption is a recognized risk factor for elevated serum uric acid (UA) levels, hyperuricemia, and gout. However, the relationship between the consumption of fish cooked by different methods and the risk of hyperuricemia is unclear. Therefore, we aimed to investigate the relationship between the consumption of fish cooked by different methods and the risk of hyperuricemia in Japanese adults.

METHODS AND RESULTS

A 3-year follow-up study was conducted with 424 Japanese adults aged 29-74 years. Fish consumption was assessed using a validated self-administered dietary history questionnaire, and hyperuricemia was defined as serum UA ≥7 mg/dL in men and ≥6 mg/dL in women or the use of any anti-gout treatment. During the 3-year follow-up period, we documented 30 newly diagnosed cases of hyperuricemia. After adjusting for potential confounders, multivariate logistic regressions analysis revealed a significant positive relationship between the risk of hyperuricemia and raw (sashimi and sushi) or roasted fish consumption, but not boiled or fried fish consumption. The odds ratios (95% CI) for hyperuricemia with increasing raw fish consumption were 1.00 (reference), 2.51 (0.85, 7.39), and 3.46 (1.07, 11.14) (P for trend: 0.036). Similarly, the odds ratios (95% CI) with increasing roasted fish consumption were 1.00 (reference), 3.00 (0.75, 11.89), and 5.17 (1.30, 20.62) (P for trend: 0.018).

CONCLUSION

This 3-year follow-up study showed that the consumption of raw or roasted fish, but not boiled or fried fish, was related with a higher risk of hyperuricemia in Japanese adults.

from Japanese retail ready-to-eat raw fish

Little information is available on the diversity and distribution of resistance and virulence factors in enterococci isolated from retail fish. In this study, 200 samples of retail ready-to-eat raw fish (sashimi) collected from the Japanese prefecture of Hiroshima were analyzed for incidence of Enterococcus spp. We recovered 96 enterococcal isolates from 90 (45%, 90/200) samples. Fifty-six strains were identified at the species level: E. faecalis (n = 31), E. faecium (n = 7), E. casseliflavus (n = 7), E. gallinarum (n = 3), E. phoeniculicola (n = 4), E. raffinosus (n = 2), E. saccharolyticus (n = 1), and E. gilvus (n = 1). Twenty-five (26%, 25/96) strains carried antibiotic resistance genes. These included the tet(M), tet(L), tet(K), erm(B), msr(A/B), aph(3'), and blaZ genes, which were detected in 12.5%, 9.3%, 2%, 14.5%, 1%, 1%, and 2% of isolates, respectively. The virulence genes gelE and asa1 were detected in 31 and 24 E. faecalis strains, respectively. Both genes were detected in one E. faecium strain. In conclusion, this is the first study to underscore the importance of sashimi as not only a reservoir of Enterococcus spp. carrying resistance and virulence genes, but also a reservoir for unusual Enterococcus spp.