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38 Cards in this Set
- Front
- Back
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What is Kaposi's sarcoma herpes virus (KSHV)?
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AKA Human Herpes Virus-8
Enveloped, DNA virus from Herpesviridae family Replicates in nucleus Causes Kaposi's Sarcoma Latent virus Immunosuppression = reactivation |
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What is the transmission for KSHV?
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Mainly sexual transmission in US (more commonly homosexual)
In Africa and Amazon, mostly vertical and/or horizontal (non-sexual) - virus abundant in saliva of pts |
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What are the 4 variants of Kaposi's Sarcoma and risk group for each?
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Classic - elderly men of Mediterranean origin
Endemic - African children, adults Post-transplant - organ recipients AIDS-KS - HIV/AIDS pts |
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Describe classic Kaposi's Sarcoma.
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Indolent, lesions confined to skin, usually legs
Slow spreading, dissemination from skin uncommon Start as flat discolorations, progress to plaques, to raised nodules Usually non-lethal; cells not malignant by classic definition Lesions identical to AIDS-KS lesions |
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How is Kaposi's Sarcoma not a typical cancer?
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Made up of diverse cell types: spindle cells of endothelial origin, B/T cells, abundant neurovascularity
Angiogenesis occurs prior to mass formation Cells generally diploid (no genetic instability) Do not form tumors in mice, or grow on their own in vitro |
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Describe AIDS-KS.
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FAR more malignant; lesions first appear on skin
Dissemination across body (lungs, GI tract) Life threatening to patient (1-2 yr median survival) Polyclonal cancer |
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How is Kaposi's Sarcoma diagnosed?
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Clinically and histologically
Tissue samples stain positive for viral DNA/proteins Are not diagnosing pt with a KSHV infection -- latent infection, most seropositive people do not suffer from Kaposi's sarcoma |
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What is human cytomegalovirus (CMV)?
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Herpesvirus: dsDNA, enveloped virus
Symptoms (immunocompetent): asymptomatic, non-specific febrile illness, mono-like syndrome CMV enters latency - leukocytes, endothelial, renal epithelium, salivary glands |
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What are the risk groups for CMV?
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AIDS
Transplant recipients Cancer pts The fetus - primary CMV infection |
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What is most commonly seen in AIDS pts with CMV?
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Retinitis - white, fluffy retinal infiltrates, infection of retina
Untreated = irreversible blindness Less common: CNS disease, pneumonitis, GI disease |
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What is seen in organ transplant recipients with CMV?
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Primary disease or re-activation
Donor CMV +ve, recipient CMV -ve = primary CMV Fever, myelosuppression, GI tract Pneumonitis also common Retinitis rare |
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What is the transmission for CMV?
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Congenital: placental transfer, breast milk
Person-person: saliva, sexual fluids Blood transfusions, organ or bone marrow transplants |
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How is CMV infection diagnosed?
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Difficult due to viral latency
Abs and viral DNA present even if asymptomatic PCR more quantitative (gold standard) CMV retinitis: clinical signs alone Transplant pts: serology to compare donor vs. recipient (recipient neg, donor pos serious consequences) |
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What is cryptosporidium spp.?
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Intestinal sporozoite
Oocysts: 4-6 um wide double-walled ovals Immunocompetent: self-limiting disease, diarrhea, abdominal pain |
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What is the transmission for cryptosporidium spp?
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Fecal-oral (person-person)
Zoonotic Waterborne, foodborne |
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How does cryptosporidium present in immunosuppressed?
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Auto-infective disease (NOT self-limiting) = chronic auto-infection
May lead to diarrhetic fluid loss No known completely effective therapy Infects entire GI tract, dissemination to respiratory surfaces, bile duct Susceptible pts: CD40 deficiencies, SCID, IFN-gamma deficiencies, XLA, AIDS, acute leukemic pts |
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How is cryptosporidium diagnosed?
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Acid-fast staining of stool samples for oocysts
Immunoassays (direct fluorescence, DFA) Commercial EIA tests to detect cryptosporidium antigens in stool PCR assay at the CDC |
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What is toxoplasma gondii?
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Intracellular parasite that causes toxoplasmosis
Forms tissue cysts found in skeletal muscle, myocardium, brain Life-time chronic infection |
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What are the risk groups and transmission for T. gondii?
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Risk groups: immunocompromised pts, unborn fetus
Transmission: contaminated meat, congenital, fecal-oral, contact with cat fecal matter (cats are definitive host) |
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What are the clinical manifestations for T. gondii?
