Influenza pneumonia in lung transplant recipients: clinical features and association with bronchiolitis obliterans syndrome

JAK-STAT activation contributes to cytotoxic T cell-mediated basal cell death in human chronic lung allograft dysfunction

Chronic lung allograft dysfunction (CLAD) is the leading cause of death in lung transplant recipients. CLAD is characterized clinically by a persistent decline in pulmonary function and histologically by the development of airway-centered fibrosis known as bronchiolitis obliterans. There are no approved therapies to treat CLAD, and the mechanisms underlying its development remain poorly understood. We performed single-cell RNA-Seq and spatial transcriptomic analysis of explanted tissues from human lung recipients with CLAD, and we performed independent validation studies to identify an important role of Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling in airway epithelial cells that contributes to airway-specific alloimmune injury. Specifically, we established that activation of JAK-STAT signaling leads to upregulation of major histocompatibility complex 1 (MHC-I) in airway basal cells, an important airway epithelial progenitor population, which leads to cytotoxic T cell-mediated basal cell death. This study provides mechanistic insight into the cell-to-cell interactions driving airway-centric alloimmune injury in CLAD, suggesting a potentially novel therapeutic strategy for CLAD prevention or treatment.

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.

Influenza Virus Infection and Transplantation

Influenza infection poses significant risk for solid organ transplant recipients who often experience more severe infection with increased rates of complications, including those relating to the allograft. Although symptoms of influenza experienced by transplant recipients are similar to that of the general population, fever is not a ubiquitous symptom and lymphopenia is common. Annual inactivated influenza vaccine is recommended for all transplant recipients. Newer strategies such as using a higher dose vaccine or multiple doses in the same season appear to provide greater immunogenicity. Neuraminidase inhibitors are the mainstay of treatment and chemoprophylaxis although resistance may occur in the transplant setting. Influenza therapeutics are advancing, including the recent licensure of baloxavir; however, many remain to be evaluated in transplant recipients and are not yet in routine clinical use. Further population-based studies spanning multiple influenza seasons are needed to enhance our understanding of influenza epidemiology in solid organ transplant recipients. Specific assessment of newer influenza therapeutics in transplant recipients and refinement of prevention strategies are vital to reducing morbidity and mortality.

Infection prophylaxis and management of viral infection

Viral infections are associated with significant morbidity and mortality in lung transplant recipients. Importantly, several viral infections have been associated with the development of chronic lung allograft dysfunction (CLAD). Community-acquired respiratory viruses (CARV) such as influenza and respiratory syncytial virus (RSV), are frequently associated with acute and chronic rejection. Cytomegalovirus (CMV) remains a significant burden in regards to morbidity and mortality in lung transplant recipients. Epstein-Barr virus (EBV) is mostly involved with the development of post-transplant lymphoproliferative disorder (PTLD), a lymphoid proliferation that occurs in the setting of immunosuppression. On the other hand, the development of direct acting antivirals for hepatitis C virus (HCV) is changing the use of HCV-positive organs in transplantation. In this article we will focus on reviewing common viral infections that have a significant impact on lung transplant recipients looking at epidemiology, prevention and potential treatment.

Community-acquired respiratory viruses in solid organ transplant

PURPOSE OF REVIEW

Respiratory viruses are common in solid organ transplant (SOT) recipients and recognized as a significant cause of mortality and morbidity. This review examines the literature on influenza and noninfluenza viruses in the SOT recipient.

RECENT FINDINGS

Advances in immunosuppression and antimicrobial prophylaxis have led to improved patient and graft survival, yet respiratory viruses continue to be a common cause of disease in this population. Influenza viruses have received top priority regarding prevention and treatment, whereas advances in molecular diagnostic tests detecting an array of other respiratory viruses have expanded our knowledge about the epidemiology and impact of these viruses in both the general population and SOT patients. Effective treatment and prevention for noninfluenza respiratory viruses are only emerging.

SUMMARY

Respiratory viruses can contribute to a wide array of symptoms in SOT, particularly in lung transplant recipients. The clinical manifestations, diagnosis, and treatment options for influenza and noninfluenza viruses in SOT patients are reviewed. PCR and related molecular techniques represent the most sensitive diagnostic modalities for detection of respiratory viruses. Early therapy is associated with improved outcomes. Newer classes of antivirals and antibodies are under continuous development for many of these community acquired respiratory viruses.

Use of oseltamivir in lung transplant recipients with suspected or proven influenza infection: a 1-year observational study of outcomes and safety

BACKGROUND

Influenza virus infections in lung transplant recipients (LTRs) have an increased risk of unfavourable outcomes. Early initiation of treatment is associated with improved outcomes. In clinical practice, empirical oseltamivir treatment is therefore commonly started prior to diagnostic microbiological confirmation. There is limited data on the patient characteristics, outcomes and safety of this practice. This study investigated outcomes and safety of this pre-emptive treatment strategy using oseltamivir.

METHODS

Descriptive analysis of LTRs who received oseltamivir for ≥2 days for suspected influenza infection between July 2011 and June 2012. Analyses were based on data from electronic medical records and our standardized LTR database with prospective documentation of clinical information including medication, laboratory and radiological results, outcomes and adverse events.

