Nonculture diagnostic methods for invasive fungal infections

An unusual infection in an immunocompetent male from a non-endemic area: Lessons from a vacation

Primary pulmonary histoplasmosis is found worldwide, and is particularly endemic in some areas of North America, usually those surrounding the Ohio and Mississippi river valleys. It is not common in the East Coast of the United States, and is in fact reportable in Pennsylvania. It has been rarely described in immunocompetent individuals residing in a non-endemic region. We present a case of a previously healthy middle-aged male, a Pennsylvania resident, who presented with mid-sternal chest discomfort, fatigue, chills and mild shortness of breath, and was diagnosed with primary pulmonary histoplasmosis.

Chronic Cavitary Infections Other than Tuberculosis: Clinical Aspects

Lung cavitation may be due to infectious or noninfectious pathologic processes. The latter category includes nonmalignant conditions, such as granulomatosis with polyangiitis, and malignant conditions, such as squamous cell carcinoma of the lung. Infectious etiologies that produce lung cavitation usually cause chronic illness, although some, particularly pyogenic bacteria, may produce acute cavitary disease. Tuberculosis is the most common cause of chronic pulmonary infection with cavitation. The goal of this review was to highlight a selection of the better-known infectious agents, other than tuberculosis, that can cause chronic lung disease with cavitation. Emphasis is placed on the following organisms: nontuberculous mycobacteria, Histoplasma, Blastomyces, Coccidioides, Paracoccidioides, Aspergillus, Burkholderia pseudomallei, Paragonimus westermani, and Rhodococcus equi. These organisms generally produce clinical features and radiologic findings that overlap or mimic those of tuberculosis. In a companion article, we have further emphasized aspects of the same conditions that are more pertinent to radiologists.

Isolated Pancreatic Histoplasmosis: An Unusual Suspect of Pancreatic Head Mass in an Immunocompetent Host

Histoplasmosis is endemic to the Mississippi and Ohio River valley regions in the US. It usually affects patients with underlying immunodeficiency but can also be seen in immunocompetent hosts. Although gastrointestinal involvement is common in the setting of disseminated histoplasmosis, isolated gastrointestinal involvement is uncommon. We report a case of isolated pancreatic histoplasmosis in an immunocompetent patient, presenting as painless jaundice and pancreatic head mass.

Investigating the presence of fungal agents in febrile neutropenic patients using different microbiological, serological, and molecular methods

This study aimed to investigate fungal agents in febrile neutropenic patients with hematological malignancies. Direct microscopy and cultures were performed on clinical samples collected from febrile neutropenic episodes. The galactomannan (GM) antigen was tested using enzyme-linked immunosorbent assays, and Aspergillus fumigatus and Candida albicans deoxyribonucleic acid (DNA) assessed using real-time polymerase chain reaction (PCR) in consecutive serum samples. Of the 199 episodes investigated, 1.5% were classified as definite invasive aspergillosis (IA), 4.0% as IA with high probability, and 4.0% as IA with low probability. Additionally, candidaemia was detected in eight episodes (4.1%). The GM antigen was found negative for 86.4% of episodes, as one positive for 7.0% of episodes, as two or more consecutive positives for 5.5% of episodes, and as positive in any two serum samples in 1.0% of episodes. While no C. albicans DNA was detected in 98.5% of 199 episodes, one positive result was obtained in 1.0% of episodes, and two or more consecutive positives in 0.5% of episodes. A. fumigatus PCR results were found negative in 81.9% of episodes, as one positive in 16.1% of episodes, as positive in any two serum samples in 1.0% of episodes, and consecutively positive in 1.0% of episodes. GM antigen tests were found consecutively positive in all three patients diagnosed as having definite IA. These findings indicate that conventional, serological, and molecular methods should be used in combination to detect fungal agents in febrile neutropenic patients.

Endemic fungal infections in inflammatory bowel disease associated with anti-TNF antibody therapy

Patients with inflammatory bowel disease are susceptible to complications from pharmacologic treatment of their disease. Tumor necrosis factor (TNF)-α inhibitors are being used increasingly in the treatment of inflammatory bowel disease and can be associated with adverse events, including common infections, and rarely the development of serious life-threatening opportunistic infections. TNF-α inhibitors have the ability to prevent an effective patient granulomatous response, and this may be associated with an increased risk of developing mycobacterial and certain fungal infections, including histoplasmosis, blastomycosis, and coccidioidomycosis, endemic in several parts of the United States. The concern for invasive fungal infection was realized during clinical trials and further demonstrated after the marketing of TNF-α inhibitors. Because of this awareness, the Food and Drug Administration developed an adverse event-reporting system to capture cases of infections associated with the use of TNF-α inhibitors. These opportunistic fungi have a great degree of regional variability, and it has been very difficult to quantify the incidence of infection in patients treated with TNF-α inhibitors. Currently, there are no formal guidelines regarding the use of TNF-α inhibitors and these fungal infections. Considering that gastroenterologists have embraced the use TNF-α inhibitors as a valuable armamentarium in the treatment of inflammatory bowel disease, they must be aware of therapy-related infectious complications, including appropriate diagnostic, therapeutic, and preventive strategies. In this article, we explore the association of these fungal entities in relation to the TNF-α inhibitor therapy by considering information provided in the gastroenterology, infectious diseases, rheumatology, and transplant literature. Finally, we provide some recommendations on diagnosis and treatment.

Laboratory diagnostics of invasive fungal infections: an overview with emphasis on molecular approach

Although invasive fungal diseases (IFDs) are relatively rare, they have become an increasingly common life-threatening complication in a variety of critically ill patients. Due to changes in treatment strategies, patterns of IFDs have changed substantially as well. Yeast infections have shifted toward a higher proportion of non-albicans Candida species, but their overall incidence has remained stable. In contrast, IFDs caused by molds, including particularly various species of Aspergillus, Fusarium, and Mucorales, have increased in number. In view of the growing incidence and the high mortality rates of IFDs, accurate diagnostic techniques permitting timely onset of adequate antifungal treatment are of paramount importance. Although conventional approaches such as microscopy, cultivation, histopathological examination, and imaging methods still represent the gold standard, the diagnosis remains difficult because of limited sensitivity and specificity. Noninvasive and culture-independent diagnostic techniques, including fungal antigen detection, and different molecular-based techniques are becoming increasingly important. Of the fungal surrogate markers such as cell wall components, galactomannan and (1,3)-β-D-glucan by commercially available diagnostic kits have become widely used, but the results are still controversial. A plethora of PCR-based diagnostic methods targeting different gene regions and exploiting a variety of amplicon detection tools have been published. Molecular assays have the capacity to overcome the limitations of other diagnostic approaches, but the current lack of methodological standardization and validation, together with not always clear interpretation of the results, has prevented broad application in the clinical setting.

Interlaboratory discrepancy of antigenuria results in 2 patients with AIDS and histoplasmosis

Histoplasma polysaccharide antigen testing is used routinely to diagnose histoplasmosis. At least 3 antigen tests are commercially available. Controversy exists about the relative accuracy of these tests. We report 2 patients with AIDS and culture-confirmed Histoplasma capsulatum meningitis from whom discrepant Histoplasma polysaccharide antigen results were obtained from different laboratories and discuss the potential clinical implications of these results.