Mycology, pathogenesis, and epidemiology of blastomycosis
- Robert W Bradsher, Jr, MD
Robert W Bradsher, Jr, MD
- Professor of Medicine
- University of Arkansas for Medical Sciences
Blastomycosis is a systemic pyogranulomatous infection, primarily involving the lungs, that arises after inhalation of the conidia of Blastomyces dermatitidis. Blastomycosis of the lung can be an asymptomatic infection or can manifest as acute or chronic pneumonia. Hematogenous dissemination frequently occurs; extrapulmonary disease of the skin, bones, and genitourinary system is common, but almost any organ can be infected.
The basic mycology, pathogenesis, and epidemiology of blastomycosis will be reviewed here. The clinical manifestations and treatment of blastomycosis are discussed separately. (See "Clinical manifestations and diagnosis of blastomycosis" and "Treatment of blastomycosis".)
Phylogenetic analysis of 78 clinical and environmental isolates of B. dermatitidis from different geographic regions has revealed two distinct species of the fungus, B. dermatitidis and B. gilchristii . B. gilchristii was isolated from two North American locations known to be hyperendemic for blastomycosis, the Kenora region of Ontario and the Eagle River region of Wisconsin. There is speculation as to whether the high rates of infection in these areas might be due to B. gilchristii being a more pathogenic species or whether favorable environmental factors allowed emergence of this species.
The natural habitat of 169 strains of organisms collected from various geographic areas were examined with 25 microsatellite loci for phylogeographic analysis . B. gilchristii strains were found only in isolates from Canada and some northern states in the US, while B. dermatitidis were from those same locations, plus along the Mississippi River drainage system and in southeastern states. Both were closely linked to freshwater drainage systems, and the diversity was speculated to have begun with receding glaciers covering much of North America in the Pleistocene epoch .
Clinically, the organisms appear to cause similar clinical illness and will be referred to as B. dermatitidis hereafter. B. dermatitidis refers to both the sexual and asexual stage of the organism. Previously, Ajellomyces dermatitidis was the name of the sexual stage of the organism, and B. dermatitidis was the name for the asexual state of the organism. Production of a sexual spore requires fusion of the nucleus of a positive type with a negative, the so-called heterothallic property; both mating types are equally capable of causing infection .To continue reading this article, you must log in with your personal, hospital, or group practice subscription. For more information on subscription options, click below on the option that best describes you:
- Brown EM, McTaggart LR, Zhang SX, et al. Phylogenetic analysis reveals a cryptic species Blastomyces gilchristii, sp. nov. within the human pathogenic fungus Blastomyces dermatitidis. PLoS One 2013; 8:e59237.
- McTaggart LR, Brown EM, Richardson SE. Phylogeographic Analysis of Blastomyces dermatitidis and Blastomyces gilchristii Reveals an Association with North American Freshwater Drainage Basins. PLoS One 2016; 11:e0159396.
- McDonough ES, Lewis AL. Blastomyces dermatitidis: production of the sexual stage. Science 1967; 156:528.
- Kaufman L, Standard PG, Weeks RJ, Padhye AA. Detection of two Blastomyces dermatitidis serotypes by exoantigen analysis. J Clin Microbiol 1983; 18:110.
- Axtell RC, Scalarone GM. Serological differences in two Blastomyces dermatitidis isolates from different geographical regions of North America. Mycopathologia 2002; 153:141.
- Axtell RC, Scalarone GM. Serological differences in three Blastomyces dermatitidis strains. Mycoses 2002; 45:437.
- Abuodeh RO, Chester EM, Scalarone GM. Comparative serological evaluation of 10 Blastomyces dermatitidis yeast phase lysate antigens from different sources. Mycoses 2004; 47:143.
- Kaufman L, Standard PG. Specific and rapid identification of medically important fungi by exoantigen detection. Annu Rev Microbiol 1987; 41:209.
- Stockman L, Clark KA, Hunt JM, Roberts GD. Evaluation of commercially available acridinium ester-labeled chemiluminescent DNA probes for culture identification of Blastomyces dermatitidis, Coccidioides immitis, Cryptococcus neoformans, and Histoplasma capsulatum. J Clin Microbiol 1993; 31:845.
- Nemecek JC, Wüthrich M, Klein BS. Global control of dimorphism and virulence in fungi. Science 2006; 312:583.
- Drutz DJ, Frey CL. Intracellular and extracellular defenses of human phagocytes against Blastomyces dermatitidis conidia and yeasts. J Lab Clin Med 1985; 105:737.
- Rooney PJ, Sullivan TD, Klein BS. Selective expression of the virulence factor BAD1 upon morphogenesis to the pathogenic yeast form of Blastomyces dermatitidis: evidence for transcriptional regulation by a conserved mechanism. Mol Microbiol 2001; 39:875.
