Indirect fluorescent antibody testing of nasopharyngeal swabs for influenza diagnosis in lung transplant recipients

Viral infections in lung transplantation

Viral infections account for up to 30% of all infectious complications in lung transplant recipients, remaining a significant cause of morbidity and even mortality. Impact of viral infections is not only due to the direct effects of viral replication, but also to immunologically-mediated lung injury that may lead to acute rejection and chronic lung allograft dysfunction. This has particularly been seen in infections caused by herpesviruses and respiratory viruses. The implementation of universal preventive measures against cytomegalovirus (CMV) and influenza (by means of antiviral prophylaxis and vaccination, respectively) and administration of early antiviral treatment have reduced the burden of these diseases and potentially their role in affecting allograft outcomes. New antivirals against CMV for prophylaxis and for treatment of antiviral-resistant CMV infection are currently being evaluated in transplant recipients, and may continue to improve the management of CMV in lung transplant recipients. However, new therapeutic and preventive strategies are highly needed for other viruses such as respiratory syncytial virus (RSV) or parainfluenza virus (PIV), including new antivirals and vaccines. This is particularly important in the advent of the COVID-19 pandemic, for which several unanswered questions remain, in particular on the best antiviral and immunomodulatory regimen for decreasing mortality specifically in lung transplant recipients. In conclusion, the appropriate management of viral complications after transplantation remain an essential step to continue improving survival and quality of life of lung transplant recipients.

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.

A Mini-Review of Adverse Lung Transplant Outcomes Associated With Respiratory Viruses

Due to their overall immunocompromised state, lung transplant recipients (LTRs) are at increased risk for the development of viral respiratory infections compared to the general population. Such respiratory infections often lead to poor transplant outcomes. We performed a systematic review of the last 30 years of medical literature to summarize the impact of specific respiratory viruses on LTRs. After screening 2,150 articles for potential inclusion, 39 manuscripts were chosen for final review. We found evidence for an association of respiratory viruses including respiratory syncytial virus (RSV), parainfluenza virus, and influenza viruses with increased morbidity following transplant. Through the literature search, we also documented associations of RSV and adenovirus infections with increased mortality among LTRs. We posit that the medical literature supports aggressive surveillance for respiratory viruses among this population.

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.

Human metapneumovirus in lung transplant recipients and comparison to respiratory syncytial virus

RATIONALE

Human metapneumovirus is a newly described virus isolated in 2001 from children with acute respiratory viral infection. It has subsequently been reported globally, although there are limited data in lung transplant recipients.

OBJECTIVES

To prospectively analyze whether human metapneumovirus was circulating in our adult lung transplant community and assess the morbidity of this infection and to compare the clinical presentation and outcome after intravenous ribavirin of human metapneumovirus with that of respiratory syncytial virus (RSV).

METHODS

Lung transplant patients with clinical features of respiratory viral infection underwent nasopharyngeal aspirates. Patients with a positive specimen for RSV or human metapneumovirus by reverse transcriptase-polymerase chain reaction analysis and graft dysfunction received intravenous ribavirin and pulse steroid therapy.

MEASUREMENTS AND MAIN RESULTS

Eighty-nine patients had 199 visits for aspirate studies. A viral cause was determined for 62 visits in 47 patients (19 human metapneumovirus, 18 RSV, 13 parainfluenza, 9 influenza A, 2 adenovirus, and 1 influenza B). A significant percentage of patients with metapneumovirus (63%) and RSV (72%) developed graft dysfunction, with average declines in FEV(1) of 30 +/- 12.4% and 25.9 +/- 11.2%, respectively. In these patients, bronchiolitis obliterans syndrome onset or progression occurred in no patients with human metapneumovirus compared with 5 of 13 (38%) patients with RSV at 6 months.

CONCLUSIONS

Human metapneumovirus is a leading cause of acute respiratory tract illness in lung transplant recipients. The incidence and clinical spectrum at presentation are similar to RSV, although the latter seems to be associated with a higher risk of chronic rejection. We recommend testing of nasopharyngeal aspirates for human metapneumovirus with polymerase chain reaction to assess local epidemiologic patterns.

Severity of lymphocytic bronchiolitis predicts long-term outcome after lung transplantation

RATIONALE

Severe and recurrent acute vascular rejection of the pulmonary allograft is an accepted major risk factor for obliterative bronchiolitis.

OBJECTIVES

We assessed the role of lymphocytic bronchiolitis as a risk factor for bronchiolitis obliterans syndrome (BOS) and death after lung transplantation.

METHODS

Retrospective analysis of 341 90-day survivors of lung transplant performed in 1995-2005 who underwent 1,770 transbronchial lung biopsy procedures.

MEASUREMENTS AND MAIN RESULTS

Transbronchial biopsies showed grade B0 (normal) (n = 501), B1 (minimal) (n = 762), B2 (mild) (n = 176), B3 (moderate) (n = 70), B4 (severe) (n = 4) lymphocytic bronchiolitis, and Bx (no bronchiolar tissue) (n = 75). A total of 182 transbronchial biopsies were ungraded (8 inadequate, 142 cytomegalovirus, 32 other diagnoses). Lung transplant recipients were grouped by highest B grade before diagnosis of BOS: B0 (n = 12), B1 (n = 166), B2 (n = 89), and B3-B4 (n = 51). Twenty-three were unclassifiable. Cumulative incidence of BOS and death were dependent on highest B grade (Kaplan-Meier, P < 0.001, log-rank). Multivariable Cox proportional hazards analysis showed significant risks for BOS were highest B grade (relative risk [RR], 1.62; 95% confidence interval [CI], 1.31-2.00) (P < 0.001), longer ischemic time (RR, 1.00; CI, 1.00-1.00) (P < 0.05), and recent year of transplant (RR, 0.93; CI, 0.87-1.00) (P < 0.05), whereas risks for death were BOS as a time-dependent covariable (RR, 19.10; CI, 11.07-32.96) (P < 0.001) and highest B grade (RR, 1.36; CI, 1.07-1.72) (P < 0.05). Acute vascular rejection was not a significant risk factor in either model.

CONCLUSIONS

Severity of lymphocytic bronchiolitis is associated with increased risk of BOS and death after lung transplantation independent of acute vascular rejection.

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.

Community acquired respiratory viral infections after lung transplantation: clinical features and long-term consequences

Community acquired respiratory viruses (CARVs) are increasingly recognized as serious threats to lung transplant recipients. While CARVs such as respiratory syncytial virus, parainfluenza, influenza, and adenovirus usually cause self-limited illnesses in immunocompetent subjects, infections in the transplant recipient can be dramatic. As transplant recipients live longer and diagnostic methods improve, the burden of CARVs will undoubtedly increase. Because of limited therapeutic options, some patients may succumb to CARV infections, while many survivors develop chronic allograft dysfunction. Recognition of this latter phenomenon has implicated CARVs in the pathogenesis of bronchiolitis obliterans.