Sobria Infection Research Articles

Antimicrobial activity of trans-cinnamic acid and commonly used antibiotics against important fish pathogens and nonpathogenic isolates.

Antibiotics and several other chemicals have been used to prevent fish diseases. However, this situation results in economic loss for the companies in the aquaculture industry and most importantly it pollutes the environment. Cinnamic acid is a naturally occurring aromatic acid and is considered to be safe for human consumption. Therefore, in this study, the antibacterial activity of trans-cinnamic acid and commonly used antibiotics, namely chloramphenicol, vancomycin, streptomycin and erythromycin, were tested against 32 bacteria, including fish pathogens, nonpathogenic isolates and collection strains. Trans-cinnamic acid was applied against the bacteria using the disc diffusion and microdilution method under invitro conditions. Antibiotics were also tested under similar conditions against all tested bacteria using the disc diffusion method. The results show that among 32 bacterial strains trans-cinnamic acid exhibited potent inhibitory effect on the Gram-negative fish pathogen Aeromonas sobria. In addition, a moderate inhibition of trans-cinnamic acid of fish pathogens Aeromonas salmonicida, Vibrio (Listonella) anguillarum, Vibrio crassostreae and Yersinia ruckeri was also observed for trans-cinnamic acid in our study. On the contrary, the majority of nonpathogenic intestinal isolates were resistant to trans-cinnamic acid. To the best of our knowledge, this is the first report on the antimicrobial activity of trans-cinnamic acid on 24 of the studied bacteria isolated from fish. In conclusion, trans-cinnamic acid can be used as an environmentally friendly alternative additive to prevent and control primarily A. sobria, as well as other pathogenic bacteria such as A. salmonicida, V. anguillarum, V. crassostreae and Y. ruckeri. This study indicated that trans-cinnamic acid may present an environmentally friendly alternative therapeutic agent against A. sobria infections in the aquaculture industry.

Aeromonas Sobria Infection in Patients with Acute Leukemia:Clinical Features and Outcome

To investigate the clinical features and outcome of patients with acute leukemia and Aeromonas sobria infection. The clinical data of two patients from Peking Union Medical College Hospital from 1994 to 2014 as well as patients reported in English literature (from PubMed and Medline databases) and Chinese literature (China Hospital Knowledge Database) during the same period were retrospectively analysed. Data were extracted and analyzed using Chi-square tests. Totally 15 patients worldwide were available for analysis with a male-to-female ratio of 12:3 and an acute myeloid leukemia to acute lymphoblastic leukemia ratio of 10:5. The median age was 49.5 years (range:27-80 years). Most patients were neutropenic at the time of onset of fever,and the most common manifestation was lower limb infection (66.7%). Despite empirical antibiotics treatment,the mortality was still as high as 80%. Chi-square tests revealed that among the dead patients,the rates of lower limb infection (P<0.01) and septic shock (P=0.02) were significantly higher. Aeromonas sobria infection is an uncommon but highly fatal condition that requires special attention in clinical settings.

Molecular Cloning and Functional Characterization of Mannose Receptor in Zebra Fish (Danio rerio) during Infection with Aeromonas sobria.

Mannose receptor (MR) is a member of pattern-recognition receptors (PRRs), which plays a significant role in immunity responses. Much work on MR has been done in mammals and birds while little in fish. In this report, a MR gene (designated as zfMR) was cloned from zebra fish (Danio rerio), which is an attractive model for the studies of animal diseases. The full-length cDNA of zfMR contains 6248 bp encoding a putative protein of 1428 amino acids. The predicted amino acid sequences showed that zfMR contained a cysteine-rich domain, a single fibronectin type II (FN II) domain, eight C-type lectin-like domains (CTLDs), a transmembrane domain and a short C-terminal cytoplasmic domain, sharing highly conserved structures with MRs from the other species. The MR mRNA could be detected in all examined tissues with highest level in kidney. The temporal expression patterns of MR, IL-1β and TNF-α mRNAs were analyzed in the liver, spleen, kidney and intestine post of infection with Aeromonas sobria. By immunohistochemistry assay, slight enhancement of MR protein was also observed in the spleen and intestine of the infected zebra fish. The established zebra fish-A. sobria infection model will be valuable for elucidating the role of MR in fish immune responses to infection.

