Infection prophylaxis and management of fungal infections in lung transplant

Infections in lung transplanted patients: A review

Lung transplantation can improve the survival of patients with severe chronic pulmonary disorders. However, the short- and long-term risk of infections can increase morbidity and mortality rates. A non-systematic review was performed to provide the most updated information on pathogen, host, and environment-related factors associated with the occurrence of bacterial, fungal, and viral infections as well as the most appropriate therapeutic options. Bacterial infections account for about 50% of all infectious diseases in lung transplanted patients, while viruses represent the second cause of infection accounting for one third of all infections. Almost 10% of patients develop invasive fungal infections during the first year after lung transplant. Pre-transplantation comorbidities, disruption of physical barriers during the surgery, and exposure to nosocomial pathogens during the hospital stay are directly associated with the occurrence of life-threatening infections. Empiric antimicrobial treatment after the assessment of individual risk factors, local epidemiology of drug-resistant pathogens and possible drug-drug interactions can improve the clinical outcomes.

Biogenesis, germination, and pathogenesis of Cryptococcus spores

SUMMARYSpores are primary infectious propagules for the majority of human fungal pathogens; however, relatively little is known about their fundamental biology. One strategy to address this deficiency has been to develop the basidiospores of Cryptococcus into a model for pathogenic spore biology. Here, we provide an update on the state of the field with a comprehensive review of the data generated from the study of Cryptococcus basidiospores from their formation (sporulation) and differentiation (germination) to their roles in pathogenesis. Importantly, we provide support for the presence of basidiospores in nature, define the key characteristics that distinguish basidiospores from yeast cells, and clarify their likely roles as infectious particles. This review is intended to demonstrate the importance of basidiospores in the field of Cryptococcus research and provide a solid foundation from which researchers who wish to study sexual spores in any fungal system can launch their studies.

Opportunistic Infections Post-Lung Transplantation: Viral, Fungal, and Mycobacterial

Opportunistic infections are a leading cause of lung transplant recipient morbidity and mortality. Risk factors for infection include continuous exposure of the lung allograft to the external environment, high levels of immunosuppression, impaired mucociliary clearance and decreased cough reflex, and impact of the native lung microbiome in single lung transplant recipients. Infection risk is mitigated through careful pretransplant screening of recipients and donors, implementation of antimicrobial prophylaxis strategies, and routine surveillance posttransplant. This review describes common viral, fungal, and mycobacterial infectious after lung transplant and provides recommendations on prevention and treatment.

Fungal Infections and Colonization after Bilateral Lung Transplant: A Six-Year Single-Center Experience

Fungal infections (FIs) are one of the leading causes of morbidity and mortality within the first year of lung transplant (LT) in LT recipients (LTRs). Their prompt identification and treatment are crucial for a favorable LTR outcome. The objectives of our study were to assess (i) the FI incidence and colonization during the first year after a bilateral LT, (ii) the risk factors associated with FI and colonization, and (iii) the differences in fungal incidence according to the different prophylactic strategies. All bilateral LTRs admitted to the intensive care unit of Padua University Hospital were retrospectively screened, excluding patients <18 years of age, those who had been re-transplanted, and those who had received ventilation and/or extracorporeal membrane oxygenation before LT. Overall, 157 patients were included. A total of 13 (8%) patients developed FI, and 36 (23%) developed colonization, which was mostly due to Aspergillus spp. We did not identify independent risk factors for FI. Groups of patients receiving different prophylactic strategies reported a similar incidence of both FI and colonization. The incidence of FI and fungal colonization was 8% and 23%, respectively, with no differences between different antifungal prophylaxes or identified predisposing factors. Further studies with larger numbers are needed to confirm our results.

Invasive Aspergillosis among Lung Transplant Recipients during Time Periods with Universal and Targeted Antifungal Prophylaxis-A Nationwide Cohort Study

The optimal prevention strategy for invasive aspergillosis (IA) in lung transplant recipients (LTXr) is unknown. In 2016, the Danish guidelines were changed from universal to targeted IA prophylaxis. Previously, we found higher rates of adverse events in the universal prophylaxis period. In a Danish nationwide study including LTXr, for 2010-2019, we compared IA rates in time periods with universal vs. targeted prophylaxis and during person-time with vs. person-time without antifungal prophylaxis. IA hazard rates were analyzed in multivariable Cox models with adjustment for time after LTX. Among 295 LTXr, antifungal prophylaxis was initiated in 183/193 and 6/102 during the universal and targeted period, respectively. During the universal period, 62% discontinued prophylaxis prematurely. The median time on prophylaxis was 37 days (IQR 11-84). IA was diagnosed in 27/193 (14%) vs. 15/102 (15%) LTXr in the universal vs. targeted period, with an adjusted hazard ratio (aHR) of 0.94 (95% CI 0.49-1.82). The aHR of IA during person-time with vs. person-time without antifungal prophylaxis was 0.36 (95% CI 0.12-1.02). No difference in IA was found during periods with universal vs. targeted prophylaxis. Prophylaxis was protective of IA when taken. Targeted prophylaxis may be preferred over universal due to comparable IA rates and lower rates of adverse events.

