Detection and quantification of <i>Aeromonas salmonicida</i> in fish tissue by real‐time <scp>PCR</scp>

Bartkova, Simona; Kokotovic, Branco; Skall, Helle Frank; Lorenzen, Niels; Dalsgaard, Inger

doi:10.1111/jfd.12505

Cited by 21 publications

(13 citation statements)

References 25 publications

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“…Indeed, such Aeromonas species could be well adapted to a estuarine environment having a cooler surface water with mean temperature of 13.4°C (min: 5.3°C/ max 21.3°C). Except for A. salmonicida (Henriques et al, 2006), these species, previously observed in farmed fishes (water and fish) (Esteve et al, 1995; Schmidt et al, 2001; Hatha et al, 2005; Behbahani et al, 2014; Bartkova et al, 2016) and in waste water (Figueira et al, 2011; Marti and Balcázar, 2015; Popovic et al, 2015; Vaz-Moreira et al, 2015; Varela et al, 2016), have never been, as far as we know, described in coastal and anthropized estuary waters. Only the species A. hydrophila , A. caviae , A. sobria , and A. veronii have been reported in coastal or estuarine environments (the Adriatic Sea, Italy) (Dumontet et al, 1996; Fiorentini et al, 1998; Gugliandolo et al, 2008).…”

Section: Discussionmentioning

confidence: 87%

Distinct Aeromonas Populations in Water Column and Associated with Copepods from Estuarine Environment (Seine, France)

et al. 2017

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Aeromonas spp. are ubiquitous bacteria primarily recovered from aquatic ecosystems. They are found in fresh water as well as estuarine and marine waters, and in association with numerous autochthonous aquatic organisms in these environments. However, aeromonads are also etiologic agents of fish diseases and are now recognized as emerging pathogens in humans. The estuary is therefore a key environment, harboring autochthonous aeromonads, and aeromonads originating from humans and animals, mainly released by treated WWTP effluent or watershed run-off via tributaries. The present study compares the abundance and the diversity of Aeromonas populations. Over 2 years of monitoring (eight campaigns from February 2013 to November 2015), the occurrence of Aeromonas was investigated within the water column (water and fluid mud) and in association with copepods. Moreover, the diversity of Aeromonas populations was ascertained by analyzing gyrB and radA sequences, and the antibiotic-resistance phenotypes were determined using the disk diffusion method. This study shows, for the first time, the presence of Aeromonas spp. in water (1.1 × 102 to 1.2 ± 0.3 × 103 CFU.100 mL-1), fluid mud (2.6 ± 2.6 × 102 to 9.8 ± 0.9 × 103 CFU.g-1) and in association with living copepods (1.9 ± 0.7 × 102 to >1.1 × 104 CFU.g-1) in the Seine estuary. Moreover, the diversity study, conducted on 36 strains isolated from the water column and 47 strains isolated from copepods, indicates distinct populations within these two compartments. Strains distributed in five clusters corresponding to A. bestiarum (n = 6; 5.45%), A. encheleia (n = 1; 0.91%), A. media (n = 22; 20.0%), A. rivipollensis (n = 34; 30.91%) and A. salmonicida (n = 47; 42.73%). A. salmonicida is the most abundant species associated with Eurytemora affinis (n = 35; 74.47%). In contrast, A. salmonicida accounts for only 30.56% (n = 11) of isolates in the water column. This study shows the coexistence of distinct populations of Aeromonas in the oligohaline area of an anthropized estuary. Moreover, A. media, a putative human pathogen, present in the water column and abundant in the WWTP samples, was not detected in association with living copepods.

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Section: Discussionmentioning

confidence: 87%

Distinct Aeromonas Populations in Water Column and Associated with Copepods from Estuarine Environment (Seine, France)

et al. 2017

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“…Molecular methods with their high sensitivity and specificity have become the favoured options in many laboratories for the diagnosis of fish diseases (e.g. Abu-Elala et al 2015; Bartkova et al 2017;Fernandez-Alvarez et al 2016;Keeling et al 2013;Mooney et al 1995;. Techniques capable of detecting virtually single cells have been described.…”

Section: Culture-independent Methods-molecular Biologymentioning

confidence: 99%

Methods for the diagnosis of bacterial fish diseases

Austin

2019

Mar Life Sci Technol

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The diagnosis of bacterial fish diseases has progressed from traditional culture-dependent methods involving the recovery of pathogens on agar-containing media and identification by examination of phenotypic traits. Newer approaches centre on culture-independent approaches. A problem with culturing is that it lacks sensitivity, tends to be slow, and its success depends on the composition of the media and incubation conditions employed. In contrast, culture-independent methods, now centring on molecular methods, are highly specific and sensitive. This raises an important issue that detection of very low numbers of bacterial cells does not necessarily imply the presence of clinical disease. Positivity could reflect background populations of the pathogen that may be present in the aquatic environment.

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“…Re-challenge of survivors would also confirm the pathogenfree status. A. salmonicida has been found in the gut and brain of asymptomatic carrier fish 51 suggesting that a low number of pathogens are kept at distance by the innate (SAA, C3, cathelicidins, lysozyme) and adaptive (IgM) immune genes activated in the resistant surviving fish.…”

Section: Discussionmentioning

confidence: 99%

Whole-genome association study searching for QTL for Aeromonas salmonicida resistance in rainbow trout

Marana

Karami

Ødegård

et al. 2021

Sci Rep

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Aeromonas salmonicida subsp. salmonicida, the causative agent of furunculosis, has extensive negative effects on wild and farmed salmonids worldwide. Vaccination induces some protection under certain conditions but disease outbreaks occur even in vaccinated fish. Therefore, alternative disease control approaches are required to ensure the sustainable expansion of rainbow trout aquaculture. Selective breeding can be applied to enhance host resistance to pathogens. The present work used genome-wide association study (GWAS) to identify quantitative trait loci (QTL) associated with A. salmonicida resistance in rainbow trout. A total 798 rainbow trout exposed to A. salmonicida by bath challenge revealed 614 susceptible and 138 resistant fish. Genotyping was conducted using the 57 K single nucleotide polymorphism (SNP) array and the GWAS was performed for survival and time to death phenotypes. We identified a QTL on chromosome 16 and located positional candidate genes in the proximity of the most significant SNPs. In addition, samples from exposed fish were examined for expression of 24 immune-relevant genes indicating a systematic immune response to the infection. The present work demonstrated that resistance to A. salmonicida is moderately heritable with oligogenic architecture. These result will be useful for the future breeding programs for improving the natural resistance of rainbow trout against furunculosis.

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Detection and quantification of Aeromonas salmonicida in fish tissue by real‐time PCR

Cited by 21 publications

References 25 publications

Distinct Aeromonas Populations in Water Column and Associated with Copepods from Estuarine Environment (Seine, France)

Distinct Aeromonas Populations in Water Column and Associated with Copepods from Estuarine Environment (Seine, France)

Methods for the diagnosis of bacterial fish diseases

Whole-genome association study searching for QTL for Aeromonas salmonicida resistance in rainbow trout

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