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Biomedical subjects

S E Vartivarian

Publications and source records attributed to S E Vartivarian.

At least 19 recordsLinked to original sources
PubMed2000

The clinical spectrum of stenotrophomonas (xanthomonas) maltophilia respiratory infection.

During a 15-month retrospective clinical study in an academic referral-based cancer center, 26 patients with S. maltophilia respiratory tract infections were identified (which were associated with bacteremia in 13 patients). Five of these 26 patients had previously undescribed sinopulmonary involvement. The infections were typically nosocomial. Nine patients with solid tumors had malignant involvement of the respiratory tract (five with obstruction). In two patients, the infection co-existed with pulmonary aspergillosis. Fifteen patients (58%) died of the infection. The factors that correlated with a poor outcome included bacteremic pneumonia, persistent neutropenia, presence of obstruction, development of septic shock or multiple organ dysfunction, and delay in institution of appropriate antibiotic therapy. In multivariate analysis, only septic shock and delayed therapy remained significant. Trimethoprim-sulfamethoxazole and/or ticarcillin-clavulanate were most commonly associated with a favorable outcome.

Journal Article↗
PubMed1999

Extracellular iron reductases: identification of a new class of enzymes by siderophore-producing microorganisms.

This study identifies extracellular iron reductases in culture supernatant fluids of the siderophore-producing microorganisms Escherichia coli and Pseudomonas aeruginosa. These enzymes were constitutively produced and reduced and released iron from a variety of ferric chelators. Dialyzable cofactors, necessary for the transfer of electrons in the enzymatic reduction of iron, were identified. The reductases were sensitive to treatment with proteinase K and guanidine-HCl, were not associated with siderophore activity, and were apparently released from the cell as extracellular enzymes. The acquisition of 59Fe2+ by cell suspensions of E. coli and P. aeruginosa was saturable, suggesting that the ferrous iron generated by these reductases can be bound and transported. Salmonella typhimurium mutants feoB, tonB, entB, and entBfeoB, deficient in numerous known iron uptake pathways, were found to exhibit substantial extracellular iron-reducing activities over that of the parent. A hypothesis is proposed in which the extracellular iron reductases excreted by siderophore-producing microorganisms may be responsible for the mobilization of iron during conditions of iron repletion when siderophores are repressed and may also function in concert with siderophores during periods of iron starvation.

Endopeptidase K↗
PubMed1997

Treatment of neutropenia-related fungal infections with granulocyte colony-stimulating factor-elicited white blood cell transfusions: a pilot study.

Neutropenia-related fungal infections can be life-threatening despite antifungal therapy. We evaluated the role of recombinant granulocyte colony-stimulating factor (rG-CSF)-elicited white blood cell (WBC) transfusions in patients with neutropenia-related fungal infections. Adult patients with hematologic malignancies, absolute neutrophil counts (ANC) <500/microl and fungal infections refractory to amphotericin B, received daily transfusions of rG-CSF-elicited and irradiated WBC transfusions from related donors. Donors received 5 microg/kg/day of rG-CSF subcutaneously. Donors achieved a mean ANC of 29.4 x 10(3) per microliter. The mean yield of neutrophils per transfusion was 41 x 10(9) (range, 10-116). Fifteen patients received a median of eight transfusions (range, 3-16). Fourteen patients had received rG-CSF for a median of 12 days. The median ANC baseline was 20/microl. Eleven patients had favorable responses and eight of them remained free of infection 3 weeks after therapy. Favorable responses occurred among patients with better Zubrod performance status (median, 3 vs 4) and shorter duration of both profound neutropenia (median, 15 vs 25 days) and active infection (median, 8 vs 17 days). The mean 1- and 24-h post-transfusion ANCs were 594/microl (range, 98-1472/microl) and 396/microl (range, 50-1475/microl), respectively. Adverse reactions were observed in nine of 35 donors and in the recipients of six of 130 transfusions. rG-CSF-elicited WBC transfusions may be a safe and promising approach for treating neutropenia-related fungal infections.

Adolescent↗
PubMed1997

Stenotrophomonas maltophilia meningitis. Report of two cases and review of the literature.

