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PubMed1991

Effect of Aeromonas proteases on the binding of Aeromonas hydrophila strains to connective tissue proteins.

125I-labelled connective tissue protein binding to cells of Aeromonas hydrophila, A. caviae, and A. sobria strains isolated from diseased fish, was correlated with the Aeromonas protease degradation of 125I-labelled collagen types I and IV, fibronectin and laminin, immobilized on tissue culture microtitre plates. An inverse relation between 125I-labelled connective tissue protein binding to cells of Aeromonas strains and proteolytic degradation of immobilized connective tissue proteins by Aeromonas proteases was established. Inhibition of the Aeromonas proteolytic activity by protease inhibitors enhances the 125I-labelled connective tissue protein binding to cells of Aeromonas hydrophila strains. Culture conditions were found to influence both expression of proteolytic activity and binding properties.

Aeromonas↗
PubMed1992

Nucleotide sequences and characterization of haemolysin genes from Aeromonas hydrophila and Aeromonas sobria.

Extracellular haemolysin is thought to be one of the important virulence factors in Aeromonas infection. Two extracellular haemolysin genes (AHH3 and AHH4) from Aeromonas hydrophila strain 28SA, one (AHH5) from A. hydrophila strain AH-1 and one (ASA1) from Aeromonas sobria strain 33 were cloned into cosmid and plasmid vector DNA in Escherichia coli. The nucleotide sequences of the open reading frames of AHH3 and AHH4 are both 1476 basepairs (bp), whereas AHH5 and ASA1 are 1455 and 1467 bp in length, respectively. The deduced amino acid sequences of AHH3, AHH4, AHH5 and the previously reported aerolysin from A. hydrophila showed a significant degree of sequence homology of over 90% each. The amino acid identity of the ASA1 haemolysin and those from A. hydrophila and Aeromonas trota aerolysins ranged from 58-68%. From DNA hybridization analysis using our cloned haemolysin genes as probes, we found that the AHH5 and ASA1 DNA probes hybridized with about 31 and 75% strains of motile Aeromonas species, respectively. The activity of haemolysins of cloned genes were different in medium agar containing various erythrocytes.

Aeromonas↗
PubMed2006

Secondary Aeromonas peritonitis is associated with polymicrobial ascites culture and absence of liver cirrhosis compared to primary Aeromonas peritonitis.

Aeromonas peritonitis remains a rare condition. In this study we describe the clinical features of primary and secondary Aeromonas peritonitis, and compare the differences between these two diseases entities. Patients with Aeromonas peritonitis were identified from microbiological and medical records during the period between March 1994 and March 2003. Clinical characteristics, laboratory data, microbiological results, treatment and outcome of patients were obtained by retrospective chart review. 22 and 27 patients with primary or secondary peritonitis caused by Aeromonas species were identified. All except two of these patients were adults, with a median age of 62.4 (31-76) vs 65.8 (8-85) years, respectively. Males were predominant (82 vs 78%). Peritonitis was community acquired in 73% and 56% of patients in these two groups, respectively. Significantly higher prevalence of underlying liver cirrhosis (96 vs 7%, p<0.001), which was Child-Pugh class C in 91% of cases, in primary peritonitis was noted. Primary peritonitis was more likely to be monomicrobial (100 vs 15%, p<0.001) and complicated by bacteremia (50 vs 7%, p=0.011). A source of intraabdominal infection should be sought when Aeromonas peritonitis occurs in a patient who has no history of liver cirrhosis or who has a polymicrobial result of ascites culture.

Adolescent↗
PubMed1997

Quorum sensing in Aeromonas hydrophila and Aeromonas salmonicida: identification of the LuxRI homologs AhyRI and AsaRI and their cognate N-acylhomoserine lactone signal molecules.

