Opportunistic Mycoses Flashcards

Question

What is the life cycle of c.neoformans

Answer 1

* Primary infection in lungs (may mimic TB) * Can spread to skin, eye, adrenals, bone and prostate * **Cryptococcal meningitis is most common disseminated manifestation** Symptoms: mild headaches, memory lapses or personality changes. Low grade fever. Chronic meningitis: Differentials: brain tumor, brain abscess, degenerative central nervous system disease, or any mycobacterial or other fungal meningitis CSF findings ???? Meningism, headaches, disorientation Cryptococcoma; signs of SOL (space occupying lesion) such as: blurred vision, diplopia, opthalmoplegia, slurred speech, double vision, and instead gait. AIDS 5-8%

Answer 2

* Specimens: CSF, tissue, exudates, sputum, blood, cutaneous scrapings and urine. * Negative staining with India ink /Nigrosin 60% of infected diagnosed positive by India Ink preparation on examination of CSF * Cerebrospinal fluid examination may reveal an increase in lymphocytes, low glucose levels, and elevated protein……..?? Cultures on Sabouraud dextrose agar-mucoid, brownish colonies * Serology: detection of Cryptococcal antigen in serum or CSF (CRAG)-90% of cryptococcal meningitis Type of CRAG detection tests: 1. Latex agglutination 2. Enzyme immunoassay Tests can also be Prognostic

Answer 3

Treatment; 1. Induction: rapid fungal clearance 2. Maintenance: suppress latent infection p 3. Consolidation: prevent relapse Amphotericin B 5-Flucytosine Fluconazole effective for prevention of recurrence prevention Relapses with fatal outcomes common in AIDS

Answer 4

Only few of the > 100 species of Aspergillus are important human pathogens Aspergillus spp. are molds (saprophytes), living in soil and on plants Especially abundant during construction and when dust is spread around they have small conidia that are aerosolised Most common species are: A.fumigatus, A.flavus, A.niger, A.terreus, A.nidulans

Answer 5

Chronic granulomatous disease of childhood (inability to form toxic free radicals after phagocytosis) Haematological malignancies e.g acute leukemia. Bone marrow and organ transplantation(25 – 40%) IV drug abuse HIV/AIDS Diabetes mellitus Tuberculosis COPD Alcoholism Corticosteroid therapy

Answer 6

Disease spectrum is wide Ubiquitous Incubation; between 36 hours to months Spore size, organism growth rate, adherence to host epithelial surfaces and toxin/enzyme production are factors that the organism contributes to disease type and severity Alveolar macrophages in lungs engulf and kill conidia when capable Otherwise germinate, produces hyphae and invades

Answer 7

Allergic Bronchopulmonary Aspergillosis – Atopic individuals, with elevated IgE levels (10-20% of Asthmatics react to A. fumigatus) Asthma, recurrent chest infiltrates, eosinophilia, and both type I (immediate) and type III (Arthus) skin test hypersensitivity to Aspergillus antigen Aspergilloma – A fungal ball, fungus colonize preexisting cavities from TB, sarcoidosis, emphysema in the lung and form compact ball of mycelium surrounded by dense fibrous wall Asymptomatic Symptomatic- cough, dyspnea, weight loss, fatigue, and hemoptysis. (rarely invasive) Invasive Aspergillosis: Aspergillus develop in lung tissue causing invasive infection (spreading through the tissue and involving blood vessels); then spread can occur to other organs gastrointestinal tract, kidney, liver, brain, or other organs, producing abscesses and necrotic lesions chronic necrotizing pulmonary aspergillosis for moderate immunocompetence Non-invasive Aspergillus species may involve the nasal sinuses, the ear canal, the cornea, or the nails

Answer 8

Specimens Respiratory secretions Bronchoalveolar lavage Lung biopsy Serum /blood rarely Investigations Direct microscopy; KOH and calcofluor white???? Cultures on SDA at ???? Speciation based on conidial arrangement Histology Serum antigen tests for galactomannan and 1-3 beta – D – glucan Ancillary tests MRI of brain Diagnosis of aspergilloma is radiological (CT scan)

Answer 9

Amphotericin B Itraconazole and new triazoles such as posaconazole for Amphotericin resistant species 5 -Flucytosine Steroids for Allergic attacks in ABPA Surgery may be indicated Prevented by avoiding exposure to conidia (abundant in constructions and uncompleted buildings)

Answer 10

Phylum Glomeromycota Molds found everywhere with high mortality Major agents are Rhizopus, Rhizomucor, Absidia, Mucor Major risk factors: - Diabetic ketoacidosis Haematologic malignancies 3rd degree burns Corticosteroids therapy. Bone marrow transplantation dialysis with the iron chelator deferoxamine

Answer 11

Acquired through inhalation of spores There is impaired phagocytosis by alveolar macrophages and polymorphonuclear leucocytes. Neutrophil dysfunction and accumulation of sugar and acids enable relentless growth of organisms Hyphae invades the walls of blood vessels once a primary infection is established results in the dissemination of mycotic thrombi and the formation of metastatic foci in many organs Invasiveness is appreciated in tissues

Answer 12

A life-threatening form of zygomycosis known as the Rhinocerebral mucormycosis Begins in the paranasal sinuses following inhalation of sporangiospores, may extend to involve the orbit, palate, face, nose, brain Results in septic necroses of tissues of nasopharynx and orbit Pulmonary zygomycosis: Follows inhalation of sporangiospores into the lungs Fever, shortness of breath, cough haemoptysis Direct inoculation of traumatic breaks in the skin and mucousmembranes may lead to primary mucocutaneous infection

Answer 13

Specimens: skin scrapings from cutaneous lesions sputum and needle biopsies from pulmonary lesions; nasal discharges, scrapings and aspirates from sinuses in patients with rhinocerebral lesions Biopsy tissue - disseminated disease Direct microscopy : aseptate to pauci-septate hyphae of zygomycetes with KOH Culture: rapidly growing molds Morphology varies among the species.

Answer 14

Treatment early diagnosis; reversal of underlying predisposing risk factors, if possible; surgical debridement; and prompt antifungal therapy (Amphotericin B, Capsofungins) Prognosis: Very poor

Answer 15

Pneumocystis jiroveci Penicillium marneffei Fusarium Bipolaris Exophiala Scedosporium Sporothrix Wangiella Curvularia Alternaria

Answer 16

identification of microorganisms by a mass spectrometric profile of the proteins, largely rRNA proteins, of the organism This is placed into the mass spectrometer, wherein this spot will be activated by a laser The matrix absorbs much of the energy from the laser and converts it into heat. The heat vaporizes the outer portion of the specimen The molecules move through a vacuum space at a different rate based on the mass-to-charge (m/z) ratio, and this “time of flight” is determined by the arrival of the different molecules at the detector A summation of the time of flight for all molecules present will produce a spectrum Best match in database to identify organism

Opportunistic Mycoses Flashcards

(41 cards)