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Nina Singh

Publications and source records attributed to Nina Singh.

At least 37 records · Page 2Linked to original sources
PubMed2005

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

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.

Adult↗
PubMed2005

Efficacy of valganciclovir administered as preemptive therapy for cytomegalovirus disease in liver transplant recipients: impact on viral load and late-onset cytomegalovirus disease.

BACKGROUND: The efficacy of valganciclovir used as preemptive therapy for cytomegalovirus (CMV) disease in liver transplant recipients is not known. METHODS: Between 1996 and 2004, surveillance testing using CMV antigenemia was performed at weeks 2, 4, 6, 8, 10, 12, and 16 posttransplant. A total of 28.8% (17/59) of the patients from 2001 to 2004 with antigenemia who received valganciclovir as preemptive therapy were compared with 26.2% (21/80) of the patients from 1996 to 2000 who received oral ganciclovir as preemptive therapy. RESULTS: The mean decline in the antigenemia level after initiation of valganciclovir and oral ganciclovir was 80.5% versus 50.7% at 1 week, 99.5% versus 89.4% at 2 weeks, and 100% versus 97.7% at 4 weeks, respectively. A higher proportion of patients who received valganciclovir (64.7%) belonged to the high-risk group (R-/D+) than patients who received oral ganciclovir (33.3%, P=0.10). Recurrent shedding was documented in 47.1% (8/17) of the patients in the valganciclovir group and 28.6% (6/21) of the patients in the oral ganciclovir group (P>0.20). Recurrent shedding correlated significantly with R-/D+ CMV serostatus and baseline CMV antigenemia level, regardless of the study group. No patient in either group developed CMV disease during or after the period of surveillance monitoring. The incidence of opportunistic infections and patient outcome did not differ for the valganciclovir group versus the oral ganciclovir group or patients without CMV infection (P>0.20). CONCLUSION: Antigenemia-directed valganciclovir as preemptive therapy seems to be effective for the prevention of CMV disease in liver transplant recipients, including high-risk patients.

Adult↗
PubMed2005

Interactions between viruses in transplant recipients.

Viral coinfections may modulate disease expression, enhance pathogenicity, and lead to greater cumulative immunosuppression in the host. The pathophysiological basis of these may be direct virus-virus interactions, effect of cohabitating viruses on host cell function, or impaired host immune responses. The interrelationship between viral pathogens has become increasingly more relevant and its scope wider as new or previously unrecognized viruses continue to emerge as pathogens in transplant recipients. The pathways and mediators that modulate biological activity represent potential targets for immunomodulatory interventions as adjunctive therapies for transplant recipients.

Humans↗
PubMed2005

Who among cytomegalovirus-seropositive liver transplant recipients is at risk for cytomegalovirus infection?

A vast majority of the transplant recipients are cytomegalovirus (CMV)-seropositive (R+). We sought to assess variables predictive of CMV infection, specifically in R+ liver transplant recipients. Study patients comprised 182 consecutive liver transplant recipients who survived at least 14 days after transplantation. Surveillance testing was used to detect CMV infection. Pre-emptive therapy was employed for the prevention of CMV disease, however, no antiviral prophylaxis was used for CMV infection. CMV infection developed in 32.5% (38 of 117) of R+ patients, 84.6% (33 of 39) of R-/D+, and 3.8% (1 of 26) of R-/D- patients. In R+ patients, Hispanic race (21.6% vs. 7.8%, P = 0.06), donor CMV seropositivity (73.7% vs. 45.6%, P = 0.005), and hepatocellular carcinoma (23.7% vs. 6.3%, P = 0.05) correlated with a higher risk of CMV infection. In a multivariate model, Hispanic race (OR: 3.5, 95% CI: 1.03-11.6, P = 0.045), donor CMV serostatus (OR: 4.0, 95% CI: 1.6-10.2, P = 0.003) and hepatocellular carcinoma (OR: 5.8, 95% CI: 1.6-20.5, P = 0.006) were all significant independent predictors of CMV infection. The aforementioned variables did not portend a higher risk of CMV infection in R-/D+ patients; donor CMV seropositivity overwhelmed all other risk factors in R- patients (P < 0.00001). In conclusion, CMV-seropositive liver transplant recipients at risk for CMV infection can be identified based on readily assessable variables. Preventive strategies may be selectively targeted toward these patients.

