Systemic Mycoses PDF

Systemic Mycoses : MYCOLOGY Jason Biraquit, RMT, MSPH Emilio Aguinaldo College – Cavite School of Medical Technology Systemic Mycoses Infections that affect internal organs or deep tissues of the body Initial site of infection is the lung Generalized symptoms include fever and...

Systemic Mycoses : MYCOLOGY Jason Biraquit, RMT, MSPH Emilio Aguinaldo College – Cavite School of Medical Technology Systemic Mycoses Infections that affect internal organs or deep tissues of the body Initial site of infection is the lung Generalized symptoms include fever and fatigue. Chronic cough and chest pain might also accompany these infections Agents of systemic mycoses share several characteristics, such as mode of transmission, dimorphism, and systemic dissemination Systemic Mycoses Histoplasma capsulatum Blastomyces dermatitidis Paracoccidiodes brasiliensis Coccidiodes immitis Histoplasma capsulatum It is a dimorphic fungi It has two reproductive phase – Sexual phase (Ajellomyces capsulatus) – Asexual phase The mycelial phase is seen at 25° C – characterized by a typical macroconidia with a diameter of 8-14 u. – The microconidia are measured about 2-4 u in diameter At 37° c or at body temperature, the organism is a budding yeast 2-3 x 3-4 u in diameter – found predominantly in histiocytes Histoplasma capsulatum Histoplasmosis is acquired by the inhalation of the microconidia of Histoplasma capsulatum Soil with high nitrogen content, associated with bat and bird guano – Rotting guano mixed with soil & feathers of the birds. Caves, the main habitat of bats, which are the reservoir of Histoplasma capsulatum Histoplasma capsulatum Life Cycle Histoplasmosis TYPE OF INFECTION SPECIFIC DISORDER COMMENTS Normal Hosts Asymptomatic or mild Occurs with normal like flu illness exposure Acute pulmonary Occurs with heavy histoplasmosis exposure Rare complications Pericarditis, mediastinal fibrosis Opportunistic Disseminated Occurs in individuals histoplasmosis who have an immune Infection Chronic pulmonary defect histoplasmosis Occurs in individuals who have a structural defect  Histoplasmosis CLINICAL FORMS SYMPTOMS Primary Acute Asymptomatic or flu-like syndrome Chest pain, shortness of breath and hoarseness Radiologically, discrete lung lesion may or may not develop Chronic cavitary Large pulmonary lesions develop lesions may exist in a relative quiescent state Often mistaken for tuberculosis Severe Only small percentage progress into this clinical forms disseminated Disease of reticuloendothelial system in which organs infection may develop In massive dissemination, it could be fatal Histoplasmosis Laboratory Diagnosis Direct Examination – KOH (sputum) reveals the small yeast cells of H. capsulatum – Giemsa and Wright Stain (blood) the yeast cells are commonly seen within monocytes and macrophages – Gomori Methylene Stain (tissue) resemble the blastoconidia of Candida glabrata Histoplasmosis Histoplasmosis Laboratory Diagnosis Culture (25° to 30°C; 2 to 4 weeks) – SDA – Smith and Goodman (for contaminated specimen) – Yeast Extract (place in a plastic bag) – Conversion of the mold form to the yeast form, using brain-heart infusion (BHI) agar incubated at 37° C, is confirmatory for H. capsulatum Histoplasmosis Laboratory Diagnosis Serological Test – Antigen EIA (Blood, CSF, Urine) Skin test with histoplasmin ag – Antibody Complement Fixation Immunodiffusion Latex agglutination Fungal elements – Direct Fluorescent Microscopy Molecular Diagnostic – Nucleic acid probe (PCR) Histoplasmosis Treatment & Prevention Amphotericin B for disseminated infection Itraconazole for immunocompromised patients Cleaning of bat droppings Blastomyces dermatitidis It is dimorphic It has two reproductive phase – Sexual phase (Ajellomyces dermatitidis) – Asexual phase Mycelial phase is seen at 25° C – showed typical pyriform microconidia (2-4 microns) Yeast phase is seen at 37°C – Buds are produced singly and are attached to parent cell by broad base Blastomyces dermatitidis The mode of transmission of Blastomyces dermatitidis is by inhalation of the spores or the microconidia. Its natural habitat remains an enigma. Evidence indicates it favors environment with high nitrogen content, acid pH, abundant moisture, and perhaps enriched with animal excreta. Blastomyces dermatitidis Life Cycle Blastomycosis Men are most prevalent It also occur in dog It is also known as: – Gilchrist’s disease – Chicago Disease – North American Blastomycosis  Blastomycosis CLINICAL FORMS SYMPTOMS Pulmonary Fever, cough and hoarseness Productive cough, fever and weight loss after several months Radiographically resembles tuberculosis Systemic Extension of pulmonary form Common sites of involvement are liver and spleen Granulomatous lesions are present Cutaneous Indicates systemic disease May result from direct inoculation from the soil Blastomycosis Laboratory Diagnosis Direct Examination – 10-20% KOH or Calcoflour white sputum, exudates from skin lesion Large, spherical, thick-walled yeast cells (8 - 15 μm) usually with a single bud that is connected to the parent cell by a broad base Blastomycosis Laboratory Diagnosis Culture (22- 25°C; 5 days to 4 weeks) – Saborauds, Mycosel or Mycobiotic Agar – Colonies can be white, tan, or brown and may be fluffy to glabrous – Has a spicule area at the center of colonies – Culture is not routinely done Blastomycosis Laboratory Diagnosis Serological Test – Antigen – Skin test with blastomycin ag Has a tendency of high cross reactivity Molecular Diagnostic – Nucleic acid probe (PCR) confirmatory Blastomycosis Treatment & Prevention Amphotericin B has been used but with erratic results 2-hydroxystilbamidine Ketoconazole, less nephrotoxicity Prevent fomite inhalation in endemic area Coccidioides immitis It is the most virulent mycotic agent It is dimorphic It has two reproductive phase – Sexual phase (Not known) – Asexual phase Bacillus subtilis and Penicillum janthinellium are inhibitory to its growth Coccidioides immitis Mycelial phase is seen at 25° C – septate hyphae mature develop into arthroconidia being separated by vacuolized cells – “barrel-shape arthroconidia” Yeast phase is seen at 37°C – Organism develops into large spherical structures 10-60 u in diameter called spherules that are filled with endospore Coccidioides immitis Reside in Lower Sonoran life zone – low rainfall and semiarid conditions. Usually found in loose desert soil like those found in San Joaquin Valley in California Coccidioides immitis Life Cycle Coccidioidomycosis San Joaquin Valley Fever (erythrema multiforme) Desert Rheumatism (arthritis) Desert Bumps (erythrema nodosum) Posada’s Disease (Coccidioides posadasii)  Coccidioidomycosis CLINICAL FORMS SYMPTOMS Primary Occurs 7-28 days after inhalation of single Pulmonary spore Flu-like fever, malaise and cough 10% develop erythrema nodosum or erythrema multiforme Benign form Development of well defined lung cavitation Exist for years and could be unnoticed Disseminated 1% of population Form Fungi spreads into various organs Prognosis is grave Coccidioidomycosis Laboratory Diagnosis Direct Examination – Gomori Methanamine Silver Tissue, sputum , other body fluids reveal the spherules containing the endospores Small, empty spherules may resemble the yeast cells of B. dermatitidis, and the endospores can be confused with the cells of C. neoformans, H. capsulatum, and P. brasiliensis Coccidioidomycosis Laboratory Diagnosis Culture (22- 25°C; 3-5 days) – SDA with or without antibiotics – Cultures of C. immitis are a biohazard to laboratory workers – appear as a delicate, cobweb-like growth (white fluffy mold) – kill organisms with formalin before attempting to make an LPCB mount Coccidioidomycosis Laboratory Diagnosis Serological Test – Antigen Skin test with coccidiodomycin ag – Has a tendency of high cross reactivity Molecular Diagnostic – Nucleic acid probe (PCR) Coccidioidomycosis Treatment & Prevention Generally difficult to manage regardless of drug used Amphotericin B is the drug of choice Itraconazole and fluconazole have been tried with little success Prevent spores inhalation Paracoccidioides brasiliensis It is dimorphic Mycelial phase is seen at 25° C – has no typical sporulation Yeast phase is seen at 37°C – Organism is a yeast with several budding cells attached to the parent cell, some in a “mariner’s wheel” arrangement or “mickey mouse cap” appearance – yeast is about 2-30 microns Paracoccidioides brasiliensis The organism is transmitted by inhalation of the spores. It restricted to South and Central America. The fungus is also isolated in acidic soil, high-rainfall areas, and its growth requires increased humidity Its natural habitat remains to be elucidated. Paracoccidioides brasiliensis Life Cycle Paracoccidiodomycosis South American blastomycosis Brazilian