Infectious Exam 3 Answers – Flashcards
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| Typhoid Fever -salmonella typhii -etiology |
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| GN rod; not coliform only salmonella that is ENCAPSULATED, capsule designated antigen that is antiphagocytic; enables agent to survive in macrophages -facultative intracellular pathogen |
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| Typhoid Fever -salmonella typhii -epidemiology |
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| reportable disease rare in US but common worldwide because of sanitation carrier is most important; excreted in feces, sometimes urine transmission: fecal oral route high infective dose vehicle is food, water contaminated with feces or urine from carrier or patient |
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| Typhoid Fever -salmonella typhii -pathogenesis |
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| inc period is 8-14 day long agent multiplies in small intestine - peyers patches in ileum agent disseminates via lymphatics and blood agent multiplies intracellulary in macrophages CMI required to control! esp activated macrophages |
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| Typhoid Fever -salmonella typhii -clinical manifestations; first week of disease |
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| onset insiduous fever is high headache anorexia lethargy aches/pains cough CONSTIPATION not diarrhea |
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| Typhoid Fever -salmonella typhii -manifestations second week |
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| elevated temp mental dullness apathy splenomegaly rose spots maybe |
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| Typhoid Fever -salmonella typhii -manifesetations 3rd week |
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| no more fever; symptoms subside relapses can occur --ab treatable |
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| Typhoid Fever -salmonella typhii -manifestations |
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| chronic carriers develop in about 3% of cases; organisms nest in gall bladder |
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| Typhoid Fever -salmonella typhii -treatment |
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| chloramphenicol |
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| Typhoid Fever -salmonella typhii -prevention |
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| control by: enforcing sanitation education uncontaminated water good sewage disposal prompt diagnosis and treatment of patients and carriers |
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| Typhoid Fever -salmonella typhii -vaccines |
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| for all endemic area travelers 1. vivotif: - oral; 3-4 enteric coated capsules given every other day -give booster every 5 years 2. typhim Vi - parenteral; purified; single dose |
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| Bacillus Anthracis Anthrax -etiology |
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| GP boxcar shape encapsulated spore forming rod facultative intracellular pathogen with POLYGLUTAMIC acid |
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| Bacillus Anthracis Anthrax -epidemiology |
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| enzootic disease |
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| Bacillus Anthracis Anthrax -pathogenesis and manifestations |
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| multiply intracellularly in macrophages all disease forms result in toxemia and bacteremia; then death cutaneous anthrax pulmonary anthrax (wool-sorters disease) GI anthrax |
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| Bacillus Anthracis Anthrax -control |
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| subunit purified for humans live attenuated for livestock |
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| Brucella -infections it causes |
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| brucellosis undulant fever malta fever |
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| Brucella -etiology |
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| GN rods facultative intracellular pathogens disease of animals; agent is shed in milk and placenta where it survives for months species are associated with human infection: b.abortus = cattle; pasteurization of milk kills agent b.suis = swine b.melitensis = goats and sheep -causes most severe infections; associated with imported unpasteruized cheeses |
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| Brucella -transmission |
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| -ingestion of undercooked, raw contaminated meat or unpasteurized milk -direct contact of infected tissue, blood, etc with abrasions in skin -occupational hazard for vets, slaughter house workers, farmers -inhalation of infected aerosols via RT |
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| Brucella -pathogenesis |
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| inc period is long 2-3 wk organisms spread via lymphatics while multiplying primarily in macrophages immunity is CMI mediated |
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| Brucella -manifestations |
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| acute phase is incapacitating; lasts several weeks or months onset is insiduous: malaise undulant fever (aka periodic nocturnal fever; unknown origin) weakness joint pain headache night sweats GI signs enlarged lymph glands, liver, spleen |
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| Brucella -treatment |
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| prolonged; 6 wk min tetracycline with streptomycin |
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| Arthropod -etiology |
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| Insects note: ticks, flies, mosquitos, lice, etc are not the same! they are all unique arthropods |
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| Arthropod -epidemiology |
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| dengue is most common vector borne viral disease in the world lyme disease caused by borrelia burgdorferi is most common tick born disease in US |
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| Yersinia pestis |
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| The Plague the Black Death it didnt disappear; still endemic in animals |
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| Rickettsia -etiology |
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| bacteria not virus; Ab works!! small GN pleomorphic coccobacilli which are obligate intracellular parasites infect endothelial cells (cells lining blood vessels) |
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| Rickettsia -reservoirs |
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| mammans - humans are accidental hosts except for epidemic typhus infected ticks via transovarial transmission |
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| Rickettsia -vectors |
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| 1. arthropods - ticks, lice passed by arthropods but not arboviruses 2. ecology of vector is determining factor in disease prevealence |
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| Rickettsia -transmission |
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| mostly through ticks low infectious dose parenteral; through bite of infected arthropod direct human-to-human transmission does not occur |
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| Rickettsia -pathology |
