Effect of aerosolized antipseudomonals onPseudomonaspositivity and bronchiolitis obliterans syndrome after lung transplantation

Acute Rejection and Chronic Lung Allograft Dysfunction: Obstructive and Restrictive Allograft Dysfunction

Lung transplantation is an established treatment of well-selected patients with end-stage respiratory diseases. However, lung transplant recipients have the highest rates of acute and chronic rejection among transplanted solid organs. Owing to ongoing alloimmune recognition and associated immune-driven airway/vascular remodeling, precipitated by multifactorial, endogenous or exogenous, post-transplant injuries to the bronchovascular axis of the secondary pulmonary lobule, most lung transplant recipients will suffer from a pathophysiological decline of their allograft, either functionally and/or structurally. This review discusses current knowledge, barriers, and gaps in acute cellular rejection and chronic lung allograft dysfunction-the greatest impediment to long-term post-transplant survival.

Aspergillus-Specific IgG Antibodies are Associated With Fungal-Related Complications and Chronic Lung Allograft Dysfunction After Lung Transplantation

Fungal exposure and sensitization negatively affect outcomes in various respiratory diseases, however, the effect of fungal sensitization in lung transplant (LTx) recipients is still unknown. We performed a retrospective cohort study of prospectively collected data on circulating fungal specific IgG/IgE antibodies, and their correlation with fungal isolation, chronic lung allograft dysfunction (CLAD) and overall survival after LTx. 311 patients transplanted between 2014 and 2019 were included. Patients with elevated Aspergillus fumigatus or Aspergillus flavus IgG (10%) had more mold and Aspergillus species isolation (p = 0.0068 and p = 0.0047). Aspergillus fumigatus IgG was specifically associated with Aspergillus fumigatus isolation in the previous or consecutive year (AUC 0.60, p = 0.004 and AUC 0.63, p = 0.022, respectively). Elevated Aspergillus fumigatus or Aspergillus flavus IgG was associated with CLAD (p = 0.0355), but not with death. Aspergillus fumigatus, Aspergillus flavus or Aspergillus niger IgE was elevated in 19.3% of patients, but not associated with fungal isolation, CLAD or death. Mold isolation and Aspergillus species isolation from respiratory cultures were associated with CLAD occurrence (p = 0.0011 and p = 0.0005, respectively), and Aspergillus species isolation was also associated with impaired survival (p = 0.0424). Fungus-specific IgG could be useful in long-term follow-up post-LTx, as a non-invasive marker for fungal exposure, and thus a diagnostic tool for identifying patients at risk for fungal-related complications and CLAD.

Antibiotic Therapy for Difficult-to-Treat Infections in Lung Transplant Recipients: A Practical Approach

Lung transplant recipients are at higher risk to develop infectious diseases due to multi-drug resistant pathogens, which often chronically colonize the respiratory tract before transplantation. The emergence of these difficult-to-treat infections is a therapeutic challenge, and it may represent a contraindication to lung transplantation. New antibiotic options are currently available, but data on their efficacy and safety in the transplant population are limited, and clinical evidence for choosing the most appropriate antibiotic therapy is often lacking. In this review, we provide a summary of the best evidence available in terms of choice of antibiotic and duration of therapy for MDR/XDR P. aeruginosa, Burkholderia cepacia complex, Mycobacterium abscessus complex and Nocardia spp. infections in lung transplant candidates and recipients.

The lung microbiome in lung transplantation

Culture-independent study of the lower respiratory tract after lung transplantation has enabled an understanding of the microbiome - that is, the collection of bacteria, fungi, and viruses, and their respective gene complement - in this niche. The lung has unique features as a microbial environment, with balanced entry from the upper respiratory tract, clearance, and local replication. There are many pressures impacting the microbiome after transplantation, including donor allograft factors, recipient host factors such as underlying disease and ongoing exposure to the microbe-rich upper respiratory tract, and transplantation-related immunosuppression, antimicrobials, and postsurgical changes. To date, we understand that the lung microbiome after transplant is dysbiotic; that is, it has higher biomass and altered composition compared to a healthy lung. Emerging data suggest that specific microbiome features may be linked to host responses, both immune and non-immune, and clinical outcomes such as chronic lung allograft dysfunction (CLAD), but many questions remain. The goal of this review is to put into context our burgeoning understanding of the lung microbiome in the postlung transplant patient, the interactions between microbiome and host, the role the microbiome may play in post-transplant complications, and critical outstanding research questions.

