Blastomyces dermatitidis: Difference between revisions
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Blastomyces dermatitidis
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==Background== |
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= ''Blastomyces dermatitidis'' = |
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===Microbiology=== |
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*Broad-based dimorphic budding yeast |
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== Microbiology == |
|||
*Mold at 25-28ΒΊC and yeast at 37ΒΊC |
|||
*Branching hyphae 2-3 Β΅m in diameter and right-angle conidiophores resembling lollipops |
|||
**Conidia become airborne when disturbed |
|||
===Epidemiology=== |
|||
* Broad-based dimorphic budding yeast |
|||
* Mold at 25-28ΒΊC and yeast at 37ΒΊC |
|||
* Branching hyphae 2-3 Β΅m in diameter and right-angle conidiophores resembling lollipops |
|||
** Conidia become airborne when disturbed |
|||
[[File:Blastomycosis_map.png|thumb|Distribution of blastomycosis]] |
|||
== Epidemiology == |
|||
* |
*Present in the Mississippi, Ohio, and St. Lawrence River Valleys, the Great Lakes regions, and western Ontario[[CiteRef::ashraf2020re]] |
||
*May also be endemic to Africa and India[[CiteRef::ashraf2020re]], though it's unclear whether these are true cases or late reactivation |
|||
*Hosts include humans, dogs, cats, horses, brown bears, and exotic pets like the kinkajou and red ruffed lemur |
|||
*There have been point-source outbreaks associated with occupational and recreational activities, usually along streams or rivers enriched with decaying vegetation |
|||
*Possibly has cold-weather seasonality |
|||
===Pathophysiology=== |
|||
![Map of fungi in North America](Map of fungi in North America.png) |
|||
*Inhalation of conidia into the lungs |
|||
* May also be endemic to Africa and India, though it's unclear whether these are true cases or late reactivation |
|||
*Macophages can phagocytize and kill the conidia, and can also slow conversion into yeast form |
|||
* Hosts include humans, dogs, cats, horses, brown bears, and exotic pets like the kinkajou and red ruffed lemur |
|||
**A thick cell wall helps to prevent phagocytosis |
|||
* There have been point-source outbreaks associated with occupational and recreational activities, usually along streams or rivers enriched with decaying vegetation |
|||
*Some conidia successfully convert to the pathogenic yeast form |
|||
* Possibly has cold-weather seasonality |
|||
*Major antigens include BAD1 on the cell wall surface and binds CR3 (CD11b/CD18) and CD14 |
|||
*Humoral immunity has little effect; rather, immune response relies on cell-mediated immunity |
|||
==Clinical Manifestations== |
|||
== Pathophysiology == |
|||
*Can be acute pneumonia (followed by either recovery or chronic infection), or asymptomatic (followed by recovery or chronic infection) |
|||
* Inhalation of conidia into the lungs |
|||
**About 50% overall resolve without treatment |
|||
* Macophages can phagocytize and kill the conidia, and can also slow conversion into yeast form |
|||
**About half of symptomatic patients have isolated lung involvement and half are disseminated |
|||
** A thick cell wall helps to prevent phagocytosis |
|||
*When symptomatic, may have non-specific and constitutional symptoms |
|||
* Some conidia successfully convert to the pathogenic yeast form |
|||
*Can be primary or reactivation |
|||
* Major antigens include BAD1 on the cell wall surface and binds CR3 (CD11b/CD18) and CD14 |
|||
*Incubation period [[Usual incubation period::3 weeks to 3 months]] |
|||
* Humoral immunity has little effect; rather, immune response relies on cell-mediated immunity |
|||
===Respiratory Blastomycosis=== |
|||
== Clinical Presentation == |
|||
*Respiratory symptoms are the most common focus |
|||
* Can be acute pneumonia (followed by either recovery or chronic infection), or asymptomatic (followed by recovery or chronic infection) |
|||
