L. monocytogenes - P. acnes

Question 1

This bacterium is a Gram + , coccobacilli (usually in pairs), and grows well in the fridge - a unique characteristic is end-over-end motility at 20-25 degrees celsius.

Answer 1

L. monocytogenes

Question 2

How is L. monocytogenes identified?

Answer 2

blood culture, CSF, placenta and amniotic fluid

Question 3

Describe the motility L. monocytogenes shows in a liquid and agar medium?

Answer 3

liquid medium = tumbling motility

agar medium = umbrella motility

Question 4

L. monocytogenes is the #1 foodbourne mortality in the US. What foods is it found in?

Answer 4

soft cheese, raw meat, fish and veggies

Question 5

This disease caused by L. monocytogenes has an onset 48 hours after eating contaminated food. Symptoms are flu-like with GI issues. It is worse in IC people.

Answer 5

gastroenteritis

Question 6

L. monocytogenes causes ___-___% of community acquired meningitis, usually sub-acute

Answer 6

10-15% (uncommon)

Question 7

Pregnant women who contract L. monocytogenes also put their fetus in harms way. Why is this?

Answer 7

it can cross placental barrier - 100% infection rate to fetus

note: women are usually bacteremic and give a premature delivery and stillbirth is common

Question 8

For neonatal patients who contract L. monocytogenes from their mother, what are the early onset and late onset symptoms?

Answer 8

early onset: in utero, 50% fatal, micro abscesses and granulomas in liver, lung, kidney, brain, spleen, and skin

late onset: shortly after birth ->meningoencephalitis

Question 9

Almost all virulence genes of L. monocytogenes are regulated by what transcription factor?

Answer 9

PrfA

Question 10

The life cycle of L. monocytogenes is intracellular. What does this mean in regards to the host’s immune system?

Answer 10

humoral immunity plays no role, CMI is important

Question 11

In regards to motility, what helps L. monocytogenes spread in the host?

Answer 11

flagella in RT, actin-mediated

Question 12

What virulence factor helps L. monocytogenes adhere?

Answer 12

alpha-D-galactose binds E-cadherin of intestinal cells

Question 13

What virulence factor helps L. monocytogenes promote bacterial endocytosis by non-phagocytic cells (this is what helps listeria cross BBB and placental barrier)

Answer 13

internalin A/B/C

Question 14

This is a pore forming toxin that allows Listeria (L. monocytogenes) to escape from the endosome and be free in the cytoplasm

Answer 14

LLO

Question 15

This virulence factor helps build actin tails that propel Listeria (L. monocytogenes) from one cell to the next

Answer 15

ActA

Question 16

This is a polymorphic Gram + rod that is a non-motile, slow grower. A skin biopsy of this bacterium will usually be negative but it will grow slowly on common media

Answer 16

Erysipeiothrix rhusiopahtiae

Question 17

Erysipeiothrix rhusiopahtiae is a widely distribute _____ pathogen that is uncommon in the US. It is caused by scratches and punctures and occupational exposures.

Answer 17

veterinary (pigs/turkey)

Question 18

This disease caused by Erysipeiothrix rhusiopahtiae presents as localized cutaneous lesions, 1-7 d after screeches/puncture wounds of the skin. It is very painful, pruritic (itchy), and self-limited

Answer 18

erysipeloid

Question 19

In regards to Erysipeiothrix rhusiopahtiae, ___ strains are pathogenic, ____ ones are not

Answer 19

smooth; rough

Question 20

This bacterium is a pleomorphic Gram + rod. It is club shaped, and catalase +, and also facultative. It is short mycolic acid in the cell wall (non-acid fast).

Answer 20

C. diphtheria

Question 21

C. diphtheria is ID’d by clinical presentation. What does C. diphtheria look like on blood agar and tellurite agar plates? (colonies)

Answer 21

white colonies on blood agar

black colonies on tellurite

Question 22

Where does C. diphtheria colonize and how does it spread?

Answer 22

colonizes skin and URT via resp. droplets. Spreads in crowded conditions.

Question 23

This type of diphtheria caused by C. diphtheria results in mucosal ulcers with a pseudomembrane coating initially white, then turning gray or even black/green which may extend to airways and block it (fatal). There will also be a low fever and weakness associated with this disease. Dislodging of the pseudomembrane may cause bleeding.

Answer 23

Nasopharyngeal diphtheria

Question 24

This type of diphtheria caused by C. diphtheria results in massive tonsil swelling and edema of the submandibular and paratracheal regions

Answer 24

Bull-neck diphtheria

Question 25

This type of diphtheria caused by C. diphtheria is more easily transmitted and is in the form of a non-toxogenic strain. It results in punched out ulcerative lesion with necrotic sloughing

Answer 25

Cutaneous diphtheria

Question 26

This type of diphtheria caused by C. diphtheria is caused by a toxin that reaches distant organs via blood and may causes paralysis, CHF, or polyneuritis

Answer 26

septicemic diphtheria

Question 27

The diphtheria toxin is encoded by ____ ___ gene under control of DtxR

Answer 27

bacteriophage tox

note: if free ion is present it binds DtxR to shut off the tox gene

Question 28

Dtx (diphtheria toxin) is irreversible, inhibiting protein synthesis which causes what?

Answer 28

local cytotoxicity -> pseudomembrane forms

Question 29

The vaccine for C. diphtheria is not ____

Answer 29

bacterium

Question 30

This bacterium is a Gram + rod found in the normal flora of the skin. It grows well in humid/tropical places.

Answer 30

C. minutissimum

Question 31

What disease is caused by C. minutissimum

Answer 31

Erythrasma - chronic superifical infection of intertriginous regions (axilla, ano-genital).

Question 32

Erythrasma (caused by C. minutissimum) invades 1/3 of ___ ____ layer of the skin, is usually asymptomatic, and produces a dark skin discoloraiton

Answer 32

stratum corneum

Question 33

This is a Gram + anaerobic rod that makes propionic acid similar to corynebacterium, but no toxins. It is commonly found in pilosebaceous glands during puberty

Answer 33

P. acnes