Antimicrobial resistance (AMR): A major challenge for the aquaculture industry in Bangladesh

This fact sheet is to provide up-to-date information supported by scientific evidence on the importance of antimicrobial use (AMU) and antimicrobial resistance (AMR) in aquatic food systems of Bangladesh to support all relevant stakeholders to engage in interventions and actions to minimize AMU and promote One Health initiatives through responsible and sustainable aquaculture practices

Aquatic food systems and antimicrobial use in Bangladesh: A One Health perspective

This scoping review is one of the deliverables of the antimicrobial resistance work package of the CGIAR Initiative on One Health. It reviews past literature and projects on antimicrobial use and antimicrobial resistance in the aquatic food systems of Bangladesh from a One Health perspective. The purpose of this review is to gain a better understanding of the challenges of antimicrobial use and antimicrobial resistance in the prevailing aquatic food production systems in Bangladesh using a One Health approach. The review also sheds light on past and ongoing initiatives led by government agencies, non-governmental organizations and collaborative research partners to reduce the burden of antimicrobial use and antimicrobial resistance in aquaculture in Bangladesh

Genetic correlations between harvest weight and secondary traits in a silver carp (Hypophthalmichthys molitrix) genetic improvement program

In 2017, the base population of a family-based silver carp (Hypophthalmichthys molitrix) genetic improvement program was spawned in Bangladesh. This program aims to improve the growth rate of silver carp under polyculture production systems, through direct selection on the primary trait of harvest-age weight. The objective of this study was to quantify genetic variation in, and genetic correlations between, harvest-age weight (assessed on 8012 fish from 184 families) and a set of secondary traits (assessed on 1603 fish from 175 families). Secondary traits examined included feeding and digestive system traits (i.e. gill raker sponginess and gut length as a ratio of standard length), a morphometric trait (i.e. extent of overlap of pectoral and pelvic fins) and health traits (i.e. presence of Lernaea and prevalence of red spots — sites of inflammation/haemorrhaging). Despite not being under direct selection, genetic change in secondary traits is possible across generations in closed genetic improvement populations as a result of a correlated response to selection for the primary trait (i.e. indirect selection), adaptation to culture conditions, inbreeding and/or genetic drift. It was found that the additive genetic variance within genetic groups was significantly different from zero for all but the studied health traits. Heritability estimates for harvest-age weight and pectoral/pelvic fin overlap were moderate (0.24 and 0.22, respectively) but were low for gill raker score and relative gut length (0.12 and 0.09, respectively). Genetic correlations between harvest-age weight and secondary traits were not significantly different from zero, indicating that selection for harvest-age weight will not result in a correlated response to selection in the studied secondary traits

Fish bacterial pathogen genomic data

Evaluation of Oxford Nanopore Technology Minion for genome sequencing of aquatic pathogens. Folder contains a curated, complete reference-quality genome of Streptococcus iniae, an important bacterial pathogen of tilapia and other warm water fish species, assembled from PacBio and Illumina HiSeq data. The same strain (QMA0248) was sequenced using ONT Minion and an assembly prepared from subsampled reads to provide ~100 fold coverage. For comparison, alignment of the two assemblies was performed in progressive mauve single nucleotides polymorphisms (SNPs) called. A total of 5685 SNPs were detected in the 2.1MB genome, representing a basecall error rate of only 0.284%. A tab-delimited text file of the SNPs and positions in the ref genome are included in the folder. These SNPs will be mapped onto epidemiologically relevant genes that MLST-type and cps serotype

Response and function of cutaneous mucosal and serum antibodies in barramundi (Lates calcarifer) acclimated in seawater and freshwater

Mucosal and serum antibody responses were studied in sibling barramundi (Lates calcarifer) acclimated in either seawater or freshwater following vaccination by intraperitoneal injection or direct immersion in an inactivated Streptococcus iniae vaccine. As expected, route of vaccination had a marked effect on immune response, with direct immersion resulting in low serum antibody levels against S. iniae by ELISA detected 21 days post vaccination at 26 degrees C, whilst a significant response was detected in mucus. A strong specific antibody response was detected in both mucus and serum 21 days following intraperitoneal injection. Fish acclimated in seawater prior to vaccination showed a markedly higher specific mucosal antibody response than sibling fish acclimated in freshwater, regardless of the route of vaccination, whilst the serum antibody response was not affected by salinity. Both mucosal and serum antibodies from fish in seawater and freshwater were capable of binding antigen at salinities similar to full strength seawater in a modified ELISA assay. These results indicate that this euryhaline fish species is riot only able to mount significant specific antibody response in cutaneous mucus, but that these antibodies will function in the marine environment. (c) 2005 Elsevier Ltd. All rights reserved