*Can mimic community-acquired pneumonia or tuberculosis, and may have hemoptysis |
|||
** About 50% overall resolve without treatment |
|||
**Less likely cavitary, but possible |
|||
** About half of symptomatic patients have isolated lung involvement and half are disseminated |
|||
*Can be acute or chronic presentation, or asymptomatic |
|||
* When symptomatic, may have non-specific and constitutional symptoms |
|||
**Chronic typically lasts 2 to 6 months, with constitutional symptoms |
|||
* Can be primary or reactivation |
|||
*Even if there is non-pulmonary infection, there are often findings on chest x-ray |
|||
* Incubation period 3 weeks to 3 months |
|||
*Can also cause ARDS in about 10% of cases, which distinguishes it from histoplasmosis |
|||
===Extra-Pulmonary Blastomycosis=== |
|||
=== Respiratory blastomycosis === |
|||
*Next most common feature is dissemination to skin |
|||
* Respiratory symptoms are the most common focus |
|||
**Lesions usually either verrucous or ulcerative |
|||
* Can mimic community-acquired pneumonia or tuberculosis, and may have hemoptysis |
|||
**May be misdiagnosed as pyoderma gangrenosum, keratoacanthoma, BCC, squamous cell carcinoma, or mycosis fungoides |
|||
** Less likely cavitary, but possible |
|||
**Differential also contains NTM, other fungal infections, lupus |
|||
* Can be acute or chronic presentation, or asymptomatic |
|||
*Osteomyelitis, with or without evidence of lung involvement, is the third most common form |
|||
** Chronic typically lasts 2 to 6 months, with constitutional symptoms |
|||
**There are no specific clinical or radiographical features of blastomycosis |
|||
* Even if there is non-pulmonary infection, there are often findings on chest x-ray |
|||
*Genitourinary involvement, especially prostatitis and epididymo-orchitis, are next most common |
|||
* Can also cause ARDS in about 10% of cases, which distinguishes it from histoplasmosis |
|||
**May be cultured in urine collected after prostate massage |
|||
*Meningitis and cerebritis/abscess are possible |
|||
**Consider screening for it in immunocompromised people |
|||
**Cerebellum more common |
|||
**CSF culture is insenitive, though PCR is better |
|||
**Found in 5-10% of cases of disseminated blasto, but associated with high mortality |
|||
**Can have ocular involvement, as well |
|||
**Differential would involve bacterial and fungal meningitis/abscess (including cryptococcosis), and Nocardia |
|||
*Can also affect larynx, lymphatics or lymph nodes, spleen, and any other organ, though fungemia is rarely found |
|||
*Infection can cause endocrinologic abnormalities including adrenal insufficiency, thyroid infection, hypercalcemia (granulomatous) |
|||
**There are case reports of diabetes insipidus, and hyperprolactinemia |
|||
*Because it can occur in any organ, there are also case reports of breast lesions, tubo-ovarian abscess, otitis media, branchial cleft cyst infection |
|||
===Pregnancy=== |
|||
=== Extra-pulmonary blastomycosis === |
|||
*May be higher risk group, and can transmit it to the newborn |
|||
* Next most common feature is dissemination to skin |
|||
** Lesions usually either verrucous or ulcerative |
|||
** May be misdiagnosed as pyoderma gangrenosum, keratoacanthoma, BCC, squamous cell carcinoma, or mycosis fungoides |
|||
** Differential also contains NTM, other fungal infections, lupus |
|||
* Osteomyelitis, with or without evidence of lung involvement, is the third most common form |
|||
** There are no specific clinical or radiographical features of blastomycosis |
|||
* Genitourinary involvement, especially prostatitis and epididymo-orchitis, are next most common |
|||
** May be cultured in urine collected after prostate massage |
|||
* Meningitis and cerebritis/abscess are possible |
|||
** Consider screening for it in immunocompromised people |
|||
** Cerebellum more common |
|||
** CSF culture is insenitive, though PCR is better |
|||
** Found in 5-10% of cases of disseminated blasto, but associated with high mortality |
|||
** Can have ocular involvement, as well |
|||