RESULTS

We included 133 patients with a total of 261 oseltamivir treatment episodes (87.4% as outpatients). Median duration of oseltamivir treatment was 4 days (range 2 to 67) and 98.5% had concomitant antibiotic pharmacotherapy. Indications for oseltamivir included acute respiratory infection (66.7%), non-distinctive inflammatory reaction (51.3%) and influenza-like illness (2.7%). Influenza virus infection was confirmed by PCR in only 7%. Rhinovirus was the most frequent pathogen detected (14.9%). We discovered a wide range of adverse events but none occurred in >5%, and most were mild and of questionable causal relationship to oseltamivir administration.

CONCLUSIONS

This non-controlled retrospective analysis suggests that the pre-emptive use of oseltamivir for respiratory tract infections pending microbiological results is safe in LTRs.

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.

Pathology of Lung Rejection: Cellular and Humoral Mediated

Acute rejection is an important risk factor for bronchiolitis obliterans syndrome, the clinical manifestation of chronic airway rejection in lung allograft recipients. Patients with acute rejection might be asymptomatic or present with symptoms that are not specific and can be also seen in other conditions. Clinical tests such as pulmonary function tests and imaging studies among others usually are abnormal; however, their results are also not specific for acute rejection. Histopathologic features of acute rejection in adequate samples of transbronchial lung biopsy of the lung allograft are currently the gold standard to assess for acute rejection in lung transplant recipients. Acute alloreactive injury can affect both the vasculature and the airways. Currently, the guidelines of the 2007 International Society of Heart and Lung Transplantation consensus conference are recommended for the histopathologic assessment of rejection. There are no specific morphologic features recognized to diagnose antibody-mediated rejection (AMR) in lung allografts. Therefore, the diagnosis of AMR currently requires a “triple test” including clinical features, serologic evidence of donor-specific antibodies, and pathologic findings supportive of AMR. Complement 4d deposition is used to support a diagnosis of AMR in many solid organ transplants; however, its significance for the diagnosis of AMR in lung allografts is not entirely clear. This chapter discusses the currently recommended guidelines for the assessment of cellular rejection of lung allografts and summarizes our knowledge about morphologic features and immunophenotypic tests that might help in the diagnosis of AMR.

A severe Mycoplasma pneumoniae pneumonia inducing an acute antibody-mediated pulmonary graft rejection

A 40-year-old cystic fibrosis woman with a history of double-lung transplantation 2 years previously was admitted for a progressive respiratory distress. Physical examination revealed fever (39°C) and diffuse bilateral lung crackles. Laboratory findings included severe hypoxemia and inflammatory syndrome. Bronchoalveolar lavage and serological test were positive for mycoplasma pneumonia. As the patient did not improve after 3 days of antibiotics and donor-specific HLA antibodies had been detected, an acute antibody-mediated graft rejection was treated with high-dose corticosteroids, plasma exchange, intravenous immunoglobulin, and rituximab. The patient rapidly improved. Unfortunately, 6 months after this episode, she developed a bronchiolitis obliterans syndrome with a dependence to noninvasive ventilator leading to the indication of retransplantation. This case illustrates the possible relationship between infection and humoral rejection. These two diagnoses should be promptly investigated and systematically treated in lung transplant recipients.

Randomized Controlled Trial of Adjuvanted Versus Nonadjuvanted Influenza Vaccine in Kidney Transplant Recipients

BACKGROUND

Influenza vaccine containing an oil-in-water emulsion adjuvant (MF-59) may lead to greater immunogenicity in organ transplant recipients. However, alloimmunization may be a concern with adjuvanted vaccines.

METHODS

We conducted a randomized trial comparing the safety and immunogenicity of adjuvanted versus nonadjuvanted influenza vaccine in adult kidney transplant patients. Patients were randomized 1:1 to receive 2012 to 2013 influenza vaccine with or without MF59 adjuvant. Preimmunization and postimmunization sera underwent strain-specific hemagglutination inhibition assay. HLA alloantibody was determined by Luminex single-antigen bead assay.

RESULTS

We randomized 68 patients and 60 (29 nonadjuvanted; 31 adjuvanted) had complete samples available at follow-up. Seroconversion to at least 1 of 3 influenza antigens was present in 71.0% versus 55.2% in adjuvanted versus nonadjuvanted vaccine respectively (P = 0.21). Geometric mean titers and seroprotection rates were similar between groups. Seroconversion rates were especially low in those on MMF of 2 g or greater daily (44.4% vs 71.4%; P = 0.047). In the subgroup of patients 18 to 64 years old, seroconversion was significantly greater with adjuvanted vaccine (odds ratio, 6.10; 95% confidence interval, 1.25-28.6). There were no increases in HLA alloantibodies in patients who received adjuvanted vaccine.

CONCLUSIONS

Adjuvanted vaccine was safe and had similar immunogenicity to standard vaccine in the overall transplant cohort but did show a potential immunogenicity benefit for the 18 to 64 years age group.

Critical Care Aspects of Lung Transplant Patients

Major strides have been made in lung transplantation during the 1990s and it has become an established treatment option for patients with advanced lung disease. Due to improvements in organ preservation, surgical techniques, postoperative intensive care, and immunosuppression, the risk of perioperative and early mortality (less than 3 months after transplantation) has declined [1]. The transplant recipient now has a greater chance of realizing the benefits of the long and arduous waiting period.

