Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “AEROMONAS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 811 records · Page 45Linked to original sources
PubMed1991

[The Aeromonas genus].

Aeromonas hydrophila manifested itself since its discovery in 1891 as a pathogen of cold-blooded and warm-blooded animals and man. Aeromonads cause intestinal and non-intestinal disease. The genus Aeromonas comprises: A. hydrophila, A. sorbria, A. caviae, A. veronii, A. schubertii, i.e. mesophilie species and as to psychrophilie immobile species. A. salmonicida and A. media. For warm-blooded animals and man mesophilie motile species are important as pathogens. A. veronii is an ornithine-decarboxylase positive species, A. schubertii is mannitol-negative, A. caviae is non-haemolytic and VP-negative. It is difficult to differentiate. A. hydrophila with aerogenic and anaerogenic strains from A. sobria. Several practical differential diagnostic tests were suggested by Janda et al. and Joseph et al.: hydrolysis of esculine, KCN, arabinose and salicin are usually positive in A. hydrophila, in A. sobria usually negative. Existing species of mesophilie aeromonads, however, do not correspond to some strains which are found. Therefore Arduino et al. divided their aeromonads into DNA-hybridization groups: for A. hydrophila there were 5, for A. caviae 2 and for A. sobria 1 hybridization group. Biochemisal characteristics corresponded to the hybridization groups. For isolation of aeromonads from faeces selective media with ampicillin must be used and possibly enrichment in alkaline peptone water. Evidence of pathogenity factors is similar as in E. coli,: detection of adhesins and enterotoxin or cytotoxin by means of tests commonly used in cholera and E. coli. The types of adhesins are differentiated by means of fucose- galactose- and mannose resistant haemagglutination.(ABSTRACT TRUNCATED AT 250 WORDS)

Aeromonas↗
PubMed1991

Site-directed mutagenesis of a single tryptophan near the middle of the channel-forming toxin aerolysin inhibits its transfer across the outer membrane of Aeromonas salmonicida.

The channel-forming protein aerolysin must cross both the inner and outer bacterial membranes during its secretion from Aeromonas hydrophila or from Aeromonas salmonicida containing the cloned structural gene. We examined the fate of three mutant proteins in which Trp-227, near the middle of the amino acid chain, was replaced with glycine, leucine, or phenylalanine by site-directed mutagenesis. All three proteins crossed the inner membrane and entered the periplasm in the same way as wild-type, and in each case the signal sequence was removed correctly. Little or none of the proaerolysin substituted with glycine or leucine was released into the culture supernatant. Instead, significant amounts became associated with the outer membrane. The Phe-227 protoxin was secreted by the bacteria but at a reduced rate. The leucine and phenylalanine mutant proteins were purified and compared with native proaerolysin. They were processed correctly to the mature forms by treatment with trypsin, and like native aerolysin, both were resistant to further proteolysis. In each case, processing was followed by the formation of oligomers similar to those produced by native toxin. The hemolytic activity of the processed Phe-227 mutant was one-quarter that of wild-type toxin whereas Leu-227 aerolysin had less than one-hundredth the wild-type activity. These results are further evidence that aerolysin is secreted in at least two steps. As well, they show that the last step, crossing the outer membrane, can be blocked by an apparently small change in the structure of the protein.

Aeromonas↗
PubMed1991

Structure of the tetragonal surface virulence array protein and gene of Aeromonas salmonicida.

The paracrystalline surface protein array of the pathogenic bacterium Aeromonas salmonicida is a primary virulence factor with novel binding capabilities. The species-specific structural gene (vapA) for this array protein (A-protein) was cloned into lambda gt11 but was unstable when expressed in Escherichia coli, undergoing an 816-base pair deletion due to a 21-base pair direct repeat within the gene. However, the gene was stable in cosmid pLA2917 as long as expression was poor. A-protein was located in the cytoplasmic, inner membrane and periplasmic fractions in E. coli. The DNA sequence revealed a 1,506-base pair open reading frame encoding a protein consisting of a 21-amino acid signal peptide, and a 481-residue 50,778 molecular weight protein containing considerable secondary structure. When assembled into a paracrystalline protein array on Aeromonas the cell surface A-protein was totally refractile to cleavage by trypsin, but became trypsin sensitive when disassembled. Trypsin cleavage of the isolated protein provided evidence that both the NH2- and COOH-terminal regions form distinct structural domains, consistent with three-dimensional ultrastructural evidence. The NH2-terminal 274-residue domain remained refractile to trypsin activity. This segment connects by a trypsin and CNBr-sensitive 78-residue linker region to a COOH-terminal 129-residue fragment which could apparently refold into a partially trypsin-resistant structure after cleavage at residue 323.

