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HDID Block 2 > Uncommon pathogens > Flashcards

Uncommon pathogens Flashcards

1
Q

Describe the gram staining and other characteristics of Bacillus anthracis

A

B. anthracis is a non-motile, facultative anaerobic, Gram-positive, spore-forming bacillus (in chains)

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2
Q

How do humans get anthrax?

A

Contaminated animal products or contact with infected animals

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3
Q

Pathogenesis of anthrax is mediated by 2 virulence factors, namely __

A

Capsule

Toxin (3 parts to it)

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4
Q

Describe the roles of the capsule and toxin in B anthracis

A

Capsule is a protein capsule

Toxin has 3 parts:

Has protective antigen (polymerizes on host cell membrane and forms pore to deliver one of two factors, edema factor EF or lethal factor LF)

Edema factor: adenylyl cyclase >> increased cAMP >> fluid secretion >> edema

Lethal factor: MAPK inhibitor >> increased cytokine production >> tissue necrosis/hemorrhage/circulatory collapse (due to massive inflammatory response)

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5
Q

A characteristic skin feature of cutaneous anthrax is __

A

Black, painless, necrotic eschar (there’s also prominent surrounding edema)

**develops from entry of spores through breaks in skin

starts as small papule >> ulcer surrounded by vesicles (24-28h)**

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6
Q

Gastrointestinal anthrax is transmitted by __ and is characterized by GI symptoms and an __ (hint: lesion in the intestine)

A

Gastrointestinal anthrax is transmitted by ingestion of contaminated meat and is characterized by GI symptoms and an intestinal eschar (hint: lesion in the intestine)

*GI symptoms:fever, acute gastroenteritis, vomiting, hematemesis, bloody diarrhea*

(can progress to toxemia and death)

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7
Q

Inhalational anthrax results from __

The initial presentation of inhalational anthrax is characterized by __

A key feature of inhalational anthrax is __

A

Inhalation of spores

Initial presentation of inhalational anthrax: non specific, flu like symptoms

Later on: widened mediastinum on imaging

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8
Q

Terminal inhalational anthrax can progress to __ and can lead to death

A

Hemorrhagic mediastinitis/pleural effusion >> sepsis >> shock

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9
Q

Rx for anthrax

The new monoclonal antibody ___ against anthrax works against which part of the anthrax toxin?

A

Penicillin or Doxy

FQ (Ciprofloxacin)

or FQ + another agent

**raxibacumab (human mAb against protective antigen)

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10
Q

Post exposure Rx of anthrax

A

FQ (cipro) or Tetracycline (doxy) or Penicillin (or amoxicillin)

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11
Q

T/F: There is no anthrax vaccine

A

Falsehood. There is a vaccine: The active component is Protective antigen from filtrate of non-encapsulated strain

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12
Q

___ is the gram negative rod pathogen that causes Bubonic plague

A

Yersinia_pestis

**natural vector is rodent flea**

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13
Q

The pathogenesis of Y pestis is mediated by __

A

T3S and fibrinolysin (also capsule but that’s froma different lecture)

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14
Q

Key feature of bubonic plague is __

A

Inguinal, axillary, or cervical buboes (big, fluctuant lymph node/group of lymph nodes)

**remember the dude with the anti-flea spray in the sketchy video with the buboe in his arm pits**

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15
Q

Presentation of bubonic plague

A

Sudden onset headache, malaise, myalgia, fever, tender lymph nodes

Regional buboes

Cutaneous findings: Possible papule, vesicle, or pustule at inoculation site

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16
Q

How does one get pneumonic plague?

A

Ways to get pneumonic plague:

Bubonic plague first >> bacteremia >> pneumonia secondary to bubonic plague

Respiratory droplets from person with plague

17
Q

Presentation of pneumonic plague

A

Sudden onset headache, malaise, fever, myalgia, cough

Pneumonia progresses rapidly to dyspnea, cyanosis, hemoptysis

Death from respiratory collapse/sepsis

18
Q

Septicemic plague develops from ___

A

Secondary from bubonic or pneumonic forms

19
Q

Rx for plague

A

Aminoglycosides

FQs

Tetracyclines

Sulfas

**also isolation w/ droplet precaution if pneumonic plague suspected**

20
Q

Prophylaxis for plague

A

Literally the same meds you use to treat

Pneumonic: oral ciprofloxacin, doxycycline, or tetracycline

Bubonic: oral doxycycline, tetracycline, or TMP/SMX

21
Q

Tularemia is most commonly ass’d with __ and requires a high/low infectious dose

A

rabbits and ticks

low dose

**no person to person tx**

22
Q

Forms of tularemia

A

Ulceroglandular (ulcer with regional lympadenopathy)

Glandular - regional adenopathy without skin lesion

Oculoglandular - painful purulent conjunctivitis with adenopathy

Typhoidal - sepsis, no adenopathy

Pneumonic (primary or secondary)

23
Q

Pneumonic tularemia presentation

A

Non specific pneumonia symptoms

24
Q

Rx for tularemia

A

Rx:

Streptomycin or gentamicin

Fluoroquinolones

Tetracyclines

25
Q

Prophylaxis for tularemia

A

Watch for a wk

Cipro or Doxy (doxy for 2 wks if + fever)

26
Q

Describe the characteristics of listeria monocytogenes

A

Motile (at 20-28°C) Gram-positive rod

Facultative anaerobe, b-hemolytic, grows at wide temp range

27
Q

Outlines the steps in Listeria pathogenesis

A

invasion (internalin) >> phagosome escape (listeriolysin) >> burglary (hijacks actin cytoskeleton via ActA) >> propulsion (Arp2/3 complex) >> Invasion into next cell (phospholipases)

28
Q

Listeriosis can be acquired through __ transmission

A

Foodborne (contaminated food, unpasteurized milk etc)

29
Q

2 clinical forms of listeriosis are ___

A

Pregnancy ass’d and non-pregaz ass’d

30
Q

Presentation of Listeria in pregnancy

A

Undifferentiated illness: fever, chills, myalgias, bacteremia

Amnionitis: Premature labor; Septic abortion

31
Q

Disseminated micro-abscesses in the neonate (granulomatosis infantisepticum) are characteristic of which type of listeriosis?

A

Neonatal listeriosis (happens early - acquired in utero)

32
Q

Late neonatal listeriosis is characterized by __

A

Neonatal meningitis (remember that Listeria is high on the differential for this, after Group B Strept and H flu?)

33
Q

___ is the number one cause of meningitis in an immunocompromised host

A

Listeria (listerial meningoencephalitis)

34
Q

What do you use to treat Listeria meningitis?

A

Need AMPICILLIN!! 3rd generation cephalosporin does not work for this

(if not, next one is TMP-SMX)

35
Q

___ is the causative agent of cat scratch disease and bacillary angiomatosis

A

Bartonella henselae

36
Q

Describe Cat Scratch disease

What is the Rx for this disease?

A

Unilateral adenopathy several weeks following bite or scratch of cat

Rx: Azithromycin if needed but generally self limiting

37
Q

Describe Bacillary angiomatosis and the Rx for this disease

A

Neovascular proliferation involving skin or internal organs seen mostly in HIV patients

Macrolides or tetracyclines

38
Q

Brucellosis is caused by __ (describe the characteristics of the bug)

A

Brucella : Gram-negative coccobacilli

39
Q

How do people get Brucella infection?

What is the presentation and Rx?

A

Humans infected by direct contact, contaminated milk/milk products

Presentation: Prolonged febrile illness

Rx: Tetracycline + aminoglycosides

HDID Block 2 (28 decks)

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