ATBs & SSIs

Question 1

80% of nosocomial infections occur in the?

Answer 1

1) Urinary tract
- foley catheters, CAUTI

2) respiratory system
- ventilators and VAP

3) bloodstream
- IV catheters, CLABSI

Question 2

Most common cause of bacteremia and fungicemia in hospitalized patients:

Answer 2

infected hub or lumen with S. Aureus or S. epidermidis

Question 3

Patient factors that increase risk for SSIs

Answer 3

• age extremes (<5 or >65)
• poor nutrition status
• DM & periop glycemic control (want <200)
• PVD (reduced BF to area)
• smoking (quit 4-8 wks preop reduces SSI 50%)
• coexisting infections
• altered immune response
• corticosteroid use
• no preop skin prep (scrub and shave, chlorhexidine wipes)
• preop LOS

Question 4

Facility related factors that increase risk for SSIs

Answer 4

• experience of surgeon (volume-outcome relationship…. more surgery done