The authors report two cases of meningitis caused by Stenotrophomonas maltophilia in cancer patients following placement of an Ommaya reservoir for treatment of meningeal carcinomatosis. In addition, they review eight other cases of S. maltophilia that have been reported to date. Stenotrophomonas maltophilia meningitis is often associated with neurosurgical procedures; however, spontaneous infection may also occur, mainly in neonates. The disease's clinical presentation is similar to that of other forms of meningitis caused by Gram-negative bacilli. The overall mortality rate of this disease is 20% and is limited to neonates with spontaneous meningitis in whom effective antibiotic therapy is delayed. Meningitis caused by S. maltophilia in the modern era should be considered in immunocompromised hosts with significant central nervous system disease who have undergone neurosurgical procedures and who do not readily respond to broad-spectrum antimicrobial coverage.

Adult↗
PubMed1996

Stenotrophomonas (Xanthomonas) maltophilia urinary tract infection. A disease that is usually severe and complicated.

BACKGROUND: Stenotrophomonas (Xanthomonas) maltophilia has emerged as a causative agent of serious nosocomial infections. However, well-documented cases of urinary tract infection with this organism have rarely been reported. METHODS: review of the medical records of patients admitted to a large cancer center with cultures yielding S maltophilia from urinary sources during a 15-month period. RESULTS: All urinary tract infections were serious: 13 were complicated and two were acute uncomplicated pyelonephritis. The urinary tracts of 13 other patients were colonized with S maltophilia. Most of the colonized and infected patients were hospitalized with genitourinary malignancy, underwent urinary catheterization, and were receiving antibiotics inactive against S maltophilia. Neutropenia and urinary structural abnormalities were significantly associated with infection. The clinical course of infection was usually severe: fever (100%), sepsis disorder (47%), neutrophilia (70% of patients without neutropenia), bacteremia (13%) and death (7%). Still, response to treatment was prompt. CONCLUSIONS: Stenotrophomonas maltophilia urinary tract infection is usually associated with a severe clinical course. Risk factors for urinary colonization by this organism include hospitalization, urinary catheterization, and administration of inactive antibiotics. Risk factors for urinary tract infection include neutropenia and urinary structural abnormalities. In the presence of these risk factors, treatment of S maltophilia should be considered in patients with urinary colonization by the organism or in those with nosocomial urinary tract infection caused by an unknown pathogen and that is unresponsive to therapy with the antibiotics that are used to treat the common uropathogens.

Adolescent↗
PubMed1996

Fluconazole versus amphotericin B in the treatment of hematogenous candidiasis: a matched cohort study.

PURPOSE: To compare the efficacy and toxicity of fluconazole and amphotericin B in the treatment of hematogenous candidiasis in cancer patients. PATIENTS AND METHODS: A matched cohort study of cancer patients with hematogenous candidiasis was conducted. Forty-five patients with hematogenous candidiasis who received fluconazole (200 to 600 mg/day) in an open-label trial at the University of Texas M. D. Anderson Cancer Center, Houston, Texas, between February 1990 and June 1992 were matched to 45 patients treated with amphotericin B (0.3 to 1.2 mg/kg/day) for the same diagnosis. Criteria for matching included the following prognostic variables at the initiation of therapy: pneumonia, neutropenia (< 1,000 cells/mm3), number of positive blood cultures before therapy, infecting Candida species, underlying disease, and the simplified acute physiology score. Response and survival at 48 hours, after 5 days of therapy, and at the end of therapy, as well as toxicity rates were obtained. Other post hoc analyses were performed. Differences in outcomes were assessed by the McNemar, the sign, and the log rank tests. RESULTS: Patients were similar with respect to the matching criteria, age, sex, status of underlying disease, use of antibiotics and growth factors, duration of treatment, presence and removal of central venous catheters, disseminated disease, and concomitant infections. Response rates at 48 hours and 5 days were similar between the two study groups. Overall response rates at the end of therapy were 73% for patients treated with fluconazole and 71% for patients treated with amphotericin B (P = 0.78). There were no differences in survival rates or causes of death. Toxicity was observed in 9% of patients treated with fluconazole and in 67% of patients treated with amphotericin B (P < 0.0001). Toxic effects of amphotericin B included nephrotoxicity, hypokaliemia, and fever and chills. CONCLUSION: Fluconazole is effective and better tolerated than amphotericin B for the treatment of hematogenous candidiasis in cancer patients.

