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Dive into the research topics where Valentina Stosor is active.

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Featured researches published by Valentina Stosor.


The New England Journal of Medicine | 2010

Outcomes of Kidney Transplantation in HIV-Infected Recipients

Peter G. Stock; Burc Barin; Barbara Murphy; Douglas W. Hanto; Jorge Diego; Jimmy A. Light; Charles E. L. B. Davis; Emily A. Blumberg; David K. Simon; Aruna K. Subramanian; J. Michael Millis; G. Marshall Lyon; Kenneth L. Brayman; Doug Slakey; Ron Shapiro; Joseph K. Melancon; Jeffrey M. Jacobson; Valentina Stosor; Jean L. Olson; Donald Stablein; Michelle E. Roland

BACKGROUND The outcomes of kidney transplantation and immunosuppression in people infected with human immunodeficiency virus (HIV) are incompletely understood. METHODS We undertook a prospective, nonrandomized trial of kidney transplantation in HIV-infected candidates who had CD4+ T-cell counts of at least 200 per cubic millimeter and undetectable plasma HIV type 1 (HIV-1) RNA levels while being treated with a stable antiretroviral regimen. Post-transplantation management was provided in accordance with study protocols that defined prophylaxis against opportunistic infection, indications for biopsy, and acceptable approaches to immunosuppression, management of rejection, and antiretroviral therapy. RESULTS Between November 2003 and June 2009, a total of 150 patients underwent kidney transplantation; survivors were followed for a median period of 1.7 years. Patient survival rates (±SD) at 1 year and 3 years were 94.6±2.0% and 88.2±3.8%, respectively, and the corresponding mean graft-survival rates were 90.4% and 73.7%. In general, these rates fall somewhere between those reported in the national database for older kidney-transplant recipients (≥65 years) and those reported for all kidney-transplant recipients. A multivariate proportional-hazards analysis showed that the risk of graft loss was increased among patients treated for rejection (hazard ratio, 2.8; 95% confidence interval [CI], 1.2 to 6.6; P=0.02) and those receiving antithymocyte globulin induction therapy (hazard ratio, 2.5; 95% CI, 1.1 to 5.6; P=0.03); living-donor transplants were protective (hazard ratio, 0.2; 95% CI, 0.04 to 0.8; P=0.02). A higher-than-expected rejection rate was observed, with 1-year and 3-year estimates of 31% (95% CI, 24 to 40) and 41% (95% CI, 32 to 52), respectively. HIV infection remained well controlled, with stable CD4+ T-cell counts and few HIV-associated complications. CONCLUSIONS In this cohort of carefully selected HIV-infected patients, both patient- and graft-survival rates were high at 1 and 3 years, with no increases in complications associated with HIV infection. The unexpectedly high rejection rates are of serious concern and indicate the need for better immunotherapy. (Funded by the National Institute of Allergy and Infectious Diseases; ClinicalTrials.gov number, NCT00074386.).


Infection Control and Hospital Epidemiology | 1995

Recovery of Vancomycin-Resistant Enterococci on Fingertips and Environmental Surfaces

Gary A. Noskin; Valentina Stosor; Isabell Cooper; Lance R. Peterson

OBJECTIVE To determine the recovery of vancomycin-resistant enterococci (VRE) on fingertips, gloved fingertips, and environmental surfaces commonly encountered in the healthcare setting, and to examine the importance of handwashing on the removal of these organisms. DESIGN Two clinical isolates of VRE (Enterococcus faecalis and Enterococcus faecium) were inoculated onto the hands of healthy human volunteers and the following environmental surfaces: countertops, bedrails, telephones, and stethoscopes. Following inoculation, samples were obtained at various time intervals to determine rates of recovery of organisms. To evaluate the effects of handwashing on enterococcal recovery, two different soap preparations were tested. Hands were washed with water alone or with one of the soaps and water. The soap and water studies were performed with a 5-second and a 30-second wash. RESULTS Both enterococcal strains survived for at least 60 minutes on gloved and ungloved fingertips. The E faecalis was recoverable from countertops for 5 days; the E faecium persisted for 7 days. For bedrails, both enterococcal species survived for 24 hours without significant reduction in colony counts. The bacteria persisted for 60 minutes on the telephone handpiece and for 30 minutes on the diaphragmatic surface of the stethoscope. A 5-second wash with water alone resulted in virtually no change in recovery of enterococci; a 30-second wash with water plus either soap was necessary to eradicate the bacteria from hands completely. CONCLUSION VRE are capable of prolonged survival on hands, gloves, and environmental surfaces. Hands should be washed thoroughly and gloves removed following contact with patients infected or colonized with these multidrug-resistant bacteria. Finally, environmental surfaces may serve as potential reservoirs for nosocomial transmission of VRE and need to be considered when formulating institutional infection control policies.


