Pneumonia after lung transplantation in the RESITRA Cohort: a multicenter prospective study

The impact and relevance of techniques and fluids on lung injury in machine perfusion of lungs

Primary graft dysfunction (PGD) is a common complication after lung transplantation. A plethora of contributing factors are known and assessment of donor lung function prior to organ retrieval is mandatory for determination of lung quality. Specialized centers increasingly perform ex vivo lung perfusion (EVLP) to further assess lung functionality and improve and extend lung preservation with the aim to increase lung utilization. EVLP can be performed following different protocols. The impact of the individual EVLP parameters on PGD development, organ function and postoperative outcome remains to be fully investigated. The variables relate to the engineering and function of the respective perfusion devices, such as the type of pump used, functional, like ventilation modes or physiological (e.g. perfusion solutions). This review reflects on the individual technical and fluid components relevant to EVLP and their respective impact on inflammatory response and outcome. We discuss key components of EVLP protocols and options for further improvement of EVLP in regard to PGD. This review offers an overview of available options for centers establishing an EVLP program and for researchers looking for ways to adapt existing protocols.

Infections in Heart and Lung Transplant Recipients

Infections in heart and lung transplant recipients are complex and heterogeneous. This article reviews the epidemiology, risk factors, specific clinical syndromes, and most frequent opportunistic infections in heart and/or lung transplant recipients that will be encountered in the intensive care unit and will provide a practical approach of empirical management.

Legionnaires Disease in Solid Organ Transplant Recipients: A Decade-Long Nationwide Study in France

BACKGROUND

Legionnaires disease (LD) is a rare, life-threatening opportunistic bacterial infection that poses a significant risk to patients with impaired cell-mediated immunity such as solid organ transplant recipients. However, the epidemiologic features, clinical presentation, and outcomes of LD in this population are poorly described.

RESEARCH QUESTION

What are the clinical manifestations, radiologic presentation, risk factors for severity, treatment, and outcome of LD in solid organ transplant recipients?

STUDY DESIGN AND METHODS

In this 10-year multicenter retrospective cohort study in France, where LD notification is mandatory, patients were identified by hospital discharge databases. Diagnosis of LD relied on positive culture findings from any respiratory sample, positive urinary antigen test (UAT) results, positive specific serologic findings, or a combination thereof. Severe LD was defined as admission to the ICU.

RESULTS

One hundred one patients from 51 transplantation centers were eligible; 64 patients (63.4%) were kidney transplant recipients. Median time between transplantation and LD was 5.6 years (interquartile range, 1.5-12 years). UAT results were positive in 92% of patients (89/97). Among 31 patients with positive culture findings in respiratory samples, Legionella pneumophila serogroup 1 was identified in 90%. Chest CT imaging showed alveolar consolidation in 98% of patients (54 of 57), ground-glass opacity in 63% of patients (36 of 57), macronodules in 21% of patients (12 of 57), and cavitation in 8.8% of patients (5 of 57). Fifty-seven patients (56%) were hospitalized in the ICU. In multivariate analysis, severe LD was associated with negative UAT findings at presentation (P = .047), lymphopenia (P = .014), respiratory symptoms (P = .010), and pleural effusion (P = .039). The 30-day and 12-month mortality rates were 8% (8 of 101) and 20% (19 of 97), respectively. In multivariate analysis, diabetes mellitus was the only factor associated with 12-month mortality (hazard ratio, 3.2; 95% OR, 1.19-8.64; P = .022).

INTERPRETATION

LD is a late and severe complication occurring in solid organ transplant recipients that may present as pulmonary nodules on which diabetes impacts its long-term prognosis.

Donor respiratory multidrug-resistant bacteria and lung transplantation outcomes

RATIONALE

Respiratory culture screening is mandatory for all potential lung transplant donors. There is limited evidence on the significance of donor multidrug-resistant (MDR) bacteria on transplant outcomes. Establishing the safety of allografts colonized with MDR bacteria has implications for widening an already limited donor pool.

OBJECTIVES

We aimed to describe the prevalence of respiratory MDR bacteria among our donor population and to test for associations with posttransplant outcomes.

METHODS

This retrospective observational study included all adult patients who underwent lung-only transplantation for the first time at King Faisal Specialist Hospital & Research Centre in Riyadh from January 2015 through May 2022. The study evaluated donor bronchoalveolar lavage and bronchial swab cultures.

MAIN RESULTS

Sixty-seven of 181 donors (37%) had respiratory MDR bacteria, most commonly MDR Acinetobacter baumannii (n = 24), methicillin-resistant Staphylococcus aureus (n = 18), MDR Klebsiella pneumoniae (n = 8), MDR Pseudomonas aeruginosa (n = 7), and Stenotrophomonas maltophilia (n = 6). Donor respiratory MDR bacteria were not significantly associated with allograft survival or chronic lung allograft dysfunction (CLAD) in adjusted hazard models. Sensitivity analyses revealed an increased risk for 90-day mortality among recipients of allografts with MDR Klebsiella pneumoniae (n = 6 with strains resistant to a carbapenem and n = 2 resistant to a third-generation cephalosporin only) compared to those receiving culture-negative allografts (25.0% versus 11.1%, p = 0.04). MDR Klebsiella pneumoniae (aHR 3.31, 95%CI 0.95-11.56) and Stenotrophomonas maltophilia (aHR 5.35, 95%CI 1.26-22.77) were associated with an increased risk for CLAD compared to negative cultures.

CONCLUSION

Our data suggest the potential safety of using lung allografts with MDR bacteria in the setting of appropriate prophylaxis; however, caution should be exercised in the case of MDR Klebsiella pneumoniae.

Diaphragm Dysfunction Predicts Weaning Outcome after Bilateral Lung Transplant

BACKGROUND

Diaphragm dysfunction and its effects on outcomes of ventilator weaning have been evaluated in mixed critical care populations using diaphragm thickening fraction (the ratio of the difference between ultrasound diaphragm thickness at end-inspiration and end-expiration to diaphragm thickness at end-expiration) or neuroventilatory efficiency (the ratio of tidal volume and peak electrical activity of the diaphragm). Such data are not available in bilateral-lung transplant recipients. The authors hypothesized that (1) diaphragm dysfunction, as defined by a diaphragm thickening fraction less than 29%, is more likely to occur in difficult weaning; (2) diaphragm thickening fraction and neuroventilatory efficiency predict weaning outcome; and (3) duration of mechanical ventilation before the first spontaneous breathing trial is associated with diaphragm dysfunction.

METHODS

Adult bilateral-lung transplant patients admitted to the intensive care unit were screened at the time of the first spontaneous breathing trial (pressure-support of 5 cm H2O and 0 positive end-expiratory pressure). At the fifth minute, diaphragm thickening fraction and neuroventilatory efficiency were measured during three respiratory cycles. Weaning was classified as simple, difficult, or prolonged (successful extubation at the first spontaneous breathing trial, within three or after three spontaneous breathing trials, respectively).

RESULTS

Forty-four subjects were enrolled. Diaphragm dysfunction occurred in 14 subjects (32%), all of whom had difficult weaning (78% of the subgroup of 18 patients experiencing difficult weaning). Both diaphragm thickening fraction (24 [20 to 29] vs. 39 [35 to 45]%) and neuroventilatory efficiency (34 [26 to 45] vs. 55 [43 to 62] ml/µV) were lower in difficult weaning (both P < 0.001). The areas under the receiver operator curve predicting difficult weaning were 0.88 (95% CI, 0.73 to 0.99) for diaphragm thickening fraction and 0.85 (95% CI, 0.71 to 0.95) for neuroventilatory efficiency. The duration of ventilation demonstrated a linear inverse correlation with both diaphragm thickening fraction and neuroventilatory efficiency.

CONCLUSIONS

Diaphragm dysfunction is common after bilateral-lung transplantation and associated with difficult weaning. In such patients, average values for diaphragm thickening fraction and neuroventilatory efficiency were reduced compared to patients with simple weaning. Both parameters showed similar accuracy for predicting success of ventilator weaning, demonstrating an inverse relationship with duration of ventilation.

EDITOR’S PERSPECTIVE

Antimicrobial Stewardship in Immunocompromised Patients: Current State and Future Opportunities

Immunocompromised (IC) patients are high risk for complications due to a high rate of antibiotic exposure. Antimicrobial stewardship interventions targeted to IC patients can be challenging due to limited data in this population and a high risk of severe infection-related outcomes. Here, the authors review immunocompromised antimicrobial stewardship barriers, metrics, and opportunities for antimicrobial use and testing optimization. Last, the authors highlight future steps in the field.