Adult↗
PubMed2005

Infectious complications in organ transplant recipients with the use of calcineurin-inhibitor agent-based immunosuppressive regimens.

PURPOSE OF REVIEW: The rates and types of infections associated with conventional immunosuppression regimens comprising calcineurin-inhibitor agents, tacrolimus, and cyclosporine could be used to compare similar data with the use of novel immunosuppressive regimens in organ transplant recipients. RECENT FINDINGS: Tacrolimus appears to be superior to cyclosporine in preventing rejection. The frequency and spectrum of infections in organ transplant recipients does not appear to be notably modified by the choice of calcineurin-inhibitor agents per se. A higher risk of cytomegalovirus and poorer outcomes associated with hepatitis C virus with cyclosporine in some studies may be related to a greater requirement of adjunctive immunosuppression with cyclosporine-based regimens. Potent immunosuppression with tacrolimus, however, particularly when combined with mycophenolate mofetil, is believed to be a significant contributor to a higher incidence of BK virus nephropathy in renal transplant recipients in recent years. Calcineurin-inhibitor agents possess in-vitro activity against a number of fungal pathogens. In the clinical setting, however, the immunosuppressive effect outweighs their antifungal activity. SUMMARY: Calcineurin inhibitor-based regimens have been the mainstay of immunosuppression after organ transplantation for almost two decades. However, suboptimal long-term outcomes in transplant recipients have led to a growing interest in the use of calcineurin inhibitor agent-sparing regimens. Whether novel immunosuppressive agents with a more selective mechanism of action would lead to a further reduction in the risk of posttransplant infections remains to be discerned.

Calcineurin Inhibitors↗
PubMed2005

Aspergillus infections in transplant recipients.

Aspergillus infections are occurring with an increasing frequency in transplant recipients. Notable changes in the epidemiologic characteristics of this infection have occurred; these include a change in risk factors and later onset of infection. Management of invasive aspergillosis continues to be challenging, and the mortality rate, despite the use of newer antifungal agents, remains unacceptably high. Performing molecular studies to discern new targets for antifungal activity, identifying signaling pathways that may be amenable to immunologic interventions, assessing combination regimens of antifungal agents or combining antifungal agents with modulation of the host defense mechanisms, and devising diagnostic assays that can rapidly and reliably diagnose infections represent areas for future investigations that may lead to further improvement in outcomes.

Antifungal Agents↗
PubMed2005

Cryptococcus neoformans isolates from transplant recipients are not selected for resistance to calcineurin inhibitors by current immunosuppressive regimens.

The immunosuppressants tacrolimus (FK506) and cyclosporine A inhibit calcineurin and have potent antifungal activity. In this study, 24% of Cryptococcus neoformans isolates from solid-organ transplant patients exhibited altered sensitivity to these drugs, which may have an impact on the infectious course but does not appear to be the consequence of immunosuppressive therapy.

Calcineurin↗
PubMed2004

Infections due to Scedosporium apiospermum and Scedosporium prolificans in transplant recipients: clinical characteristics and impact of antifungal agent therapy on outcome.

BACKGROUND: Unique characteristics, impact of therapy with antifungal agents, and outcome of infections with Scedosporium species were assessed in transplant recipients. METHODS: The patients comprised a total of 80 transplant recipients with Scedosporium infections, including 13 patients from our institutions (University of Pittsburgh Medical Center [Pittsburgh, PA], University of Maryland [Baltimore], Duke University Medical Center [Durham, NC], Emory University [Atlanta, GA], and Hospital Gregorio Maranon [Madrid, Spain]) and 67 reported in the literature. The transplant recipients were compared with 190 non-transplant recipients with scedosporiosis who were described in the literature. RESULTS: Overall, 69% of the infections in hematopoietic stem cell transplant (HSCT) recipients and 53% of the infections in organ transplant recipients were disseminated. HSCT recipients, compared with organ transplant recipients, were more likely to have infections caused by Scedosporium prolificans (P=.045), to have an earlier onset of infection (P=.007), to be neutropenic (P<.0001), and to have fungemia (P=.04). Time elapsed from transplantation to Scedosporium infection in transplant recipients has increased in recent years (P=.002). The mortality rate among transplant recipients with scedosporiosis was 58%. In a logistic regression model using amphotericin B as comparison treatment, voriconazole was associated with a trend towards better survival (odds ratio [OR], 10.40; P=.08). Presence of disseminated infection (OR, 0.20; P=.03) predicted lower survival, and receipt of adjunctive surgery as treatment (OR, 5.52; P=.02) independently predicted a better survival in this model. CONCLUSIONS: Scedosporium infections in transplant recipients were associated with a high rate of dissemination and a poor outcome overall. The use of newer triazole agents warrants consideration as a therapeutic modality for these infections.

