Interpretation,pitfalls of biomarkers in diagnosis of invasive fungal diseases

BackgroundInvasive Fungal Diseases (IFD), account for high morbidity and mortality in immunocompromised and seriously ill patients worldwide. Early, faster and accurate diagnosis with timely and appropriate patient management is critical for improved patient outcome and antifungal stewardship. Clinical/radiological presentations in IFD are non-specific and microscopy/culture based tests have low sensitivity and long turnaround time. Biomarkers have clinical utility for diagnosing IFD but their interpretation is not straight forward.ObjectivesThis review discusses the salient characteristics, clinical usefulness and limitations of common biomarkers such as Galactomannan (GM), 1–3, β D glucan (βDG), mannan, anti-mannan antibody (Mn/antiMn), Cryptococcal antigen test (CrAg), Nucleic Acid Amplification (NAA) tests and next generation sequencing for diagnosing IFD.ContentsFungal biomarkers are useful adjuncts as screening and diagnostic tools for IFD and are much more suited for ‘ruling out’ rather than ‘ruling in’ disease. GM, NAA tests are promising biomarkers for screening of invasive Aspergillosis in high risk asymptomatic patients who are not on antifungal therapy and for diagnosis of breakthrough infections in symptomatic patients. 1–3, β D glucan has limitations both as a ‘rule in’ and ‘rule out’ test and is useful in only specific clinical settings. Two consecutive positive 1-3-βDG tests or combined positivity with GM increases its specificity. Mn/antiMn, T2Candida nano diagnostic panel are promising candidates for diagnosing invasive candidiasis. Combining two or more biomarkers improves the sensitivity for prompt initiation of antifungal therapy and the negative predictive value for suspension of empirical treatment.Serum CrAg test is a good ‘rule in’ rather than a ‘rule out’ test in immunocompetent patients but has good diagnostic accuracy in immunocompromised patients. Detection of single nucleotide polymorphisms by next generation sequencing is useful for fungal characterization and identification of host determinants responsible for increased susceptibility to fungal infections but is still in experimental stages.     

CCPG1 involved in corneal Aspergillus fumigatus infection

AIM: To investigate whether non-canonical autophagy transport receptor cell cycle progression 1 (CCPG1) is involved in the corneal antifungal immune response. METHODS: Human corneal epithelial cells (HCECs) and human myeloid leukemia mononuclear cells (THP-1) macrophages stimulated by Aspergillus fumigatus (A. fumigatus) were used as cell models. The expression of CCPG1 mRNA was detected by qRT-PCR. Western blot was used to determine the protein expression of CCPG1 and interleukin-1β (IL-1β). The dectin-1 neutralizing antibody was used to detect the association between dectin-1 and CCPG1. Immunofluorescence was used to observe the colocalization of CCPG1 and C-type lectin-like receptor-1 (CLEC-1) in THP-1 macrophages. RESULTS: The expression of CCPG1 started to increase at 4h after infection and increased in a time-dependent manner in HCECs and THP-1 macrophages. With dectin-1 neutralizing antibody pretreatment, the expression of IL-1β was down-regulated. CCPG1 up-regulation in response to A. fumigatus infection was independent of dectin-1. Immunofluorescence showed the colocalization of CCPG1 and CLEC-1 in THP-1 macrophages. CONCLUSION: As a specific autophagy protein of non-canonical autophagy pathway, CCPG1 is involved in corneal infection with A. fumigatus.     

Paradox of complex diversity: Challenges in the diagnosis and management of bacterial keratitis

Bacterial keratitis continues to be one of the leading causes of corneal blindness in the developed as well as the developing world, despite swift progress since the dawn of the “anti-biotic era”. Although, we have expeditiously developed our understanding about the different causative organisms and associated pathology leading to keratitis, extensive gaps in knowledge continue to dampen the efforts required for early and accurate diagnosis, and management in these patients, resulting in poor clinical outcomes. The ability of the causative bacteria to subdue the therapeutic challenge stems from their large genome encoding complex regulatory networks, variety of unique virulence factors, and rapid secretion of tissue damaging proteases and toxins.In this review article, we provide an overview of the established diagnostic techniques and therapeutics for keratitis caused by various bacteria. We extensively report the recent in-roads through novel tools for accurately diagnosing mono- and poly-bacterial corneal infections. Furthermore, we outline the recent progress by our groups and others in understanding the sub-cellular genomic changes that lead to antibiotic resistance in these organisms. Finally, we discuss in detail, the novel therapies and drug delivery systems in development for the efficacious management of bacterial keratitis.     

