Crunch time - ID

Question 1

List 3 risk factors of IE

Answer 1

prosthetic valves, implantable devices, prior IE

Question 2

In order, list the most common organisms associated with IE

Answer 2

• staph aereus (dont forget healthcare associated)
• streptococci
• enterococci

Question 3

What are the complications associated with IE?

Answer 3

• CHF secondary to mitral or aortic regurg (if LEFT sided IE, usually due to native or prosthetic valves)
• RIGHT sided usually due to devices/IVDU

Question 4

What size on TTE would be considered a large vegetation?

Answer 4

10mm

Question 5

What are the three sub species of staph that can cause IE?

Answer 5

• MSSA
• MRSA
• coag neg staph

Question 6

What is the mechanism of flucloxacillin?

Answer 6

• SPECIFIC, narrow spectrum penicillin antibiotic
• inhibition of cell wall synthesis and is mediated through flucloxacillin binding to penicillin binding proteins (PBPs).
  Flucloxacillin is stable against hydrolysis by a variety of beta-lactamases, including penicillinases, and cephalosporinases and extended spectrum beta-lactamases.

Question 7

What is the major adverse effect of flucloxaxillin?

Answer 7

• this is an idosyncratic drug reaction (only affects a minority who take the medication)
• cause cause drug induced cholestatic jaundice (specific mechanism unknown, ?genetic predisposition)
• esp if taken if Px >55 and >14 days
• usually resolves after withdrawal, but can take up to weeks

Question 8

List 4 drugs associated with drug induced cholestasis

Answer 8

• Antibiotics and antifungals that commonly cause DIC are penicillins, macrolides, trimethoprim/sulfamethoxazole, and tetracyclines.
• Due to its clavulanic acid component, penicillin amoxicillin-clavulanate is the most common culprit of cholestatic liver injury

Question 9

Outline how to treat MSSA endocarditis

Answer 9

Fluclox 7-10 days
when bacteramia is cleared step down to cefazolin (total 4-6 week duration)

Question 10

How does cefazolin work?

Answer 10

cephlasporin - broad spectrum, both gram positive + negative; binds penicillin binding proteins

Question 11

How does vancomycin work?

Answer 11

Vancomycin binds to D-alanyl D-alanine, which inhibits glucosyltransferase (peptidoglycan synthase) and the P-phospholipid carrier, thereby preventing the synthesis and polymerization of NAM and NAG within the peptidoglycan layer.

Question 12

Outline the clinical approach to management of IE caused by streptococcus

Answer 12

1. ben pen or cef - 4 weeks
2. gent + cef - 2 WEEKS

Question 13

How does ceftriaxone work?

Answer 13

• Ceftriaxone is a third-generation antibiotic from the cephalosporin family of antibiotics (beta lactam)
• Ceftriaxone selectively and irreversibly inhibits bacterial cell wall synthesis by binding to transpeptidases, also called transamidases, which are penicillin-binding proteins (PBPs)

Question 14

How does gentamicin work?

Answer 14

Inhibits protein synthesis by binding to bacterial ribosomes

Question 15

What is ESBL?

Answer 15

• Some bacteria can produce extended spectrum β-lactamases (ESBLs) making the infection more difficult to treat and conferring additional resistance to penicillins, cephalosporins, and monobactams
  *commonly associated with kleb pneumonia + E.coli

Question 16

Explain how beta lactams and gentamicin work in synergy?

Answer 16

The two antibiotic classes target different essential cellular processes:
- Beta-lactams inhibit cell wall synthesis by binding to penicillin-binding proteins (PBPs)14.
- Gentamicin inhibits protein synthesis by binding to bacterial ribosomes (beta lactams facilitate gent entry into the cell)

Question 17

Outline the approach for treating Enterococci IE

Answer 17

1. cef + amox OR amp - 6 weeks
2. amox/ampicillin (6 weeks) + gent (2 weeks)