** Differential would involve bacterial and fungal meningitis/abscess (including cryptococcosis), and Nocardia |
|||
* Can also affect larynx, lymphatics or lymph nodes, spleen, and any other organ, though fungemia is rarely found |
|||
* Infection can cause endocrinologic abnormalities including adrenal insufficiency, thyroid infection, hypercalcemia (granulomatous) |
|||
** There are case reports of diabetes insipidus, and hyperprolactinemia |
|||
* Because it can occur in any organ, there are also case reports of breast lesions, tubo-ovarian abscess, otitis media, branchial cleft cyst infection |
|||
=== |
===Immunocompromised Patients=== |
||
*Not as commonly described as an opportunistic infection as the other endemic fungi |
|||
* May be higher risk group, and can transmit it to the newborn |
|||
*Few cases with advanced [[HIV]], but possible |
|||
*[[Sarcoidosis]], [[transplantation]], and [[Corticosteroids|steroid]] use are all risk factors |
|||
*[[Infliximab]] and [[etanercept]] are higher risk |
|||
==Diagnosis== |
|||
=== Immunocompromise === |
|||
*Requires a microbiologic diagnosis |
|||
* Not as commonly described as an opportunistic infection as the other endemic fungi |
|||
* Few cases with AIDS, but possible |
|||
* Sarcoidosis, transplantation, and steroid use are all risk factors |
|||
* Infliximab and etanercept are higher risk |
|||
== |
===Microscopy=== |
||
*Can be directly visualized on exudate, sputum, tissue, or really any sample |
|||
* Requires a microbiologic diagnosis |
|||
*Fairly easy to see with KOH or calcofluor, showing thick-walled, multinucleated, '''broad-based budding yeast''' |
|||
*Can be seen on histology of skin lesion biopsy with Gomori methenamine silver (GMS) and periodic acid-Schiff (PAS) stains |
|||
=== |
===Culture=== |
||
*Grows as mycelial (mold) form at 25-30ΒΊC, usually after 1 to 3 weeks, starting as a white mold that slowly turns light brown |
|||
* Can be directly visualized on exudate, sputum, tissue, or really any sample |
|||
**Grows 5-10 days before they develop conidia, so relatively low risk of infection early on |
|||
* Fairly easy to see with KOH or calcofluor |
|||
*Usually needs a DNA probe to confirm the species |
|||
* Can be seen on histology of skin lesion biopsy with Gomori methenamine silver (GMS) and periodic acid-Schiff (PAS) stains |
|||
*Biosafety level 3 pathogen, so needs to be sent to Public Health |
|||
* Thick-walled, multinucleated, broad-based budding |
|||
=== |
===Serology=== |
||
*Antibody |
|||
* Grows as mycelial (mold) form at 25-30ΒΊC, usually after 1 to 3 weeks, starting as a white mold that slowly turns light brown |
|||
**Complement fixation is insensitive (Sn 9 to 43%); EIA is more sensitive but less specific |
|||
** Grows 5-10 days before they develop conidia, so relatively low risk of infection early on |
|||
**Immunodiffusion is likely better, though sensitivity still rather poor (Sn 28 to 64%, Sp 100%) |
|||
* Usually needs a DNA probe to confirm the species |
|||
***Immunodiffusion for A band is what is done in Ontario |
|||
* Biosafety level 3 pathogen, so needs to be sent to Public Health |
|||
**BAD1 antigen antibodies is 85% sensitive but not yet used |
|||
*Urinary antigen has 93% sens and 80% spec |
|||
**It cross-reacts with other dimorphic fungi, especially histoplasmosis |
|||
**Can be trended to monitor response during therapy |
|||
*Can check 1,3-Ξ²-d-glucan, but not specific or particularly sensitive |
|||
=== |
===Molecular Methods=== |
||
*Not yet well-developed, but theoretically possible to do PCR |
|||
* Antibody |
|||
** Serology with complement fixation is insensitive |
|||
** A antigen antibodies is better (Sn 65-80%, Sp 100%) |
|||
** BAD1 antigen antibodies is 85% sensitive but not yet used |
|||
* Urinary antigen has 93% sens and 80% spec |
|||
** It cross-reacts with other dimorphic fungi, especially histoplasmosis |
|||
** Can be trended to monitor response during therapy |
|||
* Can check 1,3-Ξ²-d-glucan, but not specific or particularly sensitive |
