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2012-08-19 20:59:20

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  1. 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
  2. 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
  3. 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.
  4. 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
  5. 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.
  6. What are the hepadnavirus?
    Hepatitis B = orthohepadnavirus
  7. 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
  8. 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)
  9. 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
  10. 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.
  11. 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.
  12. 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.
  13. 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.
  14. 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.
  15. 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.
  16. What is CMV?
    It is a herpesviridae that is a double stranded DNA, nuclear membrane enveloped, icosahedral .

    Forms owl's-eye inclusion bodies
  17. 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)
  18. 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)
  19. What is spiral-shaped, motile, oxidase positive, catalase positive rod with multiple flagella at one pole?
    Helicobacter pylori
  20. 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
  21. Describe Toxoplasma gondii
    • intracellular, parasitic protozoan
    • Hosts = cats or poorly cooked pork

    • AIDS:
    • ring-enhancing lesions, necrotizing lesions surrounded by chronic inflammation
  22. 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
  23. What 2 organisms could be transmitted via bird droppings?
    Cryptococcus neoformans -> meningoencephalitis

    Histoplasma capsulatum -> rarely affects brain (pneumonia)
  24. What is transmitted via cooling systems?
    • Legionella pneumophila
    • Legionnaire disease (fatal form of pneumonia)
  25. What is transmitted via rodent droppings
    • Hantavirus -> fatal respiratory illness
    • endemic in desert Southwestern part of the United States.
  26. What are the 3 main causes of meningitis in neonates?
    • Streptococcus agalactiae
    • Escherichia coli
    • Listeria monocytogenes