Physical Address

304 North Cardinal St.
Dorchester Center, MA 02124

Pneumocystis Species

Pneumocystis was discovered in 1909 in Brazil by Carlos Chagas, who mistakenly interpreted the organism as a trypanosome. In 1912 Pierre and Eugénie Delanöe, in Paris, identified Pneumocystis as a separate genus and species and named the organism in honor of Antonio Carini, another researcher. Pneumocystis first came to medical attention when in the 1940s–50s it was identified as the cause of interstitial plasma cell pneumonia…

Uncommon Fungi and Related Species

Scedosporium Apiospermum ( Pseudallescheria Boydii ) Species Complex In humans, infection with Scedosporium apiospermum, Scedosporium boydii (formerly Pseudallescheria boydii ) and Scedosporium aurantiacum (collectively, the S. apiospermum species complex) can produce two distinct diseases: mycetoma and scedosporiosis (pseudallescheriasis). Mycetoma is a chronic subcutaneous infection characterized by the production of grains (see Chapter 261 ), whereas scedosporiosis includes all other infections caused by Scedosporium spp. The most…

Paracoccidioidomycosis

Description of the Pathogen Until 2006 the genus Paracoccidioides was thought to consist of a single species, P. brasiliensis, considered the sole etiologic agent of paracoccidioidomycosis. At present however, molecular and genetic studies have revealed that this genus includes a complex of five distinct phylogenetic species (S1a, S1b, PS2, PS3, PS4) that appear to be confined to distinct regions within the endemic zones. Recently, the P.…

Dermatophytosis (Ringworm) and Other Superficial Mycoses

The superficial fungal infections include some of the most common infectious conditions, such as ringworm, tinea corporis, and pityriasis versicolor, and rare disorders such as tinea nigra. Their prevalence varies in different parts of the world, but in many tropical countries they are the most common causes of skin disease. Dermatophyte infections and other superficial mycoses are described in this chapter. Superficial candidiasis is discussed in…

Coccidioidomycosis ( Coccidioides Species)

Although the systemic fungal infection now known as coccidioidomycosis has been recognized for more than a century, its endemic domains continue to be expanded. A medical intern is credited with first identifying in 1892 a patient who had widespread disease. Organisms seen microscopically were mistakenly thought to be parasites, and only several years later was the true mycotic etiology determined and the agent given the name…

Blastomycosis

Revised October 30, 2020 The etiologic agents of blastomycosis belong to a group of fungi that are characterized by thermal dimorphism. Advances in genomics and phylogenetics have expanded the number of Blastomyces species to include B. dermatitidis, B. gilchristii, B. percursus , B. helicus, B. parvus, and B. silverae . Infection is primarily acquired through the inhalation of infectious conidia and hyphal fragments following the disruption…

Histoplasma capsulatum (Histoplasmosis)

Histoplasma capsulatum is one of the more common causes of infection in the US Midwest and Southeast. Histoplasmosis, acquired through inhalation of mycelial fragments and microconidia, is most often self-limiting but can cause potentially lethal infection in patients with preexisting conditions. It remains a frequent cause of opportunistic infection in patients whose immune system is impaired by pharmaceutic agents or by the human immunodeficiency virus (HIV).…

Cryptococcosis ( Cryptococcus neoformans and Cryptococcus gattii )

Cryptococcus neoformans and Cryptococcus gattii are encapsulated, heterobasidiomycetous fungi that have progressed from being rare human pathogens, with just over 300 cases of cryptococcosis reported in the literature before 1955, to becoming a common worldwide opportunistic pathogen as immunocompromised human populations have dramatically increased over the past 2 decades. Cryptococcosis crosses the entire spectrum of patient populations, from the apparently immunocompetent host without an underlying disease…

Agents of Mycetoma

Mycetoma is a chronic progressive granulomatous infection of the skin and subcutaneous tissue most often affecting the lower extremities, typically a single foot. The disease is unique from other cutaneous or subcutaneous diseases in its triad of localized swelling, underlying sinus tracts, and production of grains or granules (composed of aggregations of the causative organism) within the sinus tracts. These infections may be caused by fungi…