Spent culture supernatants from both Aeromonas hydrophila and Aeromonas salmonicida activate a range of biosensors responsive to N-acylhomoserine lactones (AHLs). The genes for a quorum sensing signal generator and a response regulator were cloned from each Aeromonas species and termed ahyRI and asaRI, respectively. Protein sequence homology analysis places the gene products within the growing family of LuxRI homologs. ahyR and asaR are transcribed divergently from ahyI and asaI, respectively, and in both Aeromonas species, the genes downstream have been identified by DNA sequence and PCR analysis. Downstream of both ahyI and asaI is a gene with close homology to iciA, an inhibitor of chromosome replication in Escherichia coli, a finding which implies that in Aeromonas, cell division may be linked to quorum sensing. The major signal molecule synthesized via both AhyI and AsaI was purified from spent culture supernatants and identified as N-(butanoyl)-L-homoserine lactone (BHL) by thin-layer chromatography, high-pressure liquid chromatography analysis, and mass spectrometry. In addition, a second, minor AHL, N-hexanoyl-L-homoserine lactone, was identified. Transcriptional reporter studies with ahyI::luxCDABE fusions indicate that AhyR and BHL are both required for ahyI transcription. For A. salmonicida, although the addition of exogenous BHL gives only a small stimulation of the production of serine protease with comparison to the control culture, the incorporation of a longer-chain AHL, N-(3-oxodecanoyl)-L-homoserine lactone, reduced the final level (by approximately 50%) and delayed the appearance (from an A650 of 0.9 in the control to an A650 of 1.2 in the test) of protease in the culture supernatant. These data add A. hydrophila and A. salmonicida to the growing family of gram-negative bacteria now known to control gene expression through quorum sensing.

4-Butyrolactone↗
PubMed2002

Distribution of Aeromonas hydrophila serogroups in different clinical samples and the development of polyclonal antibodies for rapid identification of the genus Aeromonas by direct agglutination.

We characterized a collection of 256 Aeromonas hydrophila strains isolated from blood, discharge and stool for their serogroup designation. Of these, 2.3% were untypable and 15.2% were rough strains. Among the typable strains, about 50% comprised serogroups O:11, O:16, O:18, O:34 and O:83. To develop rapid differentiation of Aeromonas from other oxidase-positive bacteria, antisera against Aeromonas were produced to establish a direct, genus-specific, agglutination test. It was found that among 105 isolates of Aeromonas, 102 showed positive results with the agglutination test. The calculated sensitivity and specificity were 97.1% and 90.7%, respectively.

Aeromonas↗
PubMed2005

Aeromonas culicicola Pidiyar et al. 2002 is a later subjective synonym of Aeromonas veronii Hickman-Brenner et al. 1987.

We re-investigated the taxonomic affiliation between Aeromonas culicicola Pidiyar et al. 2002 and Aeromonas veronii Hickman Brenner et al. 1987, two species that have previously been shown to be closely related on the basis of gyrB and rpoD gene sequencing and amplified fragment length polymorphism fingerprinting. From extended biochemical characterization and fatty acid analysis, it was concluded that A. culicicola did not constitute a unique phenotypic group in the genus Aeromonas but instead clearly fitted the phenotypic description of A. veronii biovar (bv.) sobria. Concordant with the phenotypic results, new DNA-DNA hybridizations revealed reassociation values in the range of 79-88% between the type strains of A. culicicola and A. veronii which indicates that both taxa belong to the same DNA hybridization group. Together with previously reported evidence, we conclude from the new taxonomic data that A. culicicola is a typical member of A. veronii bv. sobria and that its status as a new Aeromonas species is not justified. On the basis of nomenclatural priority, it is therefore proposed that A. culicicola Pidiyar et al. 2002 should be considered as later subjective synonym of A. veronii Hickman-Brenner et al. 1987.

Aeromonas↗
PubMed1997

Rapid and sensitive method for the detection of Aeromonas caviae and Aeromonas trota by polymerase chain reaction.

