OCCURRENCE OF PATHOGENIC MICROORGANISMS IN FISH SOLD IN SÃO PAULO, BRAZIL

A systematic review, meta-analysis and meta-regression of the global prevalence of foodborne Vibrio spp. infection in fishes: A persistent public health concern

Human vibriosis, caused by pathogenic Vibrio spp., such as Vibrio parahaemolyticus, Vibrio cholerae and Vibrio vulnificus, has been increasing worldwide, mediated by increasing consumption of seafood. The present study was conducted to examine the global prevalence of V. vulnificus, V. parahaemolyticus and V. cholerae in fishes. We searched PubMed, Web of Science, Scopus, and CNKI for peer-reviewed articles and dissertations prior to December 31, 2021. A total of 24,831 articles were retrieved, and 82 articles contained 61 fish families were included. The global pooled prevalence of V. cholerae, V. parahaemolyticus and V. vulnificus in fishes was 9.56 % (95 % CI: 2.12-20.92), 24.77 % (95 % CI: 17.40-32.93) and 5.29 % (95 % CI: 0.38-13.61), respectively. Subgroup and meta-regression analyses showed that study-level covariates, including temperature, country, continent, origin and detection methods partly explained the between-study heterogeneity. These heterogeneities were underpinned by differences of the three Vibrio spp. in fishes at geographical and climatic scales. These results reveal a high global prevalence of pathogenic Vibrio spp. in fishes and highlight the need for implementation of more effective prevention and control measures to reduce food-borne infection in humans.

Water Quality and Microbiological Contamination across the Fish Marketing Chain: A Case Study in the Peruvian Amazon (Lagoon Yarinacocha)

The contamination of the surface water of lagoons is a common problem in developing countries, and can affect fishing activities. A case study was conducted on water quality and microbiological contamination of the fishing marketing chain in the Peruvian Amazon (Laguna de Yarinacocha). The microbiological, physical–chemical and parasitological parameters of the surface water were evaluated in three points of the lagoon near the landing stage; and microbiological parameters of facilities, handlers and three species of fish (Prochilodus nigricans, Mylossoma duriventre and Siluriforme spp.). In the water, there were coliform counts ≥ 23 (Most probable number—MPN)/100 mL, Escherichia coli ≥ 3.6 MPN/100 mL, and Pseudomona spp. up to 2.2 MPN/100 mL; high turbidity and variable amounts of parasites. In facilities and handlers, high levels of coliforms, mainly Escherichia coli, and Staphylococcus aureus and Escherichia coli, were found in M. duriventre meat. A poor quality of the surface water of the lagoon is concluded that compromises part of the fishing marketing chain, mainly facilities and manipulators. Furthermore, the levels of Staphylococcus aureus and Escherichia coli in fish meat show poor handling practices and possible risk of contamination by water sources.

The use of the so-called 'tubs' for transporting and storing fresh fishery products

On-land transport/storage of fresh fishery products (FFP) for up to 3 days in 'tubs' of three-layered poly-ethylene filled with freshwater and ice was compared to the currently authorised practice (fish boxes of high-density poly-ethylene filled with ice). The impact on the survival and growth of biological hazards in fish and the histamine production in fish species associated with a high amount of histidine was assessed. In different modelling scenarios, the FFP are stored on-board in freshwater or seawater/ice (in tubs) and once on-land they are 'handled' (i.e. sorted or gutted and/or filleted) and transferred to either tubs or boxes. The temperature of the FFP was assumed to be the most influential factor affecting relevant hazards. Under reasonably foreseeable 'abusive' scenarios and using a conservative modelling approach, the growth of the relevant hazards (i.e. Listeria monocytogenes, Aeromonas spp. and non-proteolytic Clostridium botulinum), is expected to be < 0.2 log10 units higher in tubs than in boxes after 3 days when the initial temperature of the fish is 0°C ('keeping' process). Starting at 7°C ('cooling-keeping' process), the expected difference in the growth potential is higher (< 1 log10 for A. hydrophila and < 0.5 log10 for the other two hazards) due to the poorer cooling capacity of water and ice (tub) compared with ice (box). The survival of relevant hazards is not or is negligibly impacted. Histamine formation due to growth of Morganella psychrotolerans under the 'keeping' or 'cooling-keeping' process can be up to 0.4 ppm and 1.5 ppm higher, respectively, in tubs as compared to boxes after 3 days, without reaching the legal limit of 100 ppm. The water uptake associated with the storage of the FFP in tubs (which may be up to 6%) does not make a relevant contribution to the differences in microbial growth potential compared to boxes.