Isolation and characterization of a novel lytic cold-active bacteriophage VNPH-1 from the Napahai wetland in China

Wetlands have unique characteristics and play a number of roles in the environment, principally in water purification, flood control, and the maintenance of shoreline stability. In this work, a lytic cold-active bacteriophage designated VNPH-1 was isolated from the Napahai wetland in China together with Aeromonas sobria NPH-1 cells, and a preliminary characterization of this bacteriophage was carried out. Electron microscopy revealed that VNPH-1 had an icosahedral head (116.7 nm) and a contractile tail (10 nm in width, 166.7 nm in length). Bacteriophage VNPH-1 was classified as Myoviridae and had an approximate genome size of 110 to 120 kb. One-step growth curve revealed that the latent and burst periods were 20 and 10 min, respectively, with an average burst size of 80 bacteriophage particles per infected cell. The pH and thermal stability of bacteriophage VNPH-1 were also investigated. The maximum stability of the bacteriophage was observed at an optimal pH of 9.0, and the phage was comparatively stable at pH 5.0-10.0. The specificity of this bacteriophage for its host makes it an attractive candidate for phage therapy of A. sobria infections. As VNPH-1 is a cold-active bacteriophage with a low production temperature, it would be worthwhile to characterize it further and to deepen knowledge of its interaction with A. sobria in future studies.

Inhibition of Aeromonas sobria serine protease (ASP) by α2-macroglobulin

ASP is a serine protease secreted by Aeromonas sobria. ASP cleaves various plasma proteins, which is associated with onset of sepsis complications, such as shock and blood coagulation disorder. To investigate a host defense mechanism against this virulence factor, we examined the plasma for ASP inhibitor(s). Human plasma inhibited ASP activity for azocasein, which was almost completely abolished by treating plasma with methylamine, which inactivates α2-macroglobulin (α2-MG). The ASP-inhibitor complex in ASP-added plasma was not detected by immunoblotting using anti-ASP antibody; however, using gel filtration of the plasma ASP activity for an oligopeptide, the ASP substrate was eluted in the void fraction (Mw>200 000), suggesting ASP trapping by α2-MG. Indeed, human α2-MG inhibited ASP azocaseinolytic activity in a dose-dependent manner, rapidly forming a complex with the ASP. Fibrinogen degradation by ASP was completely inhibited in the presence of α2-MG. α1-Protease inhibitor, antithrombin, and α2-plasmin inhibitor neither inhibited ASP activity nor formed a complex with ASP. Surprisingly, ASP degraded these plasma serine protease inhibitors. Thus, α2-MG is the major ASP inhibitor in the human plasma and can limit ASP virulence activities in A. sobria infection sites. However, as shown by fluorescence correlation spectroscopy, slow ASP inhibition by α2-MG in plasma may indicate insufficient ASP control in vivo.

The tail nick augments Aeromonas sobria serine protease (ASP) activity in plasma through retarding inhibition by α2-macroglobulin

ASP is a serine protease secreted by Aeromonas sobria, a sepsis-causing bacterium, and induces sepsis-mimicking disorders through plasma protein cleavage. The pathogen also secretes nASP that has a nick in the carboxy-terminal region. Compared with single-chain ASP (sASP), nASP had near-equivalent activity for small peptide substrates but was less proteolytic. Surprisingly, nASP cleaved proteins more in plasma and was inhibited by human α2-macroglobulin more slowly than sASP. Retarded inhibition by α2-macroglobulin allows nASP to keep proteolytic activity for longer in the host and exacerbate disorders at Aeromonas sobria infection sites. nASP may be an evolutional form to augment ASP virulence.

アルコール性肝硬変に合併した劇症 &lt;i&gt;Aeromonas sobria &lt;/i&gt;感染症の 1 例

Aeromonas sobria infection is known to be very serious in immunocompromised hosts. We report a case of A. sobria infection fatal in a subject with decompensated liver cirrhosis. A 63-year-old man with liver cirrhosis admitted for fever and vomiting developed a necrotizing soft-tissue infection in the right lower leg. Despite a decompression incision in the affected limb and intensive care, he died of sepsis one day after surgery. A. sobria was detected afterward in a blood culture.

Immunoproteomic Identification of Polyvalent Vaccine Candidates from Vibrio parahaemolyticus Outer Membrane Proteins