Agents of Chromoblastomycosis

Chromoblastomycosis (chromomycosis) is a chronic, localized fungal infection of the skin and subcutaneous tissue that produces raised scaly lesions, usually of the lower extremities. The lesions of chromoblastomycosis are frequently warty or cauliflower-like in appearance, with pathognomonic muriform cells (also called “copper penny” or sclerotic bodies) found at histologic examination. This disease of tropical and subtropical distribution is produced by inoculation of the infecting fungi in…

Sporothrix schenckii

Mycology Sporothrix schenckii sensu lato (meaning in the broadest sense) is a dimorphic fungus that exists in a hyphal form in vitro at temperatures less than 37°C. Colonies are initially white but gradually become brown to black due to the production of pigmented conidia. In vivo or at 37°C on rich media such as brain heart infusion agar, the organism converts to an oval- or cigar-shaped…

Agents of Mucormycosis and Entomophthoramycosis

The disappearance of the class Zygomycetes from current taxonomy has made the term zygomycosis obsolete. The term zygomycosis encompassed both mucormycosis and entomophthoramycosis. These two infections are so different that no new name has been proposed to include both infections. Most of this chapter discusses mucormycosis, a group of filamentous fungi in the subphylum Mucoromycotina that belong to the order Mucorales. Mucorales can cause life-threatening infections…

Aspergillus Species

Revised August 7, 2021 Invasive aspergillosis (IA) remains a major cause of morbidity and mortality in the immunosuppressed population. This infection is caused by Aspergillus , a hyaline mold, and is responsible for a variety of noninvasive or semiinvasive conditions. These syndromes range from colonization, such as a fungus ball due to aspergillosis (also known as aspergilloma); allergic responses to Aspergillus , including allergic bronchopulmonary aspergillosis…

Candida Species

Revised April 26, 2022 Written descriptions of oral lesions that were probably thrush date to the time of Hippocrates and Galen. Langenbeck, in 1839, found fungi in oral lesions of a patient. In 1861, Zenker described the first well-documented case of deep-seated Candida. The first case of Candida -induced endocarditis was described in 1940. The most interesting period in the history of Candida infections began in…

Introduction to Mycoses

The advent of the human immunodeficiency virus epidemic and the ever-increasing use of immunosuppressive drugs has dramatically increased the incidence of deep mycoses and substantially broadened the range of fungi causing potentially lethal disease. Clinicians caring for highly immunosuppressed patients are rarely able to ignore a fungal isolate because the species is not “pathogenic.” An additional complication is that the rapidly moving field of diagnostic microbiology…

Agents of Actinomycosis

Actinomycosis is an indolent, slowly progressive infection caused by anaerobic or microaerophilic bacteria, primarily from the genus Actinomyces, that normally colonize the mouth, colon, and vagina. Disruption of mucosa may lead to infection of virtually any site. When the organisms invade tissue, they form tiny, sometimes visible clumps, called grains or “sulfur granules,” named for their yellow color. Lesions of actinomycosis are purulent foci surrounded by…

Nocardia Species

Nocardia is a genus of aerobic actinomycetes responsible for localized or disseminated infections in animals and humans. The genus is named after Edmond Nocard, who in 1888 described the isolation of an aerobic actinomycete from cattle with bovine farcy. The first human case of nocardiosis was reported by Eppinger in 1890. Cases of human disease have increased substantially in the past 2 decades, in association with…

Infections Caused by Nontuberculous Mycobacteria Other Than Mycobacterium avium Complex

Revised March 30, 2021 Overview The recent advances in mycobacterial culture techniques and the increasing utility of modern molecular techniques for identification of previously unidentified organisms have produced a major resurgence of interest in disease caused by the nontuberculous mycobacteria (NTM). In addition, there has been an increasing appreciation of the defects in lung structure and immune response that predispose to NTM. This group of mycobacteria…

Mycobacterium avium Complex

Mycobacterium avium complex (MAC) is the most common of all the nontuberculous mycobacteria (NTM) to cause human infection and pulmonary infection. MAC contains genetically diverse strains with different reservoirs and pathogenicity for humans. The three most common are M. avium, M. intracellulare, and M. chimaera. M. avium and M. intracellulare are often not microbiologically separated and are referred to as M. avium-intracellulare (MAI). Two major disease…