Aeromonas↗
PubMedDate not supplied

[Aeromonas spp. isolated from human feces. Species and pathogenicity factors].

The role of Aeromonas genus as a primary intestinal pathogen is still a matter of controversy. We have studied the isolation of Aeromonas spp. from human stools samples, looking for the production of pathogenic factors and its relationship with different species. From a total of 471 strains isolated, 241 were A. caviae, 127 A. sobria, 89 A. hydrophila and 14 non-typable strains. The pathogenic factors production was studied in a bacteria-free filtrate from a 18 hours trypticase-soy broth culture. Enterotoxin production was assessed by suckling-mice test, cytotoxin production by using Hela cells monolayer and hemolysin production by double dilution from the filtrate, plated in microdilution plates, against rabbit red-blood cells. Enterotoxin production test was positive for A. sobria, A. hydrophila and A. caviae in 81.1%, 62.9% and 7.0% of strains respectively. Cytotoxin production was also positive for these species in 96.6%, 76.4% and 4.1%, and hemolysin production was positive in 95.3%, 70.7% and 2.4% of the strains respectively.

Aeromonas↗
PubMed1991

Review of Aeromonas enterotoxins.

This report reviews the work of other investigators regarding Aeromonas toxins and describes work conducted in our laboratory relating to the biochemical characterization of a cytolytic factor with an antigenic moiety that cross-reacts with cholera toxin (referred to as CTC-cytolysin), as well as the purification and partial characterization of a non-CTC enterotoxin. These two toxins were produced by Aeromonas hydrophila, isolate SSU, and are capable of causing fluid accumulation in animal models.

Aeromonas↗
PubMed1991

Bacteriological and clinical aspects of Aeromonas-associated diarrhea in The Netherlands.

Aeromonas species were isolated from 0.61% of 34,311 fecal samples during a 5-year period. Most strains belonged to DNA hybridization groups (HG) 4 (A. caviae), 8 (A. sobria), and 1 (A. hydrophila). Mannitol-negative A. schubertii (HG 12) and ornithine-positive A. veronii (HG 10) were not found. Multivariate analysis of the clinical data showed that Aeromonas-associated diarrhea cannot be attributed solely to cytotoxin production of the strains, but that it is also strongly associated with host factors.

Aeromonas↗
PubMed1990

Plasmid screening amongst Aeromonas species and Plesiomonas shigelloides isolated from subjects with diarrhoea in Lagos, Nigeria.

Fifty-three Aeromonas strains and 16 Plesiomonas shigelloides isolated from subjects with diarrhoea in Lagos were screened for the presence of plasmids. Nine (17%) of the Aeromonas strains and one (6.3%) of the P. shigelloides harboured one or more plasmids, ranging in size from 2.4 to 16.8 MDa. As has been documented in other enteropathogens, the possibilities are that these plasmids code for some factors to enhance the virulence of their hosts.

Aeromonas↗
PubMed1990

Biochemical characteristics and a simple scheme for the identification of Aeromonas species and Plesiomonas shigelloides.

The biochemical characteristics of 55 strains of Aeromonas spp. and 16 P. shigelloides of human faecal origin were examined. Results of tests for the production of oxidase, acid from xylose, dulcitol, adonitol, mannitol, or inositol; greenish pigmentation on nutrient agar, and growth in 6.5% NaCl broth were found to be specific and reproducible. However, other tests such as haemolysis on blood agar (BA), production of DNase, amylase, ornithine or lysine decarboxylase; citrate utilization and the methyl red, Voges-Proskauer (MRVP) varied with different strains. On the basis of our results, we propose a simple scheme for the preliminary identification of Aeromonas and Plesiomonas isolates in laboratories with limited resources. We hope that other laboratories will evaluate it to determine its validity.

