Infectious Diseases

Question 1

Erythromycin/Clindamycin site of action

Answer 1

50s subunit of ribosome, protein synthesis inhibitors

Question 2

Linezolid side effects

Answer 2

Myelosuppression, peripheral neuropathy, seretonin syndrome,

Rare optic neuropathy

Question 3

Aminoglycoside/tetracycline site of action

Answer 3

30s subunit of ribosome, protein synthesis inhibitors

Question 4

Linezolid site of action

Answer 4

Both 50s and 30s subunit of ribosome, protein synthesis inhibitors

Question 5

Method of action of beta lactams, vancomycin

Answer 5

Cell wall synthesis

Question 6

Daptomycin method of action

Answer 6

Loss of cell wall selective permeability

Note: binds to surfactant and cannot be used in lung infections

Question 7

Quinolone method of action (ciprofloxacin, etc.)

Answer 7

Inhibits gyrase, unwinding enzyme in DNA replication

Question 8

Rifampicin method of action

Answer 8

Inhibit RNA polymerase in DNA transcription

Question 9

Method of action sulfamethoxazole, trimethoprim

Answer 9

Inhibits folate synthesis

Question 10

Which antibiotics efficacy determined by peak concentration?

Answer 10

Fluoroqinolones, aminoglycosides (ciprofloxacin, gentamicin, etc)

Question 11

Which antibiotics efficacy determined by time above MIC?

Answer 11

Beta-lactams

Question 12

Method of MRSA resistance

Answer 12

Alteration of penicillin binding protein
MecA Gene encodes for PBP2a
Resistance to all penicillins/cephalosporins/carbapenem

Question 13

What gene predominated in community-acquired MRSA?

Answer 13

Panton-valentine leucocidin (PVL)

Question 14

Daptomycin: side effects

Answer 14

Myopathy, eosinophilic pneumonia, peripheral neuropathy

Question 15

What gene confers vancomycin resistance?

Answer 15

Amino acid substitution: D-ala D-ala to D-ala D-lac
Prevents vancomycin binding to cross links
Van A gene - vanc and teicoplanin resistance
Van B/C gene - vanc resistant only

Question 16

What is the mechanism of S. pneumoniae resistance to macrolides?

Answer 16

MefA gene - efflux pump (low resistance)

ErmB gene - alteration of binding site (high resistance)

Question 17

List ESCHAPPPM organisms

Answer 17

Inducible AMP-C beta lactamase
Enterobacter
Serratia marcescens
Citrobacter freundii
Hafnia alvei
Acinetobacter and Aeromonas
Proteus vulgaris (not mirabilis)
Providencia
Pseudomonas
Morganella morganii

Question 18

What high risk criteria require a TOE in S. aureus bacteremia?

Answer 18

Community acquired bacteremia
IV drug use
High risk cardiac condition (valve, PPM, transplant, prev IE)
Indeterminate or positive TTE
Prolonger bacteremia>72 hours

Question 19

What are the indications for IE prophylaxis?

Answer 19

High risk heart condition:
Prosthetic heart valve, rheumatic heart disease, prev IE, unrepaired cyanotic congenital heart disease
AND
High risk procedure:
Dental procedure (manipulate gingival tissue, periapical teeth, perforates mucosa)
Tonsillectomy, adenectomy
Surgery at site of established infection