Community respiratory virus infections following lung transplantation

Patients With Inflammatory Bowel Disease Are at Increased Risk of Hospitalization Due to Respiratory Syncytial Virus

INTRODUCTION

Patients with inflammatory bowel disease (IBD) are at increased risk of developing respiratory infections. Respiratory syncytial virus (RSV) is a common respiratory virus with adverse outcomes in older adults. This study aimed to determine whether patients with IBD are at increased risk of a serious infection due to RSV.

METHODS

We conducted a retrospective study using the multi-institutional research network TriNetX to assess the risk of hospitalization in a cohort of patients with IBD compared with that in a non-IBD control cohort with RSV infection from January 1, 2007, to February 27, 2023. One-to-one (1:1) propensity score matching was performed for demographic variables and RSV risk factors between the 2 cohorts. Risk was expressed as adjusted odds ratio (aOR) with 95% confidence interval (CI).

RESULTS

There were 794 patients in the IBD-RSV cohort and 93,074 patients in the non-IBD-RSV cohort. The mean age of the IBD-RSV cohort was 55.6 ± 20 years, 59% were female, 80% were White, and 56.9% had Crohn's disease. The IBD-RSV cohort was at an increased risk of hospitalization (aOR 1.30, 95% CI 1.06-1.59). There was no difference in the risk (aOR 0.83, 95% CI 0.58-1.19) of a composite outcome of hospitalization-related complications between the 2 cohorts. Recent systemic corticosteroid use (<3 months) was associated with an increased risk of hospitalization (aOR 1.86, 95% CI 1.30-2.59) in the IBD-RSV cohort.

DISCUSSION

We found that adult patients with IBD and RSV infection are at an increased risk of hospitalization and may benefit from the new RSV vaccine recommended for adults aged 60 years and older.

Impact of Respiratory Viral Infections in Transplant Recipients

Respiratory viral infections (RVIs) are among the leading cause of morbidity and mortality in pediatric hematopoietic stem cell transplant (HCT) and solid organ transplant (SOT) recipients. Transplant recipients remain at high risk for super imposed bacterial and fungal pneumonia, chronic graft dysfunction, and graft failure as a result of RVIs. Recent multicenter retrospective studies and prospective studies utilizing contemporary molecular diagnostic techniques have better delineated the epidemiology and outcomes of RVIs in pediatric transplant recipients and have advanced the development of preventative vaccines and treatment interventions in this population. In this review, we will define the epidemiology and outcomes of RVIs in SOT and HSCT recipients, describe the available assays for diagnosing a suspected RVI, highlight evolving management and vaccination strategies, review the risk of donor derived RVI in SOT recipients, and discuss considerations for delaying transplantation in the presence of an RVI.

Targeted Literature Review of the Burden of Respiratory Syncytial Infection among High-Risk and Elderly Patients in Asia Pacific Region

INTRODUCTION

The burden of respiratory syncytial virus (RSV), which causes acute respiratory illness, is well recognized among the pediatric population but also imposes a significant risk to the elderly (age ≥ 60) and those with underlying comorbidities. The study aimed to review the most recent data on epidemiology and burden (clinical and economic) of RSV in the elderly/high-risk populations in China, Japan, South Korea, Taiwan, and Australia.

METHODS

A targeted review was conducted of English, Japanese, Korean, and Chinese language articles published from 1 January 2010 to 7 October 2020 relevant for the purpose.

RESULTS

A total of 881 studies were identified, and 41 were included. The median proportion of elderly patients with RSV in all adult patients with acute respiratory infection (ARI) or community acquired pneumonia was 79.78% (71.43-88.12%) in Japan, 48.00% (3.64-80.00%) in China, 41.67% (33.33-50.00%) in Taiwan, 38.61% in Australia, and 28.57% (22.76-33.33%) in South Korea. RSV was associated with a high clinical burden on those patients with comorbidities such as asthma and chronic obstructive pulmonary disease. In China, inpatients with ARI showed a significantly higher rate of RSV-related hospitalization than outpatients (13.22% versus 4.08%, p < 0.01). The median length of hospital stay among elderly patients with RSV was longest in Japan (30 days) and shortest in China (7 days). Mortality data varied by region with some studies reporting rates as high as 12.00% (9/75) in hospitalized elderly patients. Finally, data on the economic burden was only available for South Korea, with the median cost of a medical admission for an elderly patient with RSV being US dollar (USD) 2933.

CONCLUSION

RSV infection is a major source of disease burden among elderly patients, especially in regions with aging populations. It also complicates the management of those with underlying diseases. Appropriate prevention strategies are required to reduce the burden among the adult, especially the elderly, population. Data gaps regarding economic burden of RSV infection in the Asia Pacific region indicates the need for further research to increase our understanding on the burden of this disease in this region.

Community-Acquired Respiratory Viruses Post-Lung Transplant

Survival in lung transplant recipients (LTRs) lags behind heart, liver, and kidney transplant, in part due to the direct and indirect effects of infection. LTRs have increased susceptibility to infection due to the combination of a graft continually exposed to the outside world, multiple mechanisms for impaired mucus clearance, and immunosuppression. Community-acquired respiratory viral infections (CARVs) are common in LTRs. Picornaviruses have roughly 40% cumulative incidence followed by respiratory syncytial virus and coronaviruses. Although single-center retrospective and prospective series implicate CARV in rejection and mortality, conclusive evidence for and well-defined mechanistic links to long-term outcome are lacking. Treatment of viral infections can be challenging except for influenza. Future studies are needed to develop better treatments and clarify the links between CARV and long-term outcomes.

Human Metapneumovirus and Parainfluenza Virus Infections in Lung Transplant Recipients: the Effects on Lung Allograft and Clinical Outcomes

BACKGROUND

Human metapneumovirus (HMPVi) and parainfluenza virus (PIV) infections are common community acquired infection in lung transplant recipients (LTRs), but data is extremely limited.

METHODS

A retrospective study including all LTRs at the Johns Hopkins Hospital during July 2010-June 2019 with positive HMPV and PIV polymerase chain reaction (PCR) respiratory specimens was performed.

RESULTS

Thirty-one HMPV- and 53 PIV-infected LTRs were identified. LTRs with HMPVi and PIVi had similar baseline characteristics, infection parameters, treatment allocation, and allograft function outcomes. Among entire cohort, 31.6% had CLAD stage progression within 1-year post infections (29.2% vs 35.5% for PIV vs HMPV, respectively, p= 0.56). In forced expiratory volume in 1 second percent (FEV1%) trajectory analysis showed steadily decline of FEV1 across time among CLAD stage progressor from both viruses. FEV1% decline ≥ 10% at 90 days had adjusted hazard ratio for CLAD stage progression of 18.4 [4.98, 67.76] and 4.6 [1.36, 15.34] for PIVi and HMPVi, respectively. PIVi caused higher DSA development (11.8% vs 3.2%, p=0.18) and 1-year mortality (9.4% vs 0%, p=0.11), compared to HMPVi, even though the results were not statistically significant. Ribavirin did not show protective effect and mycophenolate discontinuation during infection did not increase risk of CLAD stage progression.