Despite these improvements, suboptimal long-term outcomes continue to be shaped by issues such as opportunistic infections and chronic rejection. Because of the wider use of lung transplantation and the longer life span of recipients, intensivists and ancillary intensive care unit (ICU) staff should be well versed with the care of lung transplant recipients.

In this clinical review, issues related to organ donation will be briefly mentioned. The remaining focus will be on the critical care aspects of lung transplant recipients in the posttransplant period, particularly ICU management of frequently encountered conditions. First, the groups of patients undergoing transplantation and the types of procedures performed will be outlined. Specific issues directly related to the allograft, including early graft dysfunction from ischemia-reperfusion injury, airway anastomotic complications, and infections in the setting of immunosuppression will be emphasized. Finally nonpulmonary aspects of posttransplant care and key pharmacologic points in the ICU will be covered.

Infectious Triggers of Chronic Lung Allograft Dysfunction

Survival after lung transplantation is limited in large part due to the high incidence of chronic rejection, known as chronic lung allograft dysfunction (CLAD). Pulmonary infections are a frequent complication in lung transplant recipients, due both to immunosuppressive medications and constant exposure of the lung allograft to the external environment via the airways. Infection is a recognized risk factor for the development of CLAD, and both acute infection and chronic lung allograft colonization with microorganisms increase the risk for CLAD. Acute infection by community acquired respiratory viruses, and the bacteria Pseudomonas aeruginosa and Staphylococcus aureus are increasingly recognized as important risk factors for CLAD. Colonization by the fungus Aspergillus may also augment the risk of CLAD. Fostering this transition from healthy lung to CLAD in each of these infectious episodes is the persistence of an inflammatory lung allograft environment.

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.

The lung microbiome after lung transplantation

Lung transplantation survival remains significantly impacted by infections and the development of chronic rejection manifesting as bronchiolitis obliterans syndrome (BOS). Traditional microbiologic data has provided insight into the role of infections in BOS. Now, new non-culture-based techniques have been developed to characterize the entire population of microbes resident on the surfaces of the body, also known as the human microbiome. Early studies have identified that lung transplant patients have a different lung microbiome and have demonstrated the important finding that the transplant lung microbiome changes over time. Furthermore, both unique bacterial populations and longitudinal changes in the lung microbiome have now been suggested to play a role in the development of BOS. In the future, this technology will need to be combined with functional assays and assessment of the immune responses in the lung to help further explain the microbiome's role in the failing lung allograft.

Efficacy and safety of a booster dose of influenza vaccination in solid organ transplant recipients, TRANSGRIPE 1-2: study protocol for a multicenter, randomized, controlled clinical trial

BACKGROUND

Despite administration of annual influenza vaccination, influenza-associated complications in transplant recipients continue to be an important cause of hospitalization and death. Although influenza vaccination has been proven to be the most effective measure to reduce influenza infection after transplantation, transplant recipients are still vulnerable to influenza infections, with lower serological responses to vaccination compared to the general population. In order to assess the efficacy and safety of an alternative immunization scheme for solid organ transplant recipients, the TRANSGRIPE1-2 Study Group aimed to test a booster dose administration 5 weeks after the standard vaccination. The primary objective of this trial was to compare short-term and long-term neutralizing antibody immunogenicity of a booster dose of influenza vaccination to the standard single-dose immunization scheme. Secondary objectives included the evaluation of the efficacy and/or safety, cellular immune response, incidence of influenza infection, graft rejection, retransplant and mortality rates.

METHODS/DESIGN

This phase III, randomized, controlled, open-label clinical trial was conducted between October 2012 and December 2013 in 12 Spanish public referral hospitals. Solid organ transplant recipients (liver, kidney, heart or lung), older than 16 years of age more than 30 days after transplantation were eligible to participate. Patients (N = 514) were stratified 1:1 by center, type of organ and time after transplantation and who either received the standard single dose (n = 257) or were treated according to a novel influenza vaccination schedule comprising the administration of a booster dose 5 weeks after standard vaccination (n = 254). Seroconversion rates were measured as a determinant of protection against influenza (main outcome). Efficacy and safety outcomes were followed until 1 year after influenza vaccination with assessment of short-term (0, 5, 10 and 15 weeks) and long-term (12 months) results. Intention-to-treat, per-protocol and safety analyses will be performed.

DISCUSSION

This trial will increase knowledge about the safety and efficacy of a booster dose of influenza vaccine in solid organ transplant recipients. At the time the manuscript was submitted for publication, trial recruitment was closed with a total of 499 participants included during a 2-month period (within the seasonal influenza vaccination campaign).

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01761435 (registered 13 December 2012). EudraCT Identifier: 2011-003243-21 (registered 4 July 2011).

