Alterations of lung microbiota in lung transplant recipients with pneumocystis jirovecii pneumonia.

BACKGROUND: Increasing evidence revealed that lung microbiota dysbiosis was associated with pulmonary infection in lung transplant recipients (LTRs). Pneumocystis jirovecii (P. jirovecii) is an opportunistic fungal pathogen that frequently causes lethal pneumonia in LTRs. However, the lung microbiota in LTRs with P. jirovecii pneumonia (PJP) remains unknow. METHODS: In this prospective observational study, we performed metagenomic next-generation sequencing (mNGS) on 72 bronchoalveolar lavage fluid (BALF) samples from 61 LTRs (20 with PJP, 22 with PJC, 19 time-matched stable LTRs, and 11 from LTRs after PJP recovery). We compared the lung microbiota composition of LTRs with and without P. jirovecii, and analyzed the related clinical variables. RESULTS: BALFs collected at the episode of PJP showed a more discrete distribution with a lower species diversity, and microbiota composition differed significantly compared to P. jirovecii colonization (PJC) and control group. Human gammaherpesvirus 4, Phreatobacter oligotrophus, and Pseudomonas balearica were the differential microbiota species between the PJP and the other two groups. The network analysis revealed that most species had a positive correlation, while P. jirovecii was correlated negatively with 10 species including Acinetobacter venetianus, Pseudomonas guariconensis, Paracandidimonas soli, Acinetobacter colistiniresistens, and Castellaniella defragrans, which were enriched in the control group. The microbiota composition and diversity of BALF after PJP recovery were also different from the PJP and control groups, while the main components of the PJP recovery similar to control group. Clinical variables including age, creatinine, total protein, albumin, IgG, neutrophil, lymphocyte, CD3+CD45+, CD3+CD4+ and CD3+CD8+ T cells were deeply implicated in the alterations of lung microbiota in LTRs. CONCLUSIONS: This study suggests that LTRs with PJP had altered lung microbiota compared to PJC, control, and after recovery groups. Furthermore, lung microbiota is related to age, renal function, nutritional and immune status in LTRs.

Efficacy of different durations of antifungal prophylaxis with nebulized amphotericin B after lung transplantation: a retrospective cohort study.

Background: Nebulized amphotericin B (NAB) is recommended for preventing invasive fungal diseases (IFDs) after lung transplantation. However, the optimal duration of NAB treatment is still unknown. This study aimed to compare the effectiveness of three different durations of antifungal prophylaxis with NAB after lung transplantation: a prolonged course beyond post-transplant 3 months, a medium course of 2 weeks to 3 months, and a short course of less than 2 weeks. Methods: This a single-center retrospective cohort study analyzed 333 patients who underwent lung or heart-lung transplantation between January 2015 and November 2021. Results: A prolonged course of NAB treatment was associated with a significantly lower incidence of IFDs (12.6%) at 1 year post-transplant compared with a short (50.9%) or a medium course (28.0%) (P<0.001). There was no significant difference in the rates of adverse effects among the three durations of NAB treatment (P>0.05). A prolonged course of NAB treatment was associated with a significantly higher 1-year survival rate (94.7%) compared with a short (36.8%) or a medium course (72.0%) (P<0.001). Conclusions: A prolonged course of NAB treatment provided better protection against IFDs than a short or medium course after lung transplantation. Prolonged use of NAB did not significantly increase the incidence of adverse effects.

Clinical characteristics and treatment strategy of nocardiosis in lung transplant recipients: A single-center experience.