Lancet Infectious Diseases | 2010

Outcomes from pandemic influenza A H1N1 infection in recipients of solid-organ transplants: a multicentre cohort study

Deepali Kumar; Marian G. Michaels; Michele I. Morris; Michael Green; Robin K. Avery; Catherine Liu; Lara Danziger-Isakov; Valentina Stosor; Michele M. Estabrook; Soren Gantt; Kieren A. Marr; Stanley I. Martin; Fernanda P. Silveira; Raymund R. Razonable; Upton Allen; Marilyn E. Levi; G. Marshall Lyon; Lorraine Bell; Shirish Huprikar; Gopi Patel; Kevin Gregg; Kenneth Pursell; Doug Helmersen; Kathleen G. Julian; Kevin T. Shiley; Bartholomew Bono; Vikas R. Dharnidharka; Gelareh Alavi; Jayant S Kalpoe; Shmuel Shoham

BACKGROUND There are few data on the epidemiology and outcomes of influenza infection in recipients of solid-organ transplants. We aimed to establish the outcomes of pandemic influenza A H1N1 and factors leading to severe disease in a cohort of patients who had received transplants. METHODS We did a multicentre cohort study of adults and children who had received organ transplants with microbiological confirmation of influenza A infection from April to December, 2009. Centres were identified through the American Society of Transplantation Influenza Collaborative Study Group. Demographics, clinical presentation, treatment, and outcomes were assessed. Severity of disease was measured by admission to hospital and intensive care units (ICUs). The data were analysed with descriptive statistics. Proportions were compared by use of chi(2) tests. We used univariate analysis to identify factors leading to pneumonia, admission to hospital, and admission to an ICU. Multivariate analysis was done by use of a stepwise logistic regression model. We analysed deaths with Kaplan-Meier survival analysis. FINDINGS We assessed 237 cases of medically attended influenza A H1N1 reported from 26 transplant centres during the study period. Transplant types included kidney, liver, heart, lung, and others. Both adults (154 patients; median age 47 years) and children (83; 9 years) were assessed. Median time from transplant was 3.6 years. 167 (71%) of 237 patients were admitted to hospital. Data on complications were available for 230 patients; 73 (32%) had pneumonia, 37 (16%) were admitted to ICUs, and ten (4%) died. Antiviral treatment was used in 223 (94%) patients (primarily oseltamivir monotherapy). Seven (8%) patients given antiviral drugs within 48 h of symptom onset were admitted to an ICU compared with 28 (22.4%) given antivirals later (p=0.007). Children who received transplants were less likely to present with pneumonia than adults, but rates of admission to hospital and ICU were similar. INTERPRETATION Influenza A H1N1 caused substantial morbidity in recipients of solid-organ transplants during the 2009-10 pandemic. Starting antiviral therapy early is associated with clinical benefit as measured by need for ICU admission and mechanical ventilation. FUNDING None.


Clinical Infectious Diseases | 2005

An immune reconstitution syndrome-like illness associated with Cryptococcus neoformans infection in organ transplant recipients.