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| after entry, organisms multiple locally; spread to bloodstream; infect endothelial cells of small blood vessels --can cause death because of this endothelial cells enlarge; degenerate, resulting in vasculitis in any organ/tissue microinfarcts (clots) can occur- DIC, damaging vasculature, resulting in fluid loss to tissues, producing edema, hypotensive shock type and species specific lasting immunity occurs after recovery |
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| Rickettsia -manifestations |
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| TRIAD OF FEVER, HEADACHE, RASH -rickettsemia occurs during febrile period -hypotensive shock and failure in any organ due to DIC which produces ischemia due to poor tissue perfusions |
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| Rickettsia -treatment |
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| tetracycline or chloramphenicol -doxycycline for ehrlichia -inhibit protein synthesis; no penicillin or cephalosporin |
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| R. Rickettsii -Rocky Mountain Spotted Fever -epidemiology |
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| vector is tick, which is also principle reservoir -dog tick dermacentor variabilis -wood tick d. andersoni mammalian reservoirs - wild animals and dogs distribution: southeastern states seasonality - spring and summer |
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| R. Rickettsii -Rocky Mountain Spotted Fever -manifestations |
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| inc period is short - one week prodrome: first 3-5 days high fever chills headache myalgia conjunctivitis - photophobia sepsis and septic shock bc of vasculitis - meningitis like symptoms blanching, macular rash bc of vasodilation; 3-5 d after fever on wrist and ankles; spreads to trunk and hands/feet -if not treated, then rash becomes petechial, then purpuric lesions |
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| R. Rickettsii -Rocky Mountain Spotted Fever -treatment |
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| early treatment with tetracycline or chloramphenicol is imperative before lab results are known -mortality in untreated RMSF is high -clinical response to treatment is rapid 1-2 days |
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| R. prowazekii -louse-borne, epidemic typhus -epidemiology |
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| vector is body louse - pediculus humanus humans and body lice are natural hosts-humans are reservoir occurs in crowded conditions - famine, war, concentration camps; natural disaster |
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| R. prowazekii -louse-borne, epidemic typhus -manifestations |
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| inc period is short, abt 2 wk primary infection - abrupt onset of fever, headache, rash (4-7d after onset of S&S; spreads centrifugally sparing face, palms, and soles) rash can evolve to petechial mortality without therapy is high --DIC! brill-zinsser diagnosis - recrudescent typhus; reactivation; milder |
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| Bartonella -rochalimaea -overview |
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| not like rickettsia causes: trench fever cat scratch disease bacillary angiomatosis and peliosis bartonellosis |
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| Bartonella -etiology |
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| fastidious GN rods which are facultative intracellular pathogens that target endothelial cells and RBCs |
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| Bartonella -epidemiology |
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| one of most common causes of lymphdenopathy other than neoplasm, tb, and HIV that require urgent medical attention patients with heart abnormalities or who are immunocompromised should be counseled to avoid cats |
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| R. prowazekii -louse-borne, epidemic typhus -immunity |
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| CMI |
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| R. prowazekii -louse-borne, epidemic typhus -patient management |
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| doxycylcine! cat scratch disease: in immunocompetent patients is mainly supportive bc disease is self limited and resolves in 2-4 months; enlarged lymph nodes may need to be aspirated; cat scratch disease typically does not respond to ab therapy; thus, ab treatment usually not recommended for uncomplicated localized disease bacillary angiomatosis and peliosis: use doxycylcine with rifampin -clarithromycin and azithromycin also show response relapses in bone and skin happen if ab given for shorter period of time immunocompromised patients may develop jarish-herxheimer reaction within hours of ab therapy; monitor carefully |
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| Trench Fever -b. quintana -etiology |
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| shinbone fever incapacitating febrile syndrome bartonella |
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| Trench Fever -b. quintana -epidemiology |
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| reservoir: humans and cats spread by human louse or cat flea no person to person spread associated with: poor sanitation, poor hygien, malnutrition more common in homeless disease occurs in immunocompetent and compromised individuals |
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| Trench Fever -b. quintana -manifestations |
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| insiduous - sudden onset of symptoms 5-7 days; then they abate but symptoms recur every 4-5 days recurrences can continue for a year symptoms: fever malaise headache night sweats splenomegaly bone pain - shinbone fever; becomes more severe each time transient rash may appear |
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| Cat Scratch Disease -b. henselae -epidemiology |
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| affets compromised and immunocompetent pts transmitted via cat bite/scratch or bite by infected cat flea manifestations: regional lymphadenitis + FEVER after contact with cat |
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| Borrelia burgdorferi -lyme disease -etiology |
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| most common tick borne disease in US extracellular spirochete not observed after gram staining; need dark field microscopy - not seen on blood smear agent of lyme disease in north america and europe other species of borrelia are responsible in eurasia |
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| Borrelia burgdorferi -lyme disease -epidemiology |
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| incidence: connecticut rhode island new york new jersey pennsylvania wisconsin |
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| Borrelia burgdorferi -lyme disease -reservoirs |
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| small mammals (white footed mouse) and birds |
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| Borrelia burgdorferi -lyme disease -vector |
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| hard body ticks 4 stages in development: egg, larva, nymph, adults each stage feeds only once for several days nymphs feed on and transmit infection to small mammals or humans -NYMPHS ARE RESPONSIBLE FOR MOST HUMAN INFECTIONS only find adults in winter -adults feed on and transmit agent to larger mammals -not passed from mom to eggs; eggs release larvae that is unaffected; larvae becomes nymph; nymph becomes infected; gets into adult |
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| Borrelia burgdorferi -lyme disease -immunity |
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| Ab mediated |
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| Borrelia burgdorferi -lyme disease -pathogenesis |
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| everywhere |