Objective: Nocardia are infrequent pathogens that disproportionately afflict organ transplant recipients. The present study aimed to summarize the clinical manifestations, diagnostic approaches, and treatment strategies of nocardiosis in lung transplant recipients. Methods: This retrospective study reviewed the clinical data of adult lung transplant recipients who were complicated with nocardiosis between January 2018 and December 2021 at the largest lung transplant center in South China. Results: The incidence of nocardiosis was 4.2% (13/316), including 9 cases of pulmonary nocardiosis and 4 disseminated nocardiosis (blood, pulmonary and intracranial). The accuracy in diagnosing nocardiosis was 77.8% by culture and 100% by metagenomic next-generation sequencing (mNGS). Nocardia farcinica was the most common causative pathogen. Trimethoprim-sulfamethoxazole-based combination therapy was administered initially, followed by a single antibiotic as the maintained therapy, lasting for 4-8 months. Conclusions: mNGS is more accurate than culture in diagnosing nocardiosis. Most patients responded well to the antibiotic therapy with combined antibiotics at the initial stage followed by a single antibiotic treatment.

Risk factors and prognosis of airway complications in lung transplant recipients: A systematic review and meta-analysis.

BACKGROUND: Airway complications (AC) are one of leading causes of morbidity and mortality after lung transplant (LTx), but their predictors and outcomes remain controversial. This study aimed to identify potential risk factors and prognosis of AC. METHODS: A systematic review was performed by searching PubMed, Embase, and Cochrane Library. All observational studies reporting outcome and potential factors of AC after LTx were included. The incidence, mortality, and estimated effect of each factor for AC were pooled by using the fixed-effects model or random-effects model. RESULTS: Thirty-eight eligible studies with 52,116 patients undergoing LTx were included for meta-analysis. The pooled incidence of AC was 12.4% (95% confidence interval [CI] 9.5-15.8) and the mean time of occurrence was 95.6 days. AC-related mortality rates at 30-days, 90-days, 6 months, 1 year, and 5 years were 6.7%, 17.9%, 18.2%, 23.6%, and 66.0%, respectively. Airway dehiscence was the most severe type with a high mortality at 30 days (60.9%, 95% CI 20.6-95.2). We found that AC was associated with a higher risk of mortality in LTx recipients (hazard ratio [HR] 1.71, 95% CI 1.04-2.81). Eleven significant predictors for AC were also identified, including male donor, male recipient, diagnosis of COPD, hospitalization, early rejection, postoperative infection, extracorporeal membrane oxygenation, mechanical ventilation, telescopic anastomosis, and bilateral and right-sided LTx. CONCLUSION: AC was significantly associated with higher mortality after LTx, especially for dehiscence. Targeted prophylaxis for modifiable factors and enhanced early bronchoscopy surveillance after LTx may improve the disease burden of AC.

Clinical outcomes and survival following lung transplantation for work-related lung disease: a single-center retrospective cohort study.

BACKGROUND: Patients with work-related lung disease (WRLD) are at increased risk of death caused by severe lung tissue damage and fibrosis. This study aimed to assess the clinical outcomes of lung transplantation (LTx) for WRLD and compare the results of LTx between WRLD and idiopathic pulmonary fibrosis (IPF). METHODS: This single-center retrospective cohort study reviewed the clinical data of patients who underwent LTx for WRLD or IPF at our hospital between January 2015 and December 2021. Cumulative survival rates after LTx were estimated using the Kaplan-Meier method. RESULTS: The final analysis included 33 cases of WRLD and 91 cases of IPF. The 33 WRLD patients consisted of 19 (57.6%) cases of silicosis, 8 (24.2%) cases of coal workers' pneumoconiosis, 3 (9.09%) cases of asbestosis, and 3 (9.09%) cases of other WRLD. Pneumothorax as an indication for LTx was significantly more common in the WRLD group than in the IPF group (51.5% vs. 2.2%, P < 0.001). There was no significant difference in the 5-year cumulative survival rate between the WRLD patients and the IPF patients (66.6% vs. 56.7%, P = 0.67). There was no significant difference in the best performance of exercise capacity and lung function between the two groups at 1 year post-transplant. CONCLUSIONS: LTx had similar survival outcomes and lung function for WRLD and IPF patients. Pneumothorax was the primary indication for lung transplantation in WRLD.

Application of plasma donor-derived cell free DNA for lung allograft rejection diagnosis in lung transplant recipients.

