主要致病性真菌(編輯修改稿)
2025-10-06 03:19 本頁(yè)面
【文章內(nèi)容簡(jiǎn)介】 Encounter. H. capsulatum grows in soil, especially soil contaminated by guano. Inhalation of conidia from the environment is source of infection. This is more likely in endemic areas. In . these include the Atlantic Ocean to N. Dakota (500,000 cases/year in .), except New England Florida. Most cases occur in Ohio Valley and Mississippi Valley) 42 第四十二頁(yè)，共八十一頁(yè)。 More Histoplasmosis 1. 90% of cases are asymptomatic, but in rare cases flu like respiratory symptoms occur 2. Disseminated histoplasmosis occurs in 1:200 cases and is diagnosed frequently in patients with AIDS living in the central . 3. In these cases, the anism spreads via blood from the lung to involve bone marrow, adrenal glands, heart valves and CNS 4. Spread can also be associated with underlying lung disease (., emphysema). B. Spread C. Immune Response 1. Cellmediated responses are of primary importance 2. Activated macrophage can kill yeast cells D. Evasion of Defenses 1. Survival in macrophages— elevates pH of phagosomes 2. Yeast cells absorb iron (siderophore) and calcium from host 3. Alteration of cell surface 43 第四十三頁(yè)，共八十一頁(yè)。 Histoplasmosis 1. Direct histology and culture of blood or bone marrow 2. Serological testing for antibody and histoplama antigen in blood and urine. E. Diagnosis D. Damage 1. Lungbronchial obstruction and inflammatory sequelae 2. Disseminated histoplasmosisfulminant disease that may result in toxic shock 3. CNSfatal if untreated. 44 第四十四頁(yè)，共八十一頁(yè)。 Even More Histoplasmosis F. Treatment ? Amphotericin still mainstay of therapy vs. disseminated and severe pulmonary histoplasmosis. ? Ketoconasole or itraconasole is effective as therapy for selflimited disease (used in AIDS). Ocular Histoplasmosis A small fraction of individuals form scar tissue in the retina many years after the original histoplasmosis infection. Live anisms cannot be recovered from these specimens. The scarring can obscure the macula and lead to loss of central vision. The first signs are small ―histo spots〞 . Advanced disease is treated with laser photocoagulation to limit the proliferation of blood vessels. 45 第四十五頁(yè)，共八十一頁(yè)。 Blastomycosis Granulomatous mycotic infection that predominantly involves lungs and skin。 but can spread to other ans. Most prevalent in males 4060 years of age and children. Blastomyces dermatitidis Dimorphic anism originates in the soil and infection ensues by inhalation of spores. Converts to yeast in animal hosts or at 37o in vitro. 46 第四十六頁(yè)，共八十一頁(yè)。 Blastomycosis ? Encounter: Most cases are in southern, central, and southeastern USA. Infection is by inhalation of spores. ? Spread: The pulmonary infection is either self limited or progressive. Dissemination often occurs to the skin and to the bone 80% of patients have large skin lesions。 a large number also have granulomatous pulmonary lesions. ? Risk Factors: Occupational contact with soil。 owning a dog. Living in endemic area. ? Evasion of Defenses: Escapes phagocytosis by neutrophils and monocytes by shedding its surface antigen after infection ? Damage: Consequence of the immune response to the anism—skin lesions, respiratory infiltrates. ? Diagnosis: based on clinical findings and microscopic detection of anisms in tissue specimens 47 第四十七頁(yè)，共八十一頁(yè)。 1. Amphotericin B is the drug of choice for rapidly progressive blastomycosis 2. Itraconazole or Ketoconazole for less severe cases Immune
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