Nina Singh; Olivier Lortholary; Barbara D. Alexander; Krishan L. Gupta; George T. John; Kenneth Pursell; Patricia Muñoz; Goran B. Klintmalm; Valentina Stosor; Ramon Del Busto; Ajit P. Limaye; Jyoti Somani; Marshall Lyon; Sally Houston; Andrew A. House; Timothy L. Pruett; Susan L. Orloff; Atul Humar; Lorraine A. Dowdy; Julia Garcia-Diaz; Andre C. Kalil; Robert A. Fisher; Shahid Husain

BACKGROUND We describe an immune reconstitution syndrome (IRS)-like entity in the course of evolution of Cryptococcus neoformans infection in organ transplant recipients. METHODS The study population comprised a cohort of 83 consecutive organ transplant recipients with cryptococcosis who were observed for a median of 2 years in an international, multicenter study. RESULTS In 4 (4.8%) of the 83 patients, an IRS-like entity was observed a median of 5.5 weeks after the initiation of appropriate antifungal therapy. Worsening of clinical manifestations was documented, despite cultures being negative for C. neoformans. These patients were significantly more likely to have received tacrolimus, mycophenolate mofetil, and prednisone as the regimen of immunosuppressive therapy than were all other patients (P = .007). The proposed basis of this phenomenon is reversal of a predominantly Th2 response at the onset of infection to a Th1 proinflammatory response as a result of receipt of effective antifungal therapy and a reduction in or cessation of immunosuppressive therapy. CONCLUSIONS This study demonstrated that an IRS-like entity occurs in organ transplant recipients with C. neoformans infection. Furthermore, this entity may be misconstrued as a failure of therapy. Immunomodulatory agents may have a role as adjunctive therapy in such cases.


Liver Transplantation | 2012

Outcomes of liver transplant recipients with hepatitis C and human immunodeficiency virus coinfection

Norah A. Terrault; Michelle E. Roland; Thomas D. Schiano; Lorna Dove; Michael T. Wong; Fred Poordad; Margaret V. Ragni; Burc Barin; David K. Simon; Kim M. Olthoff; Lynt B. Johnson; Valentina Stosor; Dushyantha Jayaweera; John J. Fung; Kenneth E. Sherman; Aruna K. Subramanian; J. Michael Millis; Douglas P. Slakey; Carl L. Berg; Laurie Carlson; Linda D. Ferrell; Donald Stablein; Jonah Odim; Lawrence Fox; Peter G. Stock

Hepatitis C virus (HCV) is a controversial indication for liver transplantation (LT) in human immunodeficiency virus (HIV)–infected patients because of reportedly poor outcomes. This prospective, multicenter US cohort study compared patient and graft survival for 89 HCV/HIV‐coinfected patients and 2 control groups: 235 HCV‐monoinfected LT controls and all US transplant recipients who were 65 years old or older. The 3‐year patient and graft survival rates were 60% [95% confidence interval (CI) = 47%‐71%] and 53% (95% CI = 40%‐64%) for the HCV/HIV patients and 79% (95% CI = 72%‐84%) and 74% (95% CI = 66%‐79%) for the HCV‐infected recipients (P < 0.001 for both), and HIV infection was the only factor significantly associated with reduced patient and graft survival. Among the HCV/HIV patients, older donor age [hazard ratio (HR) = 1.3 per decade], combined kidney‐liver transplantation (HR = 3.8), an anti‐HCV–positive donor (HR = 2.5), and a body mass index < 21 kg/m2 (HR = 3.2) were independent predictors of graft loss. For the patients without the last 3 factors, the patient and graft survival rates were similar to those for US LT recipients. The 3‐year incidence of treated acute rejection was 1.6‐fold higher for the HCV/HIV patients versus the HCV patients (39% versus 24%, log rank P = 0.02), but the cumulative rates of severe HCV disease at 3 years were not significantly different (29% versus 23%, P = 0.21). In conclusion, patient and graft survival rates are lower for HCV/HIV‐coinfected LT patients versus HCV‐monoinfected LT patients. Importantly, the rates of treated acute rejection (but not the rates of HCV disease severity) are significantly higher for HCV/HIV‐coinfected recipients versus HCV‐infected recipients. Our results indicate that HCV per se is not a contraindication to LT in HIV patients, but recipient and donor selection and the management of acute rejection strongly influence outcomes. Liver Transpl 18:716–726, 2012.