BACKGROUND: Donor-derived cell-free DNA (dd-cfDNA) has been applied to monitor acute rejection (AR) in kidney and heart transplantation. This study was aimed to investigate the application of dd-cfDNA levels in the diagnosis of AR and chronic lung allograft dysfunction (CLAD) among the lung transplantation recipients (LTRs). METHODS: One hundred and seventy LTRs were enrolled at the First Affiliated Hospital of Guangzhou Medical University between 1 June 2015 and 30 March 2021. Patients were divided into 4 groups: stable group, AR group, infection group and CLAD group. The level of dd-cfDNA was analyzed using target region sequencing and the performance characteristics of dd-cfDNA for diagnosis of AR and CLAD were determined, respectively. RESULTS: Kruskal-Wallis test showed that there were some significant differences in the level of dd-cfDNA (%) among the 4 groups, with p < 0.001. Among them, the level of dd-cfDNA (%) was highest (median 2.17, IQR [1.40-3.82]) in AR group, and higher in CLAD group (median 1.07, IQR [0.98-1.31]), but lower in infection group (median 0.71, IQR [0.57-1.07]) and lowest in stable group (median 0.71, IQR [0.61-0.84]). AUC-ROC curve analysis showed that the threshold of dd-cfDNA for AR was 1.17%, with sensitivity being 89.19% and specificity being 86.47%, and the optimal threshold of 0.89% was determined of CLAD, with sensitivity being 95.00% and specificity of 76.99%. CONCLUSIONS: Plasma dd-cfDNA could be a useful tool for the assessment of lung allograft rejection, including AR and CLAD, and holds promise as a noninvasive biomarker for "allograft injury" in both acute and chronic rejection following lung transplantation.

Lung transplantation for anti-MDA5-positive dermatomyositis-associated rapid progressive interstitial lung disease: report of two cases and review of the literature.

Lung transplantation is an ultimate lifesaving treatment for many patients with end-stage lung disease, whereas whether it is an optional intervention for the anti-melanoma differentiation-associated gene 5 (anti-MDA5)-positive dermatomyositis (DM)-associated rapid progressive interstitial lung disease (RP-ILD) remain controversial. We report two patients diagnosed with anti-MDA5-positive DM-associated RP-ILD, who were both bridging to lung transplant with extracorporeal membrane oxygenation (ECMO) after failing to respond to extensive immunosuppressants. The first patient received full rehabilitation, but the second patient died of DM flare at the early-stage post-lung transplantation. Most of the clinical information was parallel in these two patients except the anti-MDA5 antibody level, which gradually decreased and became negative in the first patient but always hovering in high titers in the second patient, although both of the two patients received standard immunosuppressive regimen for prevention of rejection after lung transplantation. A total of 11 patients with anti-MDA5-positive DM-associated RP-ILD who underwent lung transplantation from the literature were identified. Most patients (10/11, 90.1%) were successfully discharged and without DM flare during the follow-up period post-lung transplantation. Nine of them were followed up more than 1 year, and anti-MDA-5 antibody was reported to be negative in four patients, whereas the others were unavailable. Combined with the case series in the literature, our limited experience suggests that lung transplantation is a promising therapeutic option for end-stage patients with anti-MDA5-positive DM-associated RP-ILD, with ECMO as a bridge to lung transplantation, if necessary. However, clearance or a downtrend of anti-MDA5 antibody may be required pre-transplant to avoid DM flare and recurrent RP-ILD post-transplantation.

Cytomegalovirus seroprevalence, infection, and disease in Chinese thoracic organ transplant recipients: a retrospective cohort study.

