LMP299Y1 Lecture Notes - Myocardial Infarction, Opportunistic Infection, Pseudomonas Aeruginosa

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16 Dec 2013
September 17, 2013
Read paper before Thursday lecture
38 year old male
Symptoms of lymphoma; underwent treatment; as result of treatment, good response, mass
disappeared; developed generalized nausea, vomiting; ER visit, where lob consolidation where air space
filled with fluid as seen on X-ray; developed respiratory failure; death
Left upper lobe area of hemorrhage
Microscopic section make out the alveolar walls; most air spaces filled with blood; blood has albumin
and fibrin that coagulates once blood reaches extravascular tissues
Higher magnification gram stain microorganiss throughout the lungs rod shaped, consistent with
Invading the walls of the vessels, accounting for hemorrhage
Pneumonia and septicemia
Due to pseudomonas aeruginosa
Patient was immunosuppressed as result of therapy for his therapy of lymphoma patient able to
mount inflammatory response that would readily control this infection at the early stages
Very frequent opportunistic infection
Aquatic environments hospitals are cesspools of infection ill patients shed their bacteria; and where
they can survive, they will survive there anywhere in hospital; especially places where have water
Bacteria will infect lungs when in intensive care, intubated, which can be source of infection from
upper respiratory tract into lower respiratory tract
Aspirate gastric contents before getting intubated but the main culprit is the fact that this patient has
bone marrow that is depleted of myeloid cells this makes the patient susceptible to opportunistic
Another example HIV CD4 positive cells destroyed by virus these patients are predisposed to
opportunitist cinfections, but not by this bacteria; HIV predisposed to viral infections, TB infections,
crytobacteria not bacterial infections because it’s the innate immune system that are most critical for
that; slight differences between different types of immunosuppression and the type of opportunistic
pathogen that is susceptible to
Another example Cystic fibrosis vulnerable to psenumonas, other bacterial infectiosn CF patients
cannot clear mucus in lungs susceptible to bacterial infections in bronchii of lungs
Another example organ transplantation these patients susceptible to less so innate immunity???
Genetic conditions of immunosuppression could affect acquired immune system and/or innate
immune system ex. Conditions like genetic deficiency of integrin, ex beta2 integrins, these patients
lack leukocyte adhesion type 1 have circulating myeloid cells, because integrins are key molecules
required for exit of cells into tissues, these patients predisposed to bacterial infections
Genetic infections affecting bacteria killing, etc.
70 year old male
Developed pneumonia after surgery for femur fracture
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Decreased level of consciousness
Radiological features of pseuomenaous colitis
Arrow pointing to colon wall is thick as compared to wall of small intestine
Thickness in bowel wall
Air fluid level in bowel colon is quite dilated
Colon dilated and long
Pseudomembraneous pseudomebrane attached to mucosa pus being deposited and adherent to
surface of bowel
Section through colon normal looking mucosa; destruction of mucosa, leukocytes and fibrin deposited
Higher magivication still remnants of mucosa top of mucosa been destroyed and see neutrophils
this is what caused the pseudomembrane
A lot of edema on radiological study, there is fluid that exits from the blood vessels, causing dilation of
submucosa this is why radiologically, the wall looks so thick on CT scan
Mechanism of pseudomembraneous colitis
Broad-spectrum antibiotics cause destruction of normal bacterial flora in bowel
Clostridium usually resistant to antibiotics now less competition for nutrients and if patient is infected
with clostridium different in balance between normal microbiota versus pathogen allows pathogen
to proliferate and to take over
Spores can survive for months in hospital environment hard to eradicate
If thesepatients exposed to antibiotics decrease normal flora clostridium will grow and take over
Clostridium makes two toxins entertoxins they disrupt the barrier function of colonic mucosa
some subset of clostridium that makes binary toxin some studies that suggest particularly severe cases
of this disease also associated with this binary toxin another example to reinforce the normal
microbiota in this intestine
What causes these patients to die? Can produce various factors/cytokines that are released into
Low blood pressure blood vessels become leaky, but more importantly, ther ies decreased peripheral
vascular resistance; cardiac output of blood what maintains the blood pressure at certain level is the
ability of the blood to exit from those arteries this is regulated at level of arterioles; if dilate arteirioles,
more blood let into a particular tissues; if dilate all arterioles, the heart in these patients pumping very
fast (cn get cardiogenic shock if infarction, the pump doesn’t work very well), get low blood pressure
Resistance decreased- blood into tissues at higher rate
Learning objectives:
Mechanisms of inflammation
Rapidly destroy dilute or isolate the injurious agent or infectious agent the inflammatory response,
evolutionarily goes all the way back to beginning even unicellular organisms have ability to combat
various pathogens
Amoeba can phagocytose bacteria, destroying it
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