Ten Issues to Update in Nosocomial or Hospital-Acquired Pneumonia: An Expert Review

Nosocomial pneumonia, or hospital-acquired pneumonia (HAP), and ventilator-associated pneumonia (VAP) are important health problems worldwide, with both being associated with substantial morbidity and mortality. HAP is currently the main cause of death from nosocomial infection in critically ill patients. Although guidelines for the approach to this infection model are widely implemented in international health systems and clinical teams, information continually emerges that generates debate or requires updating in its management. This scientific manuscript, written by a multidisciplinary team of specialists, reviews the most important issues in the approach to this important infectious respiratory syndrome, and it updates various topics, such as a renewed etiological perspective for updating the use of new molecular platforms or imaging techniques, including the microbiological diagnostic stewardship in different clinical settings and using appropriate rapid techniques on invasive respiratory specimens. It also reviews both Intensive Care Unit admission criteria and those of clinical stability to discharge, as well as those of therapeutic failure and rescue treatment options. An update on antibiotic therapy in the context of bacterial multiresistance, in aerosol inhaled treatment options, oxygen therapy, or ventilatory support, is presented. It also analyzes the out-of-hospital management of nosocomial pneumonia requiring complete antibiotic therapy externally on an outpatient basis, as well as the main factors for readmission and an approach to management in the emergency department. Finally, the main strategies for prevention and prophylactic measures, many of them still controversial, on fragile and vulnerable hosts are reviewed.

Association between Hospital-Acquired Pneumonia and In-Hospital Mortality in Solid Organ Transplant Admissions: An Observational Analysis in Spain, 2004-2021

(1) Background: To analyze the association between hospital-acquired pneumonia (HAP) and in-hospital mortality (IHM) during hospital admission for solid organ transplant in Spain during 2004-2021. (2) Methods: We used national hospital discharge data to select all hospital admissions for kidney, liver, heart, and lung transplants. We stratified the data according to HAP status. To examine time trends, we grouped data into three consecutive 6-year periods (2004-2009; 2010-2015; and 2016-2021). We assessed in-hospital mortality (IHM) in logistic regression analyses and obtained odds ratios (ORs) with their 95% confidence intervals (CIs). (3) Results: We identified a total of 71,827 transplants (45,262, kidney; 18,127, liver; 4734, heart; and 4598, lung). Two thirds of the patients were men. Overall, the rate of HAP during admission was 2.6% and decreased from 3.0% during 2004-2009 to 2.4% during 2016-2021. The highest rate of HAP corresponded to lung transplant (9.4%), whereas we found the lowest rate for kidney transplant (1.1%). Rates of HAP for liver and heart transplants were 3.8% and 6.3%, respectively. IHM was significantly lower during 2016-2021 compared to 2004-2009 for all types of transplants (ORs (CIs) = 0.65 (0.53-0.79) for kidney; 0.73 (0.63-0.84) for liver; 0.72 (0.59-0.87) for heart; and 0.39 (0.31-0.47) for lung). HAP was associated with IHM for all types of transplants (ORs (CIs) = 4.47 (2.85-9.08) for kidney; 2.96 (2.34-3.75) for liver; 1.86 (1.34-2.57) for heart; and 2.97 (2.24-3.94) for lung). (4) Conclusions: Rates of HAP during admission for solid organ transplant differ depending on the type of transplant. Although IHM during admission for solid organ transplant has decreased over time in our country, HAP persists and is associated with a higher IHM after accounting for potential confounding variables.

Management of Atrial Arrhythmias After Lung Transplant

The overall survival in patients undergoing lung transplantation is poor. Although postsurgical atrial arrhythmias seem to play a major role in the morbidity and mortality of this population, data regarding the clinical and interventional management of this complication are still controversial. Through a review of the literature in the field, we observed that not only the surgical technique is clearly arrhythmogenic, but the new administration of peri-procedure beta-blockers and amiodarone for arrhythmia prevention and treatment, respectively, seems harmful in these postsurgical patients. However, low-dose beta-blockers administered after surgery seem feasible in arrhythmia prevention in specific patient subgroups, and, aside from amiodarone, alternative antiarrhythmic agents can be safely and effectively used to treat symptomatic patients on top of adequate rate control. Finally, as to complex atrial arrhythmias occurring late after lung transplant surgery, radiofrequency catheter ablation seems a feasible treatment option. In light of this evidence and considering the absence of clear recommendations in the field, we suggest a practical approach that may help the clinician in the management of this postsurgical complication. However, as most of these considerations are drawn from small-sized and retrospective studies, more evidence is needed in the future to clarify which medical and interventional strategies may best treat these postsurgical arrhythmias and thus potentially improve the outcome of these frail patients.

Multidrug-resistant organisms in lung transplant: a narrative review

PURPOSE OF REVIEW

The purpose of this narrative review is presenting the current knowledge of multidrug-resistant (MDR) pathogens in lung transplant recipients, considering both Gram-positive and Gram-negative bacteria.

RECENT FINDINGS

Overall prevalence of Gram-negative pathogens has increased remarkably (4.33/1000 recipient-days) in solid organ transplant recipients, while the prevalence of Gram-positive bacteria seems to be decreasing (0.20 cases/100 transplant-years). In lung transplant, the prevalence of postoperative infections due to MDR-GN bacteria has been assessed between 31 and 57%, and the incidence of carbapenem-resistant Enterobacterales is between 0.4 and 20%, with a related mortality up to 70%. MDR Pseudomonas aeruginosa is common in lung transplant recipients with cystic fibrosis and may contribute to bronchiolitis obliterans syndrome. The prevalence of MDR Gram-positive bacteria is around 30% (predominantly Methicillin-resistant Staphylococcus aureus and Coagulase-negative staphylococcus).

SUMMARY

Survival after lung transplant, although lower than in other SOT, is increasing and currently at 60% at 5 years. This review highlights the potential clinical and social burden of postoperative infections in lung transplant recipients, and confirmed that a PI due to MDR bacteria negatively affects survival. A prompt diagnosis, prevention and management of these MDR pathogens should remain the cornerstone for higher goals of care.

Prediction of mortality in pneumonia patients with connective tissue disease treated with glucocorticoids or/and immunosuppressants by machine learning

Objectives

The assessment of accurate mortality risk is essential for managing pneumonia patients with connective tissue disease (CTD) treated with glucocorticoids or/and immunosuppressants. This study aimed to construct a nomogram for predicting 90-day mortality in pneumonia patients using machine learning.

Methods

Data were obtained from the DRYAD database. Pneumonia patients with CTD were screened. The samples were randomly divided into a training cohort (70%) and a validation cohort (30%). A univariate Cox regression analysis was used to screen for prognostic variables in the training cohort. Prognostic variables were entered into the least absolute shrinkage and selection operator (Lasso) and a random survival forest (RSF) analysis was used to screen important prognostic variables. The overlapping prognostic variables of the two algorithms were entered into the stepwise Cox regression analysis to screen the main prognostic variables and construct a model. Model predictive power was assessed using the C-index, the calibration curve, and the clinical subgroup analysis (age, gender, interstitial lung disease, diabetes mellitus). The clinical benefits of the model were assessed using a decision curve analysis (DCA). Similarly, the C-index was calculated and the calibration curve was plotted to verify the model stability in the validation cohort.

Results

A total of 368 pneumonia patients with CTD (training cohort: 247; validation cohort: 121) treated with glucocorticoids or/and immunosuppressants were included. The univariate Cox regression analysis obtained 19 prognostic variables. Lasso and RSF algorithms obtained eight overlapping variables. The overlapping variables were entered into a stepwise Cox regression to obtain five variables (fever, cyanosis, blood urea nitrogen, ganciclovir treatment, and anti-pseudomonas treatment), and a prognostic model was constructed based on the five variables. The C-index of the construction nomogram of the training cohort was 0.808. The calibration curve, DCA results, and clinical subgroup analysis showed that the model also had good predictive power. Similarly, the C-index of the model in the validation cohort was 0.762 and the calibration curve had good predictive value.

Conclusion

In this study, the nomogram developed performed well in predicting the 90-day risk of death in pneumonia patients with CTD treated with glucocorticoids or/and immunosuppressants.