BACKGROUND: Cytomegalovirus (CMV) infection is a leading cause of morbidity and mortality after transplantation. This study aimed to investigate CMV seroprevalence, infection, and disease in Chinese thoracic organ transplant recipients. METHODS: The clinical data of the patients who underwent lung and/or heart transplantation between January 2015 and October 2020 were retrospectively collected from four transplantation centers in China. RESULTS: A total of 308 patients were analyzed. The CMV serostatus was donor positive (D+) recipient negative (R-) in 19 (6.17%) patients, D+/R+ in 233 (75.65%), D-/R+ in 36 (11.69%), and D-/R- in 20 (6.50%). CMV DNAemia was detected in 52.3% of the patients and tissue-invasive CMV disease was diagnosed in 16.2% of the patients. Only 31.8% of the patients adhered to the postdischarge valganciclovir therapy. The D+/R- serostatus (odds ratio [OR]: 18.32; 95% confidence interval [CI]:1.80-188.68), no valganciclovir prophylaxis (OR: 2.64; 95% CI: 1.05-6.64), and higher doses of rabbit anti-human thymocyte globulin (> 2 mg/kg) (OR: 4.25; 95% CI: 1.92-9.42) were risk factors of CMV disease. CONCLUSION: CMV seroprevalence was high in Chinese thoracic organ transplant donors and recipients. The low adherence rate to the postdischarge CMV prophylaxis therapy in Chinese patients is still an unresolved issue.

Antifungal prophylactic effectiveness and intrapulmonary concentrations of voriconazole versus posaconazole in lung transplant recipients.

Invasive fungal diseases (IFDs) are one of the leading causes of death in lung transplant recipients. This study aimed to compare the antifungal prophylactic effectiveness, intrapulmonary and plasma levels of voriconazole with posaconazole in lung transplant recipients. This retrospective cohort study analyzed adult recipients who underwent lung transplantation between June 2017 and December 2020. Voriconazole oral tablets or posaconazole oral suspension was used for prophylaxis against posttransplant IFD. Drug concentrations in bronchoalveolar lavage fluid (BALF) and plasma were measured by using liquid chromatography-mass spectrometry. The 182 recipients included 142 in the voriconazole group and 40 in the posaconazole group. The trough plasma levels were comparable between voriconazole and posaconazole (1.65 ± 0.09 vs. 1.69 ± 0.03 µg/ml, P = 0.55). However, the BALF levels were significantly higher for posaconazole than voriconazole (17.47 ± 11.51 vs. 0.56 ± 0.49 µg/ml, P < 0.001). There was no significant difference in the total incidence of breakthrough IFDs between the voriconazole and posaconazole groups (10.6% vs. 7.5%, P = 0.77). The intrapulmonary concentrations of posaconazole were significantly higher than voriconazole. The two agents had comparable antifungal prophylactic effectiveness.

The Airway Microbiota Signatures of Infection and Rejection in Lung Transplant Recipients.

Infection and rejection are the two most common complications after lung transplantation (LT) and are associated with increased morbidity and mortality. We aimed to examine the association between the airway microbiota and infection and rejection in lung transplant recipients (LTRs). Here, we collected 181 sputum samples (event-free, n = 47; infection, n = 103; rejection, n = 31) from 59 LTRs, and performed 16S rRNA gene sequencing to analyze the airway microbiota. A significantly different airway microbiota was observed among event-free, infection and rejection recipients, including microbial diversity and community composition. Nineteen differential taxa were identified by linear discriminant analysis (LDA) effect size (LEfSe), with 6 bacterial genera, Actinomyces, Rothia, Abiotrophia, Neisseria, Prevotella, and Leptotrichia enriched in LTRs with rejection. Random forest analyses indicated that the combination of the 6 genera and procalcitonin (PCT) and T-lymphocyte levels showed area under the curve (AUC) values of 0.898, 0.919 and 0.895 to differentiate between event-free and infection recipients, event-free and rejection recipients, and infection and rejection recipients, respectively. In conclusion, our study compared the airway microbiota between LTRs with infection and acute rejection. The airway microbiota, especially combined with PCT and T-lymphocyte levels, showed satisfactory predictive efficiency in discriminating among clinically stable recipients and those with infection and acute rejection, suggesting that the airway microbiota can be a potential indicator to differentiate between infection and acute rejection after LT. IMPORTANCE Survival after LT is limited compared with other solid organ transplantations mainly due to infection- and rejection-related complications. Differentiating infection from rejection is one of the most important challenges to face after LT. Recently, the airway microbiota has been reported to be associated with either infection or rejection of LTRs. However, fewer studies have investigated the relationship between airway microbiota together with infection and rejection of LTRs. Here, we conducted an airway microbial study of LTRs and analyzed the airway microbiota together with infection, acute rejection, and clinically stable recipients. We found different airway microbiota between infection and acute rejection and identify several genera associated with each outcome and constructed a model that incorporates airway microbiota and clinical parameters to predict outcome. This study highlighted that the airway microbiota was a potential indicator to differentiate between infection and acute rejection after LT.