CONCLUSION

One-third of HMPV- and PIV- infected LTRs developed CLAD stage progression within 1 year. The lack of early lung function recovery may predict long term CLAD progression.

Influenza vaccination in immunocompromised populations: Strategies to improve immunogenicity

Immunocompromised individuals are at high risk of severe illness and complications from influenza infection. For this reason, immunization using inactivated influenza vaccines is recommended for transplant patients, individuals receiving immunosuppressant treatments, and other persons with immunodeficiency. However, these immunocompromised populations are more likely to have lower and non-protective responses to annual vaccination with a standard influenza vaccine. Here, we review strategies aimed to improve the immunogenicity of influenza vaccines in immunocompromised populations. The different strategies employed have included adjuvanted vaccines, high-dose vaccines, booster doses, intradermal vaccination, and temporary discontinuation of immunosuppressant treatment regimens. High-dose trivalent, inactivated, split-virus influenza vaccine (IIV3-HD) is so far one of the leading strategies for improving vaccine responses in HIV patients, transplant patients, and persons receiving immunosuppressant therapies for inflammatory diseases. Several studies in these populations have shown stronger humoral responses with IIV3-HD than existing standard-dose trivalent vaccine, and comparable safety. Accordingly, some scientific societies have stated that high-dose influenza vaccine could be a preferred option for immunocompromised patients. However, larger randomized controlled studies are needed to validate relative immunogenicity and safety of IIV3-HD and other enhanced vaccines and vaccination strategies in immunocompromised individuals.

Morbidity and mortality of respiratory syncytial virus infection in hospitalized adults: Comparison with seasonal influenza

INTRODUCTION

Respiratory syncytial virus (RSV) is considered a major pathogen that causes acute influenza-like illness. The objective of this study was to compare the clinical outcomes of patients with laboratory-confirmed RSV and patients with influenza infection.

METHODS

Adults hospitalized in Beilinson Hospital (October 2017-April 2018) with laboratory-confirmed RSV or influenza were included. The primary outcome was the composite of RSV/influenza complications: 30-day mortality, pneumonia, mechanical ventilation, vasopressor support, intensive care unit admission, and myocarditis/encephalitis. Secondary outcomes were individual components of the primary outcome, 90-day mortality, 90-day readmission, and length of hospital stay.

RESULTS

A total of 639 patients with RSV (n = 113) and influenza (n = 526) were included. The composite primary outcome was 21.4% (136/633), and was higher in RSV patients (30% (34/113) vs 19% (102/526), p = 0.002). Pneumonia was more common in RSV patients (21.2% (24/113) vs 9.1% (48/526), p = 0.001). On multivariable analysis, hypoalbuminemia (odds ratio (OR) 3.3, 95% confidence interval (CI) 2.1-5.3, p < 0.001), reduced room-air saturation (OR 1.1, 95% CI 1.02-1.1, p = 0.001), and infection with RSV (OR 1.67, 95% CI 1.01-2.76, p = 0.046) were predictors of complications.

CONCLUSIONS

RSV infection in hospitalized adults resulted in serious respiratory illness with complications that are comparable to those caused by influenza.

Pneumococcal vaccination in lung transplant patients

Introduction: This review analyzes the efficacy of pneumococcal vaccinations in lung transplant patients before and after transplantation.Areas covered: This review addresses the risk for respiratory infections, in particular pneumococcal infections, in lung transplantation patients in the context of immunodeficiency and immunosuppressive medication. Vaccination is recommended to counteract the increased risk of pneumococcal infection, and the relevant guidelines are discussed in this review. The design of specific vaccination schedules is required because of the impaired antibody response in specific patient categories.Expert opinion: Lung transplantation candidates should be vaccinated with pneumococcal vaccines prior to transplantation. Currently, the 23-valent pneumococcal polysaccharide vaccine offers the broadest coverage, but the antibody response should be monitored. New generation pneumococcal conjugate vaccines with equally broad serotype coverage could be used in the future. During the post-transplantation period, the immune status of the patients should be monitored regularly, and vaccination should be repeated when indicated.

A Real-World Analysis of Patient Characteristics and Predictors of Hospitalization Among US Medicare Beneficiaries with Respiratory Syncytial Virus Infection

Introduction

Little has been published on respiratory syncytial virus (RSV) among Medicare patients at high risk (HR) of RSV complications due to age or comorbidity.

Methods

Adult patients (at least 18 years of age) with at least 1 diagnostic code for RSV were identified using the 5% US Medicare database from 2011 through 2015. Patients were required to have continuous health plan enrollment for 180 days pre- and 180 days post-RSV diagnosis (baseline and follow-up periods, respectively). HR was defined as diagnosis of chronic lung disease, congestive heart failure, or weakened immune system for 180 days during the baseline period. Patients were categorized as initially hospitalized if hospitalized within 1 day of RSV diagnosis. Logistic regression models were developed to determine predictors of initial hospitalization. Healthcare utilization and costs for 180 days pre- and post-RSV diagnosis were compared.

Results

The study included 756 HR patients who were initially hospitalized with RSV diagnoses. Among these, 61.7% were diagnosed in the emergency department vs 15.3% in a physician’s office, with hypertension (76.3%), chronic obstructive pulmonary disease (COPD) (53.7%), and high cholesterol (52.0%) observed as the most prevalent comorbidities. Of these, COPD, congestive heart failure, chronic kidney disease, and previous evidence of pneumonia were significant predictors of hospitalization. Other significant predictors of hospitalization included older age, hematological malignancies, stroke, and baseline healthcare resource use. Among both HR and non-HR hospitalized patients, there was a significant increase in healthcare resource utilization following hospitalization, including the number of inpatient admissions and longer hospital stays post-RSV diagnosis. The total mean all-cause healthcare costs among HR hospitalized patients increased by $9210 per patient (p < 0.0001) post-RSV diagnosis.

Conclusion

Hospitalized Medicare beneficiaries with RSV infections pose a significant healthcare burden as compared with non-hospitalized patients, mainly driven by higher comorbidity, higher likelihood of multiple inpatient admissions, and costly medical interventions.