Trends and Outcomes in Lung Transplantation in Patients with and without Idiopathic Pulmonary Fibrosis in Spain during the Period 2016-2020

(1) Background: This paper aims to assess temporal trends (2016-2020) in incidence, patient's characteristics, complications, length of hospital stay (LOHS) and in-hospital mortality (IHM) among patients with and without idiopathic pulmonary fibrosis (IPF) undergoing lung transplantation (LTx). We also analyse the effect of the COVID-19 pandemic on LTx in these populations. (2) Methods: A retrospective, population-based observational study was conducted using the Spanish National Hospital Discharge Database. Multivariable adjustment was conducted with logistic regression to analyse the IHM. (3) Results: We identified 1777 admissions for LTx during the study period, of which 573 (32.2%) were performed in patients with IPF. The number of hospital admissions for LTx rose from 2016 to 2020, both in patients with and without IPF, but a marked reduction was observed from year 2019 to year 2020. Over time, the proportion of single LTx decreased and bilateral LTx increased significantly in both groups. The incidence of LTx complications increased significantly over time along with the increase in the incidence of IPF. No significant differences in the incidence of complications or in the IHM between patients with and without IPF were found. Suffering any complication of the LTx and pulmonary hypertension were conditions positively associated with IHM in patients with and without IPF. The IHM remained stable from 2016 to 2020 in both study populations and was not affected by the COVID pandemic. (4) Conclusions: Patients with IPF account for almost a third of all lung transplants. The number of LTx increased over time in patients with and without IPF, but a marked reduction was observed from 2019 to 2020. Although the proportion of LTx complications increased significantly over time in both groups, the IHM did not change. IPF was not associated with increased complications or IHM after LTx.

Correlation analysis of the peripheral blood lymphocyte count and occurrence of pneumonia after lung transplantation

BACKGROUND

Infections are the most common complication in patients after lung transplantation and the main cause of death at all stages after transplantation; therefore, awareness regarding the occurrence of infectious pneumonia after lung transplantation is vital. This study aimed to explore the correlation between the absolute lymphocyte and T-lymphocyte subpopulation counts in the peripheral blood and the occurrence of pneumonia after lung transplantation and to predict the risk of pneumonia development after lung transplantation.

MATERIALS

Patients who underwent lung transplantation with long-term follow-up between June 2018 and December 2021 were prospectively included. The patients were divided into pneumonia and non-pneumonia groups. Demographic and clinical characteristics, and the levels of leukocytes, neutrophils, platelets, C-reactive protein (CRP), procalcitonin (PCT), serum albumin, peripheral blood T lymphocytes, and CD4+ and CD8+ T cells in the peripheral blood were measured in both groups.

RESULTS

We included 22 patients with post-lung transplants in the analysis. Of the 104 collected samples, 26 (56.5%) were pathogenically positive, 16 (61.5%) had bacterial infections, 7 samples (26.9%) had fungal infections, and 8 (30.8%) had viral infections. Patients with pneumonia had higher levels of peripheral blood neutrophils (P = 0.01), platelets (P = 0.03), and CRP (P < 0.001) than did those without pneumonia. Logistic regression analysis showed that the levels of peripheral blood neutrophils, total T lymphocytes, CRP, and PCT were associated with the development of pneumonia after transplantation (P < 0.05), as documented by their area under the curve (AUC) values of 0.702, 0.792, 0.899, and 0.789, respectively. The AUC for the combined receiver operating characteristic curve for predicting the development of pneumonia was 0.943, with a sensitivity of 91.3% and specificity of 93.1%. There was no significant difference in T-lymphocyte counts in patients with lung transplants between the pneumonia and non-pneumonia groups who were treated with two anti-rejection agents. In contrast, the absolute lymphocyte, total T-lymphocyte, and CD4+ and CD8+ T-cell counts in patients who developed pneumonia after treatment with three anti-rejection agents were lower than those in patients who did not develop pneumonia (P < 0.05).

CONCLUSION

Bacterial pneumonia is more common after lung transplantation than after fungal or viral infections. Peripheral blood T-lymphocyte counts combined with neutrophil, CRP, and PCT levels had good predictive value for the development of pneumonia after lung transplantation. Monitoring of patients should be strengthened by implementing peripheral blood T-lymphocyte counts to improve the early identification and prevention of pneumonia after lung transplantation.

Analysis of Donor to Recipient Pathogen Transmission in Relation to Cold Ischemic Time and Other Selected Aspects of Lung Transplantation-Single Center Experience

BACKGROUND

Infections are one of the leading causes of death in the early postoperative period after lung transplantation (LuTx).

METHODS

We analyzed 59 transplantations and culture results of the donor bronchial aspirates (DBA), graft endobronchial swabs (GES), and recipient cultures (RC) before and after the procedure (RBA). We correlated the results with a cold ischemic time (CIT), recipient intubation time, and length of stay in the hospital and intensive care unit (ICU), among others.

RESULTS

CIT of the first and second lungs were 403 and 541 min, respectively. Forty-two and eighty-three percent of cultures were positive in DBA and GES, respectively. Furthermore, positive results were obtained in 79.7% of RC and in 33.9% of RBA. Longer donor hospitalization was correlated with Gram-negative bacteria isolation in DBA. Longer CIT was associated with Gram-positive bacteria other than Staphylococcus aureus in GES and it resulted in longer recipient stay in the ICU. Furthermore, longer CIT resulted in the development of the new pathogens in RBA.

CONCLUSION

Results of GES brought more clinically relevant information than DBA. Donor hospitalization was associated with the occurrence of Gram-negative bacteria. Positive cultures of DBA, GES, and RBA were not associated with recipient death.

Microbiological and Clinical Outcomes of Methicillin-Susceptible Staphylococcus aureus Isolated in Lung Transplant Perioperative Donor and Recipient Respiratory Cultures

Staphylococcus aureus is one of the most common organisms isolated from respiratory secretions in lung transplant donors and recipients perioperatively. Within the first 90 days after lung transplantation, methicillin-susceptible Staphylococcus aureus (MSSA) infections have been associated with increased mortality and acute and chronic rejection. However, it is unclear whether respiratory cultures positive for MSSA at the time of transplantation can lead to clinically significant infection. The aim of this study was to assess the microbiological and clinical outcomes for lung transplant recipients (LTRs) with positive perioperative donor or/and recipient respiratory cultures for MSSA. A retrospective study was conducted evaluating MSSA-positive respiratory cultures at the time of lung transplantation from donors and/or recipients from January 1, 2008, to December 30, 2019. Patients who did not have a bronchoalveolar lavage at 2 weeks after the lung transplant or died within 2 weeks of lung transplant were excluded. The main outcome was MSSA eradication at 2-week bronchoscopy. Recipients were evaluated for MSSA infections at the 12-week period after the transplant. Of the 1,678 individuals who underwent lung transplantation, 218 LTRs had S. aureus isolated in perioperative donor or recipient respiratory cultures, and 29 were subsequently excluded. Of the remaining 189 LTRs, MSSA eradication at the 2-week bronchoscopy was achieved in 186 (98.4%) recipients. During the 12-week follow-up, 15 (7.9%) recipients were diagnosed with MSSA pneumonia; concurrent MSSA bacteremia was noted in one recipient. No anastomotic infection, empyema, or lung abscess related to MSSA was diagnosed during the follow-up period.In LTRs, the rate of MSSA eradication at 2-week post-transplant recipients is high, and it is associated with a low rate of infectious complication within the first 12 weeks after transplant. Most of the recipients received a combination therapy with at least one agent active against MSSA. More studies to evaluate the optimal antimicrobial stewardship policies regarding the regimen and duration of antibiotic therapy for these patients are needed.

Prognostic impact of preoperative respiratory colonization on early-onset pneumonia after lung transplantation

Background

The number of lung transplantation procedures is rapidly increasing worldwide. Little is known about the effect of perioperative respiratory microbial colonization on pneumonia during lung transplantation. We evaluated the microbiome composition and incidence of early pneumonia in patients undergoing lung transplantation. We investigated factors related to post-transplant pneumonia (PTP) after lung transplantation.

Methods

A retrospective analysis of patients subjected to lung transplantation between May 2013 and December 2019 was performed. Perioperative microbial colonization, and its relationship with early pneumonia, were examined in specimens from bronchial washing, bronchoalveolar lavage, and sputum aspiration before and after surgery. One-year mortality, as the primary outcome, was analyzed using the Kaplan-Meier curve model.