Etiologic characteristics revealed by mNGS-mediated ultra-early and early microbiological identification in airway secretions from lung transplant recipients

Background

Post-operative etiological studies are critical for infection prevention in lung transplant recipients within the first year. In this study, mNGS combined with microbial culture was applied to reveal the etiological characteristics within one week (ultra-early) and one month (early) in lung transplant recipients, and the epidemiology of infection occurred within one month.

Methods

In 38 lung transplant recipients, deep airway secretions were collected through bronchofiberscope within two hours after the operation and were subjected to microbial identification by mNGS and microbial culture. The etiologic characteristics of lung transplant recipients were explored. Within one month, the infection status of recipients was monitored. The microbial species detected by mNGS were compared with the etiological agents causing infection within one month.

Results

The detection rate of mNGS in the 38 airway secretions specimens was significantly higher than that of the microbial culture (P<0.0001). MNGS identified 143 kinds of pathogenic microorganisms; bacterial pathogens account for more than half (72.73%), with gram-positive and -negative bacteria occupying large proportions. Fungi such as Candida are also frequently detected. 5 (50%) microbial species identified by microbial culture had multiple drug resistance (MDR). Within one month, 26 (68.42%) recipients got infected (with a median time of 9 days), among which 10 (38.46%) cases were infected within one week. In the infected recipients, causative agents were detected in advance by mNGS in 9 (34.62%) cases, and most of them (6, 66.67%) were infected within one week (ultra-early). In the infection that occurred after one week, the consistency between mNGS results and the etiological agents was decreased.

Conclusion

Based on the mNGS-reported pathogens in airway secretions samples collected within two hours, the initial empirical anti-infection regimes covering the bacteria and fungi are reasonable. The existence of bacteria with MDR forecasts the high risk of infection within 48 hours after transplant, reminding us of the necessity to adjust the antimicrobial strategy. The predictive role of mNGS performed within two hours in etiological agents is time-limited, suggesting continuous pathogenic identification is needed after lung transplant.

Biofire pneumonia panel in lung donors: faster detection but limited pathogens

BACKGROUND

Culture of bronchoalveolar lavage (BAL) specimens takes time to report. We tested whether a molecular diagnostic test could accelerate donor lung assessment and treatment.

METHODS

We compared BioFire Film Array Pneumonia Panel (BFPP) with standard of care (SOC) tests on lung allograft samples at three time points: (1) donor BAL at organ recovery, (2) donor bronchial tissue and airway swab at implantation, and (3) first recipient BAL following lung implantation. Primary outcomes were the difference in time to result (Wilcoxon signed-ranked tests) and the agreement in results between BFPP and SOC assays (Gwet's agreement coefficient).

RESULTS

We enrolled 50 subjects. In donor lung BAL specimens, BFPP detected 52 infections (14 out of 26 pathogens in the panel). Viral and bacterial BFPP results were reported 2.4 h (interquartile range, IQR 2.0-6.4) following BAL versus 4.6 h (IQR 1.9-6.0, p = 0.625) for OPO BAL viral SOC results and 66 h (IQR 47-87, p < .0001) for OPO BAL bacterial SOC results. Although there was high overall agreement of results between BAL-BFPP versus OPO BAL-SOC tests (Gwet's AC p < .001 for all), the level of agreement differed among 26 pathogens designed in BFPP and differed by types of specimens. BFPP could not detect many infections identified by SOC assays.

CONCLUSIONS

BFPP decreased time to detection of lung pathogens among donated lungs, but it cannot replace SOC tests due to the limited number of pathogens in the panel.

Diagnosis and Treatment of Fungal Infections in Lung Transplant Recipients

Fungal infections are a significant source of morbidity in the lung transplant population via direct allograft damage and predisposing patients to the development of chronic lung allograft dysfunction. Prompt diagnosis and treatment are imperative to limit allograft damage. This review article discusses incidence, risk factors, and symptoms with a specific focus on diagnostic and treatment strategies in the lung transplant population for fungal infections caused by Aspergillus, Candida, Coccidioides, Histoplasma, Blastomyces, Scedosporium/Lomentospora, Fusarium, and Pneumocystis jirovecii. Evidence for the use of newer triazole and inhaled antifungals to treat isolated pulmonary fungal infections in lung transplant recipients is also discussed.