Adolescent↗
PubMed2004

Antifungal prophylaxis in solid-organ transplant recipients: considerations for clinical trial design.

BACKGROUND: There are several key issues regarding clinical trial design for antifungal prophylaxis in organ transplant recipients. METHODS: The existing and emerging data on the epidemiology and risk factors for invasive mycoses in organ transplant recipients formed the basis for discerning the subgroups that may be targeted for prophylaxis, the unique end points to be considered, and the attributes of currently available drugs that may be suitable candidates for antifungal prophylaxis. RESULTS: Epidemiological characteristics of invasive mycoses in organ transplant recipients have evolved sufficiently to warrant thoughtful reconsideration of the subsets of patients and the fungal pathogens to be targeted for antifungal prophylactic trials in the current era. Safety and tolerability of antifungal agents and outcome stratified by severity of illness are important end points given the potential for drug interactions with immunosuppressive agents and the fact that a beneficial effect of prophylaxis on outcome has been difficult to document in organ transplant recipients. CONCLUSIONS: Clinical trial design for antifungal prophylaxis must carefully consider the unique issues pertaining to the selection of patients most likely to benefit, as well as the tolerability and drug interactions of antifungal agents in organ transplant recipients.

Antifungal Agents↗
PubMed2004

Antifungal attributes of immunosuppressive agents: new paradigms in management and elucidating the pathophysiologic basis of opportunistic mycoses in organ transplant recipients.

The currently available immunosuppressive agents cyclosporine A, tacrolimus, and rapamycin have potent antifungal activity against a number of opportunistic fungi in organ transplant recipients, most notably, C. neoformans, Candida, and Aspergillus species. The targets of their antifungal activity are fungal homologs of the signaling molecules that mediate their immunosuppressive action in humans, which has implications for further unraveling the pathogenesis of these infections. Corroborative clinical data suggest that despite the apparent paradox between the antifungal activity of the immunosuppressive agents and the occurrence of fungal infections during their administration, the antifungal attributes of these drugs may influence the spectrum and clinical characteristics of these infections after organ transplantation. Finally, the potent synergistic interactions between the immunosuppressive agents and antifungal drugs against many pathogenic fungi, including those that are typically resistant to traditional antifungal agents, could potentially have a role in devising novel therapeutic strategies for opportunistic mycoses in transplant recipients.

Antifungal Agents↗
PubMed2004

Impact of evolving trends in recipient and donor characteristics on cytomegalovirus infection in liver transplant recipients.

BACKGROUND: This study determines whether the recipient and donor characteristics that influence the cytomegalovirus (CMV) infection rate after liver transplantation have changed. METHODS: The recipient and donor characteristics that may affect the rate of CMV infection were assessed in 232 liver transplant recipients at our institution during a 14-year period (1989-2003). RESULTS: Since 1989, the age of recipients (P=0.0001) and donors (P=0.0001) has increased significantly. Pretransplant CMV seropositivity in recipients has decreased significantly (P=0.0001, 86.4% [1989-1992] to 53.7% [2000-2003]), whereas donor CMV seropositivity has remained unchanged (P>0.20). As a result, there has been a significant increase in the proportion of high-risk (CMV recipient-/donor+) patients (P=0.012); 10.6% of recipients from 1989 to 1992 versus 24.1% of recipients from 2000 to 2003 were CMV recipient-/donor+. The Child-Pugh scores of recipients have remained unchanged over time. However, the proportion of patients undergoing transplantation while being cared for in the intensive care unit has decreased significantly over time (P=0.0002). Despite an increase in the rate of CMV infection (P=0.09), the incidence of CMV disease has decreased significantly (P=0.0004). CONCLUSIONS: The proportion of high-risk patients (CMV recipient-/donor+) has increased significantly over time, attributable largely to a declining rate of CMV seropositivity in recipients before transplantation. These data have implications for guiding prophylactic practices and resource use after liver transplantation.