|||
==Management== |
|||
=== Molecular methods === |
|||
*Chronic blastomycosis doesn't resolve without treatment, and mortality is as high as 60% |
|||
* Not yet well-developed, but theoretically possible to do PCR |
|||
*Although many cases of acute pulmonary blastomycosis self-resolve, it is still recommended to treat, since triazoles are well-tolerated |
|||
*Severity is based on clinical judgement, as there are no validated criteria |
|||
===Pulmonary Blastomycosis=== |
|||
== Management == |
|||
*Mild-to-moderate: [[Is treated by::itraconazole]] 200 mg po tid for 3 days followed by bid for 6-12 months |
|||
* Chronic blasto doesn't resolve without treatment, and mortality is as high as 60% |
|||
*Moderate severe-to-severe: [[Is treated by::liposomal amphotericin B]] 3-5 mg/kg per day for 1-2 weeks or until improvement, followed by [[itraconazole]] 200 mg po tid for 3 days, followed by [[itraconazole]] 200 mg po bid, for a total of 6 to 12 months |
|||
* Although many cases of acute pulmonary blasto self-resolve, it is still recommended to treat, since azoles are well-tolerated |
|||
**May need up 6 to 8 weeks of induction with [[liposomal amphotericin B]] |
|||
* Severity is based on clinical judgement, as there are no validated criteria |
|||
*Monitor serum [[itraconazole]] after 2 weeks, targeting 1 to 10 ΞΌg/mL |
|||
* Pulmonary blastomycosis |
|||
** Mild-to-moderate: itraconazole 200 mg po tid for 3 days followed by bid for 6-12 months |
|||
** Moderate severe-to-severe: liposomal amphotericin B 3-5 mg/kg per day for 1-2 weeks or until improvement, followed by itraconazole 200 mg po tid for 3 days, followed by itraconazole 200 mg po bid, for a total of 6 to 12 months |
|||
*** May need 6 to 8 weeks of induction |
|||
** Monitor serum itraconazole after 2 weeks |
|||
* Disseminated extrapulmonary blastomycosis |
|||
** Same as for pulmonary blastomycosis |
|||
** 12 months for bone and CNS involvement |
|||
* CNS blastomycosis |
|||
** Amphotericin 5 mg/kg per day for 4-6 weeks followed by an azole for at least 12 months and until resolution of CSF abnormalities |
|||
** Azoles include fluconazole 800 mg daily, itraconazole 200 mg bid or tid, or voriconazole 200-300 mg bid |
|||
*** Vori ''may'' be better for CNS disease |
|||
* Immunosuppressed patients with blastomycosis, including AIDS |
|||
** Same as for severe pulmonary blastomycosis, but duration is at least 12 months |
|||
** May be followed by lifelong suppressive itraconazole 200 mg po daily if immunosuppression cannot be decreased and they have relapsed despite appropriate therapy |
|||
* Blastomycosis in pregnant women |
|||
** Use liposomal amphotericin 3-5 mg/kg per day |
|||
** Avoid azoles for risk of teratogenicity |
|||
* Blastomycosis in newborns: AmB deoxycholate 1 mg/kg per day |
|||
* Blastomycosis in children |
|||
** Mild-to-moderate: itraconazole 10 mg/kg po per day (up to 400 mg) for 6 to 12 months |
|||
** Severe blastomycosis: AmB deoxycholate 0.7-1 mg/kg per day or liposomal AmB at 3-5 mg/kg per day, followed by itraconazole 10 mg/kg po per day (up to 400 mg), for a total of 12 months |
|||
** Monitor serum levels after 2 weeks |
|||
===Disseminated Extrapulmonary Blastomycosis=== |
|||
=== Itraconazole === |
|||
*Same as for pulmonary blastomycosis, but treated for at least 12 months if bone involvement |
|||
* Tablet formulation has poorer oral bioavailability than liquid formulation |
|||
* Need to avoid PPI and H2 blockers, as it needs an acidic stomach environment to get absorbed, especially for tablet formulation |
|||
* Not as good CNS penetration as other azoles |
|||
* Needs therapeutic drug monitoring after 2 weeks with goal of maintaining serum levels between 1.0 and 10.0 τ±€g/ml |
|||
===CNS Blastomycosis=== |
|||
== Further Reading == |
|||
*[[Is treated by::Amphotericin B]] 5 mg/kg per day for 4-6 weeks followed by an azole for at least 12 months and until resolution of CSF abnormalities |
|||
