Immunocompromised Information and Courses from MediaLab, Inc.
These are the MediaLab courses that cover Immunocompromised and links to relevant pages within the course.
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|Central Nervous System (CNS) Toxoplasmosis continued|
This is a higher power view of this same smear demonstrating a neutrophil that is filled with Toxopasma gondii tachyzoites (blue arrow).There are a few free organisms in this image well, indicated by the red arrows. Again, the typical morphology for toxoplasmsa organisms is lavender cytoplasm with a red granular cluster in the center of each parasite.This patient was negative for Toxoplasma gondii prior to a transplant but had received 15 units of blood products due to cytopenias.It is believed that a donor for one of the transfused units had been exposed to Toxoplasma gondii either through cats or contaminated food and had transient circulating Toxoplasma gondii in his or her blood when the donation was made. In this case, the recipient was profoundly immunocompromised, which lead to rapidly developing systemic disease.
Rocourt J. Jacquet C. Reilly A.: Epidemiology of human listeriosis and seafoods. International Journal of Food Microbiology. 62:197-209, 2000 While rarely diagnosed prior to 1960, more than 10,000 cases of listeriosis were recorded in the medical literature between 1960 and 1982, and thousands more have been reported annually world-wide. This widespread increase in reporting is most likely due to demographic trends and changes in food production, processing and storage, especially the extended cold food chain and the ability of Listeria monocytogenes to grow at low temperatures L. monocytogenes is a bacterium responsible for opportunistic infections, preferentially affecting individuals whose immune system is perturbed, including pregnant women, newborns, people over 65 years, immunocompromised patients, such as cancer victims, transplant recipients, people on hemodialysis and AIDS patients. Thus, the increasing lifespan and medical progress allowing immunodeficient individuals to survive, partially explains the increasing incidence of listeriosis. Moreover, L. monocytogenes is ubiquitous and can grow at temperatures as low as 0 degrees C. At this temperature growth is very slow. The expansion of the agro-food industry, the widespread use of systems of cold storage and changes in consumers demands have led to a large increase in the pool of Listeria that can cause food-borne infections.
Rouquette C. Berche P. The pathogenesis of infection by Listeria monocytogenes Microbiologia. 12:245-58, 1996 Listeria monocytogenes is a Gram-positive bacterium responsible for severe infections in human and a large variety of animal species. It is a facultative intracellular pathogen which invades macrophages and most tissue cells of infected hosts where it can proliferate. The molecular basis of this intracellular parasitism has been to a large extent elucidated. The virulence factors, including internalin, listeriolysin O, phospholipases and a bacterial surface protein, ActA, are encoded by chromosomal genes organized in operons. Following internalisation into host cells, the bacteria escape from the phagosomal compartment and enter the cytoplasm. They then spread from cell to cell by a process involving actin polymerisation. In infected hosts, the bacteria cross the intestinal wall at Peyer's patches to invade the mesenteric lymph nodes and the blood. The main target organ is the liver, where the bacteria multiply inside hepatocytes. Early recruitment of polymorphonuclear cells lead to hepatocyte lysis, and thereby bacterial release This causes prolonged septicaemia, particularly in immunocompromised hosts, thus exposing the placenta and brain to infection. The prognosis of listeriosis depends on the severity of meningoencephalitis, due to the elective location of foci of infection in the brain stem (rhombencephalitis). Despite bactericidal antibiotic therapy, the overall mortality is still high (25 to 30%).
|Mucicarmine: Diagnostic Applications|
The mucicarmine staining procedure is very specific in its detection of mucins of epithelial origin and is used to identify adenocarcinomas. It is particularly useful in detecting adenocarcinomas originating in the gastrointestinal tract. This procedure can also successfully stain and detect the capsule of a fungal organism known as Cryptococcus neoformans . This fungus is usually identified in the lungs and in nervous tissues. C. neoformans is more likely to infect immunocompromised patients than persons with active immune systems.
|With regard to blood cultures, which blood to broth ratio is most conducive to growth:||View Page|
|Which of the following organisms is not an aerobic organism:||View Page|
|Risk Factors and Resistance|
Enterococci are largely commensal organisms that are opportunistic pathogens. Underlying disease, an immunocompromised state, age, lengthy hospital stays or long term care, invasive treatments, and/or prior antimicrobial therapy are factors that are associated with significant infections with these species. As noted previously, Enterococci are intrinsically resistant to many antibiotics. Intrinsic resistance affects not only beta lactams (including a broad range of cepahlosporins) and aminoglycosides, but also clindamycin and trimethoprim/sulfamethoxazole. The standard recommended therapy for systemic infections is a combination of either penicillin or vancomycin and an aminoglycoside (gentamicin or streptomycin). The goal of combination therapy is to achieve a synergistic bacteriocidal effect between the cell wall agent and the aminoglycoside.In recent decades, increasing resistance to other antibiotics through acquired resistance mechanisms has become a growing therapeutic and infection control problem. Of key concern are high level resistance (HLR) to aminoglycosides and increasing resistance to glycopeptides such as vancomycin.
|Match the names of each of the fungi listed with its appropriate category indicating the degree of pathogenicity.||View Page|
|Immunocompromised patients, such as those with AIDS are at an increased risk of contracting which of the following conditions?||View Page|
|A 50 year old male domestic airline pilot was rushed to the hospital after complaining of tremendous fluid loss due to severe diarrhea. History revealed that the patient was diagnosed with AIDS 6 months ago. The doctor ordered a battery of tests including a stool for parasite examination. Since the sample was properly labeled indicating that the patient was immunocompromised, the lab performed both the standard processing procedures and a modified acid-fast (mod AFB) stain. The mod AFB stain revealed this suspicious form which measured a mere 4 µm. This patient is most likely infected with:||View Page|
|Epidemiology of the Virus|
The Influenza A 2009 H1N1 virus spreads from person to person in a similar way to the seasonal flu in previous years.The primary route of influenza virus transmission and infection are by respiratory droplets and aerosols. Transmission may also occur via contaminated hands (person-to-person) and surfaces. Infected individuals can shed the virus and spread Influenza A 2009 H1N1 to others anywhere from 1 day prior to getting sick up until 5-7 days after symptoms arise. This range of viral shedding can be even longer in children and in some individuals who are immunocompromised.
|Definition and Incidence|
Transfusion-associated graft versus host disease (TA-GVHD) is a rare but highly lethal adverse reaction. The disease has a 90% mortality rate. It is caused by the transfusion of donor lymphocytes to a recipient who is immunocompromised. The donor lymphocytes engraft and escalate an immune response against the host's tissues including organs such as the lungs, skin, intestines, and liver. The recipient is unable to destroy the foreign lymphocytes and the cells proliferate and respond to incompatible antigens in the host. Certain recipients have increased risk for developing TA-GVHD. They are: Neonates less than 4 months of age Fetuses Recipients with a congenital or acquired immunodeficiency Recipients of donor units from a blood relative
|Which of the following patients are at risk for transfusion-associated graft versus host disease (TA-GVHD) and require irradiated cellular blood products? (Choose all that apply)||View Page|