Metagenomic Next-Generation Sequencing for Diagnosing Infections in Lung Transplant Recipients: A Retrospective Study.

Background: Accurate identification of pathogens is essential for the diagnosis and control of infections. We aimed to compare the diagnostic performance of metagenomic next-generation sequencing (mNGS) and conventional detection methods (CDM) in lung transplant recipients (LTRs). Methods: We retrospectively analyzed 107 LTRs with suspected infection of pulmonary, blood, central nervous system or chest wall between March 2018 and November 2020. Bronchoalveolar lavage fluid and other body fluids were subject to pathogen detection by both mNGS and CDM. Results: Of the 163 specimens, 84 (51.5%) tested positive for both mNGS and culture, 19 (11.7%) of which were completely consistent, 44 (27.0%) were partially congruent, and 21 (12.9%) were discordant (kappa = .215; p = .001). Compared with CDM, mNGS detected a higher diversity of pathogens. Moreover, the turn-around time was significantly shorter for mNGS compared with culture (2.7 ± .4 vs. 5.5 ± 1.6 days, p < .001). As an auxiliary method, treatment strategies were adjusted according to mNGS findings in 31 cases (29.0%), including eight patients with non-infectious diseases, who were finally cured. Conclusion: mNGS can identify pathogens with a shorter turn-around time and therefore provide a more accurate and timely diagnostic information to ascertaining pulmonary infections. mNGS might have a role in differentiating infectious from non-infectious lung diseases in LTRs.

Outcomes after lung transplantation among Chinese patients with connective tissue disease-associated interstitial lung disease and pulmonary hypertension: a retrospective cohort study.

OBJECTIVES: The present study aimed to compare the post-lung transplant survival and complications of connective tissue disease (CTD)-related interstitial lung disease (ILD) and/or pulmonary arterial hypertension with idiopathic pulmonary fibrosis (IPF). METHODS: The clinical data of patients with CTD-ILD or IPF who received lung transplantation between 2015 and 2020 were retrospectively reviewed. Cumulative survival rates after transplantation were estimated using the Kaplan-Meier method. RESULTS: The study included 31 patients with confirmed CTD-ILD and 98 with IPF. Patients with CTD-ILD were significantly younger (53.2 ± 13.7 vs. 62.3 ± 7.2 years, p=0.001) and more likely female (61.3% vs. 7.1%, p<0.001) than patients with IPF. No significant difference was noticed in the 1-year and 5-year survival rates between CTD-ILD and IPF patients (1-year, 73.2% vs 71.4%, p=0.76; 5-year, 69.1% vs. 39.5%, p=0.21). The incidence of primary graft dysfunction was significantly higher in CTD-ILD patients (90.3% vs. 70.4%, p=0.03), while there was no significant difference in primary graft dysfunction-related mortality (6.5% vs. 6.1%, p=0.95) between the two groups. CONCLUSIONS: There was no significant difference in post-lung transplant survival and complications between CTD-ILD and IPF.

Epidemiology and Prognosis of Invasive Fungal Disease in Chinese Lung Transplant Recipients.

