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HDID 2 > 52. Uncommon Bacterial pathogens > Flashcards

52. Uncommon Bacterial pathogens Flashcards

1
Q

bacillus antracis microbiology?

A
  • non-motile
  • facultative anaerobe
  • GP
  • spore-forming bacillus
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2
Q

bacillus antracis epi?

A
  • Bioweapon
  • primarily a disease of herbivores
  • human transmission via contact w/infected animals or contaminated animal products
  • soil reservoir (spores live forever)
  • no person-to-person transmission of inhalation anthrax
  • occupational hazard to farmers, animal hide workers
  • GI = poverty disease (eat dead/dying animals that are infected)
  • inhalational: long incubation period (1-43 days)
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3
Q

bacillus antracis pathogenesis/virulence factors?

A
  • 2 plasmids:
  • 1 encodes poly-D-glutamic acid capsule
  • 1 encodes tripartite toxin: protective agent (PA), edema factor (EF), lethal factor (LF)
  • cutaneous: spores enter through breaks in skin
  • GI: ingest contaminated meat
  • inhalation of spores
  • PA: binding/ translocation of subunit. Abs vs PA protect vs infection
  • LF+PA = lethal toxin
  • LF: deadly, zinc metalloprotease that cleaves and inactivates MAPK kinases
  • EF + PA = edema toxin
  • EF: an AC causes local edema where injected
  • capsule
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4
Q

bacillus antracis disease?

A
  • Cutaneous (95%): small papule -> ulcer surrounded by vesicles -> painless eschar w/edema -> death 20% if untreated
  • GI: fever, acute gastroenteritis, vomiting, hematemesis, bloody diarrhea, intestinal eschar (hemorrhagic) -> generalized toxemia -> 50-100% mortality w/tx
  • Woolsorter’s disease: inhalation anthrax): fever, cough, myalgia, malaise -> high fever, dyspnea, cyanosis, hemorrhagic mediastinitis/pleural effusion -> sepsis/dissemination -> shock/death
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5
Q

bacillus antracis tx/prevention?

A
  • FQ + clindamycin or rifampin
  • (used to use PCN or doxy or Cipro)
  • supportive care
  • no quarantine needed
  • raxibacumab (mAb vs PA)
  • Oral abx ASAP s/p
  • Abx 60 days w/out vaccine or 30 days w/3 doses of vaccine (need long term abx thnx spores)
  • vaccine for ppl 18-65 y/o = active PA from non-encapsulated strain works for cutaneous and maybe inhalational
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6
Q

yersinia pestis microbiology?

A
  • GN bacillus

- close relative of Y.pseudotuberculosis

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7
Q

yersinia pestis epi?

A
  • Bioweapon
  • rodent flea vector w/mammalian hosts
  • bubonic form most common
  • peron-to-person spread for pneumonic via respiratory droplet
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8
Q

yersinia pestis pathogenesis/virulence?

A

2 plasmids:

  • large common to other Yersinias encodes T3SS
  • small encodes fibrinolysin
  • lacks invasion (mutated) which is common to other Yersinias
  • w/out fibrinolysin causes localized infection but no spreading of disease
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9
Q

yersinia pestis clinical?

A

bubonic: inguinal, axillary, or cervical lymph nodes -> 80% bacteremia -> 60% mortality untreated
- headache, malaise, myalgia, fever, tender LNs
- regional lymphadenitis (buboes)
- cutaneous papule, vesicle, or pustule at inoc site
- late purpura
pneumonic:aerosol or septicemic spread to lungs -> 100% mortality untreated
- headache, malaise, fever, myalgia, cough
- dyspnea, cyanosis, hemoptysis
- death from respiratory collapse/sepsis
Septicemic: primary or secondary, 100% mortality untreated, endotoxemia, sepsis, shock, DIC, ARDS

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10
Q

yersinia pestis tx/prevention?