Results

Among 76 patients who underwent lung transplantation, 34 donors (44.7%) and 28 recipients (36.8%) showed positive respiratory cultures with respect to preoperative respiratory colonization. A separate analysis of donors and recipients showed that 42 donors and 48 recipients were in respiratory non-colonized state, and 28 (53.8%) donors and 36 (69.2%) recipients survived 1 year after lung transplantation. Acinectobacter baumannii was the most common respiratory multidrug-resistant (MDR) pathogen. PTP was significantly lower in the survivor group (38.5% vs. 70.8%, P=0.009). Out of the recipients with preoperative respiratory colonization, 57.1% survived 1 year after lung transplantation. Patients with PTP had significantly higher 1-year mortality than those without PTP (P=0.009). Preoperative respiratory colonization of the recipients (P=0.010) and PTP patients (P=0.005) was associated with high 1-year mortality rate. Perioperative respiratory colonization of donors was not associated with the incidence of PTP and 1-year survival.

Conclusions

Perioperative colonization of recipients was a powerful predictive factor for PTP, which was associated with 1-year mortality in patients subjected to lung transplantation. Our results suggest that donor acceptance criteria may change to better address potential shortages in organ donation.

Cell-free DNA in lung transplantation: research tool or clinical workhorse?

PURPOSE OF REVIEW

Recent evidence indicates that plasma donor-derived cell-free DNA (dd-cfDNA) is a sensitive biomarker for the detection of underlying allograft injury, including rejection and infection. In this review, we will cover the latest evidence revolving around dd-cfDNA in lung transplantation and its role in both advancing mechanistic insight into disease states in lung transplant recipients as well as its potential clinical utility.

RECENT FINDINGS

Plasma dd-cfDNA increases in the setting of allograft injury, including in primary graft dysfunction, acute cellular rejection, antibody-mediated rejection and infection. Dd-cfDNA has demonstrated good performance characteristics for the detection of various allograft injury states, most notably with a high negative-predictive value for detection of acute rejection. Elevated levels of dd-cfDNA in the early posttransplant period, reflecting molecular evidence of lung allograft injury, are associated with increased risk of chronic lung allograft dysfunction and death.

SUMMARY

As a quantitative, molecular biomarker of lung allograft injury, dd-cfDNA holds great promise in clinical and research settings for advancing methods of posttransplant surveillance monitoring, diagnosis of allograft injury states, monitoring adequacy of immunosuppression, risk stratification and unlocking pathophysiological mechanisms of various disease.

Secondary Prophylaxis With Inhaled Colistin to Prevent Recurrence of Pseudomonas aeruginosa and Extended-spectrum β-lactamase-producing Enterobacterales Pneumonia in ICU After Lung Transplantation: A Before-and-after Retrospective Cohort Analysis

BACKGROUND

Early pneumonia is an independent risk factor for 1-y mortality after lung transplantation (LTx). Pseudomonas aeruginosa is the most common isolate in early pneumonia and is also associated with an increased risk of chronic lung allograft dysfunction. The aim of our study was to evaluate the efficacy of secondary prophylaxis with inhaled colistin (IC) in preventing the recurrence of P aeruginosa or extended-spectrum β-lactamase-producing Enterobacterales (ESBL-PE) pneumonia in the postoperative period in the intensive care unit after LTx.

METHODS

We conducted a before-and-after retrospective cohort study by including all patients who underwent LTx between January 2015 and December 2020 in our center. Secondary prophylaxis with IC was instituted in January 2018 (observation period from January 2015 to December 2017, intervention period from January 2018 to December 2020).

RESULTS

A total of 271 lung transplants were included (125 in the observation period and 146 in the intervention period). The patients were predominately male (64.2%) with a median age of 57 y and received double LTx (67.9%) for chronic obstructive pulmonary disease/emphysema (36.2%) or interstitial lung disease (48.3%). The proportion of patients who experienced at least 1 recurrence of P aeruginosa or ESBL-PE pneumonia was significantly lower in the intervention period than in the observation period (0.7% versus 7.2%, P = 0.007).

CONCLUSIONS

Our study suggests a potential benefit of secondary prophylaxis with IC to prevent the recurrence of P aeruginosa or ESBL-PE pneumonia in the intensive care unit after LTx.

Bronchial Culture Growth From the Donor and Recipient as Predictive Factors in the Detection of Primary Graft Dysfunction and Pneumonia After Lung Transplant

OBJECTIVES

In this study, our aim was to investigate whether bacterial culture growth from donors and recipients is related to early posttransplant complications and to analyze its role in primary graft dysfunction and posttransplant pneumonia in lung transplant recipients.

MATERIALS AND METHODS

This retrospective cohort study included patients diagnosed with end-stage lung disease who received a lung transplant for treatment. We examined relationships between donor bronchial lavage, pretransplant recipient sputum, and recipient posttransplant serial bronchial lavage culture results, as well as the development of both primary graft dysfunction and pneumonia after lung transplant during the early posttransplant period.

RESULTS

Our study included 77 patients with median age of 48 years (25%-75% IQR, 34-56 years) and who were mostly men (79.2%; n = 61). Donor culture positivity was 62.3% (n = 48), and the positivity of sputum culture from patients before transplant was 20.8% (n = 16). Compared with that shown in those without versus those with primary graft dysfunction, there were significantly more positive sputum cultures from patients before transplant (P = .003). Recipients with donor culture growth had a longer duration of invasive mechanical ventilation (median of 4 days [IQR, 2-13 days] vs 1 day [IQR, 1-2 days]; P = .001, respectively) than those without. Multivariate logistic analysis identified both donor culture positivity (odds ratio: 3.391; 95% CI, 1.12-20.46; P = .0028) and sputum culture positivity in pretransplant recipient candidates (odds ratio: 6.494; 95% CI, 1.80-36.27; P = .004) as independent predictors of primary graft dysfunction.

CONCLUSIONS

Bacterial growth shown in donor bronchial lavage and sputum culture positivity in patients before transplant were found to be independent predictors of primary graft dysfunction in the early posttransplant period. Organism growth in both the donor and the recipient during the pretransplant period are important determinants for the development of primary graft dysfunction.

Optimization of Early Antimicrobial Strategies for Lung Transplant Recipients Based on Metagenomic Next-Generation Sequencing

The management of perioperative antibiotic options after lung transplantation varies widely around the world, but there is a common trend to limit antibiotic use duration. Metagenomic next-generation sequencing (mNGS) has become a hot spot in clinical pathogen detection due to its precise, rapid, and wide detection spectrum of pathogens. Thus, we defined a new antibiotic regimen adjustment strategy in the very early stage (within 7 days) after lung transplantation mainly depending on mNGS reports combined with clinical conditions to reduce the use of antibiotics. To verify the clinical effect of the strategy, we carried out this research. Thirty patients who underwent lung transplantation were finally included, whose information including etiology, antibiotic adjustment, and the effect of our strategy was recorded. Lung transplant recipients in this study were prescribed with initial antibiotic regimen immediately after surgery; their antibiotic regimens were adjusted according to the strategy. According to our study, the entire effectiveness of the strategy was 90.0% (27/30). Besides, a total of 86 samples containing donor lung tissue, recipient lung tissue, and bronchoalveolar lavage fluid (BALF) were obtained in this study; they were all sent to mNGS test, while BALF was also sent to pathogen culture. Their results showed that the positive rate of BALF samples was higher (86.67%) than that of donor’s lung tissue (20.0%) or recipient’s lung tissue (13.33%) by mNGS test, indicating BALF samples are more valuable than other clinical samples from early postoperative period to guide the early adjustment of antibiotics after lung transplantation. It is effective for mNGS combined with traditional methods and clinical situations to optimize antibiotic regimens in lung transplantation recipients within 7 days after surgery.

Multidrug-resistant infections in solid organ transplant recipients: a focus on risk factors, prevention and treatment strategies

Solid organ transplantation is the best therapeutic option for patients with end-stage organ disease and, according to the data from international registries, there has been a steady increase in numbers and results. However, post-transplant infections remain a fearsome complication with, in the last decade, an increasing incidence of episodes due to antibiotic-resistant bacteria and opportunistic agents. In this paper, we summarize the most relevant and updated knowledge concerning infections from multidrug-resistant germs in solid organ transplant recipients, focusing on risk factors, treatment and prevention strategies, and antimicrobial pharmacokinetics relevant to this particular population of patients.

