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123 Cards in this Set

  • Front
  • Back
Diagnosis of infectious mononucleosis depends on what 3 findings?
lymphocytosis with the characterstic atypical lymphocytes in the peripheral blood, a positive heterophile antibody reaction (monospot test), and specific antibodies for EBV antigens or Epstein-Barr nuclear antigens
What effect does the HPV protein E6 have on cellular proteins?
It stimulates ubiquitination and degradation of p53
What effect does the HPV protein E7 have on cellular proteins
Binds to Rb and releases E2F transcription factor
What genus of gram positive cocci form grapelike clusters?
What endothelial proteins does S. aeurous express surface receptros for?
fibrinogen, fibronectin, vitronectin
Which S. aureus toxin is a pore-forming protein that intercalates into the plasma membrane of host cells and depolarizes them?
alpha toxin
Which S. aureus toxin is a sphingomyelinase?
beta toxin
Which staph toxin is a detergent like peptide?
delta toxin?
Which staph toxin lyses erythrocytes? Which lyses phagocytic cells?
gamma toxin and leukocidin
What staph toxins are responsible for causing the superficial epidermis to split away from the deeper skin making the patient vulnerable to secondary infections?
serine proteases
What are 2 organisms that can cause toxic shock syndrome?
Staphylococcus aureus and streptococcus pyogenes
How do super antigens activate up to 20% of T lymphocytes?
they bind to conserved portions of MHC molecules and to relatively concerved portions of TCR beta chains. This can lead to very high levels of cytokine release.
What is hidradenitis suppurativa?
Chronic abscess formation of aporine gland regions, most frequently of the axilla
What is a paronychia?
chronic abscess formation of the nail bed
What is a felon?
chronic abscess formation of the palmar side of the fingertips
What is Ritter disease?
an exfoliative dermatitis causes by the A and B toxins of staph. There is a sunburn like rash that spreads over the entire body and forms fragile bullae. The intraepithelial split is in the granulosa layer.
Which what genus of facultative or obligate anaerobic gram positive cocci grow in pairs or chains?
Which streptococcus causes pharyngitis, scarlet fever, erysipelas, impetigo, rheumatic fever, TSS, and glomerulonephritis?
Strep. pyogenes (group A)
Which Sreptococci colonizes the female genital tract, causes sepsis and meningitis in neonates, and choriamnionitis in pregnancy?
Strep. agalactiae (group B)
What protein does Streptococcus pyogenes express that can cause the formation of antibodies that cross react with cardiac myosin (causing acute rheumatic fever?)
M protein
Which streptococcus bacteria is responsible for rapidly progressive necrotizing fasciitis?
Strep. pyogenes
Which is the most clinically important alpha hemolytic streptococcus?
Streptococcus pneumoniae
Which streptococcus is a major cause of dental carries?
Streptococcus mutans
Which genus (strep or staph) has a greater tendency to form discrete abscesses?
What is erysipelas?
Superficial infection with S. pyogenes characterized by a rapidly spreading erythematous cutaneous swelling that has a sharp, well-demarcated border.
What does the histological examination of erysipelas look like?
diffucse acute edematous, neutrophili inflammatory reaction in the dermis and epidermis extending into the subcutaneous tissues. Intence leukocytic infiltration around vessels and skin adnexa. Minor tissue necrosis
Scarlet fever is associated with tonsillitis causes by which organism?
S. pyogenes
Which organisms, staph or strep, cause more local destructiveness of host tissues?
What orgnaism causes diphtheria?
Corynebacterium diphtheriae
What is the microscopic morphology of C. diphtheriae?
slender gram positive rods with clubbed ends
How is C. diphtheria passed?
From person to person through aerosols or skin shedding
What is the range of illnesses caused by C. diphtheriae?
asymptomatic carriage, skin lesions from wounds, life-threatening syndrome that includes formation of a tough pharyngeal membrane and toxin mediated damage to heart, nerves, other organs
What toxin does C. diphtheriae have and what is its mechanism of cellular damage?
phage-encoded A-B toxin that blocks host cell protein synthesis by ADP-ribosylating and thus inactivating elongation factor 2.
How does Listeria monocytoenes gram stain?
Gram positive
How is host protection against L.monocytogenes different compared to most other gram positive bacteria?
Protection against L. monocytoenes is mediated largely by IFN gamma
What types of illnesses can be caused by L. monocytogenes?
foodborne infections, amnionitis in pregnant women, disseminated disease and exudative meningitis in neonates and immunosuppressed adults.
What is the morphology of bacillus anthracis?
Large, spore forming gran positive rod
How is Bacillus anthracis typically acquired?
through exposure to animals or animal products such as wool or hides
Which anthrax syndrome makes up 95% of naturally occurring infections?
Cutaneous anthrax
What is the B subunit of the anthrax toxin?
The protective antigen because antibodies against this protein protect animals against the toxin
What are the 2 alternate A subunits of the anthrax toxin? What are their mechanisms of action
Edema factor-binds to Ca2+ and calmodulin to form an adenylate cyclase to produce cAMP-elevated levels lead to an efflux of water from teh cell to form edema.