Adult↗
PubMed1995

Protection of human polymorphonuclear leukocyte function from the deleterious effects of isolation, irradiation, and storage by interferon-gamma and granulocyte-colony-stimulating factor.

BACKGROUND: Fungal infections represent a difficult challenge to clinicians caring for neutropenic patients with hematologic malignancies, as antifungal therapy often has limited success in that setting. One promising yet problematic alternative approach is leukocyte transfusion. The isolation of polymorphonuclear leukocytes (PMNs) induces apoptosis and functional deterioration, and irradiation to prevent transfusion-associated graft-versus-host disease causes further functional deterioration. STUDY DESIGN AND METHODS: The ability of interferon-gamma and granulocyte-colony-stimulating factor (G-CSF), used both alone and in combination, to protect PMNs after 0 or 20 hours' storage in cell culture (as a model for function after transfusion) and irradiation with 0, 5, or 30 Gy was studied. RESULTS: Without cytokine treatment, 20-hour-old PMNs showed marked apoptosis, no appreciable chemotaxis, and no ability to kill Candida albicans. In contrast, cytokine treatment significantly reduced apoptosis and protected chemotaxis, C. albicans killing, and surface-receptor expression from both storage and irradiation. Although the majority of the benefit appeared to be due to G-CSF, consistent trends suggested better function of PMNs after combined treatment with interferon-gamma and G-CSF. CONCLUSION: Judicious use of cytokines may preserve PMN function. These findings have important implications for the transfusion of PMNs to cytopenic patients.

Apoptosis↗
PubMed1995

Stenotrophomonas maltophilia: an unusual cause of biliary sepsis.

We report three cases of cholangitis caused by Stenotrophomonas maltophilia and review two other cases reported in the literature. All five episodes occurred in patients with hepatobiliary malignancy complicated by biliary tract obstruction. All five episodes occurred in patients with hepatobiliary malignancy complicated by biliary tract obstruction. All patients had undergone biliary tract instrumentation. Before infection developed, four of the five patients had received therapy with antibiotics that do not have in vitro activity against this organism. Four patients responded to appropriate antibiotic therapy and biliary tract decompression, whereas the fifth patient, who had persistent biliary obstruction, did not respond to appropriate antibiotic therapy.

Aged↗
PubMed1995

Safety, plasma concentrations, and efficacy of high-dose fluconazole in invasive mold infections.

A trial of the antifungal triazole fluconazole was conducted in cancer patients with presumed or proven mold infection. Groups of patients received fluconazole at four dosages (800, 1200, 1600, or 2000 mg/day). Adverse events, plasma levels, and clinical response were examined. Thirty-nine patients were enrolled. The 28 evaluable patients had presumed (13 patients) or proven (15) mold infection with Aspergillus (4) and Fusarium (3) species, Zygomycetes organisms (1), or nonspeciated mold (7). Adverse effects included elevated liver function test results (8 patients), nausea and vomiting (2), and erythema multiforme (1). Neurologic toxicity occurred in 3 patients receiving 2000 mg/day. Average steady-state peak plasma concentrations were 51.8, 74.4, and 91.8 mg/L for dosages 1200, 1600, and 2000 mg/day, respectively. Seven of 28 evaluable patients responded. Response did not appear to be related to dose. Fluconazole is well tolerated at total daily doses up to 1600 mg. The data suggest a linear plasma concentration-dose relationship. The activity of fluconazole in refractory mold infections seems to be limited.

Adolescent↗
PubMed1994

Mucocutaneous and soft tissue infections caused by Xanthomonas maltophilia. A new spectrum.

