Diphtheria, Listeria, & Bacillus Flashcards Preview

Term 4: Infectious Diseases > Diphtheria, Listeria, & Bacillus > Flashcards

Flashcards in Diphtheria, Listeria, & Bacillus Deck (49):
1

What organism are we thinking when we hear "leather throat" and "Bull neck?"

Diphtheria

2

What are the microbiological characteristics of Diphtheria?

-Club shaped -Gram positive (sometimes gram variable in resp sample) -Granules (polymetaphosphate) visible when stained with methylene

3

What media can we culture Diphtheria on?

-Loeffler coagulated serum -Cystine-tellurite blood agar (black colonies)

4

How does Diphtheria spread?

-human -> human -Droplets or direct contact with skin abrasions

5

Where does diphtheria colonize?

Mucous membranes -mostly tonsils and pharynx **no invasion

6

How does diphtheria cause disease?

-virulence factor = exotoxin = diphtheria toxin

7

How does diphtheria toxin work?

-kills cells via inhibition of protein synthesis -enters cells via receptor-mediated endocytosis -Mucosal necrosis -toxin can travel in blood

8

What are the symptoms of Diphtheria?

-Soar throat -fever (doesn't exceed 102) -"pseudomembrane" of necrotic epithelium -death by suffocation or toxic myocarditis in heart (arrythmia & myocarditis) *paralysis in 10-20% of pts, also neuropathy

9

What is Bull Neck?

-caused by diphtheria -lymphadenopathy and edema

10

Is diphtheria catalase positive or negative?

-Positive

11

How do we treat diphtherai?

*Tx must be prompt! -Antitoxin (DAT) -Antibiotics (penicillin & erythomycin) *vaccination makes disease very rare

12

Where does Listeria like to live?

-food-borne pathogen -cheeses, cold cuts and hot dogs **think bluebell outbreak

13

What organisms do we worry about with soft unpasteurized cheeses?

-Listeria -Brucella

14

Who is susceptible to infection by Listeria?

-Immunocompromised: elderly & AIDS, transplant patients -pregnant women, can cross to fetus

15

What is the microbiology of Listeria?

-Gm + bacillus -Resistant to high salt and bile concentrations -covered in flagella -can multiply at 4 degrees celcius

16

Is listeria catalase positive or negative?

Positive

17

Why is listeria scary in the fridge?

It can multiply at 4 degrees celcius

18

How does listeria invade?

-enters M-cells and gets to bloodstream -Uses surface protein invasin/internalin to bind to macrophage and invade -listeriolysin O releases the bacterium from the phagosome -actin filaments allow bacteria to cross from one cell to another

19

What cells do you need to get rid of a listeria infection?

-T-cells, because it is a facultative intracellular pathogen **cell mediated immunity important! not there in neonates and immunocompromised/HIV

20

What does listeriolysin O of lysteria do?

-allows organism release from a phagosome

21

Why is there no vaccine for Listeria?

-antibody immunity will not save us

22

What diseases are caused by listeria?

-Maternal listeriosis (33%) -perinatal listerosis -focal infection (GI, Liver) -sepsis & meningitis in immunocompromised

23

What is the difference between presentation of early onset and late onset perinatal listerosis?

-Early (6days) = meningitis

24

How is listeria treated?

-sensitive to most Abx, not B-lactams -must be a drug that can penetrate eukaryotic cells

25

What are the microbiologic features of Bacillus?

-Gm + -encapsulated, spore-forming (white) -grow in long end-to-end chains (looks like fungus) -non-motile

26

What culture medium does bacillus grow on?

-simple carbon and nitrogen sources -grows pretty much everywhere

27

How is B. antrhacis distinguished from B. cereus?

-anthracis requires thiamin to grow -cereus = hemolysis on blood agar

28

How is bacillus anthracis inoculated in humans?

-cutaneous (black eschar) -intestinal -Pulmonary

29

What are the x-ray findings of inhalational anthrax?

-mediastinal widening

30

Why have anthrax infections decreased since the 60's?

Animal vaccination

31

How does B. anthracis cause disease?

-spores phagocytosed by macrophates and transported to lymphatics -releases 3 exotoxins: EF, LF, and PA -death is due to septicemia, toxemia, and shock

32

What are the virulence factors (& toxins) of B. anthracis?

-Antiphagocytic capsule (very protective) Tripartite toxin: -Lethal factor (LF) -Edema Factor (EF) -protective antigen (PA) binds to cell and activates toxin release

33

What is the treatment for anthrax?

-susceptible to penicillin (but usually too late) -anthrax vaccine

34

What disease does Bacillus cereus cause?

-food poisoning

35

What are the virulence factors produced by Bacillus cereus?

-Emetic toxin = vomiting 6hrs after -Gastrointestinal toxin = diarrhea

36

What invasive diseases are caused by Bacillus cereus?

-soft tissue disease = cellulitis in leukemics/immunocompromised -eye infection -pulmonary infection

37

Fried rice and diarrhea! what organism we thinkin?

Bacillus cereus

38

What are the two most common causes of meningitis in people over 50?

#1 Strep pneumoniae #2 Listeria

39

"mediastinal widening"

Bacillus anthracis

40

"large Gm+ rods in chains"

Bacillus anthracis

41

"re-heated fried rice"

Bacillus cereus

42

What are the toxins produced by Bacillus cereus?

-Heat labile -heat stable

43

What organisms cause pediatric meningitis at less than 3 months of age and greater than 3 months?

3 mo: -Neisseria meningitides -H. influenzae

44

"Loeffler coagulated serum & Cystine-tellurite blood agar"

-Diphtheria

45

"Bull neck"

-Diphtheria

46

"pseudomembrane in oropharynx"

-Diphtheria

47

"tumbling club-shaped bacillus"

Listeria monocytogenes

48

"soft cheese & cold cuts"

Listeria monocytogenes

49

"black eschar"

-cutaneous anthrax