Posaconazole therapeutic drug monitoring in clinical practice and longitudinal analysis of the effect of routine laboratory measurements on posaconazole concentrations

Posaconazole is indicated for prophylaxis and treatment of invasive aspergillosis. Therapeutic drug monitoring (TDM) of posaconazole is used to optimise drug exposure. The aim of this study was to analyse and describe the TDM practices and exposure of posaconazole tablets. Patients who received posaconazole for treatment or prophylaxis of fungal infections were included in the study. The following therapeutic window was defined: if concentration was low (<0.7 mg/L for prophylaxis or < 1.5 mg/L for treatment) or high (>3.75 mg/L), the hospital pharmacist provided the physician with dosage advice, which implementation to patient care was analysed. A longitudinal analysis was performed to analyse if different confounding variables had an effect on posaconazole concentrations. Forty‐seven patients were enrolled resulting in 217 posaconazole trough concentrations. A median of 3 (IQR 1‐7) samples was measured per patient. The median concentration was 1.7 mg/L (IQR 0.8‐2.7) for prophylaxis and 1.76 mg/L (IQR 1.3‐2.3) for treatment. Overall, 78 posaconazole concentrations were out of the therapeutic window. For 45 (54%) of these concentrations, a dosage change was recommended. In the longitudinal analysis, the laboratory markers and patient baseline variables did not have an effect on posaconazole concentrations. Adequate posaconazole exposure was shown in 64% (affected 28 patients) of the measured concentrations. TDM practice of posaconazole can be improved by increasing the implementation rate of dose recommendation by a multidisciplinary antifungal stewardship team.     

伏立康唑一级预防急性白血病患者化疗期间并发真菌感染的临床疗效北大核心

目的:探讨初诊急性白血病患者化疗期间应用伏立康唑进行预防侵袭性真菌病(IFD)的临床疗效及安全性。方法:回顾性分析2016年02月至2018年03月期间我院血液科收治的初诊急性白血病行化疗的患者166例,按照是否使用抗真菌药进行预防性治疗分为观察组(应用伏立康唑进行预防治疗,n=103)和对照组(未应用抗真菌药物,n=63),比较两组患者IFD发生率差异,并分析抗真菌药物应用的不良反应。结果:观察组IFD发生率为10.7%,对照组为33.3%,两组患者的IFD发生率有明显差异(P<0.05);所有应用伏立康唑进行预防治疗的患者均未出现严重的不良反应。结论:伏立康唑可以有效减低急性白血病患者化疗期间IFD发生率,并且有着较好的安全性,值得在临床推广应用。     

Fungal infections following liver transplantation

With increasing morbidity and mortality from chronic liver disease and acute liver failure, the need for liver transplantation is on the rise. Most of these patients are extremely vulnerable to infections as they are immune-compromised and have other chronic co-morbid conditions. Despite the recent advances in practice and improvement in diagnostic surveillance and treatment modalities, a major portion of these patients continue to be affected by post-transplant infections. Of these, fungal infections are particularly notorious given their vague and insidious onset and are very challenging to diagnose. This mini-review aims to discuss the incidence of fungal infections following liver transplantation, the different fungi involved, the risk factors, which predispose these patients to such infections, associated diagnostic challenges, and the role of prophylaxis. The population at risk is increasingly old and frail, suffering from various other co-morbid conditions, and needs special attention. To improve care and to decrease the burden of such infections, we need to identify the at-risk population with more robust clinical and diagnostic parameters. A more robust global consensus and stringent guidelines are needed to fight against resistant microbes and maintain the longevity of current antimicrobial therapies.