Presentation on theme: "Presented by Sarah E. Johnston. Overview HIV effects on immune system potential fungal pathogens of HIV patients Pneumonocystis jirovecii and the disease."— Presentation transcript:
Presented by Sarah E. Johnston
Overview HIV effects on immune system potential fungal pathogens of HIV patients Pneumonocystis jirovecii and the disease PCP Cryptococcus neoformans and fungal meningitis Summary Questions
Severely debilitates the human immune system by : Defecting Macrophage’s ability to properly process and present foreign particles to immune system Debilitate and deplete CD4 + T lymphocytes needed for cytokine production and assisting B cells to produce antibodies Debilitated cytokine production effect neutrophil count and function
Pneumonocystis jirovecii Was formerly known as Pneumonocystis carinii and thought to be a protozoan. Life cycle has both sexual and asexual components / Cyst Uninucleate sporocyst Interesting fact: % 80 U.S. population has antibodies to this organism
Pneumonocystis carinii pneumonia (PCP) The trophozoite form attaches to lung epithelial cells after inhalation P. jiroveci replicates extracellularly and impairs oxygen diffusion Inflammation 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.
How it is diagnosed Diagnosis 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.
How HIV contributes to risk Fortunately due to the use HAART (highly active antiretroviral therapy) PCP cases in HIV patients has decreased significantly. 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.
Cryptococcus neoformans Encapsulated Yeast- like fungus that belongs to the family Tremellaceae. Transmission occurs via inhalation of basidiospores into the lungs. Replication occurs via budding as.org/content /99/5/3165/F1.expansion.htm l
Fungal Meningitis Is 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. /
Secondary infections HIV 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.
Different media used to culture C. neoformans India ink is used in CSF to visualize capsule and creates characteristic halo effect around capsule Bird seed agar- C. neoformans is brown in color due to uptake of brown pigment I media Colonies are mucoid and cream colored on SAB de.edu.au/Fungal_Descriptio ns/Yeasts/Cryptococcus/C_n eoformans.html
Diagnosis 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
Summary HIV 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 HIV Crypotococcus 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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