Bacterial infections in lung transplantation

Lung transplantation has lower survival rates compared to other than other solid organ transplants (SOT) due to higher rates of infection and rejection-related complications, and bacterial infections (BI) are the most frequent infectious complications. Excess morbidity and mortality are not only a direct consequence of these BI, but so are subsequent loss of allograft tolerance, rejection, and chronic lung allograft dysfunction due to bronchiolitis obliterans syndrome (BOS). A wide variety of pathogens can cause infections in lung transplant recipients (LTRs), including a number of nosocomial pathogens and other multidrug-resistant (MDR) pathogens. Although pneumonia and intrathoracic infections predominate, LTRs are at risk of a number of types of infections. Risk factors include altered anatomy and function of airways, impaired immunity, the microbial flora of the donor and recipient, underlying medical conditions, and genetic factors. Further work on immune monitoring has the potential to improve outcomes. The infecting agents can be derived from the donor lung, pre-existing recipient flora, or acquired from the environment over time. Certain infections may preclude lung transplantation, but this varies from center to center, and more recent studies suggest fewer patients should be disqualified. New molecular methods allow microbiome studies of the lung, gut, and other sites that may further our knowledge of how airway colonization can result in infection and allograft loss. Surveillance, early diagnosis, and aggressive antimicrobial therapy of BI is critical in LTRs. Antibiotic resistance is a major barrier to successful management of these infections. The availability of new agents for MDR Gram-negatives may improve outcomes. Other new therapies, such as bacteriophage therapy, show promise for the future. Finally, it is important to prevent infections through peri-transplant prophylaxis, vaccination, and infection control measures.

Outcomes with alemtuzumab induction therapy in lung transplantation: a comprehensive large-scale single-center analysis

Alemtuzumab is a monoclonal antibody targeting CD52, increasingly used as induction therapy after transplantation. The aim of this study was to analyze the outcomes of alemtuzumab induction therapy followed by a low-dose maintenance immunosuppression in a large single-center cohort of lung transplant recipients. All patients, who received alemtuzumab induction followed by a low-dose maintenance immunosuppression were included in the analysis. Short- and long-term outcomes were analyzed. 721 lung transplant recipients, transplanted between January 2008 and June 2019, were included in this retrospective study. Freedom from higher-grade ACR at 1, 5, and 10 years was 98%, 96%, and 96%, respectively. Thirty-nine patients (5%) developed clinical AMR. Twenty-one percent of patients developed high-grade CKD. A total of 1488 infections were recorded. Sixteen percent were diagnosed within the first 3 months. Sixty-two patients (9%) developed a malignancy during follow-up. Freedom from CLAD at 1, 5, and 10 years was 94%, 72%, and 53%, respectively. Overall survival rates at 1, 5, and 10 years were 85%, 71%, and 61%, respectively. Alemtuzumab induction combined with a low-dose tacrolimus protocol is safe and associated with low rates of acute and chronic rejection, as well as an excellent long-term survival.

Chest Infections after Lung Transplantation

Despite substantial progress in the long-term follow-up strategies for lung transplant recipients, morbidity and mortality remain high mostly due to the elevated infectious risk and to the development of chronic lung allograft dysfunction. The high immunosuppressive levels necessary to prevent acute rejection and the graft's constant exposure to the environment come at the high price of frequent infectious complications. Moreover, some infectious agents have been shown to trigger acute rejection or chronic allograft dysfunction. A rapid diagnostic approach followed by an early treatment and follow-up strategy are of paramount importance. They are, however, challenging endeavors due to the vast spectrum of possible pathogens and to the discrete clinical features as a consequence of transplant recipients' impaired immune response. This review proposes a stratified diagnostic strategy, discusses the most relevant pathogens and the corresponding therapeutic approaches while also offering an insight in the infection prevention strategies: vaccination, prophylaxis, preemptive therapy, antibiotic stewardship.

Complications of Lung Transplantation: Update on Imaging Manifestations and Management

As lung transplantation has become the most effective definitive treatment option for end-stage chronic respiratory diseases, yearly rates of this surgery have been steadily increasing. Despite improvement in surgical techniques and medical management of transplant recipients, complications from lung transplantation are a major cause of morbidity and mortality. Some of these complications can be classified on the basis of the time they typically occur after lung transplantation, while others may occur at any time. Imaging studies, in conjunction with clinical and laboratory evaluation, are key components in diagnosing and monitoring these conditions. Therefore, radiologists play a critical role in recognizing and communicating findings suggestive of lung transplantation complications. A description of imaging features of the most common lung transplantation complications, including surgical, medical, immunologic, and infectious complications, as well as an update on their management, will be reviewed here. Keywords: Pulmonary, Thorax, Surgery, Transplantation Supplemental material is available for this article. © RSNA, 2021.

Lung Transplantation in COPD

Chronic obstructive pulmonary disease (COPD) remains one of the leading causes of morbidity and mortality both in the United States and worldwide. Despite advances in medical treatment including smoking cessation, bronchodilator therapy, oxygen administration, and pulmonary rehabilitation, patients with advanced COPD still suffer significant debility. For select patients with severe COPD, there are additional surgical options including lung volume reduction surgery and ultimately lung transplantation.This article discusses the history, clinical indications, selection of candidates, choice of procedure, and outcomes of lung transplantation in patients with advanced COPD. In addition, certain aspects of potential short- and long-term complications of transplantation will also be discussed.

Burden and Timeline of Infectious Diseases in the First Year After Solid Organ Transplantation in the Swiss Transplant Cohort Study

Background

The burden and timeline of posttransplant infections are not comprehensively documented in the current era of immunosuppression and prophylaxis.

Methods

In this prospective study nested within the Swiss Transplant Cohort Study (STCS), all clinically relevant infections were identified by transplant–infectious diseases physicians in persons receiving solid organ transplant (SOT) between May 2008 and December 2014 with ≥12 months of follow-up.

Results

Among 3541 SOT recipients, 2761 (1612 kidney, 577 liver, 286 lung, 213 heart, and 73 kidney-pancreas) had ≥12 months of follow-up; 1520 patients (55%) suffered 3520 infections during the first year posttransplantation. Burden and timelines of clinically relevant infections differed between transplantations. Bacteria were responsible for 2202 infections (63%) prevailing throughout the year, with a predominance of Enterobacteriaceae (54%) as urinary pathogens in heart, lung, and kidney transplant recipients, and as digestive tract pathogens in liver transplant recipients. Enterococcus spp (20%) occurred as urinary tract pathogens in kidney transplant recipients and as digestive tract pathogens in liver transplant recipients, and Pseudomonas aeruginosa (9%) in lung transplant recipients. Among 1039 viral infections, herpesviruses predominated (51%) in kidney, liver, and heart transplant recipients. Among 263 fungal infections, Candida spp (60%) prevailed as digestive tract pathogens in liver transplant recipients. Opportunistic pathogens, including Aspergillus fumigatus (1.4%) and cytomegalovirus (6%), were rare, scattering over 12 months across all SOT recipients.

Conclusions

In the current era of immunosuppression and prophylaxis, SOT recipients experience a high burden of infections throughout the first year posttransplantation, with rare opportunistic pathogens and a predominance of bacteria.

Divergent airway microbiomes in lung transplant recipients with or without pulmonary infection

BACKGROUND

Lung transplant (LTx) recipients are at increased risk for airway infections, but the cause of infection is often difficult to establish with traditional culture-based techniques. The objectives of the study was to compare the airway microbiome in LTx patients with and without ongoing airway infection and identify differences in their microbiome composition.

METHODS

LTx recipients were prospectively followed with bronchoalveolar lavage (BAL) during the first year after transplantation. The likelihood of airway infection at the time of sampling was graded based on clinical criteria and BAL cultures, and BAL fluid levels of the inflammatory markers heparin-binding protein (HBP), IL-1β and IL-8 were determined with ELISA. The bacterial microbiome of the samples were analysed with 16S rDNA sequencing and characterized based on richness and evenness. The distance in microbiome composition between samples were determined using Bray-Curtis and weighted and unweighted UniFrac.

RESULTS

A total of 46 samples from 22 patients were included in the study. Samples collected during infection and samples with high levels of inflammation were characterized by loss of bacterial diversity and a significantly different species composition. Burkholderia, Corynebacterium and Staphylococcus were enriched during infection and inflammation, whereas anaerobes and normal oropharyngeal flora were less abundant. The most common findings in BAL cultures, including Pseudomonas aeruginosa, were not enriched during infection.

CONCLUSION

This study gives important insights into the dynamics of the airway microbiome of LTx recipients, and suggests that lung infections are associated with a disruption in the homeostasis of the microbiome.

Infectious complications during immunochemotherapy of post-transplantation lymphoproliferative disease–can we decrease the risk? Two case reports and review of literature

BACKGROUND

Post-transplant lymphoproliferative disease (PTLD) is a heterogeneous group of diseases that develop after solid organ and hematopoietic stem cells transplantation related to intensive immunosuppression regimen, T-cell depletion and Epstein-Barr virus infection. Despite the improvement in the management of PTLD, the prognosis remains poor. Here we report the management of two transplanted patients with PTLD and infections during immunochemotherapy (ICTH).

