Systemic fungal infections: an overview

Pulsed dye laser treatment of primary cryptococcal laryngitis: A novel approach to an uncommon disease

An 82-year-old supplemental oxygen dependent woman with severe COPD presented with an eight month history of worsening hoarseness and stridor. Office laryngoscopy revealed laryngeal edema and ulcerative masses throughout the larynx. In-office biopsies were positive for Cryptococcus neoformans. This report details a novel approach to the treatment of cryptococcal laryngitis, a combination of in-office pulsed-dye laser (PDL) ablation and medical therapy. Despite treatment with oral fluconazole, the recommended treatment for cryptococcal laryngitis the patient continued to be symptomatic with dysphonia and throat discomfort. Repeated laryngeal exam demonstrated persistent cryptococcal nodules. The patient was subsequently effectively treated with an in-office PDL laser. This case demonstrates the efficacy of in-office laser treatment for residual laryngeal Cryptococcus. For patients like this one, who have failed medical therapy and are unfit for general anesthetic, the in-office laser provides an excellent alternative treatment approach.

Computed tomographic scan evaluation of pulmonary blastomycosis

BACKGROUND

Blastomycosis is an uncommon granulomatous pulmonary and extrapulmonary infectious disease caused by the thermally dimorphic fungus Blastomyces dermatitidis. Diagnosis may be delayed or difficult because of varied presentation. The characteristics of blastomycosis on computed tomographic (CT) scan of the chest are not well characterized.

METHODS

The images from 34 chest CT scans from patients with confirmed pulmonary blastomycosis were retrospectively reviewed.

RESULTS

The most common CT findings were air bronchograms in 22 patients (65%), consolidation in 21 patients (62%), nodules (smaller than 3 cm) in 21 patients (62%) and lymph node enlargement (mediastinal and hilar nodes combined) in 12 patients (35%). Only four patients (12%) had a miliary pattern.

CONCLUSIONS

A specific abnormality characteristic of pulmonary blastomycosis was not identified on CT scanning. The diagnosis can only be made in the context of a high index of clinical suspicion with histological or culture confirmation.

Aspergillus fumigatus stimulates the NLRP3 inflammasome through a pathway requiring ROS production and the Syk tyrosine kinase

Invasive aspergillosis (IA) is a life-threatening disease that occurs in immunodepressed patients when infected with Aspergillus fumigatus. This fungus is the second most-common causative agent of fungal disease after Candida albicans. Nevertheless, much remains to be learned about the mechanisms by which A. fulmigatus activates the innate immune system. We investigated the inflammatory response to conidia and hyphae of A. fumigatus and specifically, their capacity to trigger activation of an inflammasome. Our results show that in contrast to conidia, hyphal fragments induce NLRP3 inflammasome assembly, caspase-1 activation and IL-1β release from a human monocyte cell line. The ability of Aspergillus hyphae to activate the NLRP3 inflammasome in the monocytes requires K⁺ efflux and ROS production. In addition, our data show that NLRP3 inflammasome activation as well as pro-IL-1β expression relies on the Syk tyrosine kinase, which is downstream from the pathogen recognition receptor Dectin-1, reinforcing the importance of Dectin-1 in the innate immune response against fungal infection. Furthermore, we show that treatment of monocytes with corticosteroids inhibits transcription of the gene encoding IL-1β. Thus, our data demonstrate that the innate immune response against A. fumigatus infection involves a two step activation process, with a first signal promoting expression and synthesis of pro-IL-1β; and a second signal, involving Syk-induced activation of the NLRP3 inflammasome and caspase-1, allowing processing and secretion of the mature cytokine.

Isolated gastrointestinal histoplasmosis: case report and review of the literature

The usual manifestation of histoplasmosis is in the form of respiratory illness. We report the case of a 67-year-old man who presented with chronic diarrhea and did not respond to the conventional treatment, including that for Clostridium difficile. He was found to have isolated colonic histoplasmosis infection, which was treated with itraconazole. There was no evidence of any disseminated disease. His only immunocompromised state was end-stage renal disease, for which he was on chronic hemodialysis. Although it is well documented as a part of disseminated histoplasmosis, our extensive review of the literature did not reveal any reported case of isolated colonic histoplasmosis in a patient on hemodialysis.

Epidemiology and clinical spectrum of blastomycosis diagnosed at Manitoba hospitals

Blastomyces dermatitidis is a dimorphic fungus endemic to Canada and the United States. Few reports regarding blastomycosis in Canada have been published. We retrospectively reviewed the medical charts of 143 patients with confirmed cases of blastomycosis diagnosed in hospitals in Manitoba, Canada, from 1988 through 1999. The annual incidence rate of blastomycosis in Manitoba was 0.62 cases per 100,000 population, compared with 7.11 cases per 100,000 population in the Kenora, Ontario district. The average age of patients was 38.0 years, and males accounted for 65.0% of cases. An increased incidence of blastomycosis was observed in the Aboriginal subpopulation. Organ systems involved were as follows: respiratory system (93.0% of cases), skin (21.0%), bone (13.3%), genitourinary tract (1.4%), and the central nervous system (1.4%); 6.3% of patients died, and death was associated with a short clinical course. This study provides a summary of the current status of blastomycosis in this area of endemicity in Canada.