* Chapman SW ''et al.'' [https://doi.org/10.1086/588300 Clinical Practice Guidelines for the Management of Blastomycosis: 2008 Update by the Infectious Diseases Society of America]. ''Clin Infect Dis''. 2008 46(12):1801-1812. |
|||
*Azoles include [[Is treated by::fluconazole]] 800 mg daily, [[Is treated by::itraconazole]] 200 mg bid or tid, or [[Is treated by::voriconazole]] 200-300 mg bid |
|||
**[[Voriconazole]] ''may'' be better for CNS disease (better CNS penetration than [[itraconazole]], and very good in vitro activity) |
|||
===Immunocompromised Patients=== |
|||
*Same as for severe pulmonary blastomycosis, but duration is at least 12 months |
|||
*May be followed by lifelong suppressive [[Is treated by::itraconazole]] 200 mg po daily if immunosuppression cannot be decreased and they have relapsed despite appropriate therapy |
|||
===Pregnant women=== |
|||
*Use [[Is treated by::liposomal amphotericin B]] 3-5 mg/kg per day |
|||
*Avoid azoles for risk of teratogenicity |
|||
===Children=== |
|||
*Blastomycosis in newborns: [[Is treated by::amphotericin B deoxycholate]] 1 mg/kg per day |
|||
*Blastomycosis in children |
|||
**Mild-to-moderate: [[Is treated by::itraconazole]] 10 mg/kg po per day (up to 400 mg) for 6 to 12 months |
|||
**Severe blastomycosis: [[Is treated by::amphotericin B deoxycholate]] 0.7-1 mg/kg per day or [[Is treated by::liposomal amphotericin B]] at 3-5 mg/kg per day, followed by [[itraconazole]] 10 mg/kg po per day (up to 400 mg), for a total of 12 months |
|||
**Monitor serum levels after 2 weeks |
|||
===Itraconazole=== |
|||
*Tablet formulation has poorer oral bioavailability than liquid formulation |
|||
*Need to avoid [[PPIs]] and [[H2 blockers]], as it needs an acidic stomach environment to get absorbed, especially for tablet formulation |
|||
*Not as good CNS penetration as other [[triazoles]] |
|||
*Needs therapeutic drug monitoring after 2 weeks with goal of maintaining serum levels between 1.0 and 10.0 ΞΌg/ml |
|||
=== Other Azoles === |
|||
* [[Voriconazole]] is the second-line azole that is most frequently recommended |
|||
** However, relatively high risk of liver toxicity |
|||
* If there are contraindications to voriconazole, then consider |
|||
** [[Posaconazole]], which is recommended by some experts[[CiteRef::schwartz2020bl]] based on some case reports[[CiteRef::proia2012su]][[CiteRef::day2014su]], though liver toxicity is likely around the same as [[voriconazole]][[CiteRef::maertens2021po]], and [[itraconazole]] and [[fluconazole]][[CiteRef::cornely2007po]] |
|||
** [[Isavuconazole]], which has clinical data that include both case reports and a case series[[CiteRef::scolarici2022th]][[CiteRef::thompson2016is]], and far fewer hepatobiliary adverse events than [[voriconazole]][[CiteRef::maertens2016is]] |
|||
==Further Reading== |
|||
*Chapman SW ''et al.'' [https://doi.org/10.1086/588300 Clinical Practice Guidelines for the Management of Blastomycosis: 2008 Update by the Infectious Diseases Society of America]. ''Clin Infect Dis''. 2008 46(12):1801-1812. |
|||
{{DISPLAYTITLE:''Blastomyces dermatitidis''}} |
|||
[[Category:Dimorphic fungi]] |
Latest revision as of 15:11, 1 October 2024
Background
Microbiology
- Broad-based dimorphic budding yeast
- Mold at 25-28ΒΊC and yeast at 37ΒΊC
- Branching hyphae 2-3 Β΅m in diameter and right-angle conidiophores resembling lollipops
- Conidia become airborne when disturbed
Epidemiology
- Present in the Mississippi, Ohio, and St. Lawrence River Valleys, the Great Lakes regions, and western Ontario1
- May also be endemic to Africa and India1, though it's unclear whether these are true cases or late reactivation
- Hosts include humans, dogs, cats, horses, brown bears, and exotic pets like the kinkajou and red ruffed lemur
- There have been point-source outbreaks associated with occupational and recreational activities, usually along streams or rivers enriched with decaying vegetation
- Possibly has cold-weather seasonality
Pathophysiology
- Inhalation of conidia into the lungs