CASE SUMMARY

Of 65-year-old woman 11 years after kidney transplantation (first case) presented with diffuse large B-cell lymphoma (DLBCL) CS III and started ICHT according to R-CHOP protocol. Despite the secondary prevention of neutropenic fever, the patient developed grade 4 neutropenia with urinary and pulmonary tract infections after the fifth cycle. ICTH was continued in reduced doses up to 7 cycles followed by involved-field radiation therapy of the residual disease. The second case presents a 49-year-old man, 8 years after liver transplantation due to cirrhosis in the course of chronic hepatitis B, who started ICTH for DLBCL Burkitt-like CS IV. The patient received four cycles of ICTH according to R-CODOX/R-IVAC protocol, with reduced doses. In both cases initially undertaken reduction of immunosuppression was ineffective to prevent infectious complications. Despite one incomplete ICHT treatment due to recurrent infections, both our patients remain in complete remission.

CONCLUSION

Reduction of immunosuppression and the doses of chemotherapeutics may be insufficient to prevent infectious complications during ICTH in PTLD patients.

Effects of Multidrug-resistant Bacteria in Donor Lower Respiratory Tract on Early Posttransplant Pneumonia in Lung Transplant Recipients Without Pretransplant Infection

BACKGROUND

Multidrug-resistant (MDR) bacteria in the lower respiratory tracts of allografts may be risk factors for early posttransplant pneumonia (PTP) that causes detrimental outcomes in lung transplant recipients (LTRs). We evaluated the effects of immediate changes in MDR bacteria in allografts on early PTP and mortality rates in LTRs.

METHODS

We reviewed 90 adult bilateral LTRs without pretransplant infections who underwent lung transplantation between October 2012 and May 2018. Quantitative cultures were performed with the bronchoalveolar lavage fluids of the allografts preanastomosis and within 3 days posttransplant. The International Society for Heart and Lung Transplantation consensus defines early PTP as pneumonia acquired within 30 days posttransplant and not associated with acute rejection.

RESULTS

MDR Acinetobacter baumannii (11/34, 32.4%) and Staphylococcus aureus (9/34, 26.5%) were identified in 24.4% (22/90) of the preanastomosis allografts. Four LTRs had the same MDR bacteria in allografts preanastomosis and posttransplant. Allograft MDR bacteria disappeared in 50% of the LTRs within 3 days posttransplant. Early PTP and all-cause in-hospital mortality rates were not different between LTRs with and without preanastomosis MDR bacteria (P = 0.75 and 0.93, respectively). MDR bacteria ≥10 CFU/mL in the lungs within 3 days posttransplant was associated with early PTP (odds ratio, 5.8; 95% confidence interval, 1.3-27.0; P = 0.03).

CONCLUSIONS

High levels of preexisting MDR bacteria in allografts did not increase early PTP and mortality rates in LTRs. Despite the small and highly selective study population, lung allografts with MDR bacteria may be safely transplanted with appropriate posttransplant antibiotic therapy.

Chronic Obstructive Pulmonary Disease and Lung Transplantation

Lung transplantation (LTx) has been a viable option for patients with end-stage chronic obstructive pulmonary disease (COPD), with more than 20,000 procedures performed worldwide. Survival after LTx lags behind most other forms of solid-organ transplantation, with median survival for COPD recipients being a sobering 6.0 years. Given the limited supply of suitable donor organs, not all patients with end-stage COPD are candidates for LTx. We discuss appropriate criteria for accepting patients for LTx, as well as contraindications and exclusionary criteria. In the first year post-LTx, infection and graft failure are the leading causes of death. Beyond this chronic graft rejection-currently referred to as chronic lung allograft dysfunction-represents the leading cause of death at all time points, with infection and over time malignancy also limiting survival. Referral of COPD patients to a lung transplant center should be considered in the presence of progressing disease despite maximal medical therapy. As a rule of thumb, a forced expiratory volume in 1 second < 25% predicted in the absence of exacerbation, hypoxia (PaO₂ < 60 mm Hg/8 kPa), and/or hypercapnia (PaCO₂ > 50 mm Hg/6.6 kPa) and satisfactory general clinical condition should be considered the basic prerequisites for timely referral. We also discuss salient issues post-LTx and factors that impact posttransplant survival and morbidity such as infections, malignancy, renal insufficiency, and complications associated with long-term immunosuppression.

Acute respiratory failure among lung transplant adults requiring intensive care: Changing spectrum of causative organisms and impact of procalcitonin test in the diagnostic workup

BACKGROUND

The aim was to identify the causing organisms and assess the association of procalcitonin (PCT) with bacterial pneumonia within 24 hours of intensive care unit admission (ICU-A) among lung transplant (LT) adult recipients.

METHODS

Secondary analysis from a prospective cohort study. All LT adults admitted to ICU for acute respiratory failure (ARF) over 5 years were included. Patients were followed until hospital discharge or death.

RESULTS

Fifty-eight consecutive LT patients were enrolled. The most important cause of ICU-A due to ARF was pneumonia 29 (50%) followed by acute rejection 3 (5.2%) and bronchiolitis obliterans syndrome exacerbation 3 (5.2%). Microorganisms were isolated from 22/29 cases with pneumonia (75.9%): 17 (77.2%) bacterial, 4 (18.2%) viral, 1 (4.5%) Aspergillus fumigates, with Pseudomonas aeruginosa being the most common cause (45.5%) of pneumonia, with 10 patients presenting chronic colonization by P aeruginosa. Median [Interquartile range (IQR)] PCT levels within 24 hours after admission were higher in pneumonia (1.5 µg/L; IQR:0.3-22.0), than in non-pneumonia cases (0.2 µg/L; IQR:0.1-0.7) (P = .019) and PCT levels within 24 hours helped to discriminate bacterial pneumonia (8.2 µg/L; IQR:0.2-43.0) from viral pneumonia and non-pneumonia cases (0.2 µg/L; IQR:0.1-0.7). The overall negative predictive value for bacterial pneumonia was 85.1%, increasing to 91.6% among episodes after 6 months of LT.

CONCLUSIONS

Causes of severe pneumonia in LT are changing, with predominant role of P aeruginosa and respiratory viruses. PCT ≤ 0.5 μg/L within 24 hours helps to exclude bacterial pneumonia diagnosis in LT adults requiring ICU-A. A negative PCT test allows antimicrobial de-escalation and requires an alternative diagnostic to bacterial pneumonia.

Worldwide clinical practices in perioperative antibiotic therapy for lung transplantation

Background

Infection is the most common cause of mortality within the first year after lung transplantation (LTx). The management of perioperative antibiotic therapy is a major issue, but little is known about worldwide practices.

Methods

We sent by email a survey dealing with 5 daily clinical vignettes concerning perioperative antibiotic therapy to 180 LTx centers around the world. The invitation and a weekly reminder were sent to lung transplant specialists for a single consensus answer per center during a 3-month period.

Results

We received a total of 99 responses from 24 countries, mostly from Western Europe (n = 46) and the USA (n = 34). Systematic screening for bronchial recipient colonization before LTx was mostly performed with sputum samples (72%), regardless of the underlying lung disease. In recipients without colonization, antibiotics with activity against gram-negative bacteria resistant strains (piperacillin / tazobactam, cefepime, ceftazidime, carbapenems) were reported in 72% of the centers, and antibiotics with activity against methicillin-resistant Staphylococcus aureus (mainly vancomycin) were reported in 38% of the centers. For these recipients, the duration of antibiotics reported was 7 days (33%) or less (26%) or stopped when cultures of donor and recipients were reported negatives (12%). In recipients with previous colonization, antibiotics were adapted to the susceptibility of the most resistant strain and given for at least 14 days (67%).

Conclusion

Practices vary widely around the world, but resistant bacterial strains are mostly targeted even if no colonization occurs. The antibiotic duration reported was longer for colonized recipients.

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.