Identification and antibiotic susceptibility of bacterial microbiota of freshwater fish

The fish meat is an essential part of human diet. However, fish may be contaminated with different microorganisms, including pathogens. Antimicrobial resistance of fish microbiota may facilitate the spread of resistant microorganisms causing serious consequences for human health. The aim of the present study was to detect bacterial contamination in fish gill, gut and skin and to determine antimicrobial susceptibility of the bacterial isolates. Rainbow trout (Oncorhynchus mykiss) and bream (Abramis bram) were obtained from the market in Jelgava city. Chub (Leuciscus cephalus), crucian carp (Carassius carassius) and tench (Tinca tinca) were collected from fishermen. Fish samples were examined for the total bacterial count (TBC), coliforms, Enterobacteriaceae, Pseudomonas spp. and Aeromonas spp. Testing was done in accordance with International Organization for Standardization (ISO) standards. Identification of all bacteria was accomplished with the Matrix Assisted Laser Desorption Ionization – Time of Flight Mass Spectrometry (MALDI-TOF MS) method. The disc diffusion method was used for the detection of antibiotic susceptibility of isolated bacterial species. TBC ranged from 2.70 to 7.00 log CFU.g-1, coliforms from 0 to 2.67 log CFU.g-1, Enterobacteriaceae from 0 to 2.85 log CFU.g-1. The highest contamination with Pseudomonas spp. and Aeromonas spp. was observed in chub gut samples with 1.60 log CFU.g-1 and 2.23 log CFU.g-1, respectively. Altogether, 16 microbial genera and 31 bacterial species were identified. The dominant bacterial species belonged to Pseudomonas spp. (54%) and Enterobacteriaceae. Pseudomonas spp. were resistant to ticarcillin, susceptibility to ciprofloxacin showed 88% of isolates. All Enterobacteriaceae isolates were susceptible to imipenem. The microbial quality of the fish was acceptable, but the presence of antibiotic resistant bacteria may further cause a negative impact on public health.

Molecular characterization and detection of enterotoxins, methicillin resistance genes and antimicrobial resistance of Staphylococcus aureus from fish and ground beef

A total of 120 samples including 40 freshwaterfish(Oncorhynchus mykiss), 40 seawater fish (Sparus aurata) and 40 ground beef samples were examined for the presence of Staphylococcus aureus. The isolates were identified using biochemical tests and a PCR for the species-specific fragment (Sa442) and thermonuclease gene (nucA). The presence of staphylococcal enterotoxin genes (sea, seb, sec, sed and see), toxin genes (eta, etb, tsst), methicillin resistance gene (mecA) and some phenotypic virulence factors was also tested. Genotypic characterization of the isolates was analyzed by PCR-RFLP of the coa gene. Overall, 36 (30%) meat samples were contaminated with S. aureus. Of the 36 isolates, 3 (8.3%) were found to be positive for enterotoxin genes. Only 1 isolate (5.9%) from ground beef had the sea gene. In addition, 1 (12.5%) of the freshwater fish and 1 (9.1%) of the seawater fish carried both the sea and sed genes. The presence of seb, sec, see, eta, etb and tsst was not detected among the isolates of S. aureus. The amplified coa gene revealed five different clusters. Seven and six distinct RFLP patterns were obtained with AluI and HaeIII digestion, respectively. All isolates were found to be positive for slime, hemolytic and DNase activity while 41.7% of them were beta-lactamase positive. The presence of methicillin resistance was neither detected by PCR nor the disk diffusion method. A total of 94.4% of the isolates were resistant to at least one antimicrobial while 44.4% of them were resistant to at least two or more antimicrobials.

