A new Dimorphic Fungus causing Disseminated Infection in AIDS Patients in South Africa
Abstract & Commentary
By Dean L. Winslow, MD, FACP, FIDSA
Clinical Professor of Medicine and Pediatrics Division of Infectious Diseases and Geographic Medicine, Stanford University School of Medicine, Associate Editor of Infectious Disease Alert
Dr. Winslow is a consultant for Siemens Diagnostic.
SYNOPSIS: Between 2008 and 2011 surveillance at hospitals in Capetown revealed 24 cases of dimorphic fungal infection, 13 of which were shown to be caused by Emmonsia species. All 13 patients had advanced HIV infection.
SOURCE: Kenyon C, et al. A dimorphic fungus causing disseminated infection in South Africa. New Engl J Med 2013;369:1416-24.
Between July 2008 and July 2011 enhanced surveillance was conducted to identify the cause of systemic dimorphic fungal infections in patients presenting to Groote Schuur and affiliated hospitals in Capetown, South Africa. A total of 24 cases of dimorphic fungal infection were diagnosed during this time, of which 13 were subsequently shown to be due to Emmonsia species. All patients were HIV-infected and their median CD4+ lymphocyte count was 16 cells/uL. All 13 patients had evidence of disseminated fungal disease with fever, anemia and prominent skin lesions. The skin lesions included erythematous papules and plaques, to ulcers and crusted, boggy plaques. 5/11 patients had emmonsia isolated from blood cultures and 9/9 patients had the organism isolated from skin biopsies.
Three patients died soon after presentation. The remaining patients generally exhibited a favorable response to treatment with an initial 14 day course of amphotericin B deoxycholate 1 mg/kg/day followed by maintenance therapy with itraconazole. Patients were also started on ART if they were not already receiving ART at the time of diagnosis.
The isolated organism showed mycelial phase growth at 25 deg. C. and yeast phase growth at 37 deg. C. Phylogenetic analysis of 5 genes amplified by PCR revealed that this fungus belongs to the genus Emmonsia and is most closely related to E.pasteuriana.
The genus Emmonsia has included 3 species associated with human disease. E.crescens and E.parva are the agents which cause adiaspiromycosis (a pulmonary disease of small mammals and occasionally of humans). E.pasteuriana had previously been described in a single human case of an Italian patient with late stage AIDS.
The recognition of this "new" pathogen undoubtedly reflects the power of broad-range PCR to identify many pathogens. It is of note that many of these 13 patients subsequently shown to have systemic infection with Emmonsia were originally felt to have disseminated histoplasmosis. Since the institution of routine use of broad-range PCR to identify fungal pathogens, the diagnosis of histoplasmosis has declined and emmonsia infection has increased in proportion in patients in the Groote Schuur hospital system.
This is an important report for clinicians caring for patients in sub-Saharan Africa. So now we can add Emmonsia to the list of dimorphic fungi which can cause human disease.