The Journal of Infectious Diseases | 2007

Cryptococcus neoformans in Organ Transplant Recipients: Impact of Calcineurin-Inhibitor Agents on Mortality

Nina Singh; Barbara D. Alexander; Olivier Lortholary; Françoise Dromer; Krishan L. Gupta; George T. John; Ramon Del Busto; Goran B. Klintmalm; Jyoti Somani; G. Marshall Lyon; Kenneth Pursell; Valentina Stosor; Patricia Muňoz; Ajit P. Limaye; Andre C. Kalil; Timothy L. Pruett; Julia Garcia-Diaz; Atul Humar; Sally Houston; Andrew A. House; Dannah Wray; Susan L. Orloff; Lorraine A. Dowdy; Robert A. Fisher; Joseph Heitman; Marilyn M. Wagener; Shahid Husain; Corinne Antoine; Barrou Benoît; Anne Elisabeth Heng

Variables influencing the risk of dissemination and outcome of Cryptococcus neoformans infection were assessed in 111 organ transplant recipients with cryptococcosis in a prospective, multicenter, international study. Sixty-one percent (68/111) of the patients had disseminated infection. The risk of disseminated cryptococcosis was significantly higher for liver transplant recipients (adjusted hazard ratio [HR], 6.65; P=.048). The overall mortality rate at 90 days was 14% (16/111). The mortality rate was higher in patients with abnormal mental status (P=.023), renal failure at baseline (P=.028), fungemia (P=.006), and disseminated infection (P=.035) and was lower in those receiving a calcineurin-inhibitor agent (P=.003). In a multivariable analysis, the receipt of a calcineurin-inhibitor agent was independently associated with a lower mortality (adjusted HR, 0.21; P=.008), and renal failure at baseline with a higher mortality rate (adjusted HR, 3.14; P=.037). Thus, outcome in transplant recipients with cryptococcosis appears to be influenced by the type of immunosuppressive agent employed. Additionally, discerning the basis for transplant type-specific differences in disease severity has implications relevant for yielding further insights into the pathogenesis of C. neoformans infection in transplant recipients.


Antimicrobial Agents and Chemotherapy | 2000

A convenient assay for estimating the possible involvement of efflux of fluoroquinolones by Streptococcus pneumoniae and Staphylococcus aureus: evidence for diminished moxifloxacin, sparfloxacin, and trovafloxacin efflux.

Rebecca Beyer; Ekaterina Pestova; John Millichap; Valentina Stosor; Gary A. Noskin; Lance R. Peterson

ABSTRACT We developed a simplified assay for estimating efflux by measuring the effect of reserpine on the growth of Streptococcus pneumoniae and Staphylococcus aureus over 7 h. Reserpine enhanced ciprofloxacin and levofloxacin 17 to 68%. The hydrophobic drug trovafloxacin and the drug moxifloxacin, with a bulky C-7 substituent but hydrophilicity similar to that of levofloxacin, showed little (0 to 11%) reserpine-enhancing effect. The ease of resistant mutant strain selection correlated with efflux susceptibility.


American Journal of Transplantation | 2007

A Survey of CMV Prevention Strategies After Liver Transplantation

J. Levitsky; Nina Singh; Marilyn M. Wagener; Valentina Stosor; Michael Abecassis; Michael G. Ison

The degree of variability in the use of CMV prevention strategies and choice of antiviral regimens among LT centers has not been previously investigated. An electronic survey on current CMV prevention strategies was sent to all US and Canadian LT centers. A total of 58 (53%) centers completed the survey. Most use CMV PCR for screening or diagnosis. Prophylaxis was the most common prevention strategy for all donor/recipient subtypes except D‐/R‐ who often receive no prophylaxis. Prophylaxis was usually given for 3 months after LT with valganciclovir the most frequently used agent. In the small percentage of centers utilizing the preemptive approach, monitoring for CMV was typically performed with PCR for 3 months and valganciclovir was most frequently used for treatment of detectable CMV viremia. In conclusion, the majority of LT centers utilize CMV prophylaxis over other strategies. Valganciclovir is the most commonly used agent for both antiviral prophylaxis and treatment of CMV viremia in the preemptive approach.