The Impact of Resistant Bacterial Pathogens including Pseudomonas aeruginosa and Burkholderia on Lung Transplant Outcomes

Pseudomonas and Burkholderia are gram-negative organisms that achieve colonization within the lungs of patients with cystic fibrosis, and are associated with accelerated pulmonary function decline. Multidrug resistance is a hallmark of these organisms, which makes eradication efforts difficult. Furthermore, the literature has outlined increased morbidity and mortality for lung transplant (LTx) recipients infected with these bacterial genera. Indeed, many treatment centers have considered Burkholderia cepacia infection an absolute contraindication to LTx. Ongoing research has delineated different species within the B. cepacia complex (BCC), with significantly varied morbidity and survival profiles. This review considers the current evidence for LTx outcomes between the different subspecies encompassed within these genera as well as prophylactic and management options. The availability of meta-genomic tools will make differentiation between species within these groups easier in the future, and will allow more evidence-based decisions to be made regarding suitability of candidates colonized with these resistant bacteria for LTx. This review suggests that based on the current evidence, not all species of BCC should be considered contraindications to LTx, going forward.

Cystic fibrosis foundation consensus statements for the care of cystic fibrosis lung transplant recipients

Cystic fibrosis (CF) is the indication for transplantation in approximately 15% of recipients worldwide, and Cystic Fibrosis Lung Transplant Recipients (CFLTRs) have excellent long-term outcomes. Yet, CFLTRs have unique comorbidities that require specialized care. The objective of this document is to provide recommendations to CF and lung transplant clinicians for the management of perioperative and underlying comorbidities of CFLTRs and the impact of transplantation on these comorbidities. The Cystic Fibrosis Foundation (CFF) organized a multidisciplinary committee to develop CF Lung Transplant Clinical Care Recommendations. Three workgroups were formed to develop focused questions. Following a literature search, consensus recommendations were developed by the committee members based on literature review, committee experience and iterative revisions, and in response to public comment. The committee formulated 32 recommendation statements in the topics related to infectious disease, endocrine, gastroenterology, pharmacology, mental health and family planning. Broadly, the committee recommends close coordination of care between the lung transplant team, the cystic fibrosis care center, and specialists in other disciplines with experience in the care of CF and lung transplant recipients. These consensus statements will help lung transplant providers care for CFLTRs in order to improve post-transplant outcomes in this population.

Successful Pseudomonas aeruginosa eradication improves outcomes after lung transplantation: a retrospective cohort analysis

Long-term survival after lung transplantation (LTx) is hampered by development of chronic lung allograft dysfunction (CLAD). Pseudomonas aeruginosa is an established risk factor for CLAD. Therefore, we investigated the effect of P. aeruginosa eradication on CLAD-free and graft survival.

Patients who underwent first LTx between July, 1991, and February, 2016, and were free from CLAD, were retrospectively classified according to P. aeruginosa presence in respiratory samples between September, 2011, and September, 2016. P. aeruginosa-positive patients were subsequently stratified according to success of P. aeruginosa eradication following targeted antibiotic treatment. CLAD-free and graft survival were compared between P. aeruginosa-positive and P. aeruginosa-negative patients; and between patients with or without successful P. aeruginosa eradication. In addition, pulmonary function was assessed during the first year following P. aeruginosa isolation in both groups.

CLAD-free survival of P. aeruginosa-negative patients (n=443) was longer compared with P. aeruginosa-positive patients (n=95) (p=0.045). Graft survival of P. aeruginosa-negative patients (n=443, 82%) was better compared with P. aeruginosa-positive patients (n=95, 18%) (p<0.0001). Similarly, P. aeruginosa-eradicated patients demonstrated longer CLAD-free and graft survival compared with patients with persistent P. aeruginosa. Pulmonary function was higher in successfully P. aeruginosa-eradicated patients compared with unsuccessfully eradicated patients (p=0.035).

P. aeruginosa eradication after LTx improves CLAD-free and graft survival and maintains pulmonary function. Therefore, early P. aeruginosa detection and eradication should be pursued.

Prevention of chronic rejection after lung transplantation

Long-term survival after lung transplantation (LTx) is limited by chronic rejection (CR). Therapeutic strategies for CR have been largely unsuccessful, making prevention of CR an important and challenging therapeutic approach. In the current review, we will discuss current clinical evidence regarding prevention of CR after LTx.