Adult↗
PubMed2004

Bacteremias in liver transplant recipients: shift toward gram-negative bacteria as predominant pathogens.

During the 1990s, gram-positive bacteria emerged as major pathogens after liver transplantation. We sought to determine whether the pathogens associated with bacteremias in liver transplant recipients have changed. Patients included 233 liver transplant recipients transplanted between 1989 and 2003. The proportion of all infections due to bacteremias increased significantly over time (P <.0001). Of other major infections, a trend toward a decrease in fungal infections (P =.089) and a significant decrease in cytomegalovirus (CMV) disease (P =.0004) were documented. Whereas the proportion of bacteremias due to gram-negatives increased from 25% in the period of 1989-1993 to 51.8% in 1998-03, that of gram-positive bacteria decreased from 75% in the period of 1989-93 to 48.2% in the period of 1998-2003. Methicillin-resistant Staphylococcus aureus (MRSA), Klebsiella pneumoniae, and Pseudomonas aeruginosa were the most frequent pathogens in bacteremic patients. The incidence of bacteremias due to MRSA and Pseudomonas aeruginosa has remained unchanged (P <.20); however, that due to enteric gram-negative bacteria, particularly Klebsiella pneumoniae has increased (P =.02). Klebsiella pneumoniae isolates in the current quartile were not clonally related. In conclusion, bacteremias as a proportion of all infections in liver transplant recipients have increased significantly over time, due in part to a decline in infections due to other major pathogens, e.g., fungi, primarily Candida species, and CMV. Gram-negative bacteria have emerged as predominant pathogens in bacteremic liver transplant recipients.

Adult↗
PubMed2004

Cryptococcus neoformans Infection in Patients With Cirrhosis, Including Liver Transplant Candidates.

We reviewed the cases of patients with cirrhosis, including liver transplant candidates, at our institution in the last 3 years (n = 5) and those individually described in the literature (n = 28), to assess unique characteristics and outcome of cryptococcosis in these patients. Sixty-four percent (21/33) of the patients had no other recognized immunosuppression. Peritonitis (in 45%, 15/33 of the patients) with modest pleocytosis in the ascitic fluid, was the most common presenting feature. Median time to detection of Cryptococcus in the ascitic fluid cultures was 6 days. Overall mortality rate was 81% (26/32); death was deemed attributable to cryptococcosis in 24/26 patients who died. Evaluation of culture-negative neutrocytic ascites in febrile cirrhotic patients warrants consideration of cryptococcal peritonitis.

Adult↗
PubMed2004

Prospective assessment of Platelia Aspergillus galactomannan antigen for the diagnosis of invasive aspergillosis in lung transplant recipients.

The clinical utility of Platelia trade mark Aspergillus galactomannan antigen for the early diagnosis of invasive aspergillosis was prospectively assessed in 70 consecutive lung transplant recipients. Sera were collected twice weekly and tested for galactomannan. Invasive aspergillosis was documented in 17.1% (12/70) of the patients. Using the generalized estimating equation model, at the cutoff value of >or= 0.5, the sensitivity of the test was 30%, specificity 93% with positive and negative likelihood ratios of 4.2 and 0.75, respectively. Increasing the cutoff value to >or= 0.66 yielded a sensitivity of 30%, specificity of 95%, and positive and negative likelihood ratios of 5.5 and 0.74. A total of 14 patients had false-positive tests, including nine who had cystic fibrosis or chronic obstructive pulmonary disease. False-positive tests occurred within 3 days of transplantation in 43% (6/14) of the patients, and within 7 days in 64% (9/14). Thus, the test demonstrated excellent specificity, but a low sensitivity for the diagnosis of aspergillosis in this patient population. Patients with cystic fibrosis or chronic obstructive pulmonary disease may transiently have a positive test in the early post-transplant period.

Adult↗
PubMed2004

In vitro interactions between antifungals and immunosuppressants against Aspergillus fumigatus isolates from transplant and nontransplant patients.

We performed in vitro antifungal checkerboard testing on 12 Aspergillus fumigatus clinical isolates (6 transplant recipients and 6 nontransplant patients) with three antifungal agents (amphotericin B, voriconazole, and caspofungin) and three immunosuppressants (FK506, cyclosporine, and rapamycin). We were not able to detect a difference in calcineurin inhibitor antifungal activity against isolates from transplant recipients and nontransplant patients.

Amphotericin B↗