OBJECTIVE: To describe the mucocutaneous and soft tissue infections caused by Xanthomonas maltophilia in patients with cancer. DESIGN: A retrospective 15-month clinical study. SETTING: Academic, referral-based cancer center. PATIENTS: Of 237 patients with X. maltophilia isolated from all sites during the 15-month study period, 114 patients were judged to have true X. maltophilia infections. Only patients with mucocutaneous and soft tissue infections were included in the study. RESULTS: 17 (15%) of the 114 patients with X. maltophilia infection had mucocutaneous and soft tissue infections: Six patients had metastatic cellulitis, 5 had primary cellulitis usually associated with catheter use, and 6 had infected mucocutaneous ulcers. The metastatic cellulitis consisted of previously undescribed multiple, hard, tender nodules with surrounding and distant cellulitis (5 patients) or ecthyma gangrenosum (1 patient). Four of these patients died of the infection. Metastatic cellulitis and mucocutaneous infections occurred in hospitalized, neutropenic patients who received broad-spectrum antibiotics (beta-lactams, quinolones), often with in vitro activity against the infecting organisms. Response usually correlated with recovery from myelosuppression and administration of trimethoprim-sulfamethoxazole with or without ticarcillin-clavulanate. Catheter removal contributed to response in the treatment of primary cellulitis. CONCLUSIONS: Mucocutaneous and soft tissue infections caused by X. maltophilia are not uncommon, and X. maltophilia can cause metastatic nodular skin lesions that mimic disseminated fungal infections. It also causes serious morbidity and high mortality in patients with metastatic skin nodules and can cause superinfections in patients receiving broad-spectrum beta-lactam or quinolone antibiotics to which the organisms are susceptible when the infections develop. Catheter removal contributes to a favorable outcome in patients with catheter-associated cellulitis without bacteremia. Xanthomonas maltophilia infection should be added to the differential diagnosis of mucocutaneous or soft tissue infection in patients with cancer. Trimethoprim-sulfamethoxazole with or without ticarcillin-clavulanate is the current treatment of choice for culture-proven infections, but early empiric therapy may improve outcome.

Adult↗
PubMed1993

Parainfluenza virus infection in adult bone marrow transplant recipients.

The clinical course of parainfluenza virus infection occurring in 8 of 265 (3%) adult bone marrow transplant recipients during 1991 was reviewed. Parainfluenza virus type 3 was isolated from all eight patients. The clinical course ranged from self-limited upper respiratory tract infections (2 patients) to severe lower respiratory tract disease (6 patients) associated with a 50% mortality. This study highlights the important role of community respiratory viruses such as parainfluenza virus in the etiology of pneumonia in immunocompromised adults.

Adult↗
PubMed1993

Emerging fungal pathogens in immunocompromised patients: classification, diagnosis, and management.

Fungi such as Fusarium species, Trichosporon species, Curvularia species, and Alternaria species previously were thought to represent contamination or harmless colonization when isolated from immunocompromised patients. More recently, the pathogenic role of these and other fungi has been clearly established. Three diverse groups of fungi are responsible for these emerging infections: the agents of phaeohyphomycosis and hyalohyphomycosis and certain yeasts. Reports of the emergence of these organisms as significant pathogens may be ascribed to increasing awareness by physicians and microbiologists, aggressive culture of patient specimens, increasingly cytotoxic chemotherapy, and selection of resistant organisms by the widespread empirical use of amphotericin B. Infections with these fungi tend to be disseminated and are frequently fatal in immunocompromised hosts. Treatment of these infections is not standardized. Experimental therapy in murine models of fungal infections suggests a role for newer agents, combination antifungal chemotherapy, and immunotherapy.

Fungi↗
PubMed1993

Regulation of cryptococcal capsular polysaccharide by iron.

Iron is tightly controlled in mammalian tissues and regulates virulence factors in various pathogenic organisms. The influence of Fe availability upon production of cryptococcal capsular polysaccharide was studied. Polysaccharide, measured as cell-bound glucuronyl residues, increased more than threefold as available Fe in the culture medium was varied from repletion to tight sequestration and depletion in five incremental steps. Since physiologic CO2 concentration may serve as stimulus for cryptococcal polysaccharide synthesis, the combined effect of Fe availability and CO2 on encapsulation was studied. Addition of dissolved, loosely chelated Fe moderated the effect of CO2. Tight chelation of dissolved Fe potentiated the CO2 effect. Tissue from infected mice showed heavily encapsulated organisms, consistent with results with physiologic CO2 concentration and Fe deprivation. In conclusion, cryptococcal polysaccharide synthesis is increased by limitation of ferric iron availability to the cell and by dissolved CO2, and the two effects are additive.

