Diagnosis of Fungal Infections PDF

Preface

Fungal infections are a leading cause of death in multiple different patient populations; experience over the last few decades has been that these organisms are a leading cause of transplant-related mortality after stem cell transplantation, a frequent complication of organ transplantation, a leading cause of death in people with advanced human immunodeficiency virus disease, and a common cause of bloodstream infection among the hospitalized population. New studies are indicating that known fungi are involved as inciters in disease states not previously thought to be infectious (e.g., asthma and sinusitis), and "new" organisms are being discovered. Recognition of these organisms as important complications of the immunosuppressed state has generated much basic and clinical research since the 1980s and recent development of several new antifungal drugs. Despite these efforts and advancements, high mortality is at least in part resultant from difficulties in establishing confirmed diagnoses. Diagnostic difficulties have led to potentially inappropriate "empirical" antifungal administration strategies and over-utilization of antifungals and lack of appropriate therapy in the setting of established disease. Currently, appreciation of emerging resistance to several antifungal drugs complicates treatment decisions in the absence of microbial diagnoses. It appears that the field is largely at an impasse, awaiting development of new diagnostics.

Establishing the diagnosis of fungal infections is complicated, in part because these organisms are typically difficult to recover in the laboratory, either by laboratory culture, or by histopathological identification. Laboratory recovery of fungi has been improved in some settings; for instance, blood culture of Candida species has been facilitated with improvements in culture systems. However, other organisms remain elusive. For instance, filamentous organisms continue to be difficult to recover in culture, even in the presence of documented disease with visualized fungal fragments under the microscope. Recent observations suggest that there may be ways to improve laboratory cultivation of such organisms by adjusting growth conditions; however, optimized culture conditions appear to be relatively far from current practice. Other fungi, such as Pneumocystis, have never been cultivated in either clinical or basic research laboratories; we obviously have much to learn about fungal cultivation in the laboratory.