Effect of starvation on survival and virulence expression of Aeromonas hydrophila from different sources

Abstract

Aeromonas hydrophila is an aquatic bacterium responsible for several human illnesses. The aim of this work was to investigate the survival ability and virulence expression of two strains from different sources (fish, strain 87 and surface water, strain LS) maintained in a seawater microcosm. The strains were analyzed for the total and viable bacterial counts, adhesion ability to Hep-2 cells and aerA gene expression by qPCR throughout the experiment (35 days). Both strains reached a putative VBNC state and lost adhesive properties but exhibited a different behavior in the expression of aerA. This could be due to the different origin of the two strains; the former adapted to a habitat rich of nutrient and the latter already used to survive in a more hostile environment. Moreover, our results indicate that the quantitative determination of aerA mRNA can be a useful indicator of virulence expression under stress conditions.

Aeromonas

“…The authors concluded that flow cytometry was a most appropriate technique to study VBNC aeromonads. veronii, (6%) the rest <6%; d Winter peak at water temperature <14; e Summer peak but not dependent of temperature; f Nonculturable Aeromonas population ranging from 3.4 x 10 1 to 2.4 x 10 4 cells.mL-1 was detected in the drinking water; NR: Not Reported A recent study by Casabianca et al (2015) demonstrated that in response to a stress condition two different strains of Aeromonas, one from fish and the other from seawater reduced their culturability and virulence expression but with a different behavior. The strain from fish was not detected at day 35, while the one recovered from seawater remained culturable.…”

“…), extracellular enzymes (hemolysins, lipases, etc. ), secretion systems and associated toxins (Type I to Type VI secretion systems), iron acquisition systems and quorum sensing (QS) communication that is further explored in many studies cited in this chapter Khajanchi et al, 2010;Pablos et al, 2010;Berg et al, 2011;Parker and Shaw, 2011;Senderovich et al, 2012;Beaz-Hidalgo and Figueras, 2013;Morinaga et al, 2013;Casabianca et al, 2015;Rasmussen-Ivey et al, 2016a).…”

“…It have been suggested that the inability to isolate Aeromonas during the winter months or from cold waters may result not from cell death, but from the entry of cells into a viable but nonculturable (VBNC) state (Wai et al 2000;Rahman et al 2001;Maalej et al 2004a: Maalej et al 2004bCasabianca et al, 2015). Aeromonas have been described to achieve a VBNC state when cultured in freshwater at 4-5°C (Wai et al, 2000;Mary et al, 2002, Mary et al,2003.…”

Characterization of virulence, cell surface characteristics and biofilm‐forming ability of Aeromonas spp. isolates from fish and sea water

“…The pathogenic mechanisms associated with Aeromonas virulence is multifaceted and involves adhesins, S/A layer, lipopolysaccharides, motility, siderophores, biofilm production and an array of biologically active extracellular products and exoenzymes, that is cytotoxins, enterotoxins, aerolysin⁄haemolysins, lipases and proteases (Casabianca et al . ). While aeromonad pathogenicity is multifactorial, adhesion and colonization of diverse host cells is the most important factor for initiation of the disease process.…”

Expression, Purification, and Characterization of Hemolytic Toxin from Virulent Aeromonas hydrophila

“…Therefore, novel antimicrobial strategies need to be developed for the treatment of Aeromonas infections. Although there are a number of A. hydrophila strains with different genomic structures, the complexity of virulence factors carried by different strains has contributed to the pathogenicity of A. hydrophila (Chauret et al ; Casabianca et al ). In the past 20 yr, several virulence factors of A. hydrophila have been reported and characterized, and most of those reported contribute to A. hydrophila infections (Grim et al ).…”