Blastomycosis in the mountainous region of northeast Tennessee

Central nervous system blastomycosis clinical characteristics and outcomes

Blastomycosis is a local or systemic infection, caused by Blastomyces dermatitidis (B. dermatitidis) or B. gilchristii. Blastomycosis has been described as "the great pretender," alluding to the fact that it manifests in a wide range of symptoms and disease severity. Central nervous system (CNS) involvement, although rare, carries significant mortality. Due to the limited published reports of CNS blastomycosis, we present an updated cohort with eight cases of proven or probable CNS blastomycosis describing presentation, diagnosis, treatment and outcomes. Headache was the most common presenting symptom. Magnetic resonance imaging (MRI) proved to be the superior imaging study. All patients in our cohort were diagnosed by histopathological staining or cultures of tissue or fluid obtained from CNS or extra-CNS lesions. All patients that received treatment with Liposomal amphrotericin B for at least 10 days followed by a prolonged azole therapy did not have relapse. Two patients with late diagnoses died during hospitalization. Our findings confirm the importance of timely diagnosis and treatment of CNS blastomycosis to improve outcomes especially with an azole that have a high CNS penetration and a good intrinsic activity for B. dermatitidis such as voriconazole.

Mortality associated with Blastomyces dermatitidis infection: A systematic review of the literature and meta-analysis

Published case fatality in blastomycosis patients ranges between 4% and 78%. This study aimed to assess mortality associated with blastomycosis and identify its associated risk factors. We conducted a systematic review of publications related to Blastomyces dermatitidis available in PubMed and Scopus databases. Studies that reported data on blastomycosis mortality and that were published from inception through February 2018 were assessed and included in the analysis. Using the R meta package, a random-effect model meta-analysis was used to calculate pooled and stratified estimates of case-fatality proportions and risk ratios. Of 1553 publications, we included 20 studies reporting on a total of 2820 cases of blastomycosis between 1970 and 2014 and three case series reports with 10, 21, and 36 patients. The mean or median ages ranged from 28 to 59 years. Mortality was defined as attributable mortality caused by blastomycosis in 13 studies. Among 14 studies with a standard error ≤0.05, the overall pooled mortality was 6.6% (95% confidence interval [CI], 4.9-8.2) with 57% heterogeneity. The mortality rate was 37% (95% CI, 23-51) in immunocompromised patients and 75% (95% CI, 53-96) in patients who developed an acute respiratory distress syndrome (ARDS) (n = 3 studies each). ARDS was the only identified risk factor in general patients (risk ratio = 10.2). The overall mortality was significantly higher in studies involving immunocompromised patients and ARDS patients. Our analysis showed considerable heterogeneity among studies. Inconsistent mortality definitions may have contributed to the observed heterogeneity. Further research is needed to assess potential risk factors for mortality.

Re-drawing the Maps for Endemic Mycoses

Endemic mycoses such as histoplasmosis, coccidioidomycosis, blastomycosis, paracoccidioidomycosis, and talaromycosis are well-known causes of focal and systemic disease within specific geographic areas of known endemicity. However, over the past few decades, there have been increasingly frequent reports of infections due to endemic fungi in areas previously thought to be “non-endemic.” There are numerous potential reasons for this shift such as increased use of immune suppressive medications, improved diagnostic tests, increased disease recognition, and global factors such as migration, increased travel, and climate change. Regardless of the causes, it has become evident that our previous understanding of endemic regions for these fungal diseases needs to evolve. The epidemiology of the newly described Emergomyces is incomplete; our understanding of it continues to evolve. This review will focus on the evidence underlying the established areas of endemicity for these mycoses as well as new data and reports from medical literature that support the re-thinking these geographic boundaries. Updating the endemic fungi maps would inform clinical practice and global surveillance of these diseases.

Blastomycosis in Indiana: Clinical and Epidemiologic Patterns of Disease Gleaned from a Multicenter Retrospective Study

BACKGROUND

To better understand clinical and epidemiologic patterns of blastomycosis, we report on a large series of blastomycosis in Indiana.

METHODS

All microbiologically and histopathologically confirmed cases of blastomycosis from four hospitals serving Central Indiana from 1985 to 2014 were identified. Available data were collected. Data on population estimates, annual precipitation, and construction in Indiana were evaluated for correlations with incidence rates of blastomycosis.

RESULTS

A total of 114 patients were identified. The mean age was 44.4 years; 27% had diabetes mellitus, and 16% were immunosuppressed. Most presented with pneumonia (90%); 48% had extrapulmonary disease (CNS involvement in 9%), and 15% developed ARDS. Cultures, cytopathology, and histopathology were positive in 86%, 27%, and 85% of the sample, respectively, and fungal antigen was positive in 76%. Amphotericin B was administered in 49%, and 87% received an azole. Total mortality was 12%. Immunosuppression (OR = 3.0), diabetes mellitus (OR = 2.9), and multilobar pneumonia (OR = 2.9) were associated with increased likelihood of ICU admission. There was a significant increase in incidence over time in Marion County. There was no correlation with amount of precipitation, but the rise in incidence coincided with a 2005 state initiative to expand Indiana's highway infrastructure.

CONCLUSIONS

The incidence of blastomycosis in Central Indiana may be on the rise. Physicians in endemic areas should be aware of the potentially fulminant consequences of the disease.

