Infectious Disease Compendium

Blastomyces dermatitidis

Microbiology

A fungus. There are two genetic groups, 1 and 2, with different disease predilections.

Epidemiologic Risks

Found in the Mississippi river valley, Ohio river valley and the St. Lawrence Seaway. It is also in the mountains of Tennessee (PubMed). Usually people need to have their nose down in the dirt to acquire the disease; it is a bigger problem in dogs. There was an urban outbreak in Indianapolis due to summer roadwork kicking up dirt (PubMed).

There are case reports of disease acquired in Asia and the Middle East: 1 each from Israel and Saudi Arabia, and 4 from northern India.

There may be an ethnic predisposion as the was an outbreak amoung the Hmong (PubMed). Say amoung the Hmong three times real fast.

Recently found in New York (PubMed).

And a kinkojou bite, so don't go getting done bit by a kinkajou (PubMed). As if you know what a kinkajou is.

Like most fungal infections, the diagnosis is slow to be made as people do not consider it, even in endemic areas (Pubmed).

Syndromes

Often an asymptomatic pulmonary infection, it can disseminate to skin, bones, joints, prostate and epididymis commonly and anywhere uncommonly.

Group 1 are more likely to cause pulmonary infections with constitutional symptoms such as fever.

Group 2 are more likely to cause disseminated disease in older patient age with comorbidities (PubMed).

Treatment

See the IDSA guidelines.

Amphotericin B is preferred if they are sick, followed by itraconazole at 400 to 800 mg qd. From the guidelines

Pulmonary Blastomycosis

1. For moderately severe to severe disease, initial treatment with a lipid formulation of amphotericin B at a dosage of 3–5 mg/kg per day or amphotericin B deoxycholate at a dosage of 0.7–1 mg/kg per day for 1–2 weeks or until improvement is noted, followed by oral itraconazole, 200 mg 3 times per day for 3 days and then 200 mg twice per day, for a total of 6–12 months, is recommended.

2. For mild to moderate disease, oral itraconazole, 200 mg 3 times per day for 3 days and then once or twice per day for 6–12 months, is recommended

3. Serum levels of itraconazole should be determined after the patient has received this agent for at least 2 weeks, to ensure adequate drug exposure.

Disseminated Extrapulmonary Blastomycosis

4. For moderately severe to severe disease, lipid formulation amphotericin B, 3–5 mg/kg per day, or amphotericin B deoxycholate, 0.7–1 mg/kg per day, for 1–2 weeks or until improvement is noted, followed by oral itraconazole, 200 mg 3 times per day for 3 days and then 200 mg twice per day for a total of at least 12 months, is recommended.

5. For mild to moderate disease, oral itraconazole, 200 mg 3 times per day for 3 days and then once or twice per day for 6–12 months, is recommended

6. Patients with osteoarticular blastomycosis should receive a total of at least 12 months of antifungal therapy. 7. Serum levels of itraconazole should be determined after the patient has received this agent for at least 2 weeks, to ensure adequate drug exposure.

CNS Blastomycosis

8. Amphotericin B, given as a lipid formulation at a dosage of 5 mg/ kg per day over 4–6 weeks followed by an oral azole, is recommended. Possible options for azole therapy include fluconazole, 800 mg per day, itraconazole, 200 mg 2 or 3 times per day, or voriconazole, 200–400 mg twice per day, for at least 12 months and until resolution of CSF abnormalities. Perhaps voriconazole is preferred (PubMed).

Treatment for Immunosuppressed Patients with Blastomycosis

9. Amphotericin B, given as a lipid formulation, 3–5 mg/kg per day, or amphotericin B deoxycholate, 0.7–1 mg/kg per day, for 1–2 weeks or until improvement is noted, is recommended as initial therapy for patients who are immunosuppressed, including those with AIDS.

10. Itraconazole, 200 mg 3 times per day for 3 days and then twice per day, is recommended as step-down therapy after the patient has responded to initial treatment with amphotericin B and should be given to complete a total of at least 12 months of therapy.

11. Serum levels of itraconazole should be determined after the patient has received this agent for at least 2 weeks, to ensure adequate drug exposure.

12. Lifelong suppressive therapy with oral itraconazole, 200 mg per day, may be required for immunosuppressed patients if immunosuppression cannot be reversed and in patients who experience relapse despite appropriate therapy.

Treatment for Blastomycosis in Pregnant Women

13. During pregnancy, lipid formulation amphotericin B, 3–5 mg/ kg per day, is recommended. Azoles should be avoided because of possible teratogenicity. ...

17. Serum levels of itraconazole should be determined after the patient has received this agent for at least 2 weeks, to ensure adequate drug exposure.

Notes

In disseminated disease with MOSF and shock, there is one case where steroids were a help (PubMed). As if one case tells you anything.