- Macophages can phagocytize and kill the conidia, and can also slow conversion into yeast form
- A thick cell wall helps to prevent phagocytosis
- Some conidia successfully convert to the pathogenic yeast form
- Major antigens include BAD1 on the cell wall surface and binds CR3 (CD11b/CD18) and CD14
- Humoral immunity has little effect; rather, immune response relies on cell-mediated immunity
Clinical Manifestations
- Can be acute pneumonia (followed by either recovery or chronic infection), or asymptomatic (followed by recovery or chronic infection)
- About 50% overall resolve without treatment
- About half of symptomatic patients have isolated lung involvement and half are disseminated
- When symptomatic, may have non-specific and constitutional symptoms
- Can be primary or reactivation
- Incubation period 3 weeks to 3 months
Respiratory Blastomycosis
- Respiratory symptoms are the most common focus
- Can mimic community-acquired pneumonia or tuberculosis, and may have hemoptysis
- Less likely cavitary, but possible
- Can be acute or chronic presentation, or asymptomatic
- Chronic typically lasts 2 to 6 months, with constitutional symptoms
- Even if there is non-pulmonary infection, there are often findings on chest x-ray
- Can also cause ARDS in about 10% of cases, which distinguishes it from histoplasmosis
Extra-Pulmonary Blastomycosis
- Next most common feature is dissemination to skin
- Lesions usually either verrucous or ulcerative
- May be misdiagnosed as pyoderma gangrenosum, keratoacanthoma, BCC, squamous cell carcinoma, or mycosis fungoides
- Differential also contains NTM, other fungal infections, lupus
- Osteomyelitis, with or without evidence of lung involvement, is the third most common form
- There are no specific clinical or radiographical features of blastomycosis
- Genitourinary involvement, especially prostatitis and epididymo-orchitis, are next most common
- May be cultured in urine collected after prostate massage
- Meningitis and cerebritis/abscess are possible
- Consider screening for it in immunocompromised people
- Cerebellum more common
- CSF culture is insenitive, though PCR is better
- Found in 5-10% of cases of disseminated blasto, but associated with high mortality
- Can have ocular involvement, as well
- Differential would involve bacterial and fungal meningitis/abscess (including cryptococcosis), and Nocardia
- Can also affect larynx, lymphatics or lymph nodes, spleen, and any other organ, though fungemia is rarely found
- Infection can cause endocrinologic abnormalities including adrenal insufficiency, thyroid infection, hypercalcemia (granulomatous)
- There are case reports of diabetes insipidus, and hyperprolactinemia
- Because it can occur in any organ, there are also case reports of breast lesions, tubo-ovarian abscess, otitis media, branchial cleft cyst infection
Pregnancy
- May be higher risk group, and can transmit it to the newborn
Immunocompromised Patients
- Not as commonly described as an opportunistic infection as the other endemic fungi
- Few cases with advanced HIV, but possible
- Sarcoidosis, transplantation, and steroid use are all risk factors
- Infliximab and etanercept are higher risk
Diagnosis
- Requires a microbiologic diagnosis
Microscopy
- Can be directly visualized on exudate, sputum, tissue, or really any sample
- Fairly easy to see with KOH or calcofluor, showing thick-walled, multinucleated, broad-based budding yeast
- Can be seen on histology of skin lesion biopsy with Gomori methenamine silver (GMS) and periodic acid-Schiff (PAS) stains
Culture
- Grows as mycelial (mold) form at 25-30ΒΊC, usually after 1 to 3 weeks, starting as a white mold that slowly turns light brown
- Grows 5-10 days before they develop conidia, so relatively low risk of infection early on
- Usually needs a DNA probe to confirm the species
- Biosafety level 3 pathogen, so needs to be sent to Public Health
Serology
- Antibody
- Complement fixation is insensitive (Sn 9 to 43%); EIA is more sensitive but less specific
- Immunodiffusion is likely better, though sensitivity still rather poor (Sn 28 to 64%, Sp 100%)
