An acute pleuropneumonia in a pig caused by Chromobacterium violaceum

A 2.5-month-old, 30 kg Duroc pig died 10 days after showing clinical signs of dyspnoea and diarrhoea. Acute necrotizing and fibrinous pleuropneumonia with locally extensive lesions was found. Chromobacterium violaceum was isolated from pneumonic lung tissues and intratracheal inoculation of a pure culture into two SPF pigs reproduced lesions similar to those found in the natural infection.     

Chromobacterium violaceum: a review of pharmacological and industiral perspectives

Violet-pigmented bacteria, which have been described since the end of the 19th century, are occasionally the causative agent of septicemia and sometimes cause fatal infection in human and animals. Bacteria, producing violet colonies due to the production of a nondiffusible pigment violacein, were classified as a redefined genus Chromobacterium. Chromobacterium violaceum is gram-negative, and saprophyte from soil and water is normally considered nonpathogenic to human, but is an opportunistic pathogen of extreme virulence for human and animals. The biosynthesis and biological activities of violacein and the diverse effects of this pigment have been studied. Besides violacein, C. violaceum produces other antibiotics, such as aerocyanidin and aerocavin, which exhibit in vitro activity against both gram-negative and gram-positive bacteria. 3,6-Dihydroxyindoxazene and Y-TO678h exhibit a selective activity against gram-negative bacteria. Arphamenine A and B, and FR901228, that enhanced immunoresponse, and potentiators of beta-lactam antibiotics and chelators such as ferrioxamine exhibit important clinical potential applications. Lipopolysaccharides and polyhydroxyesters together with several enzymes appear as important metabolites with biotechnological applications. Many of these metabolites were already studied at the genome level.     

Chromobacterium violaceum peritonitis: case report and literature review

We report a case of Chromobacterium violaceum infection and we review the literature for all published cases. C. violaceum grew from a peritoneal fluid of a 47-year-old woman operated on for peritonitis following perforative gastroduodenal ulcer. She was just coming back from a 1-month-holyday in French Guyana, where she might have been in contact with this micro-organism. The patient fully recovered after surgical management associated with antibiotic therapy consisting of ofloxacin plus piperacillin-tazobactam. Among the more than a hundred of published cases of human infections with C. violaceum that we retrieved, there was not any other case of peritonitis.     

Fatal wound infection caused by Chromobacterium violaceum in Ho Chi Minh City, Vietnam

Chromobacterium violaceum is a proteobacterium found in soil and water in tropical regions which rarely causes infection in humans. Here, we report a fatal bacteremia caused by Chromobacterium violaceum in Vietnam. We describe a number of clinical, microbiological, and molecular aspects associated with this bacterial infection.     

Chromobacterium violaceum: A Review of Pharmacological and Industiral Perspectives

Violet-pigmented bacteria, which have been described since the end of the 19th century, are occasionally the causative agent of septicemia and sometimes cause fatal infection in human and animals. Bacteria, producing violet colonies due to the production of a nondiffus-ible pigment violacein, were classified as a redefined genus Chromobacterium. Chromobacterium violaceum is Gram-negative, and saprophyte from soil and water is normally considered nonpathogenic to human, but is an opportunistic pathogen of extreme virulence for human and animals. The biosynthesis and biological activities of violacein and the diverse effects of this pigment have been studied. Besides violacein, C. violaceum produces other antibiotics, such as aerocyanidin and aerocavin, which exhibit in vitro activity against both Gram-negative and Gram-positive bacteria. 3,6-Dihydroxyindoxazene and Y-TO678h exhibit a selective activity against Gram-negative bacteria. Arphamenine A and B, and FR901228, that enhanced immunoresponse, and potentiators of β-lactam antibiotics and chelators such as ferrioxamine exhibit important clinical potential applications. Lipopolysaccharides and polyhydroxyesters together with several enzymes appear as important metabolites with biotechnological applications. Many of these metabolites were already studied at the genome level.     

Chromobacterium violaceum infection in Taiwan: a case report and literature review.