Respiratory Viral Infections in Transplant Recipients

Respiratory viral infections (RVIs) are common among the general population; however, these often mild viral illnesses can lead to serious morbidity and mortality among recipients of hematopoietic stem cell and solid organ transplantation. The disease spectrum ranges from asymptomatic or mild infections to life-threatening lower respiratory tract infection or long-term airflow obstruction syndromes. Progression to lower respiratory tract infection or to respiratory failure is determined by the intrinsic virulence of the specific viral pathogen as well as various host factors, including the type of transplantation, status of the host’s immune dysfunction, the underlying disease, and other comorbidities. This chapter focuses on the epidemiology, clinical manifestations, diagnosis, and management of RVIs in this susceptible population and includes respiratory syncytial virus, parainfluenza virus, human metapneumovirus, influenza virus, human coronavirus, and human rhinovirus. The optimal management of these infections is limited by the overall paucity of available treatment, highlighting the need for new antiviral drug or immunotherapies.

Viral Respiratory Tract Infection During the First Postoperative Year Is a Risk Factor for Chronic Rejection After Lung Transplantation

Supplemental digital content is available in the text.

Background

Chronic lung allograft dysfunction (CLAD) is the major limiting factor for long-term survival in lung transplant recipients. Viral respiratory tract infection (VRTI) has been previously associated with CLAD development. The main purpose of this study was to evaluate the long-term effects of VRTI during the first year after lung transplantation in relation to CLAD development.

Method

Ninety-eight patients undergoing lung transplantation were prospectively enrolled between 2009 and 2012. They were monitored for infections with predefined intervals and on extra visits during the first year, the total follow-up period ranged between 5 and 8 years. Nasopharyngeal swab and bronchoalveolar lavage samples were analyzed using a multiplex polymerase chain reaction panel for respiratory pathogens. Data regarding clinical characteristics and infectious events were recorded.

Results

Viral respiratory tract infection during the first year was identified as a risk factor for long-term CLAD development (P = 0.041, hazard ratio 1.94 [1.03-3.66]) in a time-dependent multivariate Cox regression analysis. We also found that coronavirus in particular was associated with increased risk for CLAD development. Other identified risk factors were acute rejection and cyclosporine treatment.

Conclusions

This study suggests that VRTI during the first year after lung transplantation is associated with long-term CLAD development and that coronavirus infections in particular might be a risk factor.

Respiratory Viruses and Other Relevant Viral Infections in the Lung Transplant Recipient

As advances occur in surgical technique, postoperative care, and immunosuppressive therapy, the rate of mortality in the early postoperative period following lung transplantation continues to decline. With the improvements in immediate and early posttransplant mortality, infections and their sequel as well as rejection and chronic allograft dysfunction are increasingly a major cause of posttransplant mortality. This chapter will focus on infections by respiratory viruses and other viral infections relevant to lung transplantation, including data regarding the link between viral infections and allograft dysfunction.

Respiratory Viruses: Influenza, RSV, and Adenovirus in Kidney Transplantation

Although advances in immunosuppression and antimicrobial prophylaxis have led to improved patient and graft survival, respiratory viruses continue to be a common cause of morbidity and mortality in immunocompromised populations. We describe the clinical manifestations, diagnosis and treatment options for influenza, respiratory syncytial virus and adenovirus infection in the kidney transplant population.

Update in the treatment of non-influenza respiratory virus infection in solid organ transplant recipients

INTRODUCTION

Despite the improved outcomes in solid organ transplantation with regard to prevention of rejection and increased patient and graft survival, infection remains a common cause of morbidity and mortality. Respiratory viruses are a frequent and potentially serious cause of infection after solid organ transplantation. Furthermore, clinical manifestations of respiratory virus infection (RVI) may be more severe and unusual in solid organ transplant recipients (SOTRs) compared with the non-immunocompromised population. Areas covered: This article reviews the non-influenza RVIs that are commonly encountered in SOTRs. Epidemiologic and clinical characteristics are highlighted and available treatment options are discussed. Expert opinion: New diagnostic tools, particularly rapid molecular assays, have expanded the ability to identify specific RVI pathogens in SOTRs. This is not only useful from a treatment standpoint but also to guide infection control practices. More data are needed on RVIs in the solid organ transplant population, particularly regarding their effect on rejection and graft dysfunction. There is also a need for new antiviral agents active against these infections as well as markers that can identify which patients would most benefit from treatment.

Clinical characteristics and outcome of respiratory syncytial virus infection among adults hospitalized with influenza-like illness in France

OBJECTIVES

The aim of this study was to analyse characteristics and outcome of respiratory syncytial virus (RSV) infection in adults hospitalized with influenza-like illness (ILI).

METHODS

Patients hospitalized with ILI were included in this prospective, multicentre study carried out in six French hospitals during three consecutive influenza seasons (2012-2015). RSV and other respiratory viruses were detected by multiplex PCR in nasopharyngeal swabs. Risk factors for RSV infection were identified by backward stepwise logistic regression analysis.

RESULTS

A total of 1452 patients hospitalized with ILI were included, of whom 59% (861/1452) were >65 years and 83% (1211/1452) had underlying chronic illnesses. RSV was detected in 4% (59/1452), and influenza virus in 39% (566/1452). Risk factors for RSV infection were cancer (adjusted OR 2.1, 95% CI 1.1-4.1, p 0.04), and immunosuppressive treatment (adjusted OR 2.0, 95% CI 1.1-3.8, p 0.03). Patients with RSV had a median length of stay of 9 days (6-25), and 57% of them (30/53) had complications, including pneumonia (23/53, 44%) and respiratory failure (15/53, 28%). Fifteen per cent (8/53) were admitted to an intensive care unit, and the in-hospital mortality rate was 8% (4/53). Pneumonia was more likely to occur in patients with RSV than in patients with RSV-negative ILI (44% (23/53) versus 26% (362/1393), p 0.006) or with influenza virus infection (44% versus 28% (157/560), p 0.02).

CONCLUSION

RSV is an infrequent cause of ILI during periods of influenza virus circulation but can cause severe complications in hospitalized adults. Risk factors for RSV detection in adults hospitalized with ILI include cancer and immunosuppressive treatment. Specific immunization and antiviral therapy might benefit patients at risk.

Lower Respiratory Tract Infections

This review will focus on the infectious etiologies and more common noninfectious causes of lower respiratory tract syndromes among major immunosuppressed populations. The changing epidemiology of infections in the era of highly active antiretroviral therapy (HAART) in the case of HIV-positive patients and the impacts of both newer immune-suppressant therapies and anti-infective prophylaxis for other immunocompromised hosts will be discussed, with emphasis on diagnostic approaches and practice algorithms.

Antibody responses to influenza vaccine in pre- and post-lung transplant patients

BACKGROUND

Although pre-transplant immunization is routinely recommended, this recommendation is based on little data. The primary objective of this study was to compare antibody responses in lung transplant patients who received influenza vaccine before the transplant, within the first six months of transplant, between 13 and 60 months post-transplant, and 110 months or beyond transplant.

METHODS

This prospective cohort study included 357 total immunization events performed over five yr to measure H1N1, H3N2, and B antibody responses to the influenza vaccine in pre- and post-lung transplant patients. Geometric mean titers, seroprotection (antibody titer at least 1:40), seroconversion (fourfold increase between pre and post), and mean fold increases were compared.