blastomycosis Lutz-Splendore-Almeida disease Paracoccidioidal granuloma Paracoccidiodomycosis It is a chronic granulomatous disease of skin, mucous membranes, lymph nodes and internal organs Begins as a primary pulmonary infection Ulcerative lesions are commonly present in the nasal and oral mucosa, gingivae Paracoccidiodomycosis Laboratory Diagnosis Direct Examination – 10-20% KOH Sputum, mucosal biopsy and other exudates Large, round or oval, multiple budding yeast cells (8 - 40 μm) Paracoccidiodomycosis Laboratory Diagnosis Culture – SDA at RT grow very slowly (21 to 28 days) and are heaped, wrinkled, moist, and yeast-like. – Brain Heart Infusion at 35° C mycelial phase rapidly converts to yeast phase It produces yeast that is seen in tissue Paracoccidiodomycosis Laboratory Diagnosis Serological Test – Antigen Skin test with paracoccidioidin ag – Antibody Complement Fixation Immunodiffusion Molecular Diagnostic – Nucleic acid probe (PCR) Paracoccidiodomycosis Treatment & Prevention Amphotericin B Itraconazole Long term therapy is required Prevent inhalation of dust in endemic area Penicillium marneffei An emerging dimorphic pathogenic fungus endemic to Southeast Asia The only pathogenic from penicillium spp. common cause of systemic infection in immunocompromised patients Associated with the bamboo rat (Rhizomys pruinosus) and the Vietnamese bamboo rat (Rhizomys sinensis) Penicillium marneffei Causes either a focal cutaneous or mucocutaneous infection Granulomatous, suppurative, and necrotizing inflammatory responses have been demonstrated Disseminated disease is typically fatal Penicillium marneffei Laboratory Diagnosis Direct Examination – Wright-stained smears from skin lesions or biopsy specimens Reveals oval to cylindric, measuring 3 to 6 μm long, and may have a cross wall Penicillium marneffei Laboratory Diagnosis Culture – SDA at RT Grows rapidly and produces blue-green to yellowish colonies soluble, red to maroon pigment that diffuses into the agar and is often best observed by viewing the reverse of the colony Molecular Diagnostic – Nucleic acid probe (PCR) Cryptococcus neoformans The organism is monomorphic and is always in yeast form whether at 25° or at 37° C – appears as a spherical, single or multiple budding, thick- walled yeast 2 to 15 μm (polysaccharide capsule) The unique feature of the yeast is the acidic mucopolysaccharide capsule It has 4 serotypes – Serotype A (C. neoformans var. grubii) – Serotype B – Serotype C – Serotype D (C. neoformans var. neoformans) Cryptococcus neoformans Exists as a saprobe in nature It is most associated with avian excreta (pigeons) Important causes of meningitis, pulmonary disease, and septicemia Exhibit two reproductive phase – Asexual – Sexual Flobasidiella neoformans (A & D) Filobasidiella bacillispora (B & C) Cryptococcus neoformans Life Cycle Cryptococcosis Usually associated in HIV patients Primary pulmonary cryptococcosis is usually inapparent but may be chronic, subacute or acute. The clinical entity is most often seen in cryptococcal meningitis. Osseous and cutaneous disease can be present without apparent neurologic involvement. Disease; – Busse-Buschke’s Disease – Torulosis – European Blastomycosis Cryptococcosis The disease is worldwide in distribution. This yeast has been repeatedly isolated from sites inhabited by pigeons, particularly their roosts and droppings. Pigeons are not naturally infected Cryptococcosis Laboratory Diagnosis Direct Examination – India Ink (CSF) most widely used method for the rapid detection Background fluid is black, and clear unstained halos are seen around individual yeast cells – KOH respiratory secretions appears as a spherical, single or multiple budding, thick- walled yeast 2 to 15 μm (polysaccharide capsule) Cryptococcosis Laboratory Diagnosis Culture (25-30 C; 1-5 days) – SDA without cycloheximide – CSF – (0.45-mm membrane filter) – smooth, white to tan colony that may be mucoid to creamy Cryptococcosis Laboratory Diagnosis Serological Test – Latex Agglutination Cryptococcal Antigen Detection recommended for routine use in most clinical microbiology laboratoriesrecommended for routine use in most clinical microbiology laboratories Cryptococcosis Treatment & Prevention Amphotericin B in combination with 5- fluorocytosine have been successful Fluconazole is as effective too Clean pigeon droppings Avoid visiting caves without protective gears