Clinical Infectious Diseases | 2008

Pulmonary Cryptococcosis in Solid Organ Transplant Recipients: Clinical Relevance of Serum Cryptococcal Antigen

Nina Singh; Barbara D. Alexander; Olivier Lortholary; Françoise Dromer; Krishan L. Gupta; George T. John; Ramon Del Busto; Goran B. Klintmalm; Jyoti Somani; G. Marshall Lyon; Kenneth Pursell; Valentina Stosor; Patricia Muñoz; Ajit P. Limaye; Andre C. Kalil; Timothy L. Pruett; Julia Garcia-Diaz; Atul Humar; Sally Houston; Andrew A. House; Dannah Wray; Susan L. Orloff; Lorraine A. Dowdy; Robert A. Fisher; Joseph Heitman; Marilyn M. Wagener; Shahid Husain

BACKGROUND The role of serum cryptococcal antigen in the diagnosis and determinants of antigen positivity in solid organ transplant (SOT) recipients with pulmonary cryptococcosis has not been fully defined. METHODS We conducted a prospective, multicenter study of SOT recipients with pulmonary cryptococcosis during 1999-2006. RESULTS Forty (83%) of 48 patients with pulmonary cryptococcosis tested positive for cryptococcal antigen. Patients with concomitant extrapulmonary disease were more likely to have a positive antigen test result (P=.018), and antigen titers were higher in patients with extrapulmonary disease (P=.003) or fungemia (P=.045). Patients with single nodules were less likely to have a positive antigen test result than were those with all other radiographic presentations (P=.053). Among patients with isolated pulmonary cryptococcosis, lung transplant recipients were less likely to have positive cryptococcal antigen test results than were recipients of other types of SOT (P=.003). In all, 38% of the patients were asymptomatic or had pulmonary cryptococcosis detected as an incidental finding. Nodular densities or mass lesions were more likely to present as asymptomatic or incidentally detected pulmonary cryptococcosis than as pleural effusions and infiltrates (P=.008). CONCLUSIONS A positive serum cryptococcal antigen test result in SOT recipients with pulmonary cryptococcosis appears to reflect extrapulmonary or more advanced radiographic disease.


Antimicrobial Agents and Chemotherapy | 2008

Calcineurin Inhibitor Agents Interact Synergistically with Antifungal Agents In Vitro against Cryptococcus neoformans Isolates: Correlation with Outcome in Solid Organ Transplant Recipients with Cryptococcosis

Dimitrios P. Kontoyiannis; Russell E. Lewis; Barbara D. Alexander; Olivier Lortholary; Françoise Dromer; Krishan L. Gupta; George T. John; Ramon Del Busto; Goran B. Klintmalm; Jyoti Somani; G. Marshall Lyon; Kenneth Pursell; Valentina Stosor; Patricia Muňoz; Ajit P. Limaye; Andre C. Kalil; Timothy L. Pruett; Julia Garcia-Diaz; Atul Humar; Sally Houston; Andrew A. House; Dannah Wray; Susan L. Orloff; Lorraine A. Dowdy; Robert A. Fisher; Joseph Heitman; Nathaniel D. Albert; Marilyn M. Wagener; Nina Singh

ABSTRACT Synergistic interactions were observed between CIs and antifungal agents against 53 (90%) of 59 Cryptococcus neoformans isolates from solid organ transplant recipients with cryptococcosis and may account for better outcomes in patients with cryptococcosis receiving these immunosuppressive agents.

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Ajit P. Limaye

University of Washington

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Lance R. Peterson

NorthShore University HealthSystem

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