Management and prophylaxis of bacterial and mycobacterial infections among lung transplant recipients

Bacterial and mycobacterial infections are associated with morbidity and mortality in lung transplant recipients. Infectious complications are categorized by timing post-transplant: <1, 1–6, and >6 months. The first month post-transplant is associated with the highest risk of infection. During this period, infections are most commonly healthcare-associated, and include infections related to surgical complications. The lungs and bloodstream are common sites of infections. Common healthcare-associated organisms include methicillin-resistant Staphylococcus aureus (MRSA), Gram-negative bacilli such as Pseudomonas aeruginosa, and Clostridioides difficile. More than 1-month post-transplant, opportunistic infections can occur. Tuberculosis occurs in 0.8–10% of lung transplant recipients which reflects variation in background prevalence. The majority of post-transplant tuberculosis stems from reactivation of untreated or undiagnosed latent tuberculosis. Most post-transplant tuberculosis occurs in the lungs and develops within a year of transplant. Non-tuberculous mycobacteria commonly colonize the lungs of lung transplant candidates and are often hard to eradicate even with prolonged courses of antimycobacterial agents. Drug interactions between antimycobacterial agents and calcineurin and mTOR inhibitors also complicates treatment post-transplant. Given that infection adversely impacts outcomes after lung transplant, and that anti-infective therapy is often less effective after transplant, infection prevention is key to long-term success. A comprehensive approach that includes pre-transplant evaluation, perioperative prophylaxis, long-term antimicrobial prophylaxis, immunization, and safer living at home and in the community, should be employed to minimize the risk of infection.

Challenges in the Diagnosis and Management of Bacterial Lung Infections in Solid Organ Recipients: A Narrative Review

Respiratory infections pose a significant threat to the success of solid organ transplantation, and the diagnosis and management of these infections are challenging. The current narrative review addressed some of these challenges, based on evidence from the literature published in the last 20 years. Specifically, we focused our attention on (i) the obstacles to an etiologic diagnosis of respiratory infections among solid organ transplant recipients, (ii) the management of bacterial respiratory infections in an era characterized by increased antimicrobial resistance, and (iii) the development of antimicrobial stewardship programs dedicated to solid organ transplant recipients.

Diagnosis of severe respiratory infections in immunocompromised patients

An increasing number of critically ill patients are immunocompromised. Acute hypoxemic respiratory failure (ARF), chiefly due to pulmonary infection, is the leading reason for ICU admission. Identifying the cause of ARF increases the chances of survival, but may be extremely challenging, as the underlying disease, treatments, and infection combine to create complex clinical pictures. In addition, there may be more than one infectious agent, and the pulmonary manifestations may be related to both infectious and non-infectious insults. Clinically or microbiologically documented bacterial pneumonia accounts for one-third of cases of ARF in immunocompromised patients. Early antibiotic therapy is recommended but decreases the chances of identifying the causative organism(s) to about 50%. Viruses are the second most common cause of severe respiratory infections. Positive tests for a virus in respiratory samples do not necessarily indicate a role for the virus in the current acute illness. Invasive fungal infections (Aspergillus, Mucorales, and Pneumocystis jirovecii) account for about 15% of severe respiratory infections, whereas parasites rarely cause severe acute infections in immunocompromised patients. This review focuses on the diagnosis of severe respiratory infections in immunocompromised patients. Special attention is given to newly validated diagnostic tests designed to be used on non-invasive samples or bronchoalveolar lavage fluid and capable of increasing the likelihood of an early etiological diagnosis.

Airway bacteria of the recipient but not the donor are relevant to post-lung transplant pneumonia

BACKGROUND

Optimal management of early airway infection is essential for the survival of lung transplant (LTx) recipients during the first 12 months after transplantation. This study aimed to explore the main cause of post-lung transplant pneumonia (PLTP) within 30 days after LTx.

METHODS

Forty LTx patients were retrospectively analyzed. Sputum sampling from donors' and recipients' airways was performed pretransplant and posttransplant daily for the first 30 days after LTx. Organisms in the recipient's and donor's original airways were compared to pathogens responsible for PLTP. Patients with and without PLTP were also compared to identify relevant risk factors.

RESULTS

Seventeen (42.5%) patients developed pneumonia (PLTP group) and 23 had no episode of pneumonia (Non-PLTP group) during the first 30 days. In the PLTP group, median time from LTx to PLTP onset was 6 days. A significantly higher incidence of PLTP was caused by recipient's rather than donor's original airway bacteria (62% vs 13%, p < 0.01). Smoking history of the donor and pretransplant airway bacterial colonization of the recipient were independent risk factors of PLTP which was associated with prolonged posttransplant mechanical ventilation with longer intensive care unit stay and worse survival outcomes.

CONCLUSIONS

The recipient's original airway microflora rather than the donor's, was highly associated with PLTP. A combination of donor smoking history and recipient airway infection should be avoided, while evidence of donor lung infection is not a contraindication for LTx.

In situ identification of Gram-negative bacteria in human lungs using a topical fluorescent peptide targeting lipid A

Respiratory infections in mechanically ventilated patients caused by Gram-negative bacteria are a major cause of morbidity. Rapid and unequivocal determination of the presence, localization, and abundance of bacteria is critical for positive resolution of the infections and could be used for patient stratification and for monitoring treatment efficacy. Here, we developed an in situ approach to visualize Gram-negative bacterial species and cellular infiltrates in distal human lungs in real time. We used optical endomicroscopy to visualize a water-soluble optical imaging probe based on the antimicrobial peptide polymyxin conjugated to an environmentally sensitive fluorophore. The probe was chemically stable and nontoxic and, after in-human intrapulmonary microdosing, enabled the specific detection of Gram-negative bacteria in distal human airways and alveoli within minutes. The results suggest that pulmonary molecular imaging using a topically administered fluorescent probe targeting bacterial lipid A is safe and practical, enabling rapid in situ identification of Gram-negative bacteria in humans.

Pneumonia versus graft dysfunction as the cause of acute respiratory failure after lung transplant: a 4-year multicentre prospective study in 153 adults requiring intensive care admission

We aimed to assess the main causes of intensive care unit (ICU) readmissions in lung transplant adults and to identify independent predictors of ICU mortality (primary end-point).This Spanish five-centre prospective cohort study enrolled all lung transplant adults with ICU readmissions after post-transplant ICU discharge between 2012 and 2016. Patients were followed until hospital discharge or death.153 lung transplant recipients presented 174 ICU readmissions at a median (interquartile range) of 6 (2-25) months post-transplant. Chronic lung allograft dysfunction was reported in 39 (25.5%) recipients, 13 of whom (all exitus) had restrictive allograft syndrome (RAS). Acute respiratory failure (ARF) (110 (71.9%)) was the main condition requiring ICU readmission. Graft rejection (six (5.4%) acute) caused only 12 (10.8%) readmissions whereas pneumonia (56 (36.6%)) was the main cause (50 admitted for ARF and six for shock), with Pseudomonas aeruginosa (50% multidrug resistant) being the predominant pathogen. 55 (35.9%) and 69 (45.1%) recipients died in the ICU and the hospital, respectively. Bronchiolitis obliterans syndrome (BOS) stage 2 (adjusted OR (aOR) 7.2 (95% CI 1.0-65.7)), BOS stage 3 (aOR 13.7 (95% CI 2.5-95.3)), RAS (aOR >50) and pneumonia at ICU readmission (aOR 2.5 (95% CI 1.0-7.1)) were identified in multivariate analyses as independent predictors of ICU mortality. Only eight (5.2%) patients had positive donor-specific antibodies prior to ICU readmission and this variable did not affect the model.ARF was the main condition requiring ICU readmission in lung transplant recipients and was associated with high mortality. Pneumonia was the main cause of death and was also an independent predictor. RAS should receive palliative care rather than ICU admission.

Heart or lung transplant outcomes in HIV-infected recipients

BACKGROUND

Limited published data exist on outcomes related to heart and/or lung transplantation in human immunodeficiency virus (HIV)-infected individuals.

METHODS

We conducted a multicenter retrospective study of heart and lung transplantation in HIV-infected patients and describe key transplant- and HIV-related outcomes.

RESULTS

We identified 29 HIV-infected thoracic transplant recipients (21 heart, 7 lung, and 1 heart and/or lung) across 14 transplant centers from 2000 through 2016. Compared with an International Society for Heart and Lung Transplantation registry cohort, we demonstrated similar 1-, 3-, and 5-year patient and allograft survivals for each organ type with a median follow up of 1,064 (range, 184-3,745) days for heart and 1,540 (range, 116-3,206) days for lung recipients. At 1 year, significant rejection rates were high (62%) for heart transplant recipients (HTRs). Risk factors for rejection were inconclusive, likely because of small numbers, but may be related to cautious early immunosuppression and infrequent use of induction therapy. Pulmonary bacterial infections were high (86%) for lung transplant recipients (LTRs). Median CD4 counts changed from baseline to 1 year from 399 to 411 cells/µl for HTRs and 638 to 280 cells/µl for LTRs. Acquired immunodeficiency syndrome-related events, including infections and malignancies, were rare. Rates of severe renal dysfunction suggest a need to modify nephrotoxic anti-retrovirals and/or immunosuppressants.