A 16S rDNA-based polymerase chain reaction (PCR) method was developed for the detection of Aeromonas caviae and Aeromonas trota. These two species were identified from other Aeromonas spp. and closely related species by primers set (AER1 and AER2). The amplified product was 316 bp. The identity of the amplified product was confirmed by DNA-DNA hybridization. Two sets of primers (AER8 and AER9) were used for specific identification of Aer. caviae. Amplifying the 260 bp fragment of 16S rRNA gene region and digesting it with AluI restriction enzyme, yielded 180- and 80-bp fragments. For PCR assay, template DNA was released by mixing equal volumes of homogenized seeded crab meat with Aer. caviae and Chelex 100 (6%) incubated for 10 min at 56 degrees C followed by addition of an equal volume of 0.1% Triton-X-100 and boiled for 10 min. The detection limit was between 50 and 100 cells g-1 of crab meat. This method is very rapid and obviates the need for DNA isolation from complex food matrices and is specific for detecting two Aeromonas species.

Aeromonas↗
PubMed1995

DNA relatedness among Aeromonas allosaccharophila strains and DNA hybridization groups of the genus Aeromonas.

The genomic relatedness among three Aeromonas allosaccharophila strains, including the type strain, and other Aeromonas type and reference strains that were assigned to DNA hybridization groups was estimated by DNA-DNA hybridization (competition procedure using a membrane method). All A. allosaccharophila strains were highly related (70 to 100%) to strains 289T (= CECT 4199T) and ATCC 35942. Type strains of other validated Aeromonas species, reference strains of DNA groups 8 and 11, and the Aeromonas sp. strain ATCC 43946 (enteric group 501) were 0 to 41% related to A. allosaccharophila 289T and ATCC 35942. The G+Cs content of A. allosaccharophila strains were in the range 55.9 to 57.3 mol%. The G+C content of the type strain of this species was 56.9 mol%, a value somewhat lower than that reported in the original description.

Aeromonas↗
PubMed2002

DNA-DNA reassociation and phenotypic data indicate synonymy between Aeromonas enteropelogenes Schubert et al. 1990 and Aeromonas trota Carnahan et al. 1991.

Mainly on the basis of phylogenetic and genotypic evidence, it has been suggested previously that the species Aeromonas enteropelogenes Schubert et al. 1990 is identical to the species Aeromonas trota Carnahan et al. 1991. Probably because the description of A. enteropelogenes preceded the proposal of A. trota by only a few months, DNA-DNA hybridizations were never performed between representative strains of these two taxa. In the present study, new DNA-DNA hybridizations between the type strain of A. enteropelogenes, LMG 12646(T) (= DSM 6394(T)), and reference strains of A. trota, including its type strain LMG 12223(T)(= ATCC 49657(T)), showed a genomic relatedness of 81-99%. In addition, phenotypic characterization revealed that the two type strains exhibited identical API 20E and API 50CHE biochemical profiles and were both susceptible to ampicillin and carbenicillin. Collectively, our new DNA reassociation and phenotypic data confirm previous taxonomic data that indicate that the taxa A. enteropelogenes and A. trota are synonymous members of the same Aeromonas species. Although the species name A. enteropelogenes has nomenclatural priority, the authors would like to discourage the use of this name because the name A. trota has been cited much more frequently. The preferential use of A. trota in future publications may be the best option to avoid ambiguity in the description of ampicillinsusceptible aeromonads and to secure nomenclatural continuity in Aeromonas literature.

Aeromonas↗
PubMed1999

Diverse restriction fragment length polymorphism patterns of the PCR-amplified 16S rRNA genes in Aeromonas veronii strains and possible misidentification of Aeromonas species.

Restriction fragment length polymorphism analysis after PCR amplification (RFLP-PCR) of the 16S rRNA gene has been previously proposed as a rapid method to identify Aeromonas species. In the present study, the precision of RFLP-PCR was evaluated with 62 Aeromonas reference strains. The analysis revealed that Aeromonas veronii biovar sobria strains produce various patterns, possibly leading to its misidentification as an environmental species. For most other Aeromonas species little variation was noted. This study supports the usefulness of RFLP-PCR analysis to separate three clinically important species but also reveals possible misidentifications that necessitate further biochemical tests to validate the preliminary identification.