RESULTS

The geometric mean titer distributions were different for H3N2 and B (ANOVA; p = 0.002 for both). Pre-transplant antibody concentrations were higher compared to the 13- to 60-month group for H3N2 (corrected p = 0.002) and the healthy group for B (corrected p = 0.001). The ≥110-month group had higher seroconversion rates compared to the 13- to 60-month group for H3N2 and B viruses.

CONCLUSION

Lung pre-transplant patients and the long-term survivors have higher responses to the influenza vaccine than early post-transplant and the transplant control groups.

Risks and Epidemiology of Infections After Lung or Heart–Lung Transplantation

Nowadays, lung transplantation is an established treatment option of end-stage pulmonary parenchymal and vascular disease. Post-transplant infections are a significant contributor to overall morbidity and mortality in the lung transplant recipient that, in turn, are higher than in other solid organ transplant recipients. This is likely due to several specific factors such as the constant exposure to the outside environment and the colonized native airway, and the disruption of usual mechanisms of defense including the cough reflex, bronchial circulation, and lymphatic drainage. This chapter will review the common infections that develop in the lung or heart–lung transplant recipient, including the general risk factors for infection in this population, and specific features of prophylaxis and treatment for the most frequent bacterial, viral, and fungal infections. The effects of infection on lung transplant rejection will also be discussed.

Randomized, double-blind comparison of standard-dose vs. high-dose trivalent inactivated influenza vaccine in pediatric solid organ transplant patients

Children who have undergone SOT mount a lower immune response after vaccination with TIV compared to healthy controls. HD or SD TIV in pediatric SOT was given to subjects 3-17 yr and at least six months post-transplant. Subjects were randomized 2:1 to receive either the HD (60 μg) or the SD (15 μg) TIV. Local and systemic reactions were solicited after each vaccination, and immune responses were measured before and after each vaccination. Thirty-eight subjects were enrolled. Mean age was 11.25 yr; 68% male, 45% renal, 26% heart, 21% liver, 5% lung, and 5% intestinal. Twenty-three subjects were given HD and 15 SD TIV. The median time since transplant receipt was 2.2 yr. No severe AEs or rejection was attributed to vaccination. The HD group reported more tenderness and local reactions, fatigue, and body ache when compared to the SD cohort, but these were considered mild and resolved within three days. Subjects in the HD group demonstrated a higher percentage of four-fold titer rise to H3N2 compared to the SD group. HD influenza vaccine was well tolerated and may have increased immunogenicity. A phase 2 trial is needed to confirm.

Effect of hypogammaglobulinemia on the incidence of community-acquired respiratory viral infections after lung transplantation

BACKGROUND

Hypogammaglobulinemia (HGG) has been associated with an increased risk of infectious complications in lung transplant recipients, but its effect specifically on community-acquired respiratory viruses (CARVs) remains unknown. This study aimed to determine if lung transplant recipients with HGG are at an increased risk of developing CARV infection. Secondary endpoints included the effect of HGG on lung function, incidence of rejection, and mortality.

METHODS

A retrospective review of all lung transplant recipients from 2008 to 2011 was performed. Patients were stratified as either having HGG after transplantation or having normal IgG titers according to their nadir IgG level. HGG was defined a serum IgG level of <700 mg/dL. CARVs included human metapneumovirus, influenza A/B, respiratory syncytial virus A/B, parainfluenza 1/2/3, rhinovirus, and adenovirus isolated from bronchoalveolar lavage/wash, sputum, or nasal swab.

RESULTS

The cohort consisted of 263 patients with a mean follow-up time of 612 ± 356 days. The incidence of CARV infection was 27% in patients with normal IgG titers and 23.4% in patients with HGG (P = .62). No difference in rejection, mortality, or lung function was found between the groups. As expected, patients who ever had a CARV infection had a significantly lower 1-second forced expiratory volume % reference on their most recent spirometry than those who had not had a CARV infection (81.6% vs 86.9%; P = .027).

CONCLUSIONS

Although CARV infection has been shown to affect lung graft function, these data suggests that HGG is not associated with the incidence of CARV infection.

Persistence of influenza vaccine-induced antibody in lung transplant patients and healthy individuals beyond the season

BACKGROUND

The timing of influenza vaccination and susceptibility to re-circulating virus in the population is influenced by the persistence of seroprotection. Immunosuppressed transplant patients are known to have lower antibody response rates than healthy individuals, but acceptable antibody concentrations are achieved. The duration of this seroprotection beyond a single season has not been evaluated in either healthy or immunosuppressed populations.

METHODS

Influenza antibody concentrations against viruses no longer included in the vaccine were measured in serum by hemagglutination inhibition assay annually following vaccination of 73 lung transplant participants and 27 healthy controls. Seroprotection was defined as a titer of ≥ 1:40 and was compared between groups over the measured term using Fisher's exact tests.

RESULTS

Seroprotection rates for influenza A and B strains at one year following immunization were 100% for lung transplant and healthy controls. Rates at two years for the influenza A strains were 65-74% for lung transplant vs. 77-100% in healthy controls. Rates for influenza B strains two years following immunization were 27-50% for lung transplant vs. 16-38% in healthy controls. (Fisher's exact test; not significant for between group comparisons; p < 0.05 for between season comparisons)

CONCLUSIONS

Vaccine-induced antibody persistence appears to be influenced more by the vaccine virus strain than the immune status of the vaccinated individuals. Seroprotection rates are high 12 mo following influenza vaccination but wane over the second year, particularly for influenza B viruses. Annual influenza immunization is indicated, even for healthy individuals and even when the vaccine viruses do not change.

Lethal hemorrhagic alveolitis after adenovirus pneumonia in a lung transplant recipient

Viral infections are frequent and severe in lung transplant recipients. They frequently occur during the first year after transplantation. We report on a rare case of bilateral adenovirus necrotizing pneumonia with a diffuse alveolar hemorrhage, 4 years after bilateral lung transplantation. The medical evolution was lethal in 72 hours because of respiratory, renal, and cardiac failure. Considering this case and the growing evidence on the severity of adenoviral infections, we call for controlled studies and therapeutic recommendations.

Influenza, including the novel H1N1, in organ transplant patients

PURPOSE OF REVIEW

This article will review the epidemiology, diagnosis, prevention and management of influenza in solid organ transplant recipients.

RECENT FINDINGS

A number of recent studies have documented that influenza vaccination is both well tolerated and generally effective in producing an immunologic response in most solid organ transplant (SOT) recipients. Antiviral use is associated with improved clinical outcomes, but prolonged shedding may require a longer course of therapy than what is currently approved by the FDA. Antiviral resistance emerges rarely in transplant patients and should be considered in all patients with an inadequate clinical and/or virologic response.

