Uncommon pathogens

Question 1

Describe the gram staining and other characteristics of Bacillus anthracis

Answer 1

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

Question 2

How do humans get anthrax?

Answer 2

Contaminated animal products or contact with infected animals

Question 3

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

Answer 3

Capsule

Toxin (3 parts to it)

Question 4

Describe the roles of the capsule and toxin in B anthracis

Answer 4

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)

Question 5

A characteristic skin feature of cutaneous anthrax is __

Answer 5

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)**

Question 6

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

Answer 6

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)

Question 7

Inhalational anthrax results from __

The initial presentation of inhalational anthrax is characterized by __

A key feature of inhalational anthrax is __

Answer 7

Inhalation of spores

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

Later on: widened mediastinum on imaging

Question 8

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

Answer 8

Hemorrhagic mediastinitis/pleural effusion >> sepsis >> shock

Question 9

Rx for anthrax

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

Answer 9

Penicillin or Doxy

FQ (Ciprofloxacin)

or FQ + another agent

**raxibacumab (human mAb against protective antigen)

Question 10

Post exposure Rx of anthrax

Answer 10

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

Question 11

T/F: There is no anthrax vaccine

Answer 11

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

Question 12

___ is the gram negative rod pathogen that causes Bubonic plague

Answer 12

Yersinia_pestis

**natural vector is rodent flea**

Question 13

The pathogenesis of Y pestis is mediated by __

Answer 13

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

Question 14

Key feature of bubonic plague is __

Answer 14

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**

Question 15

Presentation of bubonic plague

Answer 15

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

Regional buboes

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

Question 16

How does one get pneumonic plague?

Answer 16

Ways to get pneumonic plague:

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

Respiratory droplets from person with plague

Question 17

Presentation of pneumonic plague

Answer 17

Sudden onset headache, malaise, fever, myalgia, cough

Pneumonia progresses rapidly to dyspnea, cyanosis, hemoptysis

Death from respiratory collapse/sepsis

Question 18

Septicemic plague develops from ___

Answer 18

Secondary from bubonic or pneumonic forms

Question 19

Rx for plague

Answer 19

Aminoglycosides

FQs

Tetracyclines

Sulfas

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

Question 20

Prophylaxis for plague

Answer 20

Literally the same meds you use to treat

Pneumonic: oral ciprofloxacin, doxycycline, or tetracycline

Bubonic: oral doxycycline, tetracycline, or TMP/SMX

Question 21

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

Answer 21

rabbits and ticks

low dose

**no person to person tx**

Question 22

Forms of tularemia

Answer 22

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)

Question 23

Pneumonic tularemia presentation

Answer 23

Non specific pneumonia symptoms

Question 24

Rx for tularemia

Answer 24

Rx:

Streptomycin or gentamicin

Fluoroquinolones

Tetracyclines

Question 25

Prophylaxis for tularemia

Answer 25

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

Question 26

Describe the characteristics of listeria monocytogenes

Answer 26

Motile (at 20-28°C) Gram-positive rod Facultative anaerobe, b-hemolytic, grows at wide temp range

Question 27

Outlines the steps in Listeria pathogenesis

Answer 27

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

Question 28

Listeriosis can be acquired through __ transmission

Answer 28

Foodborne (contaminated food, unpasteurized milk etc)

Question 29

2 clinical forms of listeriosis are \_\_\_

Answer 29

Pregnancy ass'd and non-pregaz ass'd

Question 30

Presentation of Listeria in pregnancy

Answer 30

Undifferentiated illness: fever, chills, myalgias, bacteremia Amnionitis: Premature labor; Septic abortion

Question 31

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

Answer 31

Neonatal listeriosis (happens early - acquired in utero)

Question 32

Late neonatal listeriosis is characterized by \_\_

Answer 32

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

Question 33

\_\_\_ is the number one cause of meningitis in an immunocompromised host

Answer 33

Listeria (listerial meningoencephalitis)

Question 34

What do you use to treat Listeria meningitis?

Answer 34

Need **AMPICILLIN**!! 3rd generation cephalosporin does not work for this (if not, next one is TMP-SMX)

Question 35

\_\_\_ is the causative agent of cat scratch disease and bacillary angiomatosis

Answer 35

Bartonella henselae

Question 36

Describe Cat Scratch disease What is the Rx for this disease?

Answer 36

Unilateral adenopathy several weeks following bite or scratch of cat Rx: Azithromycin if needed but generally self limiting

Question 37

Describe Bacillary angiomatosis and the Rx for this disease

Answer 37

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

Question 38

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

Answer 38

Brucella : Gram-negative coccobacilli

Question 39

How do people get Brucella infection? What is the presentation and Rx?

Answer 39

Humans infected by direct contact, contaminated milk/milk products Presentation: Prolonged febrile illness Rx: Tetracycline + aminoglycosides