- DISALVO AF, DENTON JF. LIPID CONTENT OF FOUR STRAINS OF BLASTOMYCES DERMATITIDIS OF DIFFERENT MOUSE VIRULENCE. J Bacteriol 1963; 85:927.
- Cox RA, Best GK. Cell wall composition of two strains of Blastomyces dermatitidis exhibiting differences in virulence for mice. Infect Immun 1972; 5:449.
- Brandhorst TT, Wüthrich M, Warner T, Klein B. Targeted gene disruption reveals an adhesin indispensable for pathogenicity of Blastomyces dermatitidis. J Exp Med 1999; 189:1207.
- Klein BS, Newman SL. Role of cell-surface molecules of Blastomyces dermatitidis in host-pathogen interactions. Trends Microbiol 1996; 4:246.
- Rooney PJ, Klein BS. Sequence elements necessary for transcriptional activation of BAD1 in the yeast phase of Blastomyces dermatitidis. Eukaryot Cell 2004; 3:785.
- Newman SL, Chaturvedi S, Klein BS. The WI-1 antigen of Blastomyces dermatitidis yeasts mediates binding to human macrophage CD11b/CD18 (CR3) and CD14. J Immunol 1995; 154:753.
- Hogan LH, Josvai S, Klein BS. Genomic cloning, characterization, and functional analysis of the major surface adhesin WI-1 on Blastomyces dermatitidis yeasts. J Biol Chem 1995; 270:30725.
- Wüthrich M, Warner T, Klein BS. IL-12 is required for induction but not maintenance of protective, memory responses to Blastomyces dermatitidis: implications for vaccine development in immune-deficient hosts. J Immunol 2005; 175:5288.
- Wüthrich M, Filutowicz HI, Klein BS. Mutation of the WI-1 gene yields an attenuated blastomyces dermatitidis strain that induces host resistance. J Clin Invest 2000; 106:1381.
- Meece JK, Anderson JL, Gruszka S, et al. Variation in clinical phenotype of human infection among genetic groups of Blastomyces dermatitidis. J Infect Dis 2013; 207:814.
- Cozad GC, Chang CT. Cell-mediated immunoprotection in blastomycosis. Infect Immun 1980; 28:398.
- Morozumi PA, Brummer E, Stevens DA. Protection against pulmonary blastomycosis: correlation with cellular and humoral immunity in mice after subcutaneous nonlethal infection. Infect Immun 1982; 37:670.
- Brummer E, Morozumi PA, Vo PT, Stevens DA. Protection against pulmonary blastomycosis: adoptive transfer with T lymphocytes, but not serum, from resistant mice. Cell Immunol 1982; 73:349.
- Klein BS, Sondel PM, Jones JM. WI-1, a novel 120-kilodalton surface protein on Blastomyces dermatitidis yeast cells, is a target antigen of cell-mediated immunity in human blastomycosis. Infect Immun 1992; 60:4291.
- Bradsher RW. Live Blastomyces dermatitidis yeast-induced responses of immune and nonimmune human mononuclear cells. Mycopathologia 1984; 87:159.
- Klein BS, Bradsher RW, Vergeront JM, Davis JP. Development of long-term specific cellular immunity after acute Blastomyces dermatitidis infection: assessments following a large point-source outbreak in Wisconsin. J Infect Dis 1990; 161:97.
- Klein BS, Vergeront JM, Davis JP. Epidemiologic aspects of blastomycosis, the enigmatic systemic mycosis. Semin Respir Infect 1986; 1:29.
- Saccente M, Woods GL. Clinical and laboratory update on blastomycosis. Clin Microbiol Rev 2010; 23:367.
- Klein BS, Aizenstein BD, Hogan LH. African strains of Blastomyces dermatitidis that do not express surface adhesin WI-1. Infect Immun 1997; 65:1505.
- Carlos WG, Rose AS, Wheat LJ, et al. Blastomycosis in indiana: digging up more cases. Chest 2010; 138:1377.
- Roy M, Benedict K, Deak E, et al. A large community outbreak of blastomycosis in Wisconsin with geographic and ethnic clustering. Clin Infect Dis 2013; 57:655.
- Seitz AE, Younes N, Steiner CA, Prevots DR. Incidence and trends of blastomycosis-associated hospitalizations in the United States. PLoS One 2014; 9:e105466.
- Klein BS, Vergeront JM, Weeks RJ, et al. Isolation of Blastomyces dermatitidis in soil associated with a large outbreak of blastomycosis in Wisconsin. N Engl J Med 1986; 314:529.
- Klein BS, Vergeront JM, DiSalvo AF, et al. Two outbreaks of blastomycosis along rivers in Wisconsin. Isolation of Blastomyces dermatitidis from riverbank soil and evidence of its transmission along waterways. Am Rev Respir Dis 1987; 136:1333.
- Baumgardner DJ, Laundre B. Studies on the molecular ecology of Blastomyces dermatitidis. Mycopathologia 2001; 152:51.