Aeromonas↗
PubMed1990

Antimicrobial susceptibility pattern of Aeromonas and Plesiomonas strains isolated from patients with diarrhoea in Nigeria.

The susceptibilities of 53 isolates of Aeromonas species and 16 Plesiomonas shigelloides, from patients with diarrhoea, to 15 commonly used antimicrobial agents were determined by the disk-agar diffusion technique. All the strains were susceptible to ofloxacin, a recent quinolone. Also, over 70 pc of our strains were susceptible to gentamicin, carbenicillin, ceftriaxone, erythromycin, Chloramphenicol, tetracycline and co-trimoxazole. However, less than 30 pc of our strains were susceptible to ampicillin. Results of this in vitro study indicate that for cases of serious Aeromonas or Plesiomonas infections requiring antimicrobial therapy, ofloxacin, gentamicin, carbenicillin or chloramphenicol could be useful.

Aeromonas↗
PubMed1990

Aeromonas species in human septicaemia & diarrhoea.

An increase was observed in the isolation of Aeromonas sp. from clinical specimens, especially faeces, from patients with diarrhoeal disease and blood cultures from patients with suspected septicaemias. The isolation rate from diarrhoeal patients was 0.2 per cent in 1978-79 and this increased to 5.0 per cent in 1986-87. It is noteworthy that 13 patients of septicaemia due to Aeromonas species were encountered, predominantly in adults with lowered resistance due to underlying disease states including chronic diseases of the liver and kidney.

Aeromonas↗
PubMed1988

Virulence factors from Aeromonas species.

Isolates (116) of Aeromonas were obtained from various sources and subjected to tests to establish their virulence factors. A high number of the isolates (69.8%) were found to be enterotoxigenic. The isolates from snails had more enterotoxigenic strains (73.3%), while those from cattle faeces had the lowest (33.3%). Haemolysin production was found to be high (60.3%) amongst the isolates, and human isolates gave the highest number of haemolysin producing strains (70.6%), while the least number (33.3%) was obtained from cattle strains. About 50% of the strains produced both enterotoxin and haemolysin. The enzyme profile of the isolates included amylase, lecithinase, lipase and protease. There was no definite pattern in the elaboration of these enzymes and the production of haemolysin and enterotoxin, thus inferring that the production of these factors is not specific to the source. Two isolates were seen to produce none of these enzymes, and one was positive for enterotoxin and haemolysin production, leaving only one isolate which yielded none of these factors. The work adds more support to the pathogenicity of Aeromonas species, and indicates the existence of non-pathogenic strains.

Aeromonas↗
PubMedDate not supplied

[Aeromonas hydrophila. Infection in Xenopus laevis].

Aeromonas hydrophila caused severe disease in a group of 50 Xenopus leavis three weeks after being transferred from their laboratory conditions. The first clinical signs observed were marked pallor, petechiae, lethargy, anorexia, and edema. The duration of the disease was about 48 days, during which 4 animals acquired the disease and 10 died. The study of the bacteriology of the skin and skeletal muscles showed at necropsy subcutaneous edema, hemorrhage, and ascitis. Aeromonas hydrophila was isolated in 14 of the 50 animals studied.

Aeromonas↗
PubMed1989

[Significance of the occurrence of Aeromonas of various biotypes in the Third World].

In investigations carried out in the refugee camps of the Polisario (South Algeria), in the neighbourhood of the inhabitants of the waste disposal sites of Cairo and in the Ayoun el Atrous and Nema (Mauritania) regions also in the Bida and Minna hospitals. Aeromonas hydrophila and Aeromonas spec. were repeatedly found in the investigated material. Therefore, it was of particular interest for us to investigate this type of organism.