Lethal factor-protease that destroys MAPKKs
What is the morphology of Nocardia? What characteristic structures do they form in culture?
Aerobic gram-positive grow in beaded looking branched chains. In culture they form aerial structures with terminal spores, resembling hyphae.
Most patients with N. asteroides have defects with what?
T cell-mediated immunity
Where are Nocardia found?
What response in host tissues are elicited by Nocardia at all sites of infection?
Suppurative response with central liquefaction and surrounding granulation and fibrosis.
What is the morphology of Neisseria?
gram-negative diplococcis flattened on the adjoining sides giving a coffee bean shape
What area does N. meningitidis commonly colonize?
Disseminated infections by Neisseria are more likely to occus in those patients deficient in what?
Membrane attack complex portions of the complement system (C5-C9)
What cell type does Neisseria adhere to and invade?
Non-ciliated epithelial cells
How do Neseria escape the immune response?
antigenic variation- additionally a mechanism that allows a single clone to ive rise to multiple antigenic types.
What organism causes whoopging cough?
Bordetella pertussis
Where does B. pertussis colonize?
brush border of the bronchial epithelium and invades macrophages.
What is the mechanism of action of pertussis toxin?
ADP-ribosylates and inactivates G-proteins. Signals are no longer transduced from the plasma membrane. This paralyze cilia impairing the pulmonary defence
What is the morphology of Pseudomonas aeruginosa?
aerobic gram-negative bacillus
What illnesses are produced by Pseudomonas aeruginosa?
opportunistic infections in cystic fibrosis pts., burns, neutropenic pts. Also corneal keratitis (b/c of contact lenses), endocarditis, osteomylitis, external otitis
In what pattern does Pseudomonas pneumonia distribute through the terminal airways?
Fleur-de-lis patern with strking whitish necrotic centers and red, hemorrhaic peripheral areas.
Gram-negative vasculitis accompanied by thrombosis and hemorrhage is sugggestive of infection with what organism?
Psuedomonas aeruginosa
What is ecthyma gangrenosum?
Well-demarcated necrotic and hemorrhagic skin lesions of oval shape often arising fro Pseudomonas aeruginoa bacteremia.
P. aeruginosa produces compounds extremely toxic to endothelial cells containing which toxin?
What organism causes a highly invasive, frequently fatal systemic infection called plague?
Yersinia pesits
Where does pathogenic Yersinia proliferate in the host?
lymphoid tissues
What are 4 distinctive histologic features of plague
massive proliferation of the organisms, early appearance of protein-rich and polysaccharide rich effusions with few inflammatory cells but with marked tissue swelling necrosis of tissues and blood vessesls with hemorrhage and thrombosis, and neutrophilic infiltrates that accumulate adjacent to necrotic areas as healing begins.
How is Yersinia pestis transmitted?
fleabites or aerosols
What is the type III secretion system encoded by the Yop virulon of Yersinia?
A hollow syringelike structure that projects from teh bacterial surface binds to host cells, and injects bacterial toxins into the cell
What organism causes chancroid?
Hemophilus ducreyi
What is chancroid?
an acute sexually transmitted ulcerative infection
What organism causes granuloma inguinale
Calymmatobacterium donavani
What is the morphology of mycobacteria?
slender aerobic rods that grow in straight or branching chains. Have a waxy cell wall made of mycolic acid which allows them to stain acid fast.
What disease states increase the risk of tuberculosis?
diabetes mellitus, Hodgkin's lymphoma, chronic renal failure, malnutrition, alcoholism, immunosuppression (i.e. HIV)
How are most tuberculosis infections acquired?
person-to-person transmission of airborne droplets of organisms from an active case to a susceptible host.
What is usually the only evidence of a primary tuberculosis infection (if any?)
tiny, fibrocalcific nodule at the site of infection
What is the primary cell type infected by M. tuberculosis?
What is the critical mediator which drives macrophages to become competent to to contain the M. tuberculosis infection?
Interferon gamma
Immunity to M. tuberculosis is primarliy mediated by which class of helper T cells?
Where is secondary pulmonary tuberculosis classically localized to?
The apex of the upper lobes of one or both lungs
What term is used to describe the parenchymal lung lesion (gray-white inflammatory consolidation) of tuberculosis?
Ghon focus
What term describes the parenchymal lung lesion and nodal involvment in primary TB?
Ghon complex
In 95% of cases, cell mediated immunological control of the tuberculosis infection causes what change to occur in the Ghon complex?
Ghon complex undergoes progressive fibrosis often followed by radiologically detectable calcification
What is the histological characteristic of sites of active involvement in a tuberculosis infection?
granulomatous inflammatory reaction that forms both caseating and no-caseating tubercles. Typically enclosed within a fibroblastic rim punctuated by lymphocytes
Do immunocompromised people with a tuberculosis infection form granulomas?