Aeromonas↗
PubMed1993

El fenómeno suicida en cepas de Aeromonas mesófilas aisladas de muestras clínicas [The suicide phenomenon in strains of mesophilic Aeromonas isolated from clinical specimens].

A study was carried out to determine the occurrence of the suicide phenomenon in Aeromonas spp strains, isolated from clinical samples, and to establish its relationship with the clinical manifestations of diarrheal diseases. 23 strains were studied: 10, of Aeromonas sobria; 7, of Aeromonas hydrophila; and 6, of Aeromonas caviae. All suicidal strains were isolated from patients with acute diarrheal disease. 3 out of 8, isolated from non-diarrheic feces, showed an intermediate phenotypic profile. Various growth patterns associated to the suicide phenomenon were reported.

Acute Disease↗
PubMed1994

O-serogrouping and surface components of Aeromonas hydrophila and Aeromonas jandaei pathogenic for eels.

The relationship between virulence, O-serogroup, and some cell-surface features (self-pelleting [SP] and precipitation after boiling [PAB], profile of lipopolysaccharides [LPSs] and outer membrane proteins [OMPs]) was investigated in strains of the pathogenic species Aeromonas hydrophila and A. jandaei isolated from eels. Virulent strains of A. hydrophila reacted mostly with O:19 antiserum, and those of A. jandaei reacted with O:4, O:11, O:15 and O:29 antisera (Guinée and Jansen system). Regarding the PAB and LPS profiles two groups could be distinguished; (i) five PAB+ strains of serotype O:19 that possessed a homogeneous O polysaccharide side chain and (ii) thirteen PAB- strains antigenically diverse that either exhibited a heterogeneous side chain or were side chain deficient. A major 50 kDa protein was only found in the PAB+ strains, whereas major OMPs detected in PAB- strains ranged from 33 to 45 kDa irrespective of the species. Epizootic eel isolates of A. hydrophila belong to serotype O:19 and share cell-surface features with the Aeromonas highly virulent for other hosts. In contrast, epizootic A. jandaei isolates were antigenically diverse. These findings reinforce the importance of an O-serotype as an epidemiological marker in motile Aeromonas strains pathogenic for eels.

Aeromonas↗
PubMed2007

Phylogenetic identification of Aeromonas strains isolated from carcasses of pig as new members of the species Aeromonas allosaccharophila.

The first description of the species Aeromonas allosaccharophila was only based on two strains (the type strain CECT4199, and a duplicate CECT4200) isolated from diseased elvers (Anguilla anguilla) of an eel-farm located in Valencia, Spain, and one stool isolate (ATCC35942) from a female with diarrhoea and food poisoning in South Carolina, U.S.A. In the present study, 17 Aeromonas isolates obtained from carcasses of pigs and from the equipment for the cleaning process, and one strain recently isolated from a clinical case of gastroenteritis, were genetically identified as Aerornonas allosaccharophila on the basis of gyrB and 16S rRNA gene sequencing. In addition, this phylogenetic approach also supports the classification of Aeromonas veronii biogroup sobria reference strains LMG13071, LMG13073 and LMG13074 within the species A. allosaccharophila. The A. allosaccharophila strains isolated from pig carcasses processed in a single slaughterhouse presented a clonal origin, on the basis of random amplified polymorphic DNA genetic typing. To our knowledge, this is the first time since the species description that A. allosaccharophila has been newly identified, being on this occasion isolated from the environment of a slaughterhouse. Our findings indicate that this species may be readily identified by a sequencing approach and, consequently, the present work supports the existence of this phylogenetic cluster.

Abattoirs↗
PubMed1991

Experimental evidence for toxin production by Aeromonas hydrophila and Aeromonas sobria in a meat extract at low temperatures.