Aeromonas↗
PubMedDate not supplied

Comparison of three assays to detect enterotoxigenicity of Aeromonas isolates from patients with diarrhoea in Vellore, south India.

Fifty strains of Aeromonas spp, isolated from patients with diarrhoea, were tested by three different assays to detect their enterotoxigenicity. Culture filtrates of the isolates were tested for their ability to produce haemolysin and to produce cytopathic changes in Vero cells and for their effects in the suckling mouse assay. The data indicated that biotypes alone are not adequate indicators of pathogenicity of different groups of Aeromonas isolated from patients with diarrhoea. No significant differences were observed in the results of the three assays for the detection of enterotoxigenicity.

Aeromonas↗
PubMedDate not supplied

[Application of the Moore swab method to the isolation of Aeromonas spp. from residual waters].

The Moore swab technique was applied in waste water from three different areas of the "Pedro Kouri" Institute of Tropical Medicine, with the view to isolate organisms of the genus Aeromonas. Swabs were placed once a week, in the wards of Medicine, Screening, and Diagnostic Laboratory. Of 13 swabs placed in the Medicine ward, 8 were positive. Of 15 swabs placed in Diagnostic Laboratory, 8 were positive, and of 18 placed in the screening ward, 12 were positive. Of a total 46 swabs, 28 disclosed organisms of the genus Aeromonas.

Aeromonas↗
PubMed1989

Segmental colitis associated with Aeromonas hydrophila.

We describe a 40-yr-old woman who presented with abdominal pain and diarrhea, and who was found to have segmental colitis involving the cecum and ascending colon. Aeromonas hydrophila was isolated from the stool, and her symptoms responded to appropriate antibiotic therapy. Follow-up colonoscopy confirmed complete endoscopic and histologic resolution of her colitis. This report further supports the belief that Aeromonas species are pathogens in healthy humans. This organism needs to be considered in the differential diagnosis of diffuse and segmental colitis.

Adult↗
PubMed1988

Incidence and biotyping of Aeromonas species from the environment.

A survey was carried out to establish the incidence rate of Aeromonas species in various environmental samples with a view to ascertaining their reservoirs and distinguishing the biotypes. High rates of isolation were obtained from snails and water. This indicates that these samples are likely reservoirs and therefore constitute high sources of human infection. Low incidence rates were realised from poultry, cattle and humans, thus suggesting that these samples may be transient hosts. Two species of Aeromonas were isolated: A. sobria, and A. hydrophila which was further split into two biotypes, viz A. hydrophila subspecies hydrophila and A. hydrophila subspecies anaerogenes. All were involved with infections in humans.

Adolescent↗
PubMed1988

Critical ionizing groups in Aeromonas neutral protease.

Aeromonas neutral protease possesses two residues critical to its activity. One has a pKa of 5.5 in both the free enzyme and the enzyme-substrate complex and must be deprotonated for maximal activity. The other, which ionizes at pH 7.1 in the free enzyme and at pH 7.4 in the enzyme-substrate complex, must be protonated for optimal enzyme action. The protease is reversibly inhibited by aminoacyl hydroxamates, peptides containing a phenylalanyl residue, phosphoryl-L-phenylalanylglycylglycine, and by beta-phenylpropionyl-L-phenylalanine. The pH dependence of inhibition by the latter revealed that a residue with a pKa of 5.6 influences inhibitor binding. Compounds containing both a hydroxamido group and a chloroacetyl group are particularly effective in inactivating the enzyme, and inhibition is enhanced by hydrophobic residues. Thus, a 33-fold molar excess of chloroacetyl-N-hydroxy-L-phenylalanyl-L-alanyl-L-alanine amide rapidly inactivated Aeromonas neutral protease. Carbethoxylation experiments resulted in a 90% loss in activity which was fully reversible by hydroxylamine; spectral analysis indicated the involvement of a single histidine residue. Protection against both esterification and carbethoxylation was furnished by the presence of beta-phenylproprionyl-L-phenylalanine. Inactivation experiments suggest that a glutamic or aspartic acid and a histidine residue are responsible for the pKa values revealed by pH dependence studies.

Aeromonas↗