This study explored the epidemiology, risk factors, and prognosis of invasive fungal disease (IFD) in Chinese lung transplant recipients (LTRs). This retrospective cohort study included patients who received lung transplants at four hospitals in South China between January 2015 and June 2019. The participants were divided into IFD and non-IFD (NIFD) groups. The final analysis included 226 LTRs (83.2% males) aged 55.0 ± 14.2 years old. Eighty-two LTRs (36.3%) developed IFD (proven or probable diagnosis). The most common pathogens were Aspergillus (57.3%), Candida (19.5%), and Pneumocystis jiroveci (13.4%). Multivariate logistic regression revealed that anastomotic disease [odds ratio (OR): 11.86; 95% confidence interval (95%CI): 4.76-29.54; P < 0.001], cytomegalovirus (CMV) pneumonia (OR: 3.85; 95%CI: 1.88-7.91; P = 0.018), and pre-transplantation IFD (OR: 7.65; 95%CI: 2.55-22.96; P < 0.001) were associated with higher odds of IFD, while double-lung transplantation (OR: 0.40; 95%CI: 0.19-0.79; P = 0.009) was associated with lower odds of IFD. Logistic regression analysis showed that anastomotic disease was associated with higher odds of death (OR: 5.01; 95%CI: 1.24-20.20; P = 0.02) and that PJP prophylaxis was associated with lower odds of death (OR: 0.01; 95%CI: 0.001-0.11; P < 0.001). Invasive fungal disease is prevalent among LTRs in southern China, with Aspergillus the most common pathogen. Prophylaxis should be optimized based on likely pathogens.

High-throughput next-generation sequencing for identifying pathogens during early-stage post-lung transplantation.

BACKGROUND: High-throughput next-generation sequencing (HT-NGS) has the potential to detect a large variety of pathogens; however, the application of HT-NGS in lung transplant (LTx) recipients remains limited. We aimed to evaluate the value of HT-NGS for pathogen detection and diagnosis of pulmonary infection during early-stage post-lung transplantation. METHODS: In this retrospective study, we enrolled 51 LTx recipients who underwent lung transplantation between January 2020 and December 2020. Bronchoalveolar lavage fluid (BALF) samples were collected for the detection of pathogens using both HT-NGS and conventional microbiological testing. The detection of pathogens and diagnostic performance of HT-NGS were compared with that of conventional methods. RESULTS: HT-NGS provided a higher positive rate of pathogen detection than conventional microbiological testing (88.24% vs. 76.47%). The most common bacteria detected via HT-NGS during early-stage post-lung transplantation were Enterococcus, Staphylococcus, Pseudomonas and Klebsiella, while all fungi were Candida and all viruses were Herpesvirus. Uncommon pathogens, including Strongyloides, Legionella, and Mycobacterium abscesses were identified by HT-NGS. The sensitivity of HT-NGS for diagnosing pulmonary infection was significantly higher than that of conventional microbiological testing (97.14% vs. 68.57%; P < 0.001). For three LTx recipients, treatment regimens were adjusted according to the results of HT-NGS, leading to a complete recovery. CONCLUSION: HT-NGS is a highly sensitive technique for pathogen detection, which may provide diagnostic advantages, especially in LTx recipients, contributing to the optimization of treatment regimens against pulmonary infection during early-stage post-lung transplantation.

Recommended prophylactic and management strategies for severe acute respiratory syndrome coronavirus 2 infection in transplant recipients.

Since December 2019, increasing attention has been paid to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) epidemic in Wuhan, China. SARS-CoV-2 primarily invades the respiratory tract and lungs, leading to pneumonia and other systemic disorders. The effect of SARS-CoV-2 in transplant recipients has raised significant concerns, especially because there is a large population of transplant recipients in China. Based on the current epidemic situation, this study reviewed publications on this virus and coronavirus disease 2019 (COVID-19), analyzed common features of respiratory viral pneumonias, and presented the currently reported clinical characteristics of COVID-19 in transplant recipients to improve strategies regarding the diagnosis and treatment of COVID-19 in this special population.