DD - Practice Questions (Week 1 and 2) Flashcards Preview

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Flashcards in DD - Practice Questions (Week 1 and 2) Deck (47)
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1
Q

Components of Gram-positive bacteria

A

Peptidoglycan
Teichoic acids
Cytoplasmic membrane

2
Q

Components of Gram-negative bacteria

A
Peptidoglycan
Lipopolysacharide
Cytoplasmic membrane
Outer membrane
Periplasmic space
Porin proteins
3
Q

Toxic portion of endotoxin

A

Lipid A: component of outer membrane in Gram-negative organisms

4
Q

O and H antigens

A

O antigen: oligosaccharide antigen

H antigen: flagellar antigen

5
Q

Why aren’t beta-lactams effective against bacteria in the stationary phase of growth?

A

Beta-lactam antibiotics target cell wall synthesis; bacteria in the stationary phase are not synthesizing cell walls and so can’t be targeted by beta lactams. Beta lactams are more effective against bacteria in the log phase.

6
Q

Targets of quinolone antibiotics

A

DNA synthesis inhibitors: DNA gyrase and DNA topoisomerase

7
Q

Immune defenses associated with Mycobacterium tuberculosis infection

A

T-cell mediated defense (M. tuberculosis is an intracellular pathogen)

8
Q

Coagulase

A

Agent that inhibits spread of microbes by promoting the deposition of fibrin and helping to “wall off” and localize infections.

9
Q

Infection

A

Process whereby a microbe enters into a relationship with the host

10
Q

Pili

A

Most commonly involved in mediating adherence of bacteria to human cells - used in bacterial conjugation

11
Q

Pediatric pneumococcal vaccine

A

Polysaccharide capsule-protein conjugate: used in children. Illicit help mechanism. Needed to elicit more than an IgM response, which is not protective in children

12
Q

Rheumatic fever

A

Caused by production of an antibody against Group A Streptococci that cross-reacts with tissue in the heart

13
Q

Bacteria causing catheter infections

A

Staphylococcus (aureus, epidermidis), Enterococcus faecalis

14
Q

Bactericidal or bacteriostatic antibiotics (in terms of MIC/MBC)

A

Bactericidal: MBC/MIC < or = 4
Bacteriostatic: MBC/MIC > 4

15
Q

Botulinum toxin

A

Cleaves a specific SNARE complex protein, preventing release of intercellular vesicular contents (neurotransmitters)

16
Q

Phosphatases in Gram-negative bacteria

A

Most likely to localize in periplasm

17
Q

Why is it difficult to become immune to Streptococcus pyogenes?

A

Immunity is related to formation of Ab against M-protein. But becoming immune to all 70 M-protein serotypes is virtually impossible.

18
Q

Why is it difficult to become immune to Streptococcus pneumoniae?

A

Immunity is related to producing Ab against the polysaccharide capsule. But becoming immune to all different capsular antigenic types is very difficult.

19
Q

Why is it difficult to become immune to Neisseria gonorrhoeae?

A

Immunity is related to producing Ab against the pilus. But you can’t become immune to gonorrhea because of intrastrain genetic variation or interstrain antigenic differences.

20
Q

Metronidazole

A

Good for C. diff, C. perfringens, and Bacteroides (DNA inhibitor, only for anaerobes)

21
Q

Organism most associated with production of coagulase

A

Staphylococcus aureus

22
Q

Organism most associated with production of glycocalyx

A

Coagulase-negative Staphylococcus

23
Q

Organism most associated with antiphagocytic capsule

A

Streptococcus pneumoniae

24
Q

Organism most associated with production of dextrans (enhance adherence to damaged heart valves and teeth)

A

Viridans streptococci (can cause infective endocarditis)

25
Q

Organism most associated with production of toxins transferring glucose from UDP-glucose to Rho family GTPases- altering cytoskeleton of enterocytes

A

Clostridium difficile

26
Q

Gram-negative rod with intrinsic resistance to penicillin, ceftriaxone, and erythromycin

A

Pseuomonas aeruginosa

27
Q

Gram-negative anaerobe frequently associated with abdominal infections and part of normal flora of colon

A

Bacteroides fragilis

28
Q

Organism most associated with production of M protein

A

Streptococcus pyogenes (Group A Strep)

29
Q

Organism most associated with antigenically distinct pili allowing repeated infection with different strains

A

Neisseria gonorrhoeae

30
Q

Organism most associated with a lack of cell wall, precluding use of beta-lactam agents

A

Mycoplasma

31
Q

Organism most associated with being an obligate intracellular pathogen

A

Chlamydia

32
Q

Which organisms would not routinely be recovered from respiratory specimens from patients?

A

Chlamydia pneumoniae, Mycoplasma pneumoniae. Would not be recovered using ROUTINE culturing methods - need special methods

33
Q

VanA mechanism of resistance

A

Vancomycin

34
Q

erm mechanism of resistance

A

Macrolides

35
Q

gyrA mutation mechanism of resistance

A

Fluoroquinolones

36
Q

KPC mutation mechanism of resistance

A

Ceftriaxone and meropenem

37
Q

TEM-1 mechanism of resistance

A

Amoxicillin

38
Q

Why does amoxicillin have better activity against E. coli than penicillin?

A

Amoxicillin has a different structure to its R group than does penicillin, so it is more hydrophobic and able to pass through the porins of E. coli to get to the target.

39
Q

Why does vancomycin work against MRSA?

A

Vancomycin inhibits stage 2 of cell wall synthesis (attacking precursor molecule) and MRSA is mutated in stage 3 (peptidoglycan crosslinking).
TL;DR vancomycin doesn’t target PBPs and so it doesn’t care if they’re altered or not

40
Q

Cefazolin has spectrum of activity most like what antibiotic?

A

Amoxicillin

41
Q

Diphtheria toxin

A

Irreversibly inhibits protein synthesis by inactivating EF-2 through ADP ribosylation

42
Q

Anthrax edema factor

A

Increases intracellular cAMP. Requires activation by calmodulin

43
Q

Pertussis toxin

A

ADP ribosyltransferase, causes increased intracellular cAMP.

44
Q

Tetanus toxin

A

Inhibits release of NTs.

45
Q

Organisms that express resistance to beta-lactams through alteration of PBPs

A

S. aureus
Coagulase-negative staphylococcus
Streptococcus pneumoniae
Enterococcus faecium

46
Q

Bacteriostatic antibiotic categories

A

Protein synthesis inhibitors (except for aminoglycosides)

Intermediary metabolic pathway inhibitors

47
Q

Bactericidal antibiotic categories

A

Cell wall synthesis inhibitors
Cell membrane function disruptors
DNA function/synthesis inhibitors
Aminoglycosides (protein synthesis inhibitors)