CONCLUSIONS

HIV-infected HTRs and LTRs have similar survival rates to their HIV-uninfected counterparts. Although optimal immunosuppression is not defined, it should be at least as aggressive as that for HIV-uninfected recipients. Such data may help pave the way for the use of hearts and lungs from HIV-infected donors in HIV-infected recipients through HIV Organ Policy Equity Act protocols.

Postoperative management of lung transplant recipients

Despite advances in surgical technique, lung transplantation is associated with worse survival when compared with other solid organ transplantations. Graft dysfunction and infection are the leading causes of mortality in the first 30 days following transplantation. Primary graft dysfunction (PGD) is a form of reperfusion injury that occurs early after transplantation. Management of PGD is mainly supportive with use of lung protective ventilation. Inhaled nitric oxide (iNO) and extracorporeal membrane oxygenation may be used in severe cases. Bacterial pneumonias are the most common infectious complication in the immediate post transplant period, but invasive fungal infections may also occur. Other potential complications in the postoperative period include atrial arrhythmias and neurologic complications such as stroke. There is a lack of multicenter, randomized trials to guide ventilation strategies, infection prophylaxis, and treatment of atrial arrhythmias, therefore prevention and management of post-transplant complications vary by transplant center.

Multidrug-resistant Gram-negative bacterial infections in solid organ transplant recipients-Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These updated guidelines from the Infectious Diseases Community of Practice of the American Society of Transplantation review the diagnosis, prevention, and management of infections due to multidrug-resistant (MDR) Gram-negative bacilli in the pre- and post-transplant period. MDR Gram-negative bacilli, including carbapenem-resistant Enterobacteriaceae, MDR Pseudomonas aeruginosa, and carbapenem-resistant Acinetobacter baumannii, remain a threat to successful organ transplantation. Clinicians now have access to at least five novel agents with activity against some of these organisms, with others in the advanced stages of clinical development. No agent, however, provides universal and predictable activity against any of these pathogens, and very little is available to treat infections with MDR nonfermenting Gram-negative bacilli including A baumannii. Despite advances, empiric antibiotics should be tailored to local microbiology and targeted regimens should be tailored to susceptibilities. Source control remains an important part of the therapeutic armamentarium. Morbidity and mortality associated with infections due to MDR Gram-negative organisms remain unacceptably high. Heightened infection control and antimicrobial stewardship initiatives are needed to prevent these infections, curtail their transmission, and limit the evolution of MDR Gram-negative pathogens, especially in the setting of organ transplantation.

Infectious complications of bronchial stenosis in lung transplant recipients

BACKGROUND

Bronchial stenosis is a known complication of lung transplantation, but there are limited data regarding whether transplant recipients with bronchial stenosis develop more infectious complications than those without bronchial stenosis.

METHODS

We conducted a retrospective single-center observational cohort study between January 1, 2011 and September 29, 2016 of 35 lung transplant recipients diagnosed with bronchial stenosis and a random sample of 35 lung transplant recipients without bronchial stenosis. Data collected included donor/recipient demographic and anatomic information, respiratory cultures, episodes of respiratory infections diagnosed using CDC-NNIS criteria, hospitalizations, and 1-year all-cause mortality. Patients were followed up to 1 year after transplant.

RESULTS

Bronchial stenosis occurred at a median of 54 days post-transplant (range 5-365 days). Bronchial stenosis patients spent more time in the hospital (87.4 vs 46.8 days, P = 0.011) and had more total hospitalizations (4.54 vs 2.37, P < 0.01) than their counterparts. The relative risk of pneumonia among cases vs controls was 4.0 (95% CI 2.2-7.3, P < 0.01); for purulent tracheobronchitis the relative risk was 3.1 (95% CI 1.6-6.1, P < 0.01). Patients with bronchial stenosis were significantly more likely to have respiratory cultures growing Staphylococcus aureus (RR 5.0; P = 0.001) and Pseudomonas aeruginosa (RR 2.1, P = 0.026). Mortality within the first year following transplant was equal in both the groups (14.3% vs 14.3%).

CONCLUSIONS

There was no significant increase in 1-year mortality for lung transplant patients who developed bronchial stenosis. However, bronchial stenosis patients had significantly higher risks of pneumonia and tracheobronchitis, and spent more days in the hospital than those without bronchial stenosis.

Pneumonia in solid organ transplantation: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These guidelines from the AST Infectious Diseases Community of Practice review the diagnosis and management of pneumonia in the post-transplant period. Clinical presentations and differential diagnosis for pneumonia in the solid organ transplant recipient are reviewed. A two-tier approach is proposed based on the net state of immunosuppression and the severity of presentation. With a lower risk of opportunistic, hospital-acquired, or exposure-specific pathogens and a non-severe presentation, empirical therapy may be initiated under close clinical observation. In all other patients, or those not responding to the initial therapy, a more aggressive diagnostic approach including sampling of tissue for microbiological and pathological testing is warranted. Given the broad range of potential pathogens, a microbiological diagnosis is often key for optimal care. Given the limited literature comparatively evaluating diagnostic approaches to pneumonia in the solid organ transplant recipient, much of the proposed diagnostic algorithm reflects clinical experience rather than evidence-based data. It should serve as a template which may be modified according to local needs. The same holds true for the suggested empiric therapies, which need to be adapted to the local resistance patterns. Further study is needed to comparatively evaluate diagnostic and empiric treatment strategies in SOT recipients.

Invasive Aspergillosis in solid-organ transplant recipients: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These updated AST-IDCOP guidelines provide information on epidemiology, diagnosis, and management of Aspergillus after organ transplantation. Aspergillus is the most common invasive mold infection in solid-organ transplant (SOT) recipients, and it is the most common invasive fungal infection among lung transplant recipients. Time from transplant to diagnosis of invasive aspergillosis (IA) is variable, but most cases present within the first year post-transplant, with shortest time to onset among liver and heart transplant recipients. The overall 12-week mortality of IA in SOT exceeds 20%; prognosis is worse among those with central nervous system involvement or disseminated disease. Bronchoalveolar lavage galactomannan is preferred for the diagnosis of IA in lung and non-lung transplant recipients, in combination with other diagnostic modalities (eg, chest CT scan, culture). Voriconazole remains the drug of choice to treat IA, with isavuconazole and lipid formulations of amphotericin B regarded as alternative agents. The role of combination antifungals for primary therapy of IA remains controversial. Either universal prophylaxis or preemptive therapy is recommended in lung transplant recipients, whereas targeted prophylaxis is favored in liver and heart transplant recipients. In these guidelines, we also discuss newer antifungals and diagnostic tests, antifungal susceptibility testing, and special patient populations.

Is hospital-acquired pneumonia different in transplant recipients?

Hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) are serious complications in transplant patients. The aim of this review is to summarize the evidence regarding nosocomial pneumonia in transplant recipients, including HAP in non-ventilated patients and VAP, and to identify future directions for improvement.A comprehensive literature search in the PubMed/MEDLINE database was performed. Articles written in English and published between 1990 and November 2018 were included. HAP/VAP in transplant patients usually occurs early post-transplant, particularly during neutropenia in haematopoietic stem cell transplant recipients. Bacteria are the leading cause of nosocomial pneumonia for both immunocompetent and transplant recipients, being Gram negative organisms, and especially Pseudomonas aeruginosa, highly prevalent. Multidrug-resistant bacteria are of special concern. Pneumonia in the transplant setting may be caused by opportunistic pathogens, and the differential diagnosis needs to be extended to other non-infectious complications. The most relevant opportunistic pathogens are Aspergillus fumigatus, Pneumocystis jirovecii and cytomegalovirus. Nevertheless, they are an exceptional cause of nosocomial pneumonia, and usually occur in severely immunosuppressed patients not receiving antimicrobial prophylaxis. Performing bronchoalveolar lavage may improve the rate of aetiological diagnosis, leading to a change in therapeutic management and improved outcomes. The optimal length of antibiotic therapy for bacterial HAP/VAP has not been well defined, but it should perhaps be longer than in the general population. Mortality associated with HAP/VAP is high. HAP/VAP in transplant patients is frequent and is associated with increased mortality. There is room for improvement in gaining knowledge about the management of HAP/VAP in this population.