A

Abx: gentamicin or streptomycin
(also FQ, tetracyclines, or sulfonamides but don’t have in vivo data)
- supportive therapy
- isolation w/droplet pecautions for pneumonic plague until sputum cx negative
- bubonic contacts: common exposure PO doxycycline, tetracycline, or TMP/SMX X 7 days; other close contacts fever watch
- pneumonic contacts: PO Cipro, doxycycline, or tetracycline X 7 days from last exposure
- no vaccine in US

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11
Q

francisella tularensis microbiology?

A
  • GN
  • cocco-bacillus
  • strict aerobe
  • fastidious
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12
Q

francisella tularensis epi?

A
  • Bioweapon
  • assoc w/rabbis in the winder and ticks in the summer
  • low infectious dose (hazard to microbiology lab workers)
  • no person-to-person transmission
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13
Q

francisella tularensis disease?

A
  • ulceroglandular: ulcer w/regional lymphadenopathy
  • pneumonic: primary from inhalation or secondary to bacteremia…range of incubation, abrupt onset fever, chills, headache, myalgia, non-productive cough; segmental/lobar infiltrates, hilar adenopathy, effusions  mortality 30% untreated (
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14
Q

francisella tularensis tx/prevention?

A
  • streptomycin or gentamicin
  • FQ (works and not nephrotoxic)
  • tetracyclines
  • prophylaxis = fever watch for 7 days (plenty of time to treat if fever develops)
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15
Q

listeria monocytogenes microbiology?

A
  • GP
  • rod
  • motile (at 20-28%C)
  • facultative anaerobe
  • B-hemolytic
  • grows well from 1-45% C
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16
Q

listeria monocytogenes epi?

A
  • outbreaks via foodborne (soft cheese, deli meats)
  • long incubation period
  • sporadic cases
  • mostly immunocompromised pts (undercooked chicken) or w/underlying illness
17
Q

listeria monocytogenes pathogenesis?

A
  • invades cells (internalin binds E=cadherin on apical surface of enterocytes after neighboring cells have undergone apoptosis, InlB binds C’receptor)
  • escapes phagosome (lysteriolysin)
  • usurps actin (ActA for intracellular motility)
  • spreads cell-to-cell (phospholipases when filopodia extend to neighbor cell to degrade membrane and enter)
18
Q

listeria monocytogenes disease?

A

Pregnancy Assoc:
- mother = flu-like, 3rd trimester
- amnionitis : premature labor or septic aborption
- early: congenital listeriosis = granulomatosis infantisepticum; lethal
- late: acquired from asymptomatic mom, meningitis
Non-pregnancy assoc:
- meningoencephalitis = leading cause of meningitis in immunocompromised (elderly, cancer pts, on steroids): fever, altered sensorium, headache 50%, focal neurological signs, brain abscesses or rhomobencephalitis (rare); high case:fatality rate
- gastroenteritis (high inoculum)
- focal infection (anything)

19
Q

listeria monocytogenes tx/prevention?

A

All anecdotal, no trials

  • PCN + ampicillin or TMP/SMX if severe pcn allergy
  • cephalosporins are ineffective so can’t use 3rd generation cephalosporin like ceftriaxone to treat meningitis empirically in immunocomp./ elderly – need ceftriaxone and ampicillin to cover listeria and other common causes of meningitis
  • good food hygiene to prevent and immunosuppressed pts should avoid soft cheeses/deli counter food
20
Q

bartonella henselae?

A
  • GNR
  • slow growing
  • transmitted by fleas, bites, scratches

cat scratch disease
- unilateral adenopathy several weeks following bite or scratch from a cat

Bacillary angiomatosis
- neovascular proliferation involving skin or internal organs seen mostly in HIV pts

tx:
Cat scratch:
- azithromycin effective but resolves spontaneously w/out treatment

Bacillary angiomatosis:
- macrolides or tetracyclines, tx required

21
Q

brucella?

A
  • GN
  • coccobacilli
  • domestic herbivores (cattle)
  • humans infec via direct contact or contaminated milk/milk products
  • org has survival in macrophages
  • bacteria replicate in lymphoid tissues/bone marrow
  • Prolonged febrile illness, usu w/out localizing features
  • bone/joint infections

tx:
Long course of tetracyclines, initially combo w/aminoglycosides

HDID 2 (32 decks)

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