- Immunodiffusion for A band is what is done in Ontario
- BAD1 antigen antibodies is 85% sensitive but not yet used
- Urinary antigen has 93% sens and 80% spec
- It cross-reacts with other dimorphic fungi, especially histoplasmosis
- Can be trended to monitor response during therapy
- Can check 1,3-Ξ²-d-glucan, but not specific or particularly sensitive
Molecular Methods
- Not yet well-developed, but theoretically possible to do PCR
Management
- Chronic blastomycosis doesn't resolve without treatment, and mortality is as high as 60%
- Although many cases of acute pulmonary blastomycosis self-resolve, it is still recommended to treat, since triazoles are well-tolerated
- Severity is based on clinical judgement, as there are no validated criteria
Pulmonary Blastomycosis
- Mild-to-moderate: itraconazole 200 mg po tid for 3 days followed by bid for 6-12 months
- Moderate severe-to-severe: liposomal amphotericin B 3-5 mg/kg per day for 1-2 weeks or until improvement, followed by itraconazole 200 mg po tid for 3 days, followed by itraconazole 200 mg po bid, for a total of 6 to 12 months
- May need up 6 to 8 weeks of induction with liposomal amphotericin B
- Monitor serum itraconazole after 2 weeks, targeting 1 to 10 ΞΌg/mL
Disseminated Extrapulmonary Blastomycosis
- Same as for pulmonary blastomycosis, but treated for at least 12 months if bone involvement
CNS Blastomycosis
- Amphotericin B 5 mg/kg per day for 4-6 weeks followed by an azole for at least 12 months and until resolution of CSF abnormalities
- Azoles include fluconazole 800 mg daily, itraconazole 200 mg bid or tid, or voriconazole 200-300 mg bid
- Voriconazole may be better for CNS disease (better CNS penetration than itraconazole, and very good in vitro activity)
Immunocompromised Patients
- Same as for severe pulmonary blastomycosis, but duration is at least 12 months
- May be followed by lifelong suppressive itraconazole 200 mg po daily if immunosuppression cannot be decreased and they have relapsed despite appropriate therapy
Pregnant women
- Use liposomal amphotericin B 3-5 mg/kg per day
- Avoid azoles for risk of teratogenicity
Children
- Blastomycosis in newborns: amphotericin B deoxycholate 1 mg/kg per day
- Blastomycosis in children
- Mild-to-moderate: itraconazole 10 mg/kg po per day (up to 400 mg) for 6 to 12 months
- Severe blastomycosis: amphotericin B deoxycholate 0.7-1 mg/kg per day or liposomal amphotericin B at 3-5 mg/kg per day, followed by itraconazole 10 mg/kg po per day (up to 400 mg), for a total of 12 months
- Monitor serum levels after 2 weeks
Itraconazole
- Tablet formulation has poorer oral bioavailability than liquid formulation
- Need to avoid PPIs and H2 blockers, as it needs an acidic stomach environment to get absorbed, especially for tablet formulation
- Not as good CNS penetration as other triazoles
- Needs therapeutic drug monitoring after 2 weeks with goal of maintaining serum levels between 1.0 and 10.0 ΞΌg/ml
Other Azoles
- Voriconazole is the second-line azole that is most frequently recommended
- However, relatively high risk of liver toxicity
- If there are contraindications to voriconazole, then consider
- Posaconazole, which is recommended by some experts2 based on some case reports34, though liver toxicity is likely around the same as voriconazole5, and itraconazole and fluconazole6
- Isavuconazole, which has clinical data that include both case reports and a case series78, and far fewer hepatobiliary adverse events than voriconazole9
Further Reading
- Chapman SW et al. Clinical Practice Guidelines for the Management of Blastomycosis: 2008 Update by the Infectious Diseases Society of America. Clin Infect Dis. 2008 46(12):1801-1812.
References
- a b Nida Ashraf, Ryan C. Kubat, Victoria Poplin, Antoine A. Adenis, David W. Denning, Laura Wright, Orion McCotter, Ilan S. Schwartz, Brendan R. Jackson, Tom Chiller, Nathan C. Bahr. Re-drawing the Maps for Endemic Mycoses. Mycopathologia. 2020;185(5):843-865. doi:10.1007/s11046-020-00431-2.