SUMMARY

Influenza is associated with significant morbidity and mortality, particularly in lung transplant recipients. Molecular diagnostics are preferred over other diagnostic modalities, if available. Influenza vaccination is well tolerated and provides protective benefit in most SOT recipients; in those with contraindications to vaccination or in whom responses are predicted to be poor, antivirals may be considered. Antiviral therapy is associated with improved outcomes in transplant patients and treatment should be continued until clinically and virologic response have been documented. Resistance, particularly with patients infected with the pandemic influenza A/H1N1, should be considered and treated with an antiviral with predicted activity.

RNA interference therapy in lung transplant patients infected with respiratory syncytial virus

RATIONALE

Lower respiratory tract infections due to respiratory syncytial virus (RSV) are associated with development of bronchiolitis obliterans syndrome in lung transplant (LTX) recipients. ALN-RSV01 is a small interfering RNA targeting RSV replication.

OBJECTIVES

To determine the safety and explore the efficacy of ALN-RSV01 in RSV infection.

METHODS

We performed a randomized, double-blind, placebo-controlled trial in LTX recipients with RSV respiratory tract infection. Patients were permitted to receive standard of care for RSV. Aerosolized ALN-RSV01 (0.6 mg/kg) or placebo was administered daily for 3 days. Viral load was determined by quantitative reverse transcriptase-polymerase chain reaction on serial nasal swabs. Patients completed symptom score cards twice daily. Lung function, including the incidence of new-onset or progressive bronchiolitis obliterans syndrome, was recorded at Day 90.

MEASUREMENTS AND MAIN RESULTS

We enrolled 24 patients (ALN-RSV01, n = 16; placebo, n = 8); randomization was stratified by ribavirin use. ALN-RSV01 was well tolerated, with no drug-related serious adverse events or post-inhalation perturbations in lung function. Interpretation of viral measures was confounded by baseline differences between the two groups in viral load and time from symptom onset to first dose. Mean daily symptom scores were lower in subjects receiving ALN-RSV01, and the mean cumulative daily total symptom score was significantly lower with ALN-RSV01 (114.7 ± 63.13 vs. 189.3 ± 99.59, P = 0.035). At Day 90, incidence of new or progressive bronchiolitis obliterans syndrome was significantly reduced in ALN-RSV01 recipients compared with placebo (6.3% vs. 50%, P = 0.027).

CONCLUSIONS

ALN-RSV01 was safe and may have beneficial effects on long-term allograft function in LTX patients infected with RSV. Clinical trial registered with www.clinicaltrials.gov (NCT 00658086).

Evaluation of a surveillance strategy for early detection of adenovirus by PCR of peripheral blood in hematopoietic SCT recipients: incidence and outcome

Adenoviruses (AdV) have emerged as important causes of morbidity and mortality in patients after hematopoietic SCT (HSCT). Early diagnosis of the infection by detection of viral DNA may improve the prognosis. A surveillance strategy was evaluated for detection of AdV DNA by PCR in a prospective study of unselected allogeneic HSCT recipients. In parallel with a routine CMV surveillance program, plasma from 20 children and 77 adults was analyzed by quantitative PCR for detection of AdV DNA. In addition, in 12 unselected patients, the presence of AdV-specific T cells were analyzed by enzyme-linked immunosorbent spot (ELISPOT) at 1 to 3 months after transplantation. A total of 5 of 97 (5%) patients had detectable AdV DNA in peripheral blood. Only one patient had high titers and none developed AdV disease. BM as a source of stem cells and myelodysplastic syndrome as the indication for transplantation were independently associated with higher risk of acquiring AdV infection. AdV-specific T cells were detected in 7 (58%) of 12 patients. Although AdV DNA was found in peripheral blood by quantitative PCR in 5% of patients undergoing allogeneic HSCT, the present surveillance program did not have a significant effect on the clinical outcome.

Community-acquired respiratory viral infections in lung transplant recipients: a single season cohort study

BACKGROUND

The impact of community-acquired respiratory virus (CARV) infections on bronchiolitis obliterans syndrome (BOS) and outcome after lung transplantation (LTx) and diagnostic techniques were prospectively evaluated.

METHODS

A single-center prospective cohort study was performed in LTx-outpatients between October 31, 2005 and April 30, 2006. Symptoms of respiratory tract infections were recorded and nasopharyngeal and oropharyngeal swabs were obtained. Lower respiratory sampling was performed when indicated. Immunofluorescence testing, cultures, and polymerase chain reaction for 12 different CARV were applied. Patients were followed up until December 31, 2007. New onset and BOS-stage was recorded 1 year after presentation.

RESULTS

Three hundred eighty-eight LTx-recipients were screened. Fifty-one percent reported of symptoms of respiratory tract infection. Seven hundred seventy upper and 180 lower respiratory samples were obtained. Thirty-four CARV were detected in 30 patients (7.7%): 12 parainfluenza, 7 respiratory syncytial virus, 6 metapneumovirus, 5 coronavirus, 3 rhinovirus, and 1 influenza virus. At 1 year, 43 new cases of BOS developed. One-year incidence of BOS was 25.0% in CARV-positive versus 9.0% in CARV-negative patients (log-rank P=0.01). Symptomatic CARV-infection proved to be a significant covariate for 1-year BOS-free survival in multivariate analysis (P=0.002, adjusted hazard ratio 4.13). CARV-infection did not influence BOS progression in 88 patients with prior BOS (P 0.45). After paramyxovirus infection, 8 of 24 patients developed new-onset BOS, whereas no case was recorded after rhinovirus and coronavirus infection.

DISCUSSION

Surveillance detected CARV in LTx outpatients infrequently. Symptomatic CARV-infection increases the risk for new onset of BOS, but not progression. Risk to develop BOS was especially increased after paramyxovirus infection.

RNA interference-mediated silencing of the respiratory syncytial virus nucleocapsid defines a potent antiviral strategy

We describe the design and characterization of a potent human respiratory syncytial virus (RSV) nucleocapsid gene-specific small interfering RNA (siRNA), ALN-RSV01. In in vitro RSV plaque assays, ALN-RSV01 showed a 50% inhibitory concentration of 0.7 nM. Sequence analysis of primary isolates of RSV showed that the siRNA target site was absolutely conserved in 89/95 isolates, and ALN-RSV01 demonstrated activity against all isolates, including those with single-mismatch mutations. In vivo, intranasal dosing of ALN-RSV01 in a BALB/c mouse model resulted in potent antiviral efficacy, with 2.5- to 3.0-log-unit reductions in RSV lung concentrations being achieved when ALN-RSV01 was administered prophylactically or therapeutically in both single-dose and multidose regimens. The specificity of ALN-RSV01 was demonstrated in vivo by using mismatch controls; and the absence of an immune stimulatory mechanism was demonstrated by showing that nonspecific siRNAs that induce alpha interferon and tumor necrosis factor alpha lack antiviral efficacy, while a chemically modified form of ALN-RSV01 lacking measurable immunostimulatory capacity retained full activity in vivo. Furthermore, an RNA interference mechanism of action was demonstrated by the capture of the site-specific cleavage product of the RSV mRNA via rapid amplification of cDNA ends both in vitro and in vivo. These studies lay a solid foundation for the further investigation of ALN-RSV01 as a novel therapeutic antiviral agent for clinical use by humans.