Occurence and antimicrobial resistance of Staphylococcus aureus and Salmonella spp. in retail fish samples in Turkey

The aims of this study were to investigate the presence of Staphylococcus aureus and staphylococcal enterotoxins, as well as Salmonella spp. and to determine the antimicrobial susceptibilities of the isolates from fish samples. A total of 100 fish samples were analysed consisting of 30 anchovy, 35 trout and 35 sea bream. The presence of SEs was detected using ELISA and its genes confirmed by mPCR. Also, S. aureus and Salmonella spp. were detected in 9 (9%) and 5 (5%) samples, respectively. None of the S. aureus isolates had SEs and SEs genes. The resistance rates of the S. aureus isolates to erythromycin, tetracycline, and penicillin G were found to be 33% while Salmonella spp. isolates were resistant to trimethoprim-sulfamethoxazole, gentamicin and neomycine in 20%, 20% and 80%, respectively of the samples. It is of utmost important for public health that retail fish markets need to use hygienic practices in handling and processing operations.

Incidence and characterization of Staphylococcus aureus in fishery products marketed in Galicia (Northwest Spain)

A total of 298 fishery products purchased from retail outlets in Galicia (NW Spain) between January 2008 and May 2009 were analyzed for the presence of Staphylococcus aureus. S. aureus was detected in a significant proportion of products (~25%). Incidence was highest in fresh (43%) and frozen products (30%), but it was high in all other categories: salted fish (27%), smoked fish (26%), ready-to-cook products (25%), non-frozen surimis (20%), fish roes (17%) and other ready-to-eat products (10%). A significant proportion of smoked fish, surimis, fish roes and other ready-to-eat products did not comply with legal limits in force. RAPD-PCR of 125 S. aureus isolated from fishery products was carried out using three primers (AP-7, ERIC-2 and S). Isolates displayed 33 fingerprint patterns. Each pattern was attributed to a single bacterial clone. Cluster analysis based on similarity values between RAPD fingerprints did not find relationship between any RAPD pattern and any product category. Isolates were also tested for se genes and susceptibility to a range of antibiotics (cephalothin, clindamycin, chloramphenicol, erythromycin, gentamicin, oxacillin, penicillin G, tetracycline, vancomycin, methicillin, ciprofloxacin and trimethoprim-sulfamethoxazole). Most isolates (88%) were found to be sea positive. Putative enterotoxigenic strains counts reached high risk levels in 17 products. No relationship was found between the presence of se genes and RAPD patterns. All isolates were resistant to penicillin, chloramphenicol and ciprofloxacin, and most to tetracycline (82.4%), but none was methicillin-resistant. A revision of pre-requisite programs leading to improve hygienic practices in handling and processing operations from fishing or farming to retail is recommended to ensure fishery products safety.

Characterization of Vibrio parahaemolyticus isolated from oysters and mussels in São Paulo, Brazil

Vibrio parahaemolyticus is a marine bacterium, responsible for gastroenteritis in humans. Most of the clinical isolates produce thermostable direct hemolysin (TDH) and TDH-related hemolysin (TRH) encoded by tdh and trh genes respectively. In this study, twenty-three V. parahaemolyticus, previously isolated from oysters and mussels were analyzed by PCR using specific primers for the 16S rRNA and virulence genes (tdh, trh and tlh) and for resistance to different classes of antibiotics and PFGE. Nineteen isolates were confirmed by PCR as V. parahaemolyticus. The tlh gene was present in 100% of isolates, the tdh gene was identified in two (10.5%) isolates, whereas the gene trh was not detected. Each isolate was resistant to at least one of the nine antimicrobials tested. Additionally, all isolates possessed the blaTEM-116 gene. The presence of this gene in V. parahaemolyticus indicates the possibility of spreading this gene in the environment. Atypical strains of V. parahaemolyticus were also detected in this study.