- ^ Ilan S. Schwartz, Carol A. Kauffman. Blastomycosis. Seminars in Respiratory and Critical Care Medicine. 2020;41(01):031-041. doi:10.1055/s-0039-3400281.
- ^ Laurie A. Proia, Darin O. Harnisch. Successful Use of Posaconazole for Treatment of Blastomycosis. Antimicrobial Agents and Chemotherapy. 2012;56(7):4029-4029. doi:10.1128/aac.00359-12.
- ^ Shandra R. Day, David B. Weiss, Kevin C. Hazen, Christopher C. Moore. Successful treatment of osseous blastomycosis without pulmonary or disseminated disease and review of the literature. Diagnostic Microbiology and Infectious Disease. 2014;79(2):242-244. doi:10.1016/j.diagmicrobio.2014.02.021.
- ^ Johan A Maertens, Galia Rahav, Dong-Gun Lee, Alfredo Ponce-de-LeΓ³n, Isabel Cristina RamΓrez SΓ‘nchez, Nikolay Klimko, Anne Sonet, Shariq Haider, Juan Diego VΓ©lez, Issam Raad, Liang-Piu Koh, Meinolf Karthaus, Jianying Zhou, Ronen Ben-Ami, Mary R Motyl, Seongah Han, Anjana Grandhi, Hetty Waskin. Posaconazole versus voriconazole for primary treatment of invasive aspergillosis: a phase 3, randomised, controlled, non-inferiority trial. The Lancet. 2021;397(10273):499-509. doi:10.1016/s0140-6736(21)00219-1.
- ^ Oliver A. Cornely, Johan Maertens, Drew J. Winston, John Perfect, Andrew J. Ullmann, Thomas J. Walsh, David Helfgott, Jerzy Holowiecki, Dick Stockelberg, Yeow-Tee Goh, Mario Petrini, Cathy Hardalo, Ramachandran Suresh, David Angulo-Gonzalez. Posaconazole vs. Fluconazole or Itraconazole Prophylaxis in Patients with Neutropenia. New England Journal of Medicine. 2007;356(4):348-359. doi:10.1056/nejmoa061094.
- ^ Michael J Scolarici, Coleton King, Alana Sterkel, Jeannina Smith, Gregory Gauthier, Christopher Saddler. The Role of Isavuconazonium Sulphate for the Treatment of Blastomycosis: A Case Series and Antifungal Susceptibility. Open Forum Infectious Diseases. 2022;9(7). doi:10.1093/ofid/ofac220.
- ^ George R. Thompson, Adrian Rendon, Rodrigo Ribeiro dos Santos, Flavio Queiroz-Telles, Luis Ostrosky-Zeichner, Nkechi Azie, Rochelle Maher, Misun Lee, Laura Kovanda, Marc Engelhardt, Jose A. Vazquez, Oliver A. Cornely, John R. Perfect. Isavuconazole Treatment of Cryptococcosis and Dimorphic Mycoses. Clinical Infectious Diseases. 2016;63(3):356-362. doi:10.1093/cid/ciw305.
- ^ Johan A Maertens, Issam I Raad, Kieren A Marr, Thomas F Patterson, Dimitrios P Kontoyiannis, Oliver A Cornely, Eric J Bow, Galia Rahav, Dionysios Neofytos, Mickael Aoun, John W Baddley, Michael Giladi, Werner J Heinz, Raoul Herbrecht, William Hope, Meinolf Karthaus, Dong-Gun Lee, Olivier Lortholary, Vicki A Morrison, Ilana Oren, Dominik Selleslag, Shmuel Shoham, George R Thompson, Misun Lee, Rochelle M Maher, Anne-Hortense Schmitt-Hoffmann, Bernhardt Zeiher, Andrew J Ullmann. Isavuconazole versus voriconazole for primary treatment of invasive mould disease caused by Aspergillus and other filamentous fungi (SECURE): a phase 3, randomised-controlled, non-inferiority trial. The Lancet. 2016;387(10020):760-769. doi:10.1016/s0140-6736(15)01159-9.