Involvement of CD14 and toll-like receptors in activation of human monocytes by Aspergillus fumigatus hyphae

Invasive fungal infections represent an increasing problem associated with high mortality. The present study was undertaken to identify leukocyte subsets that are activated by hyphal fragments in a whole-human-blood model, as well as to examine the involvement of CD14 and Toll-like receptors (TLRs) in activation of monocytes by hyphae. Incubation of whole human blood with hyphal fragments from Aspergillus fumigatus and Scedosporium prolificans for 6 h caused induction of mRNAs for tumor necrosis factor alpha (TNF-alpha), interleukin-1beta (IL-1beta), and IL-6 in T cells, B cells, and monocytes, but not in granulocytes, as analyzed by reverse transcription-PCR with mRNA isolated from very pure populations of these leukocyte subsets. In primary adherent human monocytes, induction of TNF-alpha by hyphal fragments was dependent on plasma. Heat treatment of plasma at 56 degrees C for 30 min strongly reduced the ability of plasma to prime for activation. Pretreatment of human monocytes with different concentrations (1, 3, and 10 microg/ml) of monoclonal antibody (MAb) HTA125 (anti-TLR4) or MAb 18D11 (anti-CD14) for 30 min inhibited the release of TNF-alpha induced by hyphal fragments in a dose-dependent manner. Maximal inhibitions of 35 and 70% were obtained with 10 microg of HTA125 and 18D11 per ml, respectively. In contrast, pretreatment with MAb TL2.1 (anti-TLR2) did not affect signaling induced by hyphae. Pretreatment with the lipid A antagonist B975 blocked lipopolysaccharide signaling but did not inhibit TNF-alpha production induced by hyphal fragments. Our results suggest that T cells, B cells, and monocytes are involved in the innate immune response to invasive fungal pathogens and that serum components are relevant for activation of monocytes by hyphae. CD14 and TLR4 may be involved in signaling of Aspergillus hyphae in monocytes, but further studies to elucidate this issue are warranted.

Fungal infections of the central nervous system

This review discusses a practical approach to the patient with possible fungal infection of the central nervous system (CNS). Difficulties in establishing the diagnosis come from the nonspecific clinical syndromes (subacute meningitis, meningoencephalitis, and brain abscess) and the low isolation rate of fungi from cerebrospinal fluid (CSF). Helpful diagnostic clues often come from knowledge of the patient's geographic travels, risk factors, evidence of systemic organ infection, and fungal serologic tests. Standard and new antifungal agents are evaluated and the initial and suppressive drug management of the common fungal infections is presented.

Invasive aspergillosis in systemic lupus erythematosus

Invasive aspergillosis is seldomly described in systemic lupus erythematosus. We present two cases of aspergillosis and review 21 cases reported between 1957 and 1994. The typical clinical presentation is fever and cough in a hospitalized SLE patient previously treated with corticosteroids, immunosuppressors, and broad-spectrum antibiotics. Unlike aspergillosis in other conditions, granulocytopenia is uncommon. Chest radiographs show diffuse or patchy infiltration of lung fields. Diagnosis was suspected premortem in 2 patients. Aspergillus fumigatus was identified or isolated in sputum or parenchimal tissues in the majority of cases. Twenty-two patients died (95%). The finding of hyphae in the sputum of a systemic lupus erythematosus patient with a suggestive clinical picture should lead to bronchoscopy, bronchoalveolar lavage, and lung biopsy. Proof of diagnosis will come from the demonstration of hyphae in tissues and isolation of aspergillus from tissue cultures. Long-term therapy with amphotericin B alone or in combination with fluorocytosine or itraconazole may help improve survival.

Therapy of invasive aspergillosis with itraconazole: improvement of therapeutic efficacy by early diagnosis

We report on the treatment of invasive aspergillosis with the new triazole antimycotic agent itraconazole. All 11 patients suffered from pulmonary invasive aspergillosis. Two patients also had cerebral aspergillosis; in one of these patients the paranasal sinuses were also invaded. Underlying diseases were acute lymphoblastic leukaemia (n = 3), acute myeloid leukaemia (n = 4); one patient underwent allogeneic bone marrow transplantation before he developed aspergillosis; another was transplanted after successful aspergillosis treatment, liver cirrhosis (n = 1), lung infarction after pulmonary embolism (n = 1), chronic bronchitis after pulmonary tuberculosis (n = 1) and AIDS (n = 1). In five cases initial diagnosis was established by means of mycological methods and clinical signs. In six patients invasive pulmonary aspergillosis was initially diagnosed due to the clinical criteria presented in this paper. Secondary mycological confirmation after onset of therapy was achieved in five out of these six patients. All of the patients initially responded to therapy. One female patient experienced a relapse of aspergillosis and died of cerebral involvement and relapsing leukaemia. Two further patients died due to underlying diseases (pulmonary embolism, relapsing leukaemia). Nine patients (82%) were cured of the mycosis, including the patient with cerebral involvement; two underwent surgical resection of residual pulmonary lesions. Itraconazole is a very effective drug for treatment of invasive aspergillosis. Therapeutic efficacy can be optimized by early diagnosis using clinical criteria and prompt start of treatment.