Bacterial infections of blood and vasculature Flashcards Preview

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Flashcards in Bacterial infections of blood and vasculature Deck (30):

Borrelia, unlike treponema

are large enough to see with standard microscopy


B burgdorferi causes

Lyme disease, vectored by deer ticks (not dog ticks); with mice and rats preferred by nymphs and deer preferred by adults


Lyme diagnosis depends on; serology

history of geographic area, season (highest risk in summer when nymphs are feeding) and activity; can confirm exposure but not disease and not promptly


Lyme requires

about 24 hours to transmit (REMOVE TICK SOONER)


Lyme disease has three stages:

1. flulike with erythema migrans rash (bulls-eye appearance in a minority)
2. Musculoskeletal and/or neurologic symptoms (intermittent arthritis; in Europe, bluish borrelial lymphocytoma and Acrodermatitis Chronica Atrophicans (ACA) on biopsy, a progressive fibrosing skin
3. Additional neurologic symptoms, also Post-Lyme syndrome with lingering neurological sequelae (chronic progressive encephalomyelitis, subacute encephalopathy);
worry about COINFECTION with ERLICHIA or BABESIOA meaning high fever


Treat Lyme with; give for

amoxicillin or doxycycline, alternatives ceftriaxone, cefuroxime axetil;
10-30 days, NO MORE (lingering symptoms due to DAMAGE, NOT lingering bacteria);
Can see Jarisch-Herxheimer reaction and erythema migrans could expand!


Relapsing fever may be

louse- or tick-borne, louse- is more severe (reservoir is humans; louse crushing and inoculation by scratching), tick- more likely in US (bite of infected tick, usually nocturnal); REPEATED HIGH FEVERS with well periods between, complications of pregnancy


Relapsing fever Borrelia

immediately enter bloodstream from bite site, repeated rounds of bacteremia and cleanup by IL10+neutralizing Ab's vs. antigenic variation by spirochete


Diagnose relapsing fever by

peripheral blood smear; spirochetes are usually visible during febrile periods


Treat relapsing fever with

tetracyclines (doxy); erythromycin (kids, pregnant women, and adults) and penicillin G in adults


Relapsing fever and lyme:

avoid ticks (protective clothing, DEET), daily tick checks in at-risk areas in season


Successful treatment of any spirochete infection

may cause Jarisch-Herxheimer reaction (that and response to treatment may be needed to empirically diagnose Lyme)


____, ___, ____ are all what?

Rickettsia, Ehrlichia, and Anaplasma; small cocci-to-short-rods are transferred to mammalian hosts by arthropod vectors


Rickettsiae are sensitive

to tetra (doxycycline)


Rickettsiae are ____ parasites and can

obligate intracellular; only be grown IN VITRO in tissue culture (like VIRUSES)


Rickettsiae diseases present; they can also cause

with headache, fever, and body aches; a rash (particularly RMSF, petechial, or epidemic typhus, any) or eschar (particularly Mediterranean Spotted Fever and scrub typhus)


For Rickettsiea, proper removal of a potentially-infected tick

is with tweezers, while wearing GLOVES, promptly (bacteria take time to transit)


Host, reservoir, and uniqueness for epidemic typhus? What's characteristic of the other rickettsial diseases?

Humans are the proper host and reservoir for ONLY epidemic typhus, and is also unique in having a RECRUDESCENT form (Brill-Zinsser disease), VECTORED by body louse;
accidental transmission to humans by promiscuous vectors


All four Rickettsiae group (Rickettsia, Coxiella burnetti, Ehrlichia, Anaplasma) replicate

within infected cells; Rickettsia divide throughout the cell, Ehrlichia and anaplasma from morulae in phagocytic vacuoles


All of the rickettsiae are

difficult to stain chemically and require microimmunofluorescent assay to visualize (blood and/or biopsy)


Because of the gravity of the Rickettsiae illnesses; alternate treatments for ___ and ____ patients are

small children may be treated with tetracyclines but pregnant women are not; pregnant, allergic, use chloramphenicol (Rickettsia) or fluoroquinolones (Ehrlichia, Anaplasma)


T/F: B burgdorferi has a definitive test for lyme disease

No, there is no definitive lab test (e.g. seropositivity won't tell much, though seronegativity is relatively reliable)


B. burgdorferi prevention includes

protective clothing, DEET, avoid woodsy areas, tick collars on pets


Rickettsia, Ehrlichia, and Anaplasma are like borrelia and unlike borrelia:

Like Borrelia: arthropod vectors, mammalian reservoirs, tetra sens;
unlike Borrelia: small cocci-to-short-rods, intracellular replication


RMSF is vectored by



RMSF virulence factors include:

1. OmpA&B for adhesion
2. T4SS: entry
3. Phospholipase A2: escape from endosome
4. ActA: actin-based cell-cell spread


Epidemic typhus usually begins on

trunk and spreads peripherally (the opposite of RMSF which begins on extremities)


What season would you expect to see epidemic, murine, and scrub typhus?

Cold weather: epidemic;
warm weather: murine and scrub


Brill-Zinsser disease risk factors include

malnutrition and improper or incomplete antibiotic therapy


Ehrlichia (e.g. Human Monocytic ehrlichiosis) and anaplasma (human granulocytic anaplasmosis) can grow

within neutrophils