Influenza vaccination in immunocompromised patients: efficacy and safety

Yearly administration of the influenza vaccine is the main strategy to prevent influenza in immunocompromised patients. Here, we reviewed the recent literature regarding the clinical significance of the influenza virus infection, as well as the immunogenicity and safety of the influenza vaccine in HIV‑infected individuals, solid-organ and stem-cell transplant recipients and patients receiving biological agents. Epidemiological data produced during the 2009 influenza pandemic have confirmed that immunocompromised patients remain at high risk of influenza-associated complications, namely viral and bacterial pneumonia, hospitalization and even death. The immunogenicity of the influenza vaccine is overall reduced in immunocompromised patients, although a significant clinical protection from influenza is expected to be obtained with vaccination. Influenza vaccination is safe in immunocompromised patients. The efficacy of novel strategies to improve the immunogenicity to the vaccine, such as the use of adjuvanted vaccines, boosting doses and intradermal vaccination, needs to be validated in appropriately powered clinical trials.

The impact of influenza A(H1N1)pdm09 infection on immunosuppressed patients

Before the advent of the influenza A(H1N1)pdm virus in 2009, the information available about the clinical manifestations and prognosis of influenza in immunosuppressed patients was scarce. With the 2009 pandemic, knowledge of the behavior, severity and importance of antiviral therapy for influenza A infection in immunocompromised hosts has increased considerably. The aim of the present manuscript is to review the main challenges of influenza in the most representative immunosuppressed populations such as solid organ transplant recipients, hematopoietic stem cell transplant recipients, patients with solid and hematological cancer and human immunodeficiency virus infected patients.

The natural history of influenza infection in the severely immunocompromised vs nonimmunocompromised hosts

Introduction. Medical advances have led to an increase in the world's population of immunosuppressed individuals. The most severely immunocompromised patients are those who have been diagnosed with a hematologic malignancy, solid organ tumor, or who have other conditions that require immunosuppressive therapies and/or solid organ or stem cell transplants.

Materials and methods. Medically attended patients with a positive clinical diagnosis of influenza were recruited prospectively and clinically evaluated. Nasal washes and serum were collected. Evaluation of viral shedding, nasal and serum cytokines, clinical illness, and clinical outcomes were performed to compare severely immunocompromised individuals to nonimmunocompromised individuals with influenza infection.

Results. Immunocompromised patients with influenza had more severe disease/complications, longer viral shedding, and more antiviral resistance while demonstrating less clinical symptoms and signs on clinical assessment.

Conclusions. Immunocompromised patients are at risk for more severe or complicated influenza induced disease, which may be difficult to prevent with existing vaccines and antiviral treatments. Specific issues to consider when managing a severely immunocompromised host include the development of asymptomatic shedding, multi-drug resistance during prolonged antiviral therapy, and the potential high risk of pulmonary involvement.

Clinical trials registration, ClinicalTrials.gov identifier NCT00533182.

Vaccination against Streptococcus pneumoniae does not induce antibodies against HLA or MICA in clinically stable kidney transplant recipients

There are concerns in the community that immune activation after vaccination could lead to (subclinical) rejection. Our aim was to define if pneumococcal vaccination induced HLA antibodies using highly sensitive methods. Forty-nine kidney transplant recipients were immunized with Pneumovax 23. The median interval between transplantation and vaccination was 6.5 years, the median serum creatinine concentration 1.3, 1.3 and 1.4 mg/dL pre-vaccination, at month 1 and 15 post-vaccination, respectively. In none of the patients biopsy-proven acute rejection was diagnosed within three years post-vaccination. Pneumococcal, HLA class I and II and major histocompatibility class I-related chain A (MICA) antibodies were determined by Luminex™ technology (xMAP™ Pneumococcal Immunity Panel and LABScreen™ Mixed beads, respectively) and HLA antibodies also by ELISA (Lambda Antigen Tray™). While pneumococcal antibodies were significantly higher at month 1 and 15 post- vs. pre-vaccination (p<0.0001 each), HLA/MICA antibodies remained unchanged as determined by Luminex™ and ELISA. Positive Luminex™ reactions were present in 63%, 67% and 63% (HLA class I), 47%, 47% and 55% (HLA class II) and 29%, 29% and 29% (MICA) pre-vaccination, at month 1 and 15, respectively. In clinically stable kidney transplant recipients there is no evidence for an increase in HLA antibodies after pneumococcal vaccination.

Lung transplant infection

Lung transplantation has become an accepted therapeutic procedure for the treatment of end‐stage pulmonary parenchymal and vascular disease. Despite improved survival rates over the decades, lung transplant recipients have lower survival rates than other solid organ transplant recipients. The morbidity and mortality following lung transplantation is largely due to infection‐ and rejection‐related complications. This article will review the common infections that develop in the lung transplant recipient, including the general risk factors for infection in this population, and the most frequent bacterial, viral, fungal and other less frequent opportunistic infections. The epidemiology, diagnosis, prophylaxis, treatment and outcomes for the different microbial pathogens will be reviewed. The effects of infection on lung transplant rejection will also be discussed.

Significance of and risk factors for the development of central airway stenosis after lung transplantation

Central airways stenosis (CAS) after lung transplant is a poorly understood complication. Objectives of this study were to determine if CAS was associated with chronic rejection or worse survival after transplant as well as to identify factors associated with CAS in a large cohort of lung transplant recipients. Lung transplant recipients transplanted at a single center were retrospectively reviewed for the development of CAS requiring airway dilation. A total of 467 subjects met inclusion criteria with 60 (13%) of these developing CAS requiring intervention. Of these 60 recipients, 22 (37%) had resolution of CAS with bronchoplasty alone, while 32 (53%) ultimately required stent placement. CAS that required intervention was not a risk factor for the development of bronchiolitis obliterans syndrome or worse overall survival. Significant risk factors for the subsequent development of CAS in a time-dependant multivariable model were pulmonary fungal infections and the need for postoperative tracheostomy. While CAS was not associated with BOS or worse survival, it remains an important complication after lung transplant with potentially preventable risk factors.