What type of necrosis does the center of a secondary tuberculosis lesion undergo?
caseation necrosis
What is miliary pulmonary disease? (in the context of tuberculosis)
It occurs when M. tuberculosis organisms drain through lymphatics into the lymphatic ducts of the heart and into the pulmonary arteries.
What is the most frequent form of extrapulmonary tuberculosis?
Lymphadenitis. In HIV negative people, lymphadenopathyis unifocal.
What is the hallmark of MAC infections in patient swith HIV?
abundant acid-fast bacilli within macrophages
What organsim causes leprosy or Hansen disease?
Mycobacterium leprae
Where does M. leprae grow in the host?
Relatively cool tissues of the skin an dextremities
What organsim can M. leprae be grown in?
What is the less severe form of leprosy?
Tuberculoid leprosy
What is the more severe form of leprosy?
lepromatous leprosy
What determines what pattern of leprosy a patient will have?
The t-helper response. Pts with tuberculoid leprosy have a TH1 response. Pts with lepromatous leprosy have a deficient TH1 response or a dominant TH2 response
What is the morphology of spirochetes?
Gram negative slendor cork-screw shaped bacteria with axial periplasmic flagella wound around a helical prtoplasm. Covered in a membrane called an outer sheath
What organism causes syphillis?
Treponema pallidum subspecies pallidum
What characterizes the primary stage of syphilis?
a single firm, nontender, raised, red lesion or chancre at the site of invasion of the organism
What characterizes secondary syphilis?
painless superficial skin lesions, condylomata lata, lymphadenopathy, mild fever, malaise, weight loss
What are the 3 main manifestations of tertiary syphilis?
cardiovascular syphilis, neurosyphilis, and benign tertiary syphilis
What is a syphilitic gumma?
White-grey rubbery deects or tumorlike masses that occur i most organs but particularly in skin, subcutaeous tissue, bone, and joints
What would histologic examination of gummas reveal?
Center of necrotic material and margins composted of plump or palisadd macrophages and fibroblasts surrounded by large numbers of mononuclear leukoctes (plasma cells)
What characteristic anatomical location do skin lesions of syphillis occur?
palms and soles of the feet
What is hepar lobotum
a distinctive hepatic lesion cased by scarring as the result of gummas
What is the distinctive triade of the late-occuring form of congenital spyhilis?
interstitial keratitis, hutchinson teeth, and 8th nerve deafness
What are hutchinson teeth?
dental changes usually as the result of syphilis mainly involving the incisor teeth which become small and shaped like a screwdriver or a peg often with notches in the enamel
How can diagnosis of relapsing fever be made?
identification of spirochetes in blood smears obtained during febrile periods
What organism is responsible for body-louse transmitted epidemic relapsing fever?
Borrelia recurrentis
What organism is responsible for lyme disease?
borrelia burgorferi
What is the vector for transmission of lyme disease
Ixodes deer ticks
What is the name of the skin lesion that defines stage 1 of lyme disease? What does it look like
erythema chronicum migrans- at the site of a tick bite causing an expanding area of redness, often with a pale center
The late disseminated form of which disease occurs 2-3 years after the initial bite which caused the disease and causes chronic arthritis sometimes with severe damage to large joints and encephalitis?
Lyme disease
What stimulates the inital immune response to B. burgdorferi?
binding of bacterial lipoproteins to toll-like receptor 2 expressed by macrophages
How does B. burgdorferi excape the host antibody response?
antigenic variation
What is a distinctive feature of lyme arthritis?
arteritis with onionskin-like lesions resembling those seen in lupus
What are some features of the CSF in Lyme meningitis?
CSF is hypercellular, marked lyphoplasmacytic infiltrate, anti-spirochete IgGs
What are 2 common anaerobes found in head and neck abscesses?
Gram negative bacilli prevotella and porphyromonas
What organism causes Lemierre syndrome?
Fusobacterium necrophorum
What syndrome is characterized by infection of the lateral pharyngeal space and septic jugular vein thrombosis?
Lemierre syndrome
What are 4 organsims that are the usual causes of abdominal abcesses?
peptostreptococcus, clostridium, Bacteriodes fragilis, and Escherichia coli
What types of anaerobes are usually cases of genital tract infections in women?
Gram negative bacilli including prevotella
What organism causes cellulitis, myonecrosis of wounds, uterine myonecrosis, mild food poisoning, and infection fo teh small bowel?
Clostridium perfringens and/or septicum
What toxin is produced by Clostridium tetani?
What are effects of tetanospasmin
convulsive contractions of skeletal muscles
What organism releases a potent neurotoxin that blocks synaptic release of acetylcholine and causes paralysis?
Clostridium botulium
What organism can cause pseudomembranous colitis due to overgrowth in the intestine of antibiotic-treated patients?
Clostridium difficile
What is the most important toxin produced by Clostridium perfringens and what are some of its effects?
alpha toxin-a phospholipase C that degrades lecithin, destroysRC, platelets and muscle cells, has sphingomyelinase activity and damages nerve sheaths, releases phospholipid derivatives, IP3, PGs an TXAs
Are the spores of C. perfringens killed by cooking?