Chromobacterium violaceum is a facultative anaerobic, Gram-negative bacillus which inhabits stagnant water in tropical and subtropical regions. We describe the case of an 80-year-old female patient with C. violaceum bacteremia due to traumatic wound infected by contaminated water and soil. She had persistent fever, hypotension and neutrophilic leukocytosis on admission. Two sets of blood cultures yielded C. violaceum. The patient was successfully treated with levofloxacin. Since the first case from Malaysia in 1927, about 150 cases have been reported in the world literature. To our knowledge, six other cases have been reported previously from Taiwan, including two children and four adults. Of the total of seven patients from Taiwan, four had a fatal outcome within several days, while the three survivors were apparently free of vital organ involvement. Although human infections caused by C. violaceum are rare, clinicians should be aware of this potentially fatal infection as part of the differential diagnosis of sepsis associated with a history of exposure to stagnant water.     

Two Cases of Chromobacterium violaceum Infection after Injury in a Subtropical Region

Chromobacterium violaceum is a gram-negative rod and is isolated from soil and water in tropical and subtropical regions. The species have pigmented and nonpigmented colony types. Infections caused by nonpigmented strains are rare. We report on two cases of infection caused by both pigmented and nonpigmented strains of C. violaceum. Two 24-year-old Korea Airline stewardesses were admitted to Inha University Hospital, Inchon, South Korea, on 9 August 1997, 3 days after an airplane accident in Guam. Both had multiple lacerations on exposed parts of their bodies. There was swelling, tenderness, and pus discharge. The wounds contained many small fragments of stones and weeds. A pigmented strain was isolated from the left hand and a nonpigmented strain was isolated from the left knee of one patient. For the other patient only a nonpigmented strain was isolated from a foot wound. The nonpigmented colonies from the left-knee and the left-foot wounds did not produce any pigment even after an extended period of incubation. The biochemical characteristics were the same for each strain except for oxidase and indole reactions. The pigmented strain was oxidase negative and indole positive, whereas the nonpigmented strains were oxidase positive and indole negative. The patients were successfully treated by debridement and with appropriate antibiotics.     

First case report from Argentina of fatal septicemia caused by Chromobacterium violaceum.

A case of Chromobacterium violaceum fatal septicemia is reported. The microorganism was isolated from six blood cultures and two suppurated skin lesions. It is the first such case described in Argentina, and it reinforces the need for prolonged treatment and careful clinical evaluation to ensure complete remission of human infections caused by this bacterium.     

Chromobacterium violaceum: a case report of an unusual bacterium causing puerperal sepsis

Human infections by Chromobacterium violaceum are rare. Till date 6 cases have been reported from southern and eastern parts of India. We report here a case of puerperal sepsis by C. violaceum, probably the first case from Eastern part of Orissa. The patient was successfully treated with amikacin and gatifloxacin.     

Mouse B cell activation is inhibited by CD44 cross-linking

Lymphocyte activation and trafficking are indispensable to the immune system. CD44 is an adhesion molecule with known importance in T cell activation, lymphocyte trafficking, and tumor metastasis. Although CD44 has been shown to participate in the activation, rolling and adhesion, and homing of T cells, the role of CD44 on B cells is relatively unknown. The effects of CD44 cross-linking on murine B cell activation via CD40L was explored using the anti-CD44 mAbs RK3G9 and IM7. When immobilized on a plate, both RK3G9 and IM7 were found to strongly inhibit B cell proliferation and Ig production, especially at lower cell input concentrations. IgE inhibition was especially prominent. In contrast, soluble RK3G9 added to the B cell cultures had no effect. The inhibitory effect of anti-CD44 on B cell activation was not influenced by the addition of the anti-FcγRII, indicating that Fc cross-linking did not play a role in this inhibition. As Ig production requires several days for both B cell proliferation and differentiation to occur, the effects of delayed addition of immobilized anti-CD44 mAbs were studied, and the results indicated no inhibition after 96 hrs of culture. Finally, B cells were activated by either LPS or anti-IgM F(ab')₂. While LPS-induced B cell activation was inhibited by immobilized anti-CD44 mAbs, anti-IgM activation was refractory. Interestingly, addition of both anti-IgM and CD40L or LPS resulted in some modulation of the inhibitory activity. These results suggest that CD44 cross-linking could control polyclonal B cell activation by CD40L, but allow sIgM/CD40L activation to continue.     