The host response and molecular pathogenesis associated with respiratory syncytial virus infection

Since the isolation of respiratory syncytial virus (RSV) in 1956, its significance as an important human pathogen in infants, the elderly and the immunocompromised has been established. Many important mechanisms contributing to RSV infection, replication and disease pathogenesis have been uncovered; however, there is still insufficient knowledge in these and related areas, which must be addressed to facilitate the development of safe and effective vaccines and therapeutic treatments. A better understanding of the molecular pathogenesis of RSV infection, particularly the host-cell response and transcription profiles to RSV infection, is required to advance disease intervention strategies. Substantial information is accumulating regarding how RSV proteins modulate molecular signaling and regulation of cytokine and chemokine responses to infection, molecular signals regulating programmed cell death, and innate and adaptive immune responses to infection. This review discusses RSV manipulation of the host response to infection and related disease pathogenesis.

Variability in immunization guidelines in children before and after lung transplantation

Lung transplant candidates and recipients are at high risk of infections from vaccine-preventable diseases. However, well-established guidelines neither exist for pre- and post-transplant vaccination nor do monitoring guidelines for pediatric lung transplant recipients. To ascertain the current vaccination and monitoring practices of pediatric lung transplant centers, a self-administered questionnaire was distributed to the 18 pediatric lung transplant centers within the International Pediatric Lung Transplant Collaborative in April 2006. Sixteen of 18 centers (89%) surveyed responded. Pretransplant, national vaccination guidelines are followed. Eleven centers reported following standardized vaccination guidelines post-transplant. Vaccines were more commonly provided by the primary-care physician pretransplant (69%) rather than post-transplant (38%). Post-transplant, 50% of the centers recommend live vaccines for household contacts but not for the transplant recipient. Pretransplant monitoring of response to prior vaccination was performed inconsistently except for varicella (88%). Only 44% of the transplant centers measure for response to vaccination post-transplant, mostly hepatitis B. Current vaccination practices of pediatric lung transplant centers are heterogeneous. The lung transplant community would be well served by studies designed to evaluate the efficacy of vaccinations in this population.

Respiratory Viral Infections in Transplant Recipients

A wide range of viruses affect the respiratory tract of transplant recipients, including adenovirus, influenza, human metapneumovirus, parainfluenza virus, respiratory syncytial virus (RSV) and rhinovirus. Prospective studies using contemporary diagnostic techniques have recently improved our understanding of the epidemiology and importance of these respiratory viruses among transplant recipients. From these studies, rhinovirus, in particular, has been shown to be one of the most common causes of infection in stem cell and lung transplant recipients. In addition to epidemiological data, recent studies have also advanced our understanding of management of influenza, adenovirus, and RSV infections among transplant recipients.

Viral respiratory tract infections in transplant patients: epidemiology, recognition and management

Viral respiratory tract infections (RTIs) are common causes of mild illness in immunocompetent children and adults, with occasional significant morbidity or mortality in the very young, very old or infirm. However, recipients of solid organ transplants (SOT) or haematopoietic stem cell transplants (HSCT) are at markedly increased risk for significant morbidity or mortality from these infections. The infections are generally acquired by transmission of large respiratory droplets and can be nosocomial in origin with many documented outbreaks on specialised transplant units. Typically, the infections begin as upper RTIs, with cough or rhinorrhoea predominating. Many will resolve at this stage, but more immunocompromised patients, typically closer in time to their SOT or HSCT, may develop progressive infection to lower RTI or pneumonia. The most common RTI pathogens are influenza viruses, parainfluenza viruses and respiratory syncytial viruses. Newer polymerase chain reaction-based diagnostic strategies are more sensitive than previous assays, and allow rapid and accurate diagnoses of these infections. These newer assays may also detect emerging pathogens of significance, one of which is human metapneumovirus. While diagnostic techniques have advanced significantly in the past decade, well established and effective specific treatments for these infections remain elusive. The epidemiology, clinical presentation, diagnosis and treatment of the common viral RTIs in SOT or HSCT recipients are reviewed, and recommendations presented based on a thorough review of recent literature.

Role of airway epithelial injury in murine orthotopic tracheal allograft rejection

BACKGROUND

Murine tracheal transplantation is a model used to study bronchiolitis obliterans syndrome, a major cause of morbidity and mortality after lung transplantation. Unlike murine heterotopic tracheal transplants, orthotopic transplantation does not cause luminal obliteration despite major histocompatibility antigen mismatch. Repopulation of the tracheal allografts with recipient-derived epithelium confers protection against luminal obliteration. The purpose of this study was to determine whether (1) orthotopic tracheal transplantation showed signs of allograft rejection, and (2) airway epithelial cell injury promoted orthotopic tracheal allograft rejection.

METHODS

Forty isogeneic (C57BL/6 to C57BL/6) and 40 allogeneic (BALB/c to C57BL/6) orthotopic tracheal transplants were performed. Damage to airway epithelial cells was induced by Sendai viral (SdV) infection and tracheal transplantation into non-reepithelializing matrix metalloproteinase-7 knockout (MMP7-KO) recipient mice. Percent fibrosis and lamina propria to cartilage ratio were calculated with computer assistance on harvested allografts.

RESULTS

Allografts showed significantly more intramural fibrosis compared with isografts at 30, 60, and 180 days after transplant without luminal occlusion. Tracheal allografts infected with SdV showed an increase in fibrosis and lamina propria to cartilage ratio compared with noninfected controls. Allografts retrieved from MMP7-KO recipients also showed a significant increase in fibrosis and lamina propria to cartilage ratio.

CONCLUSIONS

Although orthotopic tracheal transplantation does not cause luminal obliteration, it results in increased fibrosis in allografts. Damage to the respiratory epithelium by viral infection or defective reepithelialization after transplant as seen in MMP7-KO recipient mice leads to changes consistent with chronic allograft rejection, suggesting a role for epithelial injury in bronchiolitis obliterans syndrome development.

Transplant-related immunosuppression: a review of immunosuppression and pulmonary infections

Solid organ and hematopoietic stem cell transplantation are definitive therapies for a variety of end-stage diseases. Immunosuppression has improved graft survival but leaves the patient susceptible to infectious complications. Of these, pulmonary infections are the leading cause of morbidity and mortality in the transplant recipient. Allograft rejection is mediated primarily by T cells, with B cells playing a role via antibody production. Depending on the transplant type, rejection can be hyperacute, acute, or chronic. Hyperacute rejection occurs as an immediate response to preformed antibodies to donor human leukocyte antigens. Acute cellular rejection involves recipient T-cell recognition of human leukocyte antigen molecules expressed on donor-derived, antigen-presenting cells (direct allorecognition) or presentation of donor-derived peptides by recipient antigen-presenting cells to recipient T cells (indirect allorecognition). Once the alloantigens are recognized as foreign, the activation, proliferation, and production of cytokines by T lymphocytes and other immune cells lead to the amplification of the alloimmune response. This complex process involves the generation of effector T cells, antibody production by activated B cells, and macrophage activation. Alloimmunity is facilitated by the production of many cytokines, chemokines, and other effector molecules, such as complement. The immunosuppressants involve many classes of drugs, including antibody therapies that eliminate specific groups of cells or alter signaling pathways used by effector cells. The article reviews the agents and associated infections.

Real-time PCR in clinical microbiology: applications for routine laboratory testing

Real-time PCR has revolutionized the way clinical microbiology laboratories diagnose many human microbial infections. This testing method combines PCR chemistry with fluorescent probe detection of amplified product in the same reaction vessel. In general, both PCR and amplified product detection are completed in an hour or less, which is considerably faster than conventional PCR detection methods. Real-time PCR assays provide sensitivity and specificity equivalent to that of conventional PCR combined with Southern blot analysis, and since amplification and detection steps are performed in the same closed vessel, the risk of releasing amplified nucleic acids into the environment is negligible. The combination of excellent sensitivity and specificity, low contamination risk, and speed has made real-time PCR technology an appealing alternative to culture- or immunoassay-based testing methods for diagnosing many infectious diseases. This review focuses on the application of real-time PCR in the clinical microbiology laboratory.

Viral pneumonias other than cytomegalovirus in transplant recipients

Community-acquired respiratory viruses (CARVs) are frequent causes of upper and lower respiratory tract infections in transplant recipients. In most series, respiratory syncytial virus and parainfluenza are the most common CARVs, followed by influenza and adenovirus. Significant morbidity and mortality are associated with these infections, particularly when they progress to pneumonia or when they are associated with bacterial or fungal coinfections. Outcomes are also poor with adenovirus, frequently reflecting disseminated infection. Efforts to prevent morbidity and mortality from CARV infection should focus on prevention, because treatment options are limited with inconclusive data to support their efficacy.

Intravenous Ribavirin Is a Safe and Cost-effective Treatment for Respiratory Syncytial Virus Infection After Lung Transplantation

BACKGROUND

Community-acquired viral infections, such as respiratory syncytial virus (RSV), represent a risk factor for bronchiolitis obliterans syndrome (BOS), the major limiting factor for long-term survival after lung transplantation (LTx). RSV often presents with acute bronchiolitis and may be fatal in 10% to 20% of patients. Standard therapies for RSV include nebulized ribavirin with or without steroids, but are costly and inconvenient. We investigated the utility of intravenous (IV) ribavirin with steroids for the treatment of RSV infection after LTx.

METHODS

RSV was identified in nasopharyngeal and throat swabs (NPS) using indirect fluorescent antibody (IFA) testing in 18 symptomatic patients, which was confirmed by viral culture in 14. Data were collected for the period between April 2002 and October 2004. The study included 10 men and 8 women, mean age 42 +/- 15 (range 18 to 63) years. Transplant procedures were 5 single LTx and 13 bilateral LTx. RSV diagnosis was made on Day 1,374 +/- 1,270 (range 61 to 4,598, median 935) post-operatively. Underlying diagnoses included cystic fibrosis (n = 9), emphysema (n = 7) and pulmonary fibrosis (n = 2). All 18 patients received intravenous (IV) ribavirin (33 mg/kg on Day 1 and 20 mg/kg/day thereafter in 3 divided doses) with oral prednisolone (1 mg/kg) until repeat NPS were negative for RSV on IFA. Median therapy was 8 days (6 to 15).

RESULTS

The mortality rate was 0%. Mean FEV1 fell from 2.1 +/- 1.0 liter (0.7 to 3.7 liters) to 1.8 +/- 0.9 liter (0.5 to 3.6 liters) (p < 0.001), but recovered to 2.1 +/- 0.9 (0.7 to 3.7 liters) within 3 months and was maintained at follow-up of 521 +/- 328 days (141 to 1,023 days, median 302). Only 1 patient developed bronchiolitis obliterans syndrome (BOS). Complications included mild hemolytic anemia (blood hemoglobin fell from 122 +/- 22 [84 to 154] g/liter to 107 +/- 18 [75 to 138] g/liter, p = 0.02). Cost savings per 8-day course were $US15,913 when compared with nebulized therapy at 6 g/day (p < 0.001).

CONCLUSIONS

This is the largest reported series of treated RSV cases after LTx and the first to show that therapy with IV ribavirin and oral corticosteroids is well tolerated and effective. Cost utility vs nebulized therapy has been established. Early diagnosis and management are essential to prevent airway epithelial injury and subsequent BOS.

Human Metapneumovirus Infection in Lung Transplant Recipients: Clinical Presentation and Epidemiology

BACKGROUND

In immunocompromised patients, respiratory viruses are likely to lead to lower respiratory tract infections that cause severe morbidity and mortality. We conducted a prospective study from September 2003 to March 2004 to investigate the epidemiology and impact of human metapneumovirus (hMPV) on lung transplant recipients.

METHODS

We collected 265 nasopharyngeal aspirates and bronchoalveolar lavages: 51 samples originated from immunocompromised adults, 49 from lung transplant recipients, and 2 from a bone marrow recipient. Additionally, 209 samples from hospitalized non-immunocompromised children and 5 samples from immunocompromised children were analyzed for replicating hMPV by a combined cell culture and reverse transcriptase polymerase chain reaction method that includes DNA sequencing of selected isolates.

RESULTS

Twelve samples from lung transplant recipients (25%), 29 from non-immunocompromised children (14%), and 2 from a child with a renal transplant were positive for hMPV. Most of the cases clustered within 2 outbreaks in October/November and March. In immunocompromised patients, hMPV was isolated throughout the entire observation period. The same viral strains circulated in hospitalized children and in lung transplant recipients. A different strain was isolated during the interepidemic period, suggesting that hMPV infections may be transmitted among lung transplant recipients independently from the community outbreak situation. Clinical signs and symptoms varied from no symptoms to severe pneumonia or acute graft rejection. Significantly, the only deaths occurred in the hMPV-positive group. Of interest, identification of replicating hMPV significantly correlated with rejection symptoms present at the time point of sample collection.

CONCLUSIONS

Results of the study suggest that hMPV may be added to the list of pathogens that are possibly associated with episodes of allograft rejection.

Immunization of pediatric solid-organ transplantation candidates: immunizations in transplant candidates

Many children who receive solid-organ transplants have not completed their primary immunizations prior to transplantation. This leaves pediatric transplant recipients susceptible to the vaccine preventable illness of childhood, which if acquired post-transplantation are associated with increased rates of complications, hospitalization, graft rejection and mortality. The administration of vaccines to transplant candidates earlier and more rapidly than in the healthy child will improve vaccination rates among transplant recipients while not compromising immunogenicity. The recommended vaccines and vaccine schedule are discussed in detail.

Detection of severe human metapneumovirus infection by real-time polymerase chain reaction and histopathological assessment

BackgroundInfections with common respiratory tract viruses can cause high mortality, especially in immunocompromised hosts, but the impact of human metapneumovirus (hMPV) in this setting was previously unknown

MethodsWe evaluated consecutive bronchoalveolar lavage and bronchial wash fluid samples from 688 patients—72% were immunocompromised and were predominantly lung transplant recipients—for hMPV by use of quantitative real-time polymerase chain reaction (PCR), and positive results were correlated with clinical outcome and results of viral cultures, in situ hybridization, and lung histopathological assessment

ResultsSix cases of hMPV infection were identified, and they had a similar frequency and occurred in a similar age range as other paramyxoviral infections. Four of 6 infections occurred in immunocompromised patients. Infection was confirmed by in situ hybridization for the viral nucleocapsid gene. Histopathological assessment of lung tissue samples showed acute and organizing injury, and smudge cell formation was distinct from findings in infections with other paramyxoviruses. Each patient with high titers of hMPV exhibited a complicated clinical course requiring prolonged hospitalization

ConclusionsOur results provide in situ evidence of hMPV infection in humans and suggest that hMPV is a cause of clinically severe lower respiratory tract infection that can be detected during bronchoscopy by use of real-time PCR and routine histopathological assessment

Clinical impact of community-acquired respiratory viruses on bronchiolitis obliterans after lung transplant

Community-acquired viral respiratory tract infections (RTI) in lung transplant recipients may have a high rate of progression to pneumonia and can be a trigger for immunologically mediated detrimental effects on lung function. A cohort of 100 patients was enrolled from 2001 to 2003 in which 50 patients had clinically diagnosed viral RTI and 50 were asymptomatic. All patients had nasopharyngeal and throat swabs taken for respiratory virus antigen detection, culture and RT-PCR. All patients had pulmonary function tests at regular intervals for 12 months. Rates of rejection, decline in forced expiratory volume (L) in 1 s (FEV-1) and bacterial and fungal superinfection were compared at the 3-month primary endpoint. In the 50 patients with RTI, a microbial etiology was identified in 33 of 50 (66%) and included rhinovirus (9), coronavirus (8), RSV (6), influenza A (5), parainfluenza (4) and human metapneumovirus (1). During the 3-month primary endpoint, 8 of 50 (16%) RTI patients had acute rejection versus 0 of 50 non-RTI patients (p=0.006). The number of patients experiencing a 20% or more decline in FEV-1 by 3 months was 9 of 50 (18%) RTI versus 0 of 50 non-RTI (0%) (p=0.003). In six of these nine patients, the decline in FEV-1 was sustained over a 1-year period consistent with bronchiolitis obliterans syndrome (BOS). Community-acquired respiratory viruses may be associated with the development of acute rejection and BOS.

Treatment of respiratory syncytial virus pneumonia in a lung transplant recipient: case report and review of the literature

A 61-year-old woman who underwent lung transplantation developed severe respiratory syncytial virus (RSV) pneumonia and experienced respiratory failure requiring mechanical ventilation. She was treated initially with aerosolized ribavirin monotherapy; RSV hyperimmune globulin was later added to her regimen. Lung transplant recipients are acutely susceptible to respiratory infections, including community-acquired respiratory viruses. Respiratory syncytial virus is particularly difficult to treat in immunocompromised patients because of the lack of proved pharmaceutical agents and solid scientific evidence by which to guide therapy. The most important factor appears to be the early start of therapy; immunocompromised patients who develop RSV pneumonia and subsequent respiratory failure requiring mechanical ventilation have a mortality rate approaching 100%. This case report demonstrates the successful treatment of RSV pneumonia with the combination of aerosolized ribavirin and RSV hyperimmune globulin in a severely ill lung transplant recipient who required mechanical ventilation.

Development of a quantitative TaqMan RT-PCR for respiratory syncytial virus

Respiratory syncytial virus (RSV) is a ubiquitous RNA virus of the family Paramyxoviridae that may interfere with graft tolerance and with other interstitial lung diseases. The low viral titre observed in the immunodeficient transplanted patients requires a highly sensitive detection method. Although different tests already exist for the detection of RSV, reverse transcription-polymerase chain reaction (RT-PCR) has been shown to have the best sensitivity. In this study, a SYBR Green assay was established for the detection of RSV A and RSV B in a common screening test, and two quantitative TaqMan RT-PCRs were developed to quantify both RSV subgroups separately. Standard dilutions obtained from RSV cell infections were included in each test, and the assay was normalised using a housekeeping gene. RSV was found in 16% of the transplanted patients tested. The quantitative TaqMan assay is fast, reproducible, specific and very sensitive, and could facilitate considerably the detection of RSV virus. This would in-turn facilitate studies on the role of RSV in graft rejection.

Infectious complications in pediatric solid organ transplantation

Transplantation has emerged as one of the remarkable achievements of the latter half of the twentieth century for treatment of many end-stage organ disorders. Survival in pediatric solid organ transplantation continues to improve as strategies for immunosuppression, prevention and treatment of infectious complications progress. This article presents the summaries of the common and opportunistic pathogens that cause infectious complications for the pediatric transplant recipient. In addition, an approach to the pediatric transplant patient who presents with specific symptoms suggestive of infection is provided.

Respiratory virus infections in the immunocompromised host

The number of immunocompromised children in the population is increasing for a variety of reasons. Common respiratory viruses acquired in the community or in the hospital setting include the ortho- and paramyxoviruses and may cause severe lower respiratory tract disease in these children. Measles is again becoming a threat. Particularly in transplant patients, Herpes group viruses and adenoviruses, often part of a reactivation illness, can cause potentially life-threatening disease. The use of rapid molecular diagnostic techniques and an increasing array of antiviral therapies can help ensure a good outcome in many cases, although controlled clinical trial data are often lacking. Immunotherapeutic strategies using specific antibodies or cytotoxic T cells are being developed and are likely to have an increasing role in prophylaxis and pre-emptive therapy in the future. The development and introduction of vaccines against common respiratory diseases will help reduce the risks faced by these susceptible children.