Fungal Infections

Falciparum Malaria

Clinical Findings A. Signs and Symptoms. Fevers are often continual, with irregular spikes and associated chills and paroxysms. Patients with severe falciparum malaria may disclose central nervous system changes (prostration, convulsions, and impaired consciousness) and develop respiratory distress, abnormal bleeding, and circulatory collapse. Fatigue and malaise are nonspecific symptoms of malaria. These are in part caused by hypoglycemia and anemia. Hypoglycemia results from both decreased oral intake during illness and plasmodial use of blood glucose by the Embden-Meyerhof pathway. Anemia results from parasite-associated hemolysis and in some instances disseminated intravascular coagulation. Plasmodium infections cause elevated tumor necrosis factor alpha (TNF-a) levels, particularly in individuals with severe disease. This may also contribute …

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Pneumocystis Carinii

Essentials of Diagnosis Pneumocystis carinii, when examined using molecular techniques, most closely resembles a fungus. Stains of either bronchoalveolar-lavage (BAL) or transbronchial-biopsy samples yield a diagnosis in > 90% of patients and should be considered the gold standard in diagnosis. BAL with transbronchial biopsy increases diagnostic yield to ~ 100%. P carinii has not yet been cultured in vitro. Polymerase chain reaction (PCR) (especially on sputum) increases sensitivity but reduces specificity. The prophylactic use of aerosolized pentamidine reduces the sensitivity of sputum and bronchoscopic samples. General Considerations A. Epidemiology. In 1983, P carinii pneumonia (PCP) was described as the AIDS-defining illness in = 60% of the first 1000 patients diagnosed with …

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Extrapulmonary P Carinii Infections

Extrapulmonary P carinii infections occur in < 3% of patients and must be diagnosed with histopathologic samples. Primary prophylaxis for PCP with pentamidine may confer a higher risk for extrapulmonary infection. Symptoms of extrapulmonary involvement are nonspecific, usually consisting of fevers, chills, and sweats. Although any area of the body may be involved, splenomegaly with cysts and thyroiditis are most common. Diagnosis The practice of diagnosing PCP morphologically by traditional staining methods (silver methenamine and toluidine blue) of induced sputum samples in HIV-infected individuals has fallen out of favor. Although relatively simple and inexpensive, staining of sputum samples induced by hypertonic saline inhalation is clearly dependent on operator and laboratory experience, …

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Dermatophytes

Essentials of Diagnosis Characteristic pattern of inflammation on glabrous skin surfaces. The active border of infection is scaly, red, and slightly elevated. Wet mount preparation with potassium hydroxide (10-20%). Skin scraping of the active border shows branching, translucent, rod-shaped filaments (hyphae) in keratinized material under low-power microscopy (10-40×). Hyphae are uniformly wide and regularly septated. Wood’s light examination (UV light at 365 nm) shows blue-green fluorescence for Microsporum canis and Microsporum audouinii. Trichophyton schoenleinii is pale green, and tinea versicolor shows white-yellow fluorescence. Culture should be performed with hair, nail, and skin specimens from particularly inflammatory lesions, to make a definitive mycologic diagnosis. General Considerations Dermatophytes are molds that infect keratinized …

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Fusarium, Penicillium, Paracoccidioides, & Agents of Chromomycosis

FUSARIUM INFECTION Essentials of Diagnosis Worldwide geographic distribution. Mold, septate hyphae 3-8 um in diameter. A rare infection in severely immunocompromised patients. Blood cultures often but not always positive. No serologic tests available. Cutaneous involvement is common feature. General Considerations A. Epidemiology. Fusarium spp. is an emerging fungal pathogen. Although long recognized as a cause of local infection involving nails, traumatized skin, or the cornea (eg, in contact lens wearers), deep or disseminated infection was not described until the mid 1970s. Despite its worldwide distribution and its frequent recovery from soil and vegetative material, infection is quite rare. Only ~ 100 cases involving invasive disease in immunosuppressed patients have been described …

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Chromomycosis

Essentials of Diagnosis Patients are usually immunocompetent. Found worldwide but usually in tropical or subtropical areas. Mold in culture; forms sclerotic body or muriform cell in tissue. Infection results from direct inoculation from contaminated soil or vegetative substances. Chronic indolent cutaneous verrucous lesions, most often on the feet. General Considerations Chromomycosis, also known as chromoblastomycosis, is a chronic subcutaneous infection caused by several different fungi. Although rarely seen in the United States, it is common worldwide. A. Epidemiology. Chromomycosis occurs worldwide but is most frequently encountered in tropical and subtropical regions. The most common occurrence is in barefoot individuals, particularly among agricultural workers. The organisms causing chromomycosis are found commonly in …

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Paracoccidioidomycosis

Essentials of Diagnosis Patients usually immunocompetent. Patients in endemic areas with chronic pulmonary and mucotaneous lesions involving the mouth, nose, larynx, and face; regional or diffuse lymphadenopathy. Found in Latin America, from Mexico to Argentina. Dimorphic fungus: yeast form in tissue specimens and at 37 °C; mold form when grown at room temperature in the laboratory. Thick-walled yeast, 4-40 um, with multiple buds when seen in tissue specimens. Complement fixation or immunodiffusion. General Considerations Paracoccidioidomycosis is caused by Paracoccidioides brasiliensis. Also known as South American blastomycosis, it is the most prevalent systemic mycosis found in Central and South America and is the most common endemic mycosis in this area. A. Epidemiology. …

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Penicillium Infections

Essentials of Diagnosis Penicillium marneffei infection found in both immunocompetent and immunosuppressed patients. P marneffei found in Southeast Asia and southern China. Mold, septate hyphae 1.5-5 um in diameter. May be cultured from a variety of specimens including blood. Penicillium spp. other than P marneffei occur worldwide. Infection with Penicillium spp. is rare; occurs in immunosuppressed patients. General Considerations A. Epidemiology. Penicillium spp. are ubiquitous in nature and may be recovered with ease from a variety of sources within the hospital environment. These molds commonly contaminate clinical specimens and cause contamination in the laboratory. Colonization of nonsterile anatomical sites in humans is common. In most cases where Penicillium spp. are recovered …

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Sporothrix Schenckii

Essentials of Diagnosis Cigar-shaped yeast. Dimorphic: mycelial in nature, yeast in tissue. Associated with activities that involve contact with soil, sphagnum moss, decaying wood, or vegetation. Gardeners, forestry workers, miners, animal health care providers most at risk. Raised skin lesions with proximal spread along lymphatic channels. Recovery of microorganism from culture. General Considerations A. Epidemiology. Sporothrix schenckii, the causative agent of sporotrichosis, is a ubiquitous fungus commonly found in the soil, on sphagnum moss, on decaying wood, and on a variety of other vegetation. It is found worldwide but prefers a temperate or tropical climate with high humidity. Most cases of sporotrichosis are sporadic, but large human epidemics have been reported. …

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Aspergillus, Pseudallescheria, & Agents of Mucormycosis

ASPERGILLUS INFECTION Essentials of Diagnosis Filamentous fungus with septate hyphae 3-6 um in diameter. Branching of hyphal elements typically at 45° angle. Specific IgG antibodies generally of no use diagnostically since most patients are immunosuppressed and will not generate antibody response. Pulmonary lesions, localized or cavitary in susceptible host. General Considerations A. Epidemiology. Aspergillus spp. are found worldwide and grow in a variety of conditions. They commonly grow in soil and moist locations and are among the most common molds encountered on spoiled food and decaying vegetation, in compost piles, and in stored hay and grain. Aspergillus spp. often grow in houseplant soil, and such soil may be a source of …

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