Bacterium is still a major cause of many infectious diseases and a global threat to human health, aquaculture, and animal feeding. Prevention by vaccination is the most efficient and economical way of fighting bacterial diseases, but one of the persistent challenges to prevent bacterial infections and disease transmissions is the existence of multiple bacterial species, families, and genera and the lack of efficient polyvalent vaccines against them. The information on candidate immunogens for polyvalent vaccine development is elusive, as well. For the development of broad cross-protective vaccines, we have employed heterogeneous antiserum-based immunoproteomics approaches to identify antigenically similar outer membrane (OM) proteins that could be used as potential polyvalent vaccine candidates against Vibrio parahaemolyticus , V. alginolyticus , V. fluvialis , Aeromonas hydrophila , and A. sobria infections. VPA1435, VP0764, VPA1186, VP1061, and VP2850 could be recognized by at least three antisera and demonstrated significantly passive and active immune protection against V. parahaemolyticus infection in a crucian carp model. VP1061 and VP2850 induced higher immune and protective abilities than the other three OM proteins. Furthermore, the abilities of VP1061 and VP2850 in the generation of broad cross-protective immune reaction against the infections of V. alginolyticus , A. hydrophila , and Pseudomonas fluorescens were also investigated in fish and mouse models. Our results suggested that VP1061 and VP2850 could potentially be used as polyvalent vaccine candidates for the development of novel polyvalent vaccines against V. parahaemolyticus and other Gram-negative pathogens. On the basis of these results, characteristics of OM proteins as polyvalent vaccine candidates have been addressed.

Pseudomonas chlororaphis strain JF3835 reduces mortality of juvenile perch, Perca fluviatilis L., caused by Aeromonas sobria

Motile aeromonad septicaemia caused by Aeromonas sobria is a cause of disease in farmed perch, Perca fluviatilis L., in Switzerland. We have evaluated the potential of a Pseudomonas chlororaphis isolate, obtained from perch intestine, to control A. sobria infection. Inoculation of juvenile perch with P. chlororaphis strain JF3835 prior to infection with A. sobria caused a reduction in A. sobria associated mortalities. Infection of perch with xylE-labelled P. chlororaphis indicated the bacterium is able to transiently colonize juvenile fish and fingerlings.

Appendicitis Associated With Travelers’ Diarrhea Caused byAeromonas sobria: Table 1

Aeromonas species is an infrequent pathogen causing travelers' diarrhea and gastroenteritis. No human case of appendicitis has been reported as a complication of Aeromonas infection until now. We describe a case of acute appendicitis associated with Aeromonas sobria infection acquired in Cebu, Philippines.

Case Reports: Fatal Necrotizing Fasciitis Caused by Aeromonas sobria in Two Diabetic Patients

We report two rare cases of Aeromonas sobria necrotizing fasciitis with sepsis in patients with diabetes. In both cases, immediate fasciotomy was performed and appropriate empiric antimicrobial therapy and intensive care were administered. However, the two patients died on Day 2 and Day 11, respectively, after admission as a result of multiple organ failure. When patients present with a rapid onset of skin necrosis and progressive sepsis, an Aeromonas sobria infection or Vibrio infection should be considered in the differential diagnosis.

Production of C5a by ASP, a Serine Protease Released from Aeromonas sobria

Aeromonas sobria causes pus and edema at sites of infection. However, the mechanisms underlying these effects have not been elucidated. C5a, the amino-terminal fragment of the complement 5th component (C5), mimics these events. To investigate the involvement of C5a in the pathophysiology of A. sobria infection, we examined release of C5a from human C5 by a serine protease (ASP), a putative virulence factor secreted by this bacterium. C5 incubated with enzymatically active ASP induced neutrophil migration in a dose-dependent manner from an ASP concentration of 3 nM and in an incubation time-dependent manner in as little as 7 min, with neutrophil accumulation in guinea pigs at intradermal injection sites and neutrophil superoxide release. These effects on neutrophils were inhibited by a C5a-receptor antagonist. The ASP incubation mixture with C5 but not C3 elicited vascular leakage in a dose- and incubation time-dependent manner, which was inhibited by a histamine H(1)-receptor antagonist. Together with these C5a-like activities, ASP cleaved C5 to release only one C5a Ag, the m.w. of which was similar to that of C5a. Immunoblotting using an anti-C5a Ab revealed generation of a C5a-like fragment from human plasma incubated with ASP. These results suggest that ASP-elicited neutrophil migration and vascular leakage via C5a production from C5 could occur in vivo, which was supported by that ASP did not affect functions of C5a and neutrophil C5a receptor. Through C5a generation, ASP could be associated with the induction of pus and edema caused by infection with this bacterium.

