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1Presented by Sarah E. Johnston Opportunistic Fungal infections that can occurinHIVinfected individualsPresented by Sarah E. Johnston
2Overview HIV effects on immune system potential fungal pathogens of HIV patientsPneumonocystis jirovecii and the disease PCPCryptococcus neoformans and fungal meningitisSummaryQuestions
3Human Immunodeficiency Virus Severely debilitates the human immune system by :Defecting Macrophage’s ability to properly process and present foreign particles to immune systemDebilitate and deplete CD4+ T lymphocytes needed for cytokine production and assisting B cells to produce antibodiesDebilitated cytokine production effect neutrophil count and functionMacrophages are the 1st line of defense after pathogen gets past mechanical barriersHIV envelope glycoprotein (gp120), which suppress bone marrow progenitors , also have been implicated as causal factors in neutropenia. Apoptosis, the normal mechanism of programmed cell death characterized by DNA fragmentation, is markedly accelerated in neutrophils in patients with HIV infectionNeutrophils are a type of phagocyte and are normally found in the bloodstream. During the beginning (acute) phase of inflammation, particularly as a result of bacterial infection, environmental exposure, and some cancers, neutrophils are one of the first-responders of inflammatory cells to migrate towards the site of inflammationHuman Immunodeficiency Virus(HIV-1 & 2)
4Opportunistic Offenders Rhizopus oryzaeOpportunisticOffendersPneumonocystis jiroveciiCandida albicans*Aspergillus fumigatus. A 4-day culture on Malt Extract Agar.*Candida albican on CHROMagar green colonies*Rhizopus oryzae and R. microsporus - in tissue and in culture, these moulds form characteristic broad, non-septate or sparsely septate hyphae with right-angled branchingAspergillus fumigatusCryptococcus neoformans
5Pneumonocystis jirovecii Was formerly known as Pneumonocystis carinii and thought to be a protozoan.Life cycle has both sexual and asexual componentsP. jirovicii was previously considered a protozoan but due to molecular and genetic evidence was reclassified as a fungus.The life cycle of P. jirovicii has both sexual and asexual components and during the course of human infection can exist as a uninucleate sporocyst, free trophic form, or as a cyst. Entry of the organism is via the respiratory tract and pneumonia is the most common presentation of pneumonocystosis-P. jirovecii is a unicellular eukaryote which shares characteristics with both protozoa and fungi leading to years of debate on the proper taxonomy of this microorganism. P. jirovecii was initially reported by Chagas in 1909 as a morphologic form of Trypanosoma cruzi, but later proved to be a separate genus and was named Pneumocystis carinii in P. carinii was classified as a protozoan until 1988, when P. carinii was placed in the fungal kingdom following ribosomal RNA (rRNA) analysis. The molecular data demonstrated that despite the fact that many of P. jirovecii’s morphological features are similar to those of protozoa, the rRNA and mitochondrial sequence of Pneumocystis are homologous to those of fungi.Interesting fact: % 80 U.S.population has antibodiesto this organismUninucleate sporocystCyst
6Pneumonocystis carinii pneumonia (PCP) The trophozoite form attaches to lung epithelial cells after inhalationP. jiroveci replicates extracellularly and impairs oxygen diffusionInflammation causes host cell to lysis.Damage to the lung basement membrane generates a characteristic foamy exudate and interstitial leukemic infiltration in the alveoli, resulting in a decrease in alveolar capillary permeability.The risk of pneumonia due to P. jirovecii increases when CD4 positive cell levels are less than 200 cells per microliter. For this reason PCP was once recognized as the most common AIDS defining disease; however, the incidence of PCP in patients with AIDS has declined due to the introduction of HAART (highly active antiretroviral therapy) in P. jirovecii remains one of the major causes of opportunistic mycoses in immunocompromised patients.Check out the videos below for more information on PCP.Granulomatous inflammation in Pneumocystis pneumonia is rare but may be seen in up to 5% of lung biopsies from human immunodeficiency virus (HIV)-infected patients
