Tags: Amphotericin B

Leishmania

Leishmania & Trypanosoma The genera Leishmania and Trypanosoma are members of the family Trypanosomatidae. These protozoans cause diseases with widely varied clinical presentations as well as geographic distributions, including leishmaniasis, American trypanosomiasis (Chagas’ disease), and African trypanosomiasis (sleeping sickness). For example, the endemic zones for African and American trypanosomiasis do not overlap, the diseases are transmitted by different vectors, they involve distinct mechanisms of pathogenesis, and they follow different clinical courses. Nonetheless, the causative agents share important biological features. Each is a hemoflagellate with a kinetoplast containing its own chromosomal DNA with highly conserved and repeated elements, each forms a single flagellum at some point during its life cycle, and each …

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Pathogenic Amebas

ENTAMOEBA HISTOLYTICA & ENTAMOEBA DISPAR Essentials of Diagnosis Patient living in or having traveled to endemic area increases risk. Frequent loose stools with blood and mucus. Demonstration of cyst or trophozoite on stool wet mount or in biopsy specimen. Serology positive within 7-10 days of infection, may remain positive for years after infection resolved. Monoclonal antibodies and polymerase chain reaction emerging; may help differentiate E histolytica and E dispar. General Considerations A. Epidemiology. There are numerous distinct species of ameba within the genus Entamoeba, and the majority of these do not cause disease in humans. E histolytica is a pathogenic species that is capable of causing disease, such as colitis or …

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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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Mucormycosis: Clinical Syndromes

1. RHINOCEREBRAL MUCORMYCOSIS Rhinocerebral mucormycosis occurs most commonly in patients with uncontrolled diabetes, especially after an episode of diabetic ketoacidosis. It may also occur in leukemic patients who have had prolonged neutropenia and therapy with broad-spectrum antibiotics and occasionally in organ transplant recipients. Clinical Findings A. Signs and Symptoms. The earliest symptoms in rhinocerebral mucormycosis are facial pain, headache, and nasal stuffiness. As the disease progresses, orbital pain and facial anesthesia may be noted. Double vision or loss of vision may develop after invasion of the orbit by the rapidly spreading infection. Mental status changes herald the penetration into the brain with ensuing cavernous sinus thrombosis, carotid artery thrombosis, and cerebral …

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Pseudallescheria Boydii Infection

Essentials of Diagnosis Filamentous fungus that is morphologically similar to Aspergillus spp. Most serious infections occur in immunosuppressed patients. Recovery from culture must be distinguished from colonization or contamination. General Considerations P boydii is a mold that is capable of causing infection in immunosuppressed patients and less frequently in immunocompetent patients. Overall, infection with P boydii is rare. A. Epidemiology. Although a relatively common environmental mold, P boydii is a rare cause of human disease. It can be easily recovered from soil, water, and manure. Both community and nosocomial acquisition have been documented. In most instances, its recovery from culture specimens will reflect colonization or contamination; however, it is capable of …

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