Animals↗
PubMed1992

Virulence properties and nonimmune pathogenetic mechanisms of fungi.

This article summarizes some of the potential fungal virulence factors, their effect on the host's defense systems, and their regulation by host factors. Immunopathogenesis is not discussed, but the role of adherence by fungal organisms to human surfaces and foreign bodies in pathogenesis is described. Dimorphism and, less commonly, phenotypic switching may play important roles in initiating and establishing infections by several fungi. Toxins, especially exotoxins, do not seem to participate significantly in pathogenesis; however, various enzymes (proteases, phospholipases) may represent virulence properties of Candida, Aspergillus, and a number of other fungi. The interaction of the organisms with their hormonal milieu, the iron-scavenging capacities of various fungi, and their potential role in pathogenesis are delineated. The immunosuppressive effects of certain fungal antigens, such as yeast mannans, are discussed.

Animals↗
PubMed1992

Iron assimilation in Cryptococcus neoformans.

We studied the effects of iron chelators and of a thallium salt on growth of Cryptococcus neoformans in defined medium. An oxidant-sensitive mutant strain was found to require exogenous ferric iron for growth. Using this strain, we found that the synthetic iron chelator, N-hydroxyethylenediamine triacetate (HEDTA), in several saturation states, stimulated growth as well as the comparably saturated siderophore deferoxamine. This non-specific result makes the existence of a cryptococcal ferrihydroxamate receptor doubtful. The catechols, caffeic acid, L-3, 4-dihydroxyphenylalanine, epinephrine, gallic acid, 3-hydroxytyramine (dopamine) and norepinephrine, were tested for growth stimulation in iron deprivation, under conditions in which deferoxamine was stimulatory. Catechols were found to be either neutral or inhibitory. The ferrous iron chelator, bathophenanthroline disulfonate (BPDS), inhibited growth strongly in the absence of exogenous iron, suggesting that ferric ion must be reduced before it can be internalized. Direct evidence of extracellular reduction was provided by accumulation of red-coloured ferrous-BPDS complex. The inhibition caused by BPDS was relieved by ferric HEDTA, even in the presence of 10-fold increased BPDS, suggesting a second, low-affinity, non-reductive iron uptake pathway. This inference was further supported by the observation that toxicity of the non-reducible ferric analogue, thallium (III), is relieved by iron repletion.

Biological Transport↗
PubMed1989

Localization of mannoprotein in Cryptococcus neoformans.

Cell wall mannoprotein of nonpathogenic yeasts is surface exposed, since the cells are agglutinated by concanavalin A and antimannoprotein antibodies. However, nonencapsulated cells of Cryptococcus neoformans were agglutinated neither by concanavalin A nor by antimannoprotein antibodies. Immunogold electron microscopy located most mannoprotein in the inner cell wall. Chemical analysis of purified cell walls showed the lack of mannose, xylose, and galactose residues. These data indicate that cryptococcal mannoprotein recovered from the cultural supernatant is a nonstructural element of the cell wall.

Cell Wall↗
PubMed1987

Disseminated coccidioidomycosis. Unusual manifestations in a cardiac transplantation patient.

Because of the immunosuppressive therapy received by patients undergoing cardiac transplantation, disseminated infections, including disseminated fungal infections, often develop. Disseminated coccidioidomycosis developed in a 23-year-old man soon after undergoing orthotopic cardiac transplantation. Clinical manifestations included an unusual rash, severe myositis and arthropathy, a rapid downhill course, and pathologic evidence of widespread fungal invasion, including invasion of the cardiac graft. Detailed travel and geographic histories, and perhaps skin testing and antibody determinations for geographic-specific pathogens, should be part of the preoperative evaluation of all transplant candidates.

Adult↗