7How it is diagnosedDiagnosis use to be based on stained respiratory tissues using Giemsa and Gomori-Grocott techniques, staining sputum, branchoalveolar fluid or lung tissue.Due to inability to properly visualize trophozoite form PCR is the standard technique used to identify this pathogen.Bronchoalveolar lavage (BAL) is a medical procedure in which a bronchoscope is passed through the mouth or nose into the lungs and fluid is squirted into a small part of the lung and then collected for examination. BAL is typically performed to diagnose lung disease.Top image -Alveolar foamy exudate and severe chronic intersitial inflammationBottom image- BAL
8How HIV contributes to risk HIV individuals who have progressed to full blown AIDS have a very low CD4+ T cell count. This contributes to decreased ability to produce super oxygen radicals used by alveolar macrophages to kill foreign invaders that they take up via phagocytosis.Fortunately due to the use HAART (highly active antiretroviral therapy) PCP cases in HIV patients has decreased significantly.The infection occurs more frequently when the concentration of T helper cells is below 200 cells per cubic millimeter. In fact, a low T helper cell count can impair hydrogen peroxide and superoxide production by alveolar macrophages. In healthy individuals, P. jiroveci is cleared from the lungs via phagocytosis by alveolar macrophages. It is believed that immune cells recognize the pathogen by the mannose-containing residues. The symptoms of a pneumocystis pneumonia include progressive dyspnea, nonproductive cough, and low grade fever.For this reason PCP was once recognized as the most common AIDS defining disease; however, the incidence of PCP in patients with AIDS has declined due to the introduction of HAART (highly active antiretroviral therapy) in 1996.
9Cryptococcus neoformans Encapsulated Yeast-like fungus that belongs to the family Tremellaceae.Transmission occurs via inhalation of basidiospores into the lungs.Replication occurs via buddingCan be found in soil around the world, but is primarlily associated with bird droppings and eucalyptus trees.
10Fungal MeningitisIs the inflammation of the membrane that surrounds the brain and spinal cord.C. neoformans infections usually start in the lungs (pneumonia) and in HIV patients dissemination occurs to other areas. In this case to the CNS.Picture is of C. neoformans in lung tissue of an aids patientBottom pictue of C. neoformans in CSF (india ink)
11Secondary infectionsHIV patients with fungal meningitis usually develop a secondary infection site of the skin, prostate, and eye.Secondary infection of the prostate can contribute to acting as a reservoir in AIDs patients and contributing to relapse in previoulsy treated patients.Infections of the skin show a variety of lesion types (acneforme, papules, vesicles, tumors, etc).The prostate has been recognized for a long time as a site of cryptococcal localization and has been associated as a reservoir of the organism leading to relapse in AIDs patients previously treated. Eye infections can also occur and are commonly associated in patient with meningitis. Ocular cryptococcosis can cause permanent vision loss in the infected individual
12Different media used to culture C. neoformans India ink is used in CSF to visualize capsule and creates characteristic halo effect around capsuleBird seed agar- C. neoformans is brown in color due to uptake of brown pigment I mediaColonies are mucoid and cream colored on SAB
13Diagnosis of C. neoformans infection can be made by microscopic examination and/or culture of tissue or body fluids such as blood, cerebrospinal fluid, and sputum.cryptococcal antigen test can rapidly test blood and/or cerebrospinal fluid to make the diagnosis.A fungal culture is essential to differentiate between the different species of Cryptococcus - C. neoformans and C. gatti
14SummaryHIV critically impairs immune system and leaves it vulnerable to opportunistic fungal pathogens.Pneumocystis jirovecii causes Pneumocycstic carinii pneumonia (PCP) in AIDs patients and use to be a common indicator of HIVCrypotococcus neoformans is the leading cause of fungal meningitis and is one of the most common opportunistic infections in individuals with AIDs
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