Aeromonas Veronii Biotype Sobria Research Articles

Virulence and antimicrobial resistance potential of Aeromonas spp. associated with shellfish.

Aeromonas spp. are associated with seafood-related outbreaks worldwide. In seafood industry, shellfish play a major role in global seafood production. With this emerging trend of shellfish consumption, shellfish-related bacterial infections are being reported frequently. Aeromonas spp. are natural contaminants found in shellfish. Although 36 species have been identified, some species including Aeromonas hydrophila, Aeromonas caviae and Aeromonas veronii biotype sobria have dragged major attention as foodborne pathogenic bacteria. The ability to elaborate a variety of virulence factors of Aeromonas spp. contributes to the pathogenic activities. Also, emerging antimicrobial resistance in Aeromonas spp. has become a huge challenge in seafood industry. Furthermore, multidrug resistance increases the risk of consumer health. Studies have supplied pieces of evidence about the emerging health risk of Aeromonas spp. isolated from seafood. Therefore, the present review was intended to highlight the prevalence, virulence and antimicrobial resistance of Aeromonas spp. isolated from various types of shellfish.

Differential Regulation of Caspase-1 Activation via NLRP3/NLRC4 Inflammasomes Mediated by Aerolysin and Type III Secretion System during Aeromonas veronii Infection

Aeromonas spp. are Gram-negative bacteria that cause serious infectious disease in humans. Such bacteria have been shown to induce apoptosis in infected macrophages, yet the host responses triggered by macrophage death are largely unknown. In this study, we demonstrate that the infection of mouse bone marrow-derived macrophages with Aeromonas veronii biotype sobria triggers activation of caspase-1 with the ensuing release of IL-1β and pyroptosis. Caspase-1 activation in response to A. veronii infection requires the adaptor apoptosis-associated speck-like protein containing a caspase recruitment domain and both the NLRP3 and NLRC4 inflammasomes. Furthermore, caspase-1 activation requires aerolysin and a functional type III secretion system in A. veronii. Aerolysin-inducing caspase-1 activation is mediated through the NLRP3 inflammasome, with aerolysin-mediated cell death being largely dependent on the NLRP3 inflammasome. In contrast, the type III secretion system activates both the NLRP3 and NLRC4 inflammasomes. Inflammasome-mediated caspase-1 activation is also involved in host defenses against systemic A. veronii infection in mice. Our results indicated that multiple factors from both the bacteria and the host play a role in eliciting caspase-1 activation during A. veronii infection.

悪性リンパ腫治療中好中球減少時に合併した<I>Aeromonas veronii</I> biotype sobriaによる壊死性軟部組織感染症の1救命例

We report a 52 year-old patient with malignant lymphoma who developed necrotizing soft tissue infection in the left lower extremity by Aeromonas veronii biotype sobria during a neutropenic period after intensive chemotherapy. We decided to amputate the involved leg when signs and symptoms of necrotizing myositis were progressing despite administration of sensitive antibiotics. He survived with subsequent intensive supportive care. It is to note that even though the patient's neutrophil count is zero, he or she should be treated aggressively by drainaging the lesion or even amputation of the involved extremities in combination with proper antibiotics.

Spontaneous bacterial empyema caused by Aeromonas veronii biotype sobria

Spontaneous bacterial empyema is a complication of hepatic hydrothorax in cirrhotic patients. The pathogen, clinical course and treatment strategy are different to the empyema secondary to pneumonia. A 54-year-old man, who was a cirrhotic patient with hepatic hydrothorax, was admitted to National Taiwan University Hospital for fever, dyspnea and right side pleuritic pain. The image study revealed massive right pleural effusion and no evidence of pneumonia. The culture of pleural effusion yielded Aeromonas veronii biotype sobria. The diagnosis of spontaneous bacterial empyema caused by Aeromonas veronii biotype sobria was established. To our best knowledge, Aeromonas veronii biotype sobria had never been reported in English literature as the causative pathogen of spontaneous bacterial empyema.

Phenotypic identification of Aeromonas genomospecies from clinical and environmental sources.

A collection of 983 Aeromonas isolates from environmental and clinical sources have been identified to the genomospecies level. A phenotypic method identified 93% of the strains. The use of citrate and the production of acid from sorbitol enabled the members of the Aeromonas hydrophila complex to be separated. The most common genomospecies from intestinal sources were Aeromonas veronii biotype sobria and Aeromonas caviae. The former, together with A. hydrophila, was the most frequently isolated species of extraintestinal origin. Most pathogenic species were very prevalent in environmental samples, with A. veronii biotype sobria being the most common in lakes and reservoirs (41.5%) and in treated drinking water (25.0%), and A. caviae was the most common in sea water (26.0%) and milk products (35.5%). Aeromonas hydrophila (18.1%) was the second most prevalent species isolated in untreated drinking water. Since Aeromonas infections are generally regarded as a water- and food-borne diseases, the high environmental prevalence of these pathogenic genomospecies should be regarded as an important threat to public health.

Prevalence, in-vitro secretory activity, and cytotoxicity of Aeromonas species associated with childhood gastroenteritis in Chennai (Madras), India.

