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ID34 Infectious Diseases
Opportunistic Fungi
Toronto Notes 2019
Table 25. Endemic Mycoses
Clinical Presentation
• maybeasymptomatic
• allcancausepneumoniaandmaydisseminatehematogenously
• mayreactivateordisseminateduringimmunocompromisedstates
Treatment
• almostneverempiric,andrequiresdiagnosisfirst • commontoallendemicmycoses
■ oral azole (e.g. itraconazole for mild-moderate local infection) ■ IV amphotericin B for systemic infection
Clinical Features
Asymptomatic (in most people)
Primary pulmonary
• Fever, cough, chest pain, headache, myalgia, anorexia
• CXR (acute): pulmonary infiltrates ± hilar lymphadenopathy
• CXR (chronic): pulmonary infiltrates, cavitary disease
Disseminated (rare)
• Occurs primarily in immunocompromised patients
• Spread to bone marrow (pancytopenia), GI tract (ulcers), lymph nodes
(lymphadenitis), skin, liver, adrenals, CNS
May be asymptomatic
Primary: acute or chronic pneumonia
• Fever, cough, chest pain, chills, night sweats, weight loss
• CXR (acute): lobar or segmental pneumonia
• CXR (chronic): lobar infiltrates, fibronodular interstitial disease Disseminated
• Spread to skin (verrucous lesions that mimic skin cancer, ulcers,
subcutaneous nodules), bones (osteomyelitis, osteolytic lesions), GU tract (prostatitis, epididymitis)
Primary
• “Valley fever”: subacute fever, chills, cough, chest pain, sore throat, fatigue
that lasts for wk to mo
• Can develop hypersensitivity with arthralgias, erythema nodosum Disseminated
• Rare spread to skin (ulcers), joints (synovitis), bones (lytic lesions),
meninges (meningitis)
• Common opportunistic infection in patients with HIV
Opportunistic Fungi
Disease
Histoplasma capsulatum
Blastomyces dermatitidis
Coccidioides immitis
Endemic Region
Ohio and Mississippi River valleys in central USA, Ontario, Quebec; widespread
States east of Mississippi River, Northern Ontario and along the Great Lakes
Deserts in southwest USA, northwest Mexico
Investigations
Fungal culture, fungal stain
Antigen detection (urine and serum) Serology
Sputum smear and culture
Direct examination of clinical specimens for characteristic broad- based budding yeast (sputum, tissue, purulent material)
Sputum culture
Direct examination of clinical specimens for characteristic yeast (sputum, tissue, purulent material)
CXRinP.jiroveci
• Bilateral, diffuse opacities
• CXR may be normal (20-30% cases)
• CT shows cysts (hence the name
Pneumo”cystis”) but almost never pleural effusions
Pneumocystis jiroveci (formerly P. carinii) Pneumonia: PJP or PCP
Etiology
• respiratoryexposuretoaunicellularfungi(previouslyclassifiedasaprotozoa)
• rarelytransmittedfrompersontoperson
• without prophylaxis, HIV patients with a CD4 count <200 cells/mm3 have an 80% lifetime risk of PJP
Clinical Presentation
• symptomsofpneumonia:fever,non-productivecough,progressivedyspnea
• classicCXRfindingsofinterstitialpneumonia
• mostclinicaldiseaseisduetoreactivationoflatentinfectionorreinfectionbyadifferentgenotypein
immunocompromised patients (steroid use, HIV)
Investigations
• demonstrationoforganismininducedsputum,bronchoalveolarlavage,orendotrachealaspirate(if intubated)
Treatment and Prevention
• oxygen to keep SaO2 >90%
• antimicrobialoptions
■ TMP/SMX(POorIV)
■ dapsone and TMP
■ clindamycin and primaquine ■ pentamidine (IV)
■ atovaquone
• corticosteroidsusedasadjuvanttherapyinthosewithseverehypoxia(pO2<70mmHgorA-agradient O2 >35 mmHg)
• prophylactic TMP/SMX for those at high risk of infection (HIV patients when CD4 <200 cells/mm3 or non-HIV immunocompromised patients under specific conditions)