The Pseudomonas aeruginosa autoinducer N-3-oxododecanoyl homoserine lactone accelerates apoptosis in macrophages and neutrophils

Quorum-sensing systems are critical regulators of the expression of virulence factors of various organisms, including Pseudomonas aeruginosa. Las and Rhl are two major quorum-sensing components, and they are regulated by their corresponding autoinducers, N-3-oxododecanoyl homoserine lactone (3-oxo-C(12)-HSL) and N-butyryl-L-homoserine lactone (C(4)-HSL). Recent progress has demonstrated the potential of quorum-sensing molecules, especially 3-oxo-C(12)-HSL, for modulation of the host immune system. Here we show the specific ability of 3-oxo-C(12)-HSL to induce apoptosis in certain types of cells. When bone marrow-derived macrophages were incubated with synthetic 3-oxo-C(12)-HSL, but when they were incubated not C(4)-HSL, significant loss of viability was observed in a concentration (12 to 50 micro M)- and incubation time (1 to 24 h)-dependent manner. The cytotoxic activity of 3-oxo-C(12)-HSL was also observed in neutrophils and monocytic cell lines U-937 and P388D1 but not in epithelial cell lines CCL-185 and HEp-2. Cells treated with 3-oxo-C(12)-HSL revealed morphological alterations indicative of apoptosis. Acceleration of apoptosis in 3-oxo-C(12)-HSL-treated cells was confirmed by multiple criteria (caspases 3 and 8, histone-associated DNA fragments, phosphatidylserine expression). Structure-activity correlation experiments demonstrated that the fine structure of 3-oxo-C(12)-HSL, the HSL backbone, and side chain length are required for maximal activity. These data suggest that Pseudomonas 3-oxo-C(12)-HSL specifically promotes induction of apoptosis, which may be associated with 3-oxo-C(12)-HSL-induced cytotoxicity in macrophages and neutrophils. Our data suggest that the quorum-sensing molecule 3-oxo-C(12)-HSL has critical roles in the pathogenesis of P. aeruginosa infection, not only in the induction of bacterial virulence factors but also in the modulation of host responses.     

Selective human endothelial cell activation by chemokines as a guide to cell homing

An original model of organo-specific, immortalized and stabilized endothelial cell lines was used to delineate the part played by some chemokines (CCL21, CX3CL1, CCL5 and CXCL12) and their receptors in endothelium organo-specificity. Chemokine receptor expression and chemokine presentation were investigated on organo-specific human endothelial cell lines. Although the chemokines showed distinct binding patterns for the various endothelial cell lines, these were not correlated with the expression of the corresponding receptors (CX3CR1, CXCR4, CCR5 and CCR7). Experiments with CCL21 on peripheral lymph node endothelial cells demonstrated that the chemokine did not co-localize with its receptor but was associated with extracellular matrix components. The specific activity of chemokines was clearly shown to be related to the endothelial cell origin. Indeed, CX3CL1 and CCL21 promoted lymphocyte recruitment by endothelial cells from the appendix and peripheral lymph nodes, respectively, while CX3CL1 pro-angiogenic activity was restricted to endothelial cells from the appendix and skin. The high specificity of the chemokine/endothelium interaction allowed the design of a direct in vitro endothelial cell targeting assay. This unique cellular model demonstrated a fundamental role for chemokines in conferring on the endothelium its organo-specificity and its potential for tissue targeting through the selective binding, presentation and activation properties of chemokines.     

Mouse red cell rosette formation by subpopulations of human lymphocytes.

In six separate experiments, 7-2% of purified peripheral blood lymphocytes from normal donors were shown to form rosettes with mouse erythrocytes. Normal T and B lymphocytes were separated according to their membrane properties, by E-rosette formation or fractionation on anti F (ab')2 column. The results obtained in both the separation procedures used were in good agreement: T lymphocytes were never found to form mouse red cell rosettes. On the contrary, enrichment of suspensions in B lymphocytes resulted in an increased percentage of mouse red-cell rosette-forming cells. Under the technical condition used, peroxidase-positive monocytes were not shown to form such rosettes. However, if all the mouse red cell rosette-forming cells were shown to be of B nature, not all the B lymphocytes form rosettes with mouse erythrocytes and it is not unlikely that this marker could be characteristic for a subset of Ig-bearing B lymphocytes.