An investigation on the prevalence of Aeromonas in gastrointestinal illnesses of pediatric inpatients 1 month to 3 years of age was conducted from February 1997 through January 1998 in Madras. Sixteen Aeromonas spp. were isolated from 11 male and five female children among the 341 pediatric inpatients suffering from acute diarrhoea. A. caviae, which was isolated from nine cases, was found to be the most predominant isolate, followed by A. veronii biovar sobria, isolated from six cases, and A. hydrophila, isolated from one case. Shigella flexneri was recovered along with Aeromonas veronii biotype sobria serotype 035 from one 5-month-old female child. We did not notice any seasonal pattern in the association between Aeromonas and childhood gastroenteritis. None of the 147 stool samples obtained from age-matched non-diarrhoeic control children yielded Aeromonas spp. Isolation of Aeromonas spp. from patients suffering from gastroenteritis was found to be significant (chi 2 = 7.1312; P = 0.008, < 0.01). Among the 16 Aeromonas isolates, seven isolates of A. caviae and two isolates of A. veronii biovar sobria induced a secretory response in rabbit intestinal mucosa mounted in Ussing chambers as demonstrated by a significant increase in the short circuit current. Nine of the 16 Aeromonas isolates, including three isolates of A. caviae, five isolates of A. veronii biovar sobria, and the solitary isolate of A. hydrophila were also cytotoxic to CHO cells. Five of the six isolates of A. veronii biovar sobria and the A. hydrophila isolate produced hemolysin. The results of this study indicate that Aeromonas species are important causative agents of diarrhoea in childhood gastroenteritis and are prevalent throughout the year in Madras.

Identification and molecular characterization of two tandemly located flagellin genes from Aeromonas salmonicida A449.

Two tandemly located flagellin genes, flaA and flaB, with 79% nucleotide sequence identity were identified in Aeromonas salmonicida A449. The fla genes are conserved in typical and atypical strains of A. salmonicida, and they display significant divergence at the nucleotide level from the fla genes of the motile species Aeromonas hydrophila and Aeromonas veronii biotype sobria. flaA and flaB encode unprocessed flagellins with predicted Mrs of 32,351 and 32,056, respectively. When cloned under the control of the Ptac promoter, flaB was highly expressed when induced in Escherichia coli DH5alpha, and the FlaB protein was detectable even in the uninduced state. In flaA clones containing intact upstream sequence, FlaA was barely detectable when uninduced and poorly expressed on induction. The A. salmonicida flagellins are antigenically cross-reactive with the A. hydrophila TF7 flagellin(s) and evolutionarily closely related to the flagellins of Pseudomonas aeruginosa and Vibrio anguillarum. Electron microscopy showed that A. salmonicida A449 expresses unsheathed polar flagella at an extremely low frequency under normal laboratory growth conditions, suggesting the presence of a full complement of genes whose products are required to make flagella; e.g., immediately downstream of flaA and flaB are open reading frames encoding FlaG and FlaH homologs.

Numerical Taxonomy and Biochemical Identification of Fish Associated Motile Aeromonas spp.

Summary Four hundred and thirty-eight Aeromonas, 31 Vibrio and 3 Plesiomonas strains isolated from moribund and healthy fish, water samples and humans, including 36 reference strains, were compared using numerical taxonomy based on 128 unit characters. Data were examined by the simple matching (SSM) and Jaccard (SJ) coefficients, and by unweighted average linkage clustering. As expected, Aeromonas spp. were clearly distinct from those of Vibrio and Plesiomonas. The motile Aeromonas spp., i.e. Aeromonas hydropbila, Aeromonas caviae and Aeromonas veronii biotype sobria formed discrete homogeneous clusters, distinct from the nonmotile species Aeromonas salmonicida. Furthermore, A. caviae was divided into two biotypes with D-mannose fermentation as the most important differentiating characteristic. Of the recently described species, A. veronii biotype veronii (type strain ATCC 35624) was phenotypically closest to A. bydropbila, although from DNA: DNA hybridisation studies it was classified within the A. sobria group. Aeromonas scbubertii (type strain ATCC 43 700) was well defined and formed a single member cluster. The phenotypic boundaries of Aeromonas media (type strain ATCC 33907) and Aeromonas eucrenopbila (type strain CDC 0859-83) were not clear. All the fish isolates (n = 208) were identified, with A. bydropbila predominating (43.8%), followed by A. veronii biotype sobria (26.9%), A. caviae biotype I (16.3 %), A. salmonicida (6.7%), A. sobria (HG7) (2.9 %), A. caviae biotype II (2.4 %), and A. veronii biotype veronii (1 %).

Pili and the interaction of Aeromonas species with human peripheral blood polymorphonuclear cells.

The interaction of differentially piliated Aeromonas strains expressing pili of two broadly different morphologic types (short, rigid (S/R) and/or long, wavy (L/W)) with human peripheral blood mononuclear leukocytes (PMN) was investigated to determine whether host defense cells might exert a selective pressure on pili expression in vivo accounting for the different pili phenotypes of clinical and environmental strains. A majority of Aeromonas veronii biotype sobria strains from water (6/6) and faeces (8/11) readily associated with PMN (> 60% PMN with adherent and/or internalised bacteria), irrespective of their degree, or predominant type, of piliation. Rigid pili of Aeromonas species did not promote interaction with PMN. However, the majority (55%) of strains which interacted well with PMN were adherent to HEp-2 cells. Interaction with PMN is unlikely to be the reason few S/R pili are seen on faecal strains, but it may be a selective pressure on L/W adhesive pili, or other OMP adhesins, resulting in the shedding of strains which have lost critical adhesins.