Opportunistic Infections Post-Lung Transplantation: Viral, Fungal, and Mycobacterial

Opportunistic infections are a leading cause of lung transplant recipient morbidity and mortality. Risk factors for infection include continuous exposure of the lung allograft to the external environment, high levels of immunosuppression, impaired mucociliary clearance and decreased cough reflex, and impact of the native lung microbiome in single lung transplant recipients. Infection risk is mitigated through careful pretransplant screening of recipients and donors, implementation of antimicrobial prophylaxis strategies, and routine surveillance posttransplant. This review describes common viral, fungal, and mycobacterial infectious after lung transplant and provides recommendations on prevention and treatment.

Fungal Infections in Lung Transplantation

Purpose of Review

We aim to understand the most common fungal infections associated with the post-lung transplant period, how to diagnose, treat, and prevent them based on the current guidelines published and our center’s experience.

Recent Findings

Different fungi inhabit specific locations. Diagnosis of invasive fungal infections (IFIs) depends on symptoms, radiologic changes, and a positive microbiological or pathology data. There are several molecular tests that have been used for diagnosis. Exposure to fungal prophylaxis can predispose lung transplant recipients to these emerging molds. Understanding and managing medication interactions and drug monitoring are essential in successfully treating IFIs.

Summary

With the increasing rate of lung transplantations being performed, and the challenges posed by the immunosuppressive regimen, understanding the risk and managing the treatment of fungal infections are imperative to the success of a lung transplant recipient. There are many ongoing clinical trials being conducted in hopes of developing novel antifungals.

Antifungal Prophylaxis After Lung Transplantation: Where Are We Now?

BACKGROUND

Lung transplantation is an important treatment option for various end-stage lung diseases. However, survival remains limited due to graft rejection and infections. Despite that fungal infections are frequent and carry a bad prognosis, there is currently no consensus on efficacy, optimal drug, route, or duration of antifungal prophylaxis. This narrative review summarizes current strategies for antifungal prophylaxis after lung transplantation.

METHODS

English language articles in Embase, Pubmed, UptoDate, and bibliographies were used to assess the efficacy and safety of available antifungal agents for prophylaxis in adult lung transplant recipients.

RESULTS

Overall, there are limited high-quality data. Universal prophylaxis is more widely used and may be preferable over targeted prophylaxis. Both formulations of inhaled amphotericin B and systemic azoles are effective at reducing fungal infection rates, yet with their own specific advantages and disadvantages. The benefit of combination regimens has yet to be proven. Considering the post-transplant timing of the onset of fungal infections, postoperative prophylaxis during the first postoperative months seems indicated for most patients.

CONCLUSIONS

Based on existing literature, universal antifungal prophylaxis with inhaled amphotericin B and systemic voriconazole for at least 3-6 mo after lung transplantation may be advisable, with a slight preference for amphotericin B because of its better safety profile.

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.

Comparing posaconazole and itraconazole for antifungal prophylaxis in critically ill lung transplant recipients: Efficacy and plasma concentrations

BACKGROUND

Posaconazole and itraconazole are commonly used for systemic antifungal prophylaxis after lung transplantation. The aim of this study on critically ill lung transplant recipients was to assess the rate of adequate plasma concentrations and the frequency of fungal-induced transitions from antifungal prophylaxis to therapy after the administration of either posaconazole or itraconazole for systemic prophylaxis.

METHODS

Critically ill lung transplant recipients with postoperative posaconazole or itraconazole prophylaxis and therapeutic drug monitoring from February 2016 to November 2019 were retrospectively included in the study. Positive fungal cultures or Aspergillus antigen tests resulting in a transition from antifungal prophylaxis to therapy were analyzed from the first day of prophylaxis until 7 days after the last sample for each patient. Adequate plasma concentrations were defined as ≥500 µg/L for itraconazole and ≥700 µg/L for posaconazole.

RESULTS

Two hundred seventy-five samples from 73 patients were included in the analysis. Overall, 60% of the posaconazole and 55% of the itraconazole concentrations were subtherapeutic. Administration of posaconazole suspension resulted significantly (P < .01) more often in subtherapeutic concentrations than tablets (68% vs 10%). Patients treated with posaconazole showed less positive fungal records resulting in a transition from prophylaxis to therapy than patients treated with itraconazole (10% vs 33%, P-value: .029). The detection of a fungal pathogen was not associated with the measured plasma concentrations or the achievement of the target concentrations.

CONCLUSION

Our findings suggest that posaconazole should be used instead of itraconazole for systemic prophylaxis in critically ill lung transplant recipients.