Complications of invasive mycoses in organ transplant recipients

Fungal infections in lung transplantation

Lung transplant is a potential life-saving procedure for chronic lung diseases. Lung transplant recipients (LTRs) are at the greatest risk for invasive fungal infections (IFIs) among solid organ transplant (SOT) recipients because the allograft is directly exposed to fungi in the environment, airway and lung host defenses are impaired, and immunosuppressive regimens are particularly intense. IFIs occur within a year of transplant in 3-19% of LTRs, and they are associated with high mortality, prolonged hospital stays, and excess healthcare costs. The most common causes of post-LT IFIs are Aspergillus and Candida spp.; less common pathogens are Mucorales, other non-Aspergillus moulds, Cryptococcus neoformans, Pneumocystis jirovecii, and endemic mycoses. The majority of IFIs occur in the first year following transplant, although later onset is observed with prolonged antifungal prophylaxis. The most common manifestations of invasive mould infections (IMIs) include tracheobronchial (particularly at anastomotic sites), pulmonary and disseminated infections. The mortality rate of tracheobronchitis is typically low, but local complications such as bronchomalacia, stenosis and dehiscence may occur. Mortality rates associated with lung and disseminated infections can exceed 40% and 80%, respectively. IMI risk factors include mould colonization, single lung transplant and augmented immunosuppression. Candidiasis is less common than mould infections, and manifests as bloodstream or other non-pulmonary invasive candidiasis; tracheobronchial infections are encountered uncommonly. Risk factors for and outcomes of candidiasis are similar to those of non lung transplant recipients. There is evidence that IFIs and fungal colonization are risk factors for allograft failure due to chronic rejection. Mould-active azoles are frontline agents for treatment of IMIs, with local debridement as needed for tracheobronchial disease. Echinocandins and azoles are treatments for invasive candidiasis, in keeping with guidelines in other patient populations. Antifungal prophylaxis is commonly administered, but benefits and optimal regimens are not defined. Universal mould-active azole prophylaxis is used most often. Other approaches include targeted prophylaxis of high-risk LTRs or pre-emptive therapy based on culture or galactomannan (GM) (or other biomarker) results. Prophylaxis trials are needed, but difficult to perform due to heterogeneity in local epidemiology of IFIs and standard LT practices. The key to devising rational strategies for preventing IFIs is to understand local epidemiology in context of institutional clinical practices.

Isavuconazole Is as Effective as and Better Tolerated Than Voriconazole for Antifungal Prophylaxis in Lung Transplant Recipients

BACKGROUND

Invasive fungal infections (IFIs) are common following lung transplantation. Isavuconazole is unstudied as prophylaxis in organ transplant recipients. We compared effectiveness and tolerability of isavuconazole and voriconazole prophylaxis in lung transplant recipients.

METHODS

A single-center, retrospective study of patients who received isavuconazole (September 2015-February 2018) or voriconazole (September 2013-September 2015) for antifungal prophylaxis. IFIs were defined by EORTC/MSG criteria.

RESULTS

Patients received isavuconazole (n = 144) or voriconazole (n = 156) for median 3.4 and 3.1 months, respectively. Adjunctive inhaled amphotericin B (iAmB) was administered to 100% and 41% of patients in the respective groups. At 1 year, 8% of patients receiving isavuconazole or voriconazole developed IFIs. For both groups, 70% and 30% of IFIs were caused by molds and yeasts, respectively, and breakthrough IFI (bIFI) rate was 3%. Outcomes did not significantly differ for patients receiving or not receiving iAmB. Independent risk factors for bIFI and breakthrough invasive mold infection (bIMI) were mold-positive respiratory culture and red blood cell transfusion >7 units at transplant. Bronchial necrosis >2 cm from anastomosis and basiliximab induction were also independent risk factors for bIMI. Isavuconazole and voriconazole were discontinued prematurely due to adverse events in 11% and 36% of patients, respectively (P = .0001). Most common causes of voriconazole and isavuconazole discontinuation were hepatotoxicity and lack of oral intake, respectively. Patients receiving ≥90 days prophylaxis had fewer IFIs at 1 year (3% vs 9%, P = .02). IFIs were associated with increased mortality (P = .0001) and longer hospitalizations (P = .0005).

CONCLUSIONS

Isavuconazole was effective and well tolerated as antifungal prophylaxis following lung transplantation.

mRNA decay: an adaptation tool for the environmental fungal pathogen Cryptococcus neoformans

Fungi are ubiquitous in the environment and humans constantly encounter them in the soil, air, water, and food. The vast majority of these interactions are inconsequential. However, in the context of immunodeficiency precipitated by HIV infection, hematologic malignancy, or transplantation, a small subset of fungi can cause devastating, systemic infection. The most deadly of the opportunistic environmental fungi, Cryptococcus neoformans, is estimated to cause hundreds of thousands of deaths per year, mostly in the context of HIV co-infection. The cellular processes that mediate adaptation to the host environment are of great interest as potential novel therapeutic targets. One such cellular process important for host adaptation is mRNA decay, which mediates the specific degradation of subsets of functionally related mRNAs in response to stressors relevant to pathogenesis, including human core body temperature, carbon limitation, and reactive oxygen stress. Thus, for C. neoformans, host adaptation requires mRNA decay to mediate rapid transcriptome remodeling in the face of stressors encountered in the host. Several nodes of stress-responsive signaling that govern the stress-responsive transcriptome also control the decay rate of mRNAs cleared from the ribosome during stress, suggesting an additional layer of coupling between mRNA synthesis and decay that allows C. neoformans to be a successful pathogen of humans. WIREs RNA 2017, 8:e1424. doi: 10.1002/wrna.1424 For further resources related to this article, please visit the WIREs website.