Impaired plasma clottability induction through fibrinogen degradation by ASP, a serine protease released fromAeromonas sobria

Aeromonas sobria infection often advances to sepsis, in which interaction of bacterial components with plasma proteins possibly causes various disorders. This bacterium releases a serine protease (ASP), a putative virulence factor, and binds to fibrinogen. To study the ASP effect on fibrinogen, we incubated fibrinogen or plasma with ASP and investigated their clotting elicited by thrombin, which converts fibrinogen to a fibrin clot. Enzymatically active ASP retarded plasma clotting in a dose-dependent manner starting at an ASP concentration of 10 nM. ASP also retarded fibrinogen clotting at 3 nM and above, which appeared to correspond to ASP cleavage of fibrinogen at the Aα-chain. Consistent with containing serine protease activity for an ASP-specific substrate, the culture supernatant of an ASP gene-introduced strain retarded plasma and fibrinogen clotting more than that of the wild-type strain. The culture supernatant of an ASP gene-disrupted strain that releases negligible serine protease activity for the ASP-specific substrate did not affect plasma clotting. These results indicate that ASP is the main fibrinogenolytic protease released from A. sobria. Impaired plasma clottability induction through fibrinogen degradation is a new virulence activity of ASP and may contribute to hemorrhagic tendencies in sepsis caused by infection with this bacterium.

Activation of prothrombin by ASP, a serine protease released from Aeromonas sobria

The effect of a serine protease (ASP) secreted from Aeromonas sobria on plasma coagulation was investigated. Proteolytically active ASP promoted human plasma coagulation in a dose-dependent manner. Consistent with the preference for a factor Xa-specific oligo-peptide substrate, ASP produced enzymatic activity from human prothrombin but not from factors IX and X. ASP cleaved prothrombin to produce enzymatically active 37 kDa-fragment displaying the same molecular mass as α-thrombin. ASP is the first bacterial serine protease that produces α-thrombin, through which ASP may contribute to the induction of thrombotic tendency in disseminated intravascular coagulation complicated with sepsis caused by A. sobria infections.

Antigenic Characterization of Outer Membrane Protein of Aeromonas sobria Isolated from Goldfish (Carassius auratus L.)

Aeromonas sobria, along with A. hydrophila, has frequently been reported as a causative agent of motile aeromonas septicemia (MAS) in fish and other aquatic organisms. Currently, there are no precise tools to diagnose or vaccinate against this disease. The aim of the present study was to fractionate and characterize the outer membrane protein (OMP) antigen of A. sobria by sero- logical and cellular techniques so as to identify immunoreactive molecules that might be useful in preparing immunodiagnostic and/or immunoprophylactic tools against A. sobria infection in goldfish. Eight fractions were isolated from the crude OMP antigen using sephacryl S-200 and DEAE-cellulose chromatography. The highest seroreactivity was observed in the gel-permeated protein G1 which had an optical density (OD) of 0.72 nm, higher even than that of the crude OMP antigen, 0.63 nm. The serodiagnostic potential of G1 was assessed by using dip-stick ELISA. The in vitro goldfish lympho-proliferation ability of the fractionated antigen, G1A3, was higher than of all the other fractionated antigens and the crude OMP. Therefore, fractionated antigen G1 (molecular wt 42-67 kDa) and G1A3 (molecular wt 45-47 kDa) should be further studied in immunodiagnostic and/or immunoprophylactic preparations for A. sobria infection.

Induction of Vascular Leakage and Blood Pressure Lowering through Kinin Release by a Serine Proteinase from Aeromonas sobria

Aeromonas sobria causes septic shock, a condition associated with high mortality. To study the mechanism of septic shock by A. sobria infection, we examined the vascular leakage (VL) activity of A. sobria serine proteinase (ASP), a serine proteinase secreted by this pathogen. Proteolytically active ASP induced VL mainly in a bradykinin (BK) B(2) receptor-, and partially in a histamine-H(1) receptor-dependent manner in guinea pig skin. The ASP VL activity peaked at 10 min to 1.8-fold of the initial activity with an increased BK B(2) receptor dependency, and attenuated almost completely within 30 min. ASP produced VL activity from human plasma apparently through kallikrein/kinin system activation, suggesting that ASP can generate kinin in humans. Consistent with the finding that a major part of the ASP-induced VL was reduced by a potent kallikrein inhibitor, soybean trypsin inhibitor that does not affect ASP enzymatic activity, ASP activated prekallikrein but not factor XII to generate kallikrein in a dose- and incubation time-dependent manner. ASP produced more VL activity directly from human low m.w. kininogen than high m.w. kininogen when both were used at their normal plasma concentrations. Intra-arterial injection of ASP into guinea pigs lowered blood pressure specifically via the BK B(2) receptor. These data suggest that ASP induces VL through prekallikrein activation and direct kinin release from kininogens, which is a previously undescribed mechanism of A. sobria virulence and could be associated with the induction of septic shock by infection with this bacterium. ASP-specific inhibitors, and kinin receptor antagonists, might prove useful for the treatment or prevention of this fatal disease.