Efficacy and safety of oral oseltamivir for influenza prophylaxis in transplant recipients

BACKGROUND

Haematopoietic stem cell transplant (HSCT) and solid organ transplant (SOT) recipients are at high risk for severe influenza and its complications, and may not be adequately protected by vaccination.

METHODS

Liver, kidney, or liver-kidney transplant or allogeneic HSCT recipients aged ≥1 year were randomized to oseltamivir (75 mg once daily for those ≥13 years or weight-based dosing for children 1-12 years) or placebo for 12 weeks during periods of local influenza circulation. Patients were assessed for influenza infection via daily diary, every-other-week culture and PCR, and baseline and end-of-treatment serology.

RESULTS

A total of 477 subjects were enrolled (239 oseltamivir and 238 placebo); most were adults (96%) and SOT recipients (81%). In the intent-to-treat population, the frequency of laboratory-confirmed clinical influenza (culture positive and/or >4-fold increase in haemagglutinin antibody inhibition [primary end point]) was similar in the oseltamivir and placebo groups (2.1% [5/237] and 2.9% [7/238]). Incidence of laboratory-confirmed influenza was significantly reduced in the oseltamivir group versus placebo when determined by reverse transcriptase-PCR (1.7% [4/237] versus 8.4% [20/238]; 95% CI 2.8, 11.1) or viral culture (<1% [1/237] versus 3.8% [9/238]; 95% CI 0.7, 6.6), giving protective efficacies of 79.9 and 88.8%, respectively. Serious adverse events (oseltamivir 8% and placebo 10%) and adverse events (oseltamivir 55% and placebo 58%) were reported in both arms with a similar frequency. One illness due to oseltamivir-resistant A/H1N1 virus was detected in each group.

CONCLUSIONS

Oseltamivir prophylaxis is generally well-tolerated and may reduce culture- or PCR-confirmed influenza incidence in transplant recipients.

Respiratory viral infections post-lung transplantation

Community-acquired respiratory viruses (CARVs) are common pathogens in lung transplant recipients. Infection due to these viruses is associated with multiple complications including: rhinitis, pharyngitis, bronchitis, pneumonia, respiratory failure and even death. CARVs have also become increasingly recognized as a risk factor for acute rejection (AR) and bronchiolitis obliterans syndrome (BOS). Newer diagnostic techniques have enhanced the accuracy of diagnosis, but proven treatment options for CARVs are limited. Further insight into the immune response and allograft dysfunction associated with CARV infections is needed in order to develop novel management strategies which can reduce the morbidity and mortality caused by these infectious agents.

Novel influenza (H1N1) infection in pediatric renal transplant recipients: a single center experience

In 2009, novel influenza A H1N1 caused significant morbidity and mortality worldwide, particularly in children. Because they are immunocompromised, pediatric transplant recipients are presumed to be at high risk. This study assessed epidemiological characteristics, presenting symptoms, and clinical course among pediatric renal transplant recipients with confirmed H1N1 infection. A retrospective review was conducted in renal transplant recipients followed at The Hospital for Sick Children (Toronto) who contracted H1N1 infection between June and November, 2009. Epidemiological, clinical, and laboratory features at presentation, and clinical course were analyzed. Of 59 children, 14 (23.7%) developed H1N1 infection. Children with H1N1 infection had undergone kidney transplantation more recently than their uninfected counterparts. The most common symptoms included fever (92.9%), cough (85.7%), headache (42.9%), and vomiting (42.9%). Fifty percent of patients required hospitalization, of median duration 3.0 (1.0-5.0) days. No child required intensive care treatment. Half the H1N1-infected children had acute renal dysfunction, with serum creatinine elevated >10% above basal values (median increase 21.6 [14.3-46.2]%). In five of the seven children, serum creatinine returned to baseline within two wk. These findings indicate that H1N1 influenza infection in pediatric kidney transplant recipients followed at our center was surprisingly mild, and produced no lasting sequelae.

Pandemic influenza A(H1N1) virus infection in solid organ transplant recipients: impact of viral and non-viral co-infection