Hemiuroid trematode sporocysts are undetected by hemocytes of their intermediate host, the ark cockle Anadara trapezia: potential role of surface carbohydrates in successful parasitism

In order to establish a successful relationship with their hosts, parasites must subvert or evade immune defences. Cockle Anadara trapezia and Sydney Rock oyster (SRO) Saccostrea glomerata live in the same location but only ark cockles are infected by sporocysts of hemiuroid trematode. This provides an opportunity to explore differing interactions between the parasite and the immune system of susceptible and refractive hosts. Rapid migration and encapsulation of sporocysts was observed by SRO hemocytes but not by cockle hemocytes. This migration/encapsulation was inhibited by N-acetylglucosamine or N-acetylgalactosamine but not by the other sugars, implicating specific surface carbohydrates in immune detection. Effector responses of hemocytes were investigated in vitro in terms of production of reactive oxygen production (ROS). Hemocytes of both species strongly reacted to Zymosan, but only SRO hemocytes responded to live sporocysts. Neither species' hemocytes produced ROS in the presence of dead/fixed sporocysts, and there was no suppression of Zymosan-induced respiratory burst by sporocysts. This suggests that immune escape is mediated by avoiding encapsulation, perhaps through molecular mimicry. Membrane-shaving with proteases indicated that sporocyst surface proteins are not a key factors in hemocytic detection. Surface carbohydrates of SRO and cockle hemocytes and of sporocysts were profiled with a panel of biotinylated lectins. This revealed substantial differences between cockle and SRO hemocytes, but greater similarity between cockle hemocytes and sporocysts. Results suggest that surface carbohydrates play an integral role in hemocyte immunorecognition and that surface carbohydrate molecular mimicry is a potential strategy for immune evasion in cockles by hemiuroid trematode sporocysts. Crown Copyright (C) 2013 Published by Elsevier Ltd. All rights reserved

Small-Scale Fisheries and Aquaculture Ontology (SSFO): Labeling fish science data

Heterogeneous and multidisciplinary data are generated by research on sustainable global agriculture and agri-food systems. This data is analysed and often integrated into predictive models for climate change or decision-making tools for fisheries management and aquaculture production. WorldFish (CGIAR) research aims to improve the sustainability, productivity and resilience of aquatic food systems. Harmonising the labelling of aquatic foods data with controlled vocabularies will enable easier data aggregation, interpretation, and analysis. The Fisheries and Aquaculture Ontology Working Group was formed in 2019 to compile, update and contribute fishery related terms to existing controlled vocabularies. The objective is to improve the WorldFish data interoperability into the various projects, databases and repositories by (a) addressing inconsistent use of fisheries and aquaculture related terms across the datasets, (b) highlighting the missing terms in the main semantic resources, and (c) connecting and collaborating with the CGIAR Community of Practice for Ontology.  An ontology is a standardised representation of the definitions and relationships of data from a specific discipline. Ontologies provide a common language for different kinds of data to be easily interpretable and interoperable allowing easier aggregation and analysis

Genetic characterization and antimicrobial profiling of bacterial isolates collected from Nile tilapia (Oreochromis niloticus) affected by summer mortality syndrome

In recent years, Egyptian tilapia aquaculture has experienced mortality episodes during the summer months. The causative agents responsible for such mortalities have not been clearly identified. A total of 400 fish specimens were collected from affected tilapia farms within five Egyptian governorates. A total of 344 bacterial isolates were identified from the examined fish specimens. Bacterial isolates were grouped into seven genera based on API 20E results. The most prevalent pathogens were Aeromonas spp. (42%), Vibrio spp. (21%), and Streptococcus agalactiae (14.5%). Other emerging infections like, Plesiomonas shigelloides (10%), Staphyloccocus spp. (8%), Pseudomonas oryzihabitans, and Acinetobacter lwoffii (2.3%) were also detected. Sequence analysis of the 16S ribosomal RNA bacterial gene of some isolates, confirmed the phenotypic identification results. The analysis of antibiotic resistance genes revealed the presence of aac(6′)-Ib-cr (35.7%), blaCTX gene (23.8%), qnrS (19%), ampC (16.7%), floR (14.3%), sul1, tetA, and van.C1 (2.4%) genes in some isolates. The antimicrobia resistance gene, qac was reported in 46% of screened isolates. Bacterial strains showed variable virulence genes profiles. Aeromonas spp. harboured (act, gcat, aerA, lip, fla, and ser) genes. All Vibrio spp. possessed the hlyA gene, while cylE, hylB, and lmb genes, were detected in S. agalactiae strains. Our findings point to the possible role of the identified bacterial pathogens in tilapia summer mortality syndrome and highlight the risk of the irresponsible use of antibiotics on antimicrobial resistance in aquaculture