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What symptoms are seen with a spirochete that is transmitted via ixodes tick in the Northeast, Midwest, and west Coast?
- Borrelia burgdorferi --> Lyme disease
- - Erythema migrans (target shaped)
- - Dissemination -> neurologic symptoms & cardiac symptoms
- - Arthritis via type III hypersensitivity
TX = doxycycline
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How do you diagnose and treat an atypical pneumonia in patients with full-blown AIDS caused by an atypical, extracellular fungus?
Methenamine silver-staining cysts in frothy alveolar exudates.
TX: trimethoprim/ sulfamethoxazole
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What is the toxin produced by C. perfringens that is strongly associated with myonecrosis?
- Alpha toxin = lecithinase(phospholipase C) that lyses erythrocytes, platelets, leukocytes, and endothelial cells.
- -> massive hemolysis, increased vascular permeability and bleeding, hepatotoxicity, bradycardia, and hypotension.
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What are characteristics of Histoplasma capsulatum?
- Causes fungus flu - acute penumonia with flu-like symptoms
- Intracellular yeast which is why it is not communicable.
- Endemic region- Great lakes to Gulf of Mexico
- Disseminated infections are common in AIDS patients - mucocutaneous lesions
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What are the stages caused by treponema pallidum?
- Primary - painless, ulcerated genital lesion
- Seconday- maculopapular, bronzing rash and condylomata lata
- Tertiary- gumma formation in the CNS and vasculature.
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What are the hepadnavirus?
Hepatitis B = orthohepadnavirus
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Describe Ehrlichia Phagocytophila
Transmitted by Ixodes tick
Presents similar to Rocky mountain spotted fever but without the rash.
Pathognomic feature berry-like cluster inside granuloicytes
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What is the mechanism of action of the toxin produced by corynebacterium diphtheriae?
Inactivates eukaryotic elongation factor eER-2 -> inhibition of protein synthesis. (pseudomembrane in the oropharynx)
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How is neonatal encephalitis caused by Herpes simplex virus most likely acquired?
Through the birth canal of a women with active lesions.
- Temporal lobes involved.
- CSF- mononuclear pleocytosis and elevated protein levels
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How did the mother of a baby that presented with cutaneous hemorrhages (blueberry muffin baby), deafness and periventricular CNS calcification present?
This is CMV infection in the adult presetnation is mild fever and lymphadenopathy.
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How does streptococcus pneumoniae attach to the respiratory mucosa?
Teichoic acids in the envelope and IgA protease -> cleaves the Ig and gets coated by the Fc component which then binds to Fc receptors on mucosal cells.
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What is the most common cause of neonatal meningitis and how do you treat it?
Group B strep (agalactiae) acquired through the birth canal in a mother previously colonized by GBS
TX: is by prevention which is mom recieving intravenous ampicillin during labor.
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A neonate presents with neonatal conjunctivitis and then develops atypical pneumonia. Tachypnea, hypoxemia, crackles, wheezing, and eosinophilia are evident. What is the organism responsible?
Chlamydia trachomatis.
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Describe Naegleria fowleri
- Free living amoeba found in warm, freshwater lakes.
- Diving introduces organism through the cribiform plate resulting in the production of necrotic lesions spreading from the olfactory lobes.
Tissue form of the organism is a flagellated trophozoite.
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Describe klebsiella pneumoniae
Typical pneumonia in alcoholics with red, gelatinous sputum(currant jelly sputum)
Gram negative, oxidase-negative bacillus that is lactose-fermenting
TX: with 3rd generation cephalosporin with or without an aminoglycoside.
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What is CMV?
It is a herpesviridae that is a double stranded DNA, nuclear membrane enveloped, icosahedral .
Forms owl's-eye inclusion bodies
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What is the characterization of chronic active hepatitis?
Chronic inflammation with continuing necrosis of hepatocytes surrounding the portal tract and extending into the lobule with individual hepatocyte destruction (piecemeal necrosis)
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What is the diagnosis and treatment for the species that is:
transmitted via reduviid bug
causes heart failure, megaesophagus, and megacolon, and Romana's sign?
- This is Trypanosoma cruzi
- Diagnosed via blood films - trypomastigotes
- TX: nifurtimox (forms N oxides)
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What is spiral-shaped, motile, oxidase positive, catalase positive rod with multiple flagella at one pole?
Helicobacter pylori
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Why does Chlamydia trachomatis not grow on Thayer-Martin and also causes a type IV hypersensitivity reaction?
Chlamydia trachomatis is an intracellular organism that cannot make its own ATP.
Thayer Martin is used to differentiate between Chlamydia and Neisseria gonorrhea
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Describe Toxoplasma gondii
- intracellular, parasitic protozoan
- Hosts = cats or poorly cooked pork
- AIDS:
- ring-enhancing lesions, necrotizing lesions surrounded by chronic inflammation
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What are anopheles mosquito responsible for transmitting?
- Malaria parasites
- Plasmodium falciparum = sludging of infected RBC in the small cerebral capillaries -> vascular occlusion -> numerous small infarcts
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What 2 organisms could be transmitted via bird droppings?
Cryptococcus neoformans -> meningoencephalitis
Histoplasma capsulatum -> rarely affects brain (pneumonia)
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What is transmitted via cooling systems?
- Legionella pneumophila
- Legionnaire disease (fatal form of pneumonia)
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What is transmitted via rodent droppings
- Hantavirus -> fatal respiratory illness
- endemic in desert Southwestern part of the United States.
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What are the 3 main causes of meningitis in neonates?
- Streptococcus agalactiae
- Escherichia coli
- Listeria monocytogenes
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