Solid organ transplant recipients (SOTR) are at risk of serious influenza-related complications. The impact of respiratory co-infection in SOTR with 2009 pandemic influenza A(H1N1) is unknown. A multicentre prospective study of consecutive cases of pandemic influenza A(H1N1) in SOTR was carried out to assess the clinical characteristics and outcome and the risk factors for co-infection. Overall, 51 patients were included. Median time from transplant was 3.7 years, 5.9% of the cases occurred perioperatively and 7.8% were hospital-acquired. Pneumonia was diagnosed in 15 (29.4%) patients. Ten cases were severe (19.6%): 13.7% were admitted to intensive care units, 5.9% suffered septic shock, 5.9% developed acute graft rejection and 7.8% died. Co-infection was detected in 15 patients (29.4%): eight viral, six bacterial and one fungal. Viral co-infection did not affect the outcome. Patients with non-viral co-infection had a worse outcome: longer hospital stay (26.2 ± 20.7 vs. 5.5 ± 10.2) and higher rate of severe diseases (85.7% vs. 2.3%) and mortality (42.8% vs. 2.3%). Independent risk factors for non-viral co-infection were: diabetes mellitus and septic shock. Other factors associated with severe influenza were: delayed antiviral therapy, diabetes mellitus, time since transplantation <90 days and pneumonia. In conclusion, pandemic influenza A can cause significant direct and indirect effects in SOTR, especially in the early post-transplant period, and should be treated early. Clinicians should be aware of the possibility of non-viral co-infection, mainly in diabetic patients and severe cases. An effort should be made to prevent influenza with immunization of the patient and the environment.

Management of viral infections in solid organ transplant recipients

Management of viral infections after transplantation involves antiviral drug therapy (if available) and reduction in immunosuppression, which allows for development of pathogen-specific immunity to the offending virus. Prevention of viral infections is of the utmost importance, and this may be accomplished through vaccination, antiviral strategies and infection control measures. This article discusses the current management of selected viral pathogens that cause clinical illness in solid organ transplant recipients. The benefits and toxicities of antiviral therapies are discussed in the context of prevention and treatment of various viral diseases. The emerging issue of antiviral resistance is emphasized for cytomegalovirus, recurrent hepatitis B and influenza, while the importance of immunominimization is discussed in the management of BK nephropathy and virus-associated malignancies.

Fundoplication after lung transplantation prevents the allograft dysfunction associated with reflux

BACKGROUND

Gastroesophageal reflux disease (GERD) in lung recipients is associated with decreased survival and attenuated allograft function. This study evaluates fundoplication in preventing GERD-related allograft dysfunction.

METHODS

Prospectively collected data on patients who underwent transplantation between January 2001 and August 2009 were included. Lung transplant candidates underwent esophageal pH probe testing before transplantation and surveillance spirometry evaluation after transplantation. Bilateral lung transplant recipients who had pretransplant pH probe testing and posttransplant 1-year forced expiratory volume in the first second of expiration (FEV1) data were included for analysis.

RESULTS

Of 297 patients who met study criteria, 222 (75%) had an abnormal pH probe study before or early after transplantation and 157 (53%) had a fundoplication performed within the first year after transplantation. Patients with total proximal acid contact times greater than 1.2% or total distal acid contact times greater than 7.0% demonstrated an absolute decrease of 9.4% (±4.6) or 12.0% (±5.4) in their respective mean 1-year FEV1 values. Patients with abnormal acid contact times who did not undergo fundoplication had considerably worse predicted peak and 1-year FEV1 results compared with recipients receiving fundoplication (peak percent predicted=75% vs. 84%; p=0.004 and 1-year percent predicted=68% vs. 77%; p=0.003, respectively).

CONCLUSIONS

Lung transplant recipients with abnormal esophageal pH studies attain a lower peak allograft function as well as a diminished 1-year FEV1 after transplantation. However a strategy of early fundoplication in these recipients appears to preserve lung allograft function.

Influenza vaccination in the organ transplant recipient: review and summary recommendations

Influenza virus causes a spectrum of illness in transplant recipients with a high rate of lower respiratory disease. Seasonal influenza vaccination is an important public health measure recommended for transplant recipients and their close contacts. Vaccine has been shown to be safe and generally well tolerated in both adult and pediatric transplant recipients. However, responses to vaccine are variable and are dependent on various factors including time from transplantation and specific immunosuppressive medication. Seasonal influenza vaccine has demonstrated safety and no conclusive evidence exists for a link between vaccination and allograft dysfunction. Annually updated trivalent inactivated influenza vaccines have been available and routinely used for several decades, although newer influenza vaccination formulations including high-dose vaccine, adjuvanted vaccine, quadrivalent inactivated vaccine and vaccine by intradermal delivery system are now available or will be available in the near future. Safety and immunogenicity data of these new formulations in transplant recipients requires investigation. In this document, we review the current state of knowledge on influenza vaccines in transplant recipients and make recommendations on the use of vaccine in both adult and pediatric organ transplant recipients.

[H1N1 (2009) influenza A infection in transplant recipient patients: a comparative study versus non-transplanted patients]

OBJECTIVE

To compare H1N1 (2009) influenza A infection characteristics between transplant recipient patients and non-transplanted patients. To assess the evolution of transplanted patients up to 6 months following infection.

METHODS

Patients diagnosed with confirmed influenza A infection from three Parisian transplant centers between September 1st, 2009 and February 15th, 2010. Clinical symptoms, biological, and radiological findings, and management were analysed and retrospectively compared between transplanted (T) and non-transplanted patients (NT). The evolution was assessed by a follow-up questionnaire, CT results 1 to 3 months after influenza infection and FEV1 variation.