The ability of enterotoxigenic strains of Aeromonas hydrophila and Aeromonas sobria to produce exotoxins (enterotoxin and haemolysin) in a meat extract at low temperatures (5 and 12 degrees C) was investigated. All three strains incubated at 12 degrees C were enterotoxigenic and haemolytic in the meat extract after 5 days. At 5 degrees C, five of the six strains tested were able to produce these exotoxins after 8 days incubation while one strain was neither enterotoxigenic nor haemolytic after 5, 8 and 11 days. The possible involvement of performed toxin(s) in Aeromonas gastroenteritis is also discussed.

Aeromonas↗
PubMed1992

Aeromonas allosaccharophila sp. nov., a new mesophilic member of the genus Aeromonas.

Phenotypic and genetic studies were performed on some atypical aeromonas strains of uncertain taxonomic position. 16S rRNA gene sequence analysis revealed that these strains represent a hitherto unknown genetic line within the genus Aeromonas, for which the name Aeromonas allosaccharophila sp. nov. is proposed. The type strain is CECT 4199.

Aeromonas↗
PubMed2001

New DNA-DNA hybridization and phenotypic data on the species Aeromonas ichthiosmia and Aeromonas allosaccharophila: A. ichthiosmia Schubert et al. 1990 is a later synonym of A. veronii Hickman-Brenner et al. 1987.

Previously, a DNA fingerprinting study based on Amplified Fragment Length Polymorphism (AFLP) analysis has revealed a possible genotypic resemblance of the species Aeromonas ichthiosmia and Aeromonas allosaccharophila to Aeromonas veronii (Huys et al., Int. J. Syst. Bacteriol. 46, 572-580 [19961). Currently, two genotypically indistinguishable biovars are known to exist in the latter species, namely A. veronii biovar sobria and A. veronii biovar veronii. In the current study, new DNA-DNA hybridization experiments showed that the type strain of A. ichthiosmia, LMG 12645T (= DSM 6393T), and that of A. allosaccharophila, LMG 14059T (= CECT 4199T), were 84-96% and 78-82% related to A. veronii strain LMG 9075T (= ATCC 35624T), respectively. Based upon phenotypic characterization including a total of 151 tests, the type strain of A. ichthiosmia could be clearly allocated to A. veronii biovar sobria. On the other hand, the three strains constituting the species A. allosaccharophila were found to be phenotypically heterogeneous. None of these strains clearly fitted the biochemical description of either of the two A. veronii biovars or tightly clustered with any of the A. veronii reference strains. On the basis of published taxonomic evidence (including AFLP and phylogenetic data) and the newly reported results, there is compiling evidence to conclude that A. ichthiosmia Schubert et al. 1990 is a later synonym of A. veronii Hickman-Brenner et al. 1987. However, due to the lack of agreement encountered between the new DNA reassociation results and previously reported DNA homology and phylogenetic data, a conclusive proposal on the genotypic position of A. allosaccharophila should await further studies.

Aeromonas↗
PubMed1992

Molecular studies on the aerolysin gene of Aeromonas species and discovery of a species-specific probe for Aeromonas trota species nova.

A large group of aeromonads and other enteric microorganisms were assayed for the presence of the aerolysin gene with use of DNA-DNA hybridization. Two DNA fragments corresponding to the regulatory region (aerC) and the structural gene (aerA) were used as probes for the detection of the aerolysin gene in these strains. Sequences corresponding to the aerolysin structural gene were widespread among Aeromonas isolates. In contrast, the aerC probe was much more selective, and sequences corresponding to the aerC region were detected in only a small subset of strains. Concurrent studies using numerical taxonomy and DNA hybridization with the aerC probe on a larger set of strains led to the identification of a distinct cluster of 14 presumed atypical Aeromonas sobria strains. These strains have recently been grouped into a new species designated Aeromonas trota. Hence, the DNA fragment aerC used in the study is a species-specific gene probe for A. trota. The ability of the aerC probe to detect strains belonging to a single species suggests that there is selection pressure to maintain the clonality of this species. These results have important implications with respect to the evolution of "pathogenic profiles" among these medically important bacteria.

Aeromonas↗