Pseudomonas baetica : pathogenicity for marine fish and development of protocols for rapid diagnosis

Abstract

Pseudomonas baetica is a pathogen isolated in 2012 from wedge sole (Dicologoglossa cuneata). The aims of this study were (i) to determine the influence of temperature on its virulence, and (ii) to develop specific protocols for rapid diagnosis. Virulence assays carried out by bath using Senegalese sole fry showed that virulence is strongly influenced by temperature: LD50 at 14°C was 8.5 × 105 cfu ml-1 while at 20°C no mortalities were recorded. On the other hand, the high mortality rates observed in virulence assays involving intraperitoneal injection of 2.5 × 105 cfu g-1 suggest that P. baetica may be pathogenic for the five fish species tested (wedge sole, Senegalese sole, sea bream, European sea bass and meagre). Two PCR protocols, using specific primers targeting the gyrB and rpoD genes, were developed for rapid diagnosis from pure cultures. An additional protocol, using both primer sets, was also optimized for detection from fish tissue samples. Specificity was tested using 81 strains from 66 bacterial species, taxonomically and/or ecologically related; only the P. baetica strains showed the expected DNA amplicons. A specific dot-blot assay using polyclonal antibodies was also developed for differentiation of P. baetica from related species. Altogether, the protocols described here will constitute useful tools for diagnosis and clarify the relevance of this pathogen.

Structure of fish Toll-like receptors (TLR) and NOD-like receptors (NLR)

“…While these microorganisms are a part of the food chain, several of them are known to cause severe diseases in fish. As an example, bacteria species such as Pseudomonas [ 74 ], Vibriosis [ 75 ], and Aeromonas [ 76 ]; viruses like viral hemorrhagic septicemia virus (VHSV), grass-carp reovirus (GCRV), betanodavirus are deadly and causes severe disease to both seawater and freshwater fish (reviewed in [ 77 , 78 ]). This not only directly affects the faster growing aquaculture industry, but also poses threat to human health due to a poor understanding of the evolution of novel aquatic viruses and their diversity.…”

Quantifying dominant bacterial genera detected in metagenomic data from fish eggs and larvae using genus‐specific primers

“…due to their widespread distribution and the presence of species that are human, animal, and plant pathogens (Palleroni, 2015 ). For example, P. bactica is a pathogen of marine fish, and primers targeting the gyrB gene (c390‐F1 and c390‐R1) and rpoD gene have been developed for rapid diagnosis (López et al, 2016 ). A multiplex PCR based on oprI and oprL genes was developed for the detection of Pseudomonas strains from a bacterial collection isolated from water (Matthijs et al, 2013 ).…”

Assessing the Pyloric Caeca and Distal Gut Microbiota Correlation with Flesh Color in Atlantic Salmon (Salmo salar L., 1758)

“…Acinetobacter (G) is known as a typical opportunistic pathogen that causes Acinetobacter disease in Atlantic salmon, channel catfish, common carp, rainbow trout and striped bass [68]. Pseudomonas (G) is found as an acute septicemic bacterial disease in fish [68][69][70]. More importantly, Acinetobacter (G) and Pseudomonas (G) are known as multi-antibiotic-resistant pathogens in aquaculture [71][72][73][74], and Acinetobacter (G) has been used as an indicator of antibiotic resistance in the aquatic environment [75][76][77].…”