Peritonitis caused by Blastomyces dermatitidis in a kidney transplant recipient: case report and literature review

Blastomyces dermatitidis is a dimorphic fungus endemic to the midwestern, south-central, and southeastern United States known to cause disseminated infection in immunocompromised individuals. We report a case of B. dermatitidis peritonitis in a renal allograft recipient with new-onset ascites and cytomegalovirus encephalitis. Peritoneal blastomycosis is a rare clinical entity and, to our knowledge, this patient represents the first known case of peritoneal blastomycosis in a solid organ transplant recipient. We review the clinical characteristics of B. dermatitidis peritonitis as well as the literature on fungal peritonitis with emphasis on dimorphic fungal pathogens. Clinical features suggestive of fungal peritonitis include new-onset ascites, abdominal pain, and fevers, especially with antecedent or concomitant pneumonia. A high index of clinical suspicion, along with the use of culture and non-culture diagnostics, is needed for early diagnosis and prompt initiation of therapy.

Phylogenetic analysis reveals a cryptic species Blastomyces gilchristii, sp. nov. within the human pathogenic fungus Blastomyces dermatitidis

Background

Analysis of the population genetic structure of microbial species is of fundamental importance to many scientific disciplines because it can identify cryptic species, reveal reproductive mode, and elucidate processes that contribute to pathogen evolution. Here, we examined the population genetic structure and geographic differentiation of the sexual, dimorphic fungus Blastomyces dermatitidis, the causative agent of blastomycosis.

Methodology/Principal Findings

Criteria for Genealogical Concordance Phylogenetic Species Recognition (GCPSR) applied to seven nuclear loci (arf6, chs2, drk1, fads, pyrF, tub1, and its-2) from 78 clinical and environmental isolates identified two previously unrecognized phylogenetic species. Four of seven single gene phylogenies examined (chs2, drk1, pyrF, and its-2) supported the separation of Phylogenetic Species 1 (PS1) and Phylogenetic Species 2 (PS2) which were also well differentiated in the concatenated chs2-drk1-fads-pyrF-tub1-arf6-its2 genealogy with all isolates falling into one of two evolutionarily independent lineages. Phylogenetic species were genetically distinct with interspecific divergence 4-fold greater than intraspecific divergence and a high Fst value (0.772, P<0.001) indicative of restricted gene flow between PS1 and PS2. Whereas panmixia expected of a single freely recombining population was not observed, recombination was detected when PS1 and PS2 were assessed separately, suggesting reproductive isolation. Random mating among PS1 isolates, which were distributed across North America, was only detected after partitioning isolates into six geographic regions. The PS2 population, found predominantly in the hyper-endemic regions of northwestern Ontario, Wisconsin, and Minnesota, contained a substantial clonal component with random mating detected only among unique genotypes in the population.

Conclusions/Significance

These analyses provide evidence for a genetically divergent clade within Blastomyces dermatitidis, which we use to describe a novel species, Blastomyces gilchristii sp. nov. In addition, we discuss the value of population genetic and phylogenetic analyses as a foundation for disease surveillance, understanding pathogen evolution, and discerning phenotypic differences between phylogenetic species.

Role of histology in the diagnosis of infectious causes of granulomatous lung disease

PURPOSE OF REVIEW

Histologic examination and microbiologic cultures are the gold standards for the diagnosis of infectious granulomatous lung diseases. Although biopsies require invasive procedures, they often yield information that cannot be obtained by other methods. The aims of this article are to outline the major infections that cause granulomatous inflammation in the lung and to familiarize clinicians with the utility of histologic examination in their diagnosis.

RECENT FINDINGS

The histopathologic features of acute pulmonary histoplasmosis and granulomatous Pneumocystis pneumonia have been described in detail, the relative contributions of histology and microbiologic cultures in the diagnosis of blastomycosis have been delineated, and Cryptococcus gattii has emerged as a significant cause of granulomatous pulmonary nodules.

SUMMARY

The major infectious causes of granulomatous lung disease are mycobacteria and fungi. Histologic examination is particularly important in the diagnosis of pulmonary granulomatous infections when clinical, radiologic and serologic findings are nonspecific. Histology and microbiology play complementary but distinct roles in diagnosis. For organisms that grow slowly in cultures, histology has the additional advantage of being able to provide a rapid diagnosis.

Blastomycosis in indiana: digging up more cases

BACKGROUND

The endemic region of blastomycosis historically has included the state of Indiana. However, few published reports of blastomycosis exist to substantiate this distinction. A surge of patients with blastomycosis in central Indiana (Indianapolis and surrounding counties) beginning in 2005 prompted us to review our local experience. We propose that this surge was related to major highway construction around Indianapolis.

METHODS

We reviewed all microbiologically confirmed cases from four hospitals serving central Indiana. Chart review was completed for adult patients, and data were collected on clinical presentations, methods of diagnosis, comorbidities, radiologic findings, treatment, and outcomes. We plotted patient residence addresses with sites of highway construction.

RESULTS

Fifty-nine patients were identified from laboratory results and physician referral. Interestingly, a surge of blastomycosis incidence occurred in 34 patients between 2005 and 2008 during which time major highway projects were under way around the Indianapolis metropolitan area. The majority of these patients presented acutely and with pulmonary involvement. Fungal culture and antigen testing were the most sensitive means to diagnosis. Antifungal therapy was highly effective.

CONCLUSIONS

This urban outbreak of blastomycosis in Indianapolis should prompt clinicians to consider blastomycosis in this highly endemic area of histoplasmosis.