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Toxoplasma encephalitis - fever, convulsions, delirium, lymphadenopathy, encephalitis, death
Pulmonary toxoplasmosis - severe intestinal pneumonitis Toxoplasma chorioretinitis - blurred vision, pain, photophobia |
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How is T. gondii diagnosed?
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Microscopic analysis of biopsies
Specimen isolation/inoculation PCR Imaging |
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What is Aspergillus fumigatus?
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(Also A. flavus, A. niger, A. terreus, A. lentulus)
Ubiquitous in nature and world-wide Small conidia that are easily aerosolized Inhalation of conidia that may germinate to produce hyphae that invade the lungs (fungus ball), blood and other tissues -- immunocompromised only Aerial hyphae with characteristic conidia |
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What are the clinical presentations of aspergillus?
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Pneumonia (fungus ball)
Invasive aspergillosis (systemic disease often fatal): Cardiac lesions CNS involvement Pneumonia GI tract Kidney Hepatitis |
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How is Aspergillus diagnosed?
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Via sputum, biopsy (rarely blood)
KOH or calcofluor white for sputum Biopsy stain with Gomori methenamine silver or Grocott stain |
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What is cryptococcus neoformans?
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Spherical budding yeast with thick, non staining capsule (india ink)
Virulence factors: yeast with large polysaccharide capsules, produce urease and laccase (produce melanin) Worldwide distribution -- in pigeon feces Inhalation of desiccated yeast, dissemination from lungs to CNS - primary pulmonary infection asymptomatic or flu-like |
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What are the clinical presentations for cryptococcus?
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Cryptococcal meningioencephalitis
Symptoms: fever, headache, meningeal signs can be present or absent Can also cause infections of skin, eyes, prostate, adrenals, bone |
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How is cryptococcal meningoencephalitis diagnosed?
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Blood and CSF for cryptococcal antigen (latex agglutination)
Direct stain of CSF with India Ink Blood and CSF culture for organism |
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What is histoplasma capsulatum?
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In bat and bird fecal matter; no capsule
Facultative intracellular within macrophages Dimorphic - small brown yeast at 37C, hyphae with tuberculate macroconidia at 25C Inhalation and yeast engulfed by macrophages - replicate in macrophage, disseminate to liver, spleen, bone marrow, lymph nodes |
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What are the clinical manifestations of histoplasma capsulatum?
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Immunocompetent pts: localized pulmonary disease
Immunosuppressed: disseminated infection Anemia, hepatitis, enlarged spleen, GI ulcers, skin lesions, lymphadenopathy Blood or bone marrow cultures for diagnosis |
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What is pneumocystis jirovecii?
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Environmental organism: URT of healthy humans
Rarely causes disease unless host immunosuppressed 2 stages: Trophozoite stage: ovoid/ameboid shape with thin walls, binary fission Cyst stage: rounded with thick walls, contain developing trophozoites (4-8 nuclei), stained with silver, toluidine blue, calcofluor white |
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What is the pathogenesis for P. jirovecii?
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Respiratory droplet transmission person-to-person
Alveolar spaces: cysts rupture to release actively growing trophozoites Remain on surface of epithelial cells (extraellular pathogen) Alveolar spaces fill with foamy exudate |
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What are the clinical presentations for P. jirovecii?
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PCP pneumonia: diagnosis via bronchoalveolar lavage and staining, culture not possible
Extrapulmonary infections: spleen, liver, lymph nodes, bone marrow |
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What is candida albicans?
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Frequent opportunistic infection of HIV+
Oval budding yeast and pseudohyphae Can distinguish from other Candida by germ tube formation (true hyphae) in serum at 37C |
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What are the clinical presentations of Candida?
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Oral candidiasis (thrush): disgnosis usually clinical
Candida stomatitis and/or esophagitis (AIDS defining illness) Can be systemic if phagocytic host defenses are inadequate |
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Name an organism that is an "atypical" mycobacteria opportunistic pathogen.
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M. avium-intercellulare complex (MAC; MAI) - disseminated infection in AIDS pts
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Describe the mycobacteriaceae family?
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Obligate aerobes, non-motile, slender bacilli
Unique cell walll (major virulence determinant) Acid fast stain |
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What are symptoms of disseminated MAC?
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Fever, weight loss, night sweats, abdominal pain, nausea
Hepatitis, pneumonia, pericarditis, bone, CNS, skin lesions, lymph node, soft tissue abscesses Organisms isolated from sputum Diagnosis by culture from blood or tissue: AFB or fluorescence staining |
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What is granulobacter bethesdensis?
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First identified in April 2006
Only seen in CGD pts Family Acetobbacteriaceae Environmental, industrial for vinegar production Gram (-) rod Commonly in soil and associated with plants |
