5.2 Gram Positive Aerobic Rods 1

Question 1

describe the physical appearance and susceptibility of gram positive aerobic rods

Answer 1

have a thick cell wall; sensitive to penicillin G

Question 2

what is the habitat for bacillus

Answer 2

humans, animals, soil

Question 2

gram-positive aerobic rods are important agents of (3)

Answer 2

zoonoses, septicemia and bacteremia

Question 2

what is the habitat for listeria

Answer 2

throat and urogenital tract

Question 3

what is the habitat for actinomyces

Answer 3

mouth flora

Question 4

a cow presents with sudden death and bleeding from orifices… you suddenly suspect

Answer 4

B. anthracis

Question 5

if you suspect B. anthracis, what are two important tests to perform and what do you never want to perform

Answer 5

1) Gram stain
2) Giemsa stain

Never perform a post-mortem (do not want to open the carcass)

Question 6

how does B. anthracis appear after Gram and Giemsa staining

Answer 6

purple (G+) with a pink capsule; rod

Question 7

where is B. anthracis commonly found

Answer 7

skin and soil

Question 8

does B. anthracis form spores

Answer 8

Y; important virulence factor as it allows it to survive for decades in soil

Question 9

T/F B. anthracis is zoonotic and reportable

Answer 9

T

Question 10

B. anthracis spores are incredibly resistant because they are ___________

Answer 10

antiphagocytic

Question 11

___ and ___ are two toxins created by B. anthracis that require ____ to be released

Answer 11

EF (edema factor); LF (lethal factor); PA (protective antigen)

Question 12

what is EF and who produces it

Answer 12

edema factor; produced by B. anthracis; it is involved in the perinuclear endosomal membrane

Question 13

what is LF and who produces it

Answer 13

lethal factor; B. anthracis; involved in apoptosis

Question 14

what is PA and what does it do? who creates it?

Answer 14

protective antigen; creates a pore for transportation of EF and LF; B. anthracis

Question 15

why is B. anthracis good at causing septicemia

Answer 15

really rapid proliferation; also causes a cytokine storm from macrophages

Question 16

T/F B. anthracis infection is worst in birds

Answer 16

F; does not affect brids

Question 17

how should you dispose of an animal that was infected with B. anthracis

Answer 17

incineration and use of formaldehyde

Question 18

what 3 forms can anthrax take in humans

Answer 18

1) cutaneous
2) oral (and thus GI)
3) aerogenous (pulmonary)

Question 19

what antibiotics are Bacillus spp. sensitive to

Answer 19

Penicillin G; aminopenicillins; macrolides

Question 20

describe the nature of the anthrax vaccine… is it effective or not… why?

Answer 20

very effective since we can target the EF and LF toxins and since the bacteria is largely extracellular

Question 21

T/F Listeria is zoonotic and reportable

Answer 21

F; zoonotic but not reportable

Question 22

what is a feature of L. monocytogenes that is also similar to a gram positive aerobic cocci (and which one?)

Answer 22

hemolytic; like Streptococcus

Question 23

what are features of L. monocytogenes survival (think about characteristics of it's environment)

Answer 23

tolerates low pH and low temperature

Question 24

what is psychrophilic

Answer 24

can grow in refrigerators

Question 25

how can L. monocytogenes spread

Answer 25

feces, milk of ruminants with latent infection, contaminated food, contaminated silage

Question 26

what is a unique feature about the way that L. monocytogenes can spread in the body

Answer 26

escapes the phagolysosome and spreads directly from cell to cell, allowing it to escape the immune response

Question 27

what 3 antibiotics can we use to treat L. monocytogenes

Answer 27

penicillin, ampicillin, tetracyclines

Question 28

how can we prevent listeriosis

Answer 28

quality check silage, vaccinate

Question 29

what is THE opportunist pathogen of cattle

Answer 29

Trueperella pyogenes

Question 30

what is unique about the morphology and the ideal environment of Trueperella pyogenes

Answer 30

pleiomorphic (rods and cocci form); facultative anaerobe

Question 31

what animals can become infected with T. pyogenes

Answer 31

ruminants, pigs

Question 32

what is characteristic of T. pyogenes (what do the infections look like)

Answer 32

purulent and mixed with anaerobic organisms

Question 33

what makes T. pyogenes and its friends really great at infecting an animal

Answer 33

quorum sensing (cross-talk) and synergy between toxins; they work together to fuck shit up

Question 34

what is the characteristic appearance of Actinomyces spp.

Answer 34

branching and filamentous; microcolonies surrounded by calcified macrophages (sulphur granules)

Question 35

what disease in cattle is caused by actinomyces and what is it associated with (2)

Answer 35

lumpy jaw disease; trauma and teething

Question 36

why is treatment of Actinomyces infection problematic and difficult

Answer 36

chronic and walled-off

Question 37

describe the sequence of steps you would go through when you identify a gram positive cocci to how you would rule in/out S. aureus

Answer 37

after gram test shows G+ -> catalase test -> if positive, Staphylococcus; if negative, Streptococcus or Enterococcus -> if positive, then do coagulase test -> if positive, S. aureus; if negative; S. pseudointermedius or S. hyicus

Question 38

when would you decide to perform MALDI-TOF

Answer 38

when you want to further characterise a bacteria -> species -> subspecies -> specific isolate/strain

Question 39

what is the mass range for MALDI-TOF

Answer 39

2000-20,000 Da

Question 40

what are 5 types of proteins you can identify using MALDI-TOF

Answer 40

1) ribosomal proteins 2) DNA binding proteins 3) heat shock proteins 4) cell division proteins 5) primary cell metabolism proteins

Question 41

what are the 3 parts to MALDI-TOF

Answer 41

1) laser desorption ionization 2) mass spectrometry 3) comparison to reference database

Question 42

what are some advantages of MALDI-TOF

Answer 42

- high throughput - low exposure risk - automated - cost-effective - rapid - small footprint - single colony/simple to prep the sample

Question 43

what are some disadvantages of MALDI-TOF

Answer 43

- initial investment - regulatory issues - no susceptibility testing - difficult with polymicrobial samples - database entries

Question 44

if a neonate does not receive colostrum, what type of bacterial infections might develop and why

Answer 44

extracellular infections; low antibodies means low humoral immunity, which is needed to fight extracellular infections