RESULTS

Seventy patients were included. Thirteen patients had an allograft (lung: eight, kidney: four, stem cells: one): (1) hospitalization: 100% (13 out of 13) in group T, 54% (31 out of 57) in group NT (P=0.0013); (2) pneumonia: 62% (eight out of 13) in group T, 26% (eight out of 57) in group NT (P=0.004); (3) mortality rate among hospitalized patients: 7.7% (one out of 13) in the group T, 9.7% (three out of 57) in group NT (P=NS); (4) chest CT scan abnormalities remained in four lung transplanted patients; (5) a minimum 10% decrease in FEV1 was detected in four lung transplant recipients.

CONCLUSION

Our results suggest that H1N1(2009) influenza A infection in transplant recipient patients compared to non-transplanted patients: (1) more often leads to hospitalization; (2) is more frequently associated with pneumonia; (3) is responsible for a persistent graft functional impairment in lung transplant recipients; (4) has a low mortality rate similar to admitted non-transplanted patients.

[Lung transplantation and rejection. Basic principles, clinical aspects and histomorphology]

Lung transplantation is the ultimate therapeutical approach for the treatment of both children and adults with terminal congenital or acquired lung disease. In contrast to survival rates during the first year following transplantation, the long-term survival for patients after lung transplantation has not significantly improved in the past. In addition to other complications, acute cellular rejection constitutes a major cause for diminished function of pulmonary grafts, and can, among other factors, be causative for chronic rejection (bronchiolitis obliterans syndrome, BOS). In 2006, the International Society for Heart and Lung Transplantation (ISHLT) provided a revised version of the grading system for acute and chronic rejection of pulmonary grafts.

Respiratory viral infections in hematopoietic stem cell and solid organ transplant recipients

Respiratory viral infections (RVIs) are common causes of mild illness in immunocompetent children and adults with rare occurrences of significant morbidity or mortality. Complications are more common in the very young, very old, and those with underlying lung diseases. However, RVIs are increasingly recognized as a cause of morbidity and mortality in recipients of hematopoietic stem cell transplants (HSCT) and solid organ transplants (SOTs). Diagnostic techniques for respiratory syncytial virus (RSV), parainfluenza, influenza, and adenovirus have been clinically available for decades, and these infections are known to cause serious disease in transplant recipients. Modern molecular technology has now made it possible to detect other RVIs including human metapneumovirus, coronavirus, and bocavirus, and the role of these viruses in causing serious disease in transplant recipients is still being worked out. This article reviews the current information regarding epidemiology, pathogenesis, clinical presentation, diagnosis, and treatment of these infections, as well as the aspects of clinical significance of RVIs unique to HSCT or SOT.

Respiratory viruses in lung transplant recipients: a critical review and pooled analysis of clinical studies

Lung transplant recipients present an increased risk for severe complications associated with respiratory infections. We conducted a review of the literature examining the clinical relationship between viral respiratory infection and graft complications. Thirty-four studies describing the clinical impact of influenza, respiratory syncytial virus, parainfluenza, human metapneumovirus, rhinovirus, enterovirus, coronavirus, bocavirus or adenovirus were identified. The detection rate of respiratory viral infection ranged from 1.4% to 60%. Viruses were detected five times more frequently when respiratory symptoms were present [odds ratio (OR) = 4.97; 95% CI = 2.11-11.68]. Based on available observations, we could not observe an association between respiratory viral infection and acute rejection (OR = 1.35; 95% CI = 0.41-4.43). We found a pooled incidence of 18% (9/50) of bronchiolitis obliterans syndrome (BOS) in virus-positive cases compared to 11.6% (37/319) in virus-negative cases; however, limited number of BOS events did not allow to confirm the association. Our review confirms a causal relationship between respiratory viruses and respiratory symptoms, but cannot confirm a link between respiratory viruses and acute lung rejection. This is related in part to the heterogeneity and limitations of available studies. The link with BOS needs also to be reassessed in appropriate prospective studies.

The impact of pandemic influenza A H1N1 2009 on Australian lung transplant recipients

Influenza A H1N1 2009 led to 189 deaths during the Australian pandemic. Community-acquired respiratory viruses not only can cause prolonged allograft dysfunction in lung transplant recipients but have also been linked to bronchiolitis obliterans syndrome (BOS). We report the impact of the 2009 H1N1 pandemic on Australian lung transplant recipients. An observational study of confirmed H1N1 cases was conducted across five Australian lung transplant programs during the pandemic. An electronic database collected patient demographics, clinical presentation, management and outcomes up to a year follow-up. Twenty-four H1N1 cases (mean age 43 ± 14 years, eight females) were identified, incidence of 3%. Illness severity varied from upper respiratory tract symptoms only in 29% to lung allograft dysfunction (≥10% decline FEV1) in 75% to death in 5 (21%) cases (pre-existing BOS grade 3, n = 4). Treatment with oseltamivir occurred in all but one case confirmed after death, reduced immunosuppression, n = 1, augmented corticosteroid therapy, n = 16, and mechanical/noninvasive ventilation, n = 4. There was BOS grade decline within a year in six cases (32%). In conclusion, Australian lung transplant recipients were variably affected by the H1N1 pandemic mirroring the broader community with significant morbidity and mortality. After initial recovery, a considerable proportion of survivors have demonstrated BOS progression.

Challenges in the diagnosis of 2009 H1N1 in a lung transplant patient and the long-term implications for prevention and treatment: a case report

Although respiratory viral infections have been associated with acute rejection and bronchiolitis obliterans syndrome, the long-term impact of the novel pandemic influenza A (2009 H1N1) virus on lung transplant patients has not been defined. We describe the diagnostic challenges and long-term consequences of 2009 H1N1 infection in a lung transplant patient, discuss the potential implications for prevention and treatment, and conclude that even timely antiviral therapy may be insufficient to prevent long-term morbidity.

Pandemic (H1N1) 2009 infection in adult solid organ transplant recipients in Singapore

BACKGROUND

Influenza can produce significant complications in immunocompromised persons.

METHODS

We studied the effects of the pandemic (H1N1) 2009 (pH1N1) infection on solid organ transplant recipients in our hospital, with emphasis on clinical information, duration of viral culture positivity, polymerase chain reaction positivity, effects of oseltamivir therapy, and graft status at 6 months of follow-up.

RESULTS

Twenty-two cases of pH1N1 infection involving 18 renal, two lung, one heart, and one liver transplant recipients were seen from July 14 to September 8, 2009. Their median age was 50.5 years (range 20-70 years); 64% were women, and median time posttransplant was 40 months (range 6-204 months). Common symptoms were fever (86%), cough (77%), sore throat (55%), phlegm (32%), and myalgia (27%). The median duration of symptoms (n=21) and duration of polymerase chain reaction positivity (n=15) were 7 (range 4-13 days) and 8 days (range 4-16 days), respectively. Mean (± SD) duration of symptom resolution (7.4 ± 3.0 vs. 7.8 ± 3.0 days, P=0.76) and viral culture positivity (5.3 ± 2.8 vs. 4.3 ± 3.2 days, P=0.65) did not differ between those who received a 5-day (n=9) or 10-day (n=12) course of oseltamivir. Five patients (22.7%) developed pneumonia with three needing intensive care. Mortality rate was 4.5% (1/22). At 6 months, three graft rejections involving two renal and one lung developed.

CONCLUSIONS

Our findings indicate that the pH1N1 infection in solid organ transplant recipients is associated with some degree of morbidity and may affect the function of the transplanted organ. In this nonrandomized comparison, patients treated with 5 days of oseltamivir did not fare worse compared with those who received 10 days.

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.

Viral pneumonias in immunocompromised adult hosts

Viral infections have always been considered pediatric diseases. However, viral pneumonia has become an important cause of morbidity and mortality in immuncompromised adults. Improved diagnostic techniques, such as the introduction of highly sensitive nucleic acid amplification tests, have not only allowed us to discover new viruses but also to determine the etiology of viral pneumonia in immunocompromised adult hosts. Unfortunately, only a few antiviral agents are available. Thus, early diagnosis and treatment are crucial to patient outcome. In this article, we review the most common viruses that have been implicated as etiologic agents of viral pneumonia in immunocompromised adults. We discuss the epidemiologic characteristics and clinical presentation of these viral infections and the most appropriate diagnostic approaches and therapies when available.

Long-term impact of respiratory viral infection after pediatric lung transplantation

To evaluate the epidemiology and to investigate the impact of RVI on chronic allograft rejection after pediatric lung transplantation, a retrospective study of pediatric lung transplant recipients from 2002 to 2007 was conducted. Association between RVI and continuous and categorical risk factors was assessed using Wilcoxon rank-sum tests and Fisher's exact tests, respectively. Association between risk factors and outcomes were assessed using Cox proportional hazards models. Fifty-five subjects were followed for a mean of 674 days (range 14-1790). Twenty-eight (51%) developed 51 RVI at a median of 144 days post-transplant (mean 246; range 1-1276); 41% of infections were diagnosed within 90 days. Twenty-five subjects developed 39 LRI, and eight subjects had 11 URI. Organisms recovered included rhinovirus (n = 14), adenovirus (n = 10), parainfluenza (n = 10), influenza (n = 5), and RSV (n = 4). Three subjects expired secondary to their RVI (two adenovirus, one RSV). Younger age and prior CMV infection were risks for RVI (HR 2.4 95% CI 1.1-5.3 and 17.0; 3.0-96.2, respectively). RVI was not associated with the development of chronic allograft rejection (p = 0.25) or death during the study period. RVI occurs in the majority of pediatric lung transplant recipients, but was not associated with mortality or chronic allograft rejection.

Complications of seasonal and pandemic influenza

Influenza is a seasonal viral infection associated with significant morbidity and mortality. In 2009, a novel H1N1 influenza A virus emerged and has been classified as a pandemic. In contrast to seasonal influenza, severe disease from pandemic H1N1 seems concentrated in older children and young adults, with almost no cases reported in patients older than 60 yrs. Although patients with underlying cardiopulmonary disease remain at risk, most complications have occurred among previously healthy individuals, with obesity and respiratory disease as the strongest risk factors. Pulmonary complications are common. Primary influenza pneumonia occurs most commonly in adults and may progress rapidly to acute lung injury requiring mechanical ventilation. Secondary bacterial infection is more common in children. Staphylococcus aureus, including methicillin-resistant strains, is an important cause of secondary bacterial pneumonia with a high mortality rate. Treatment of pneumonia should include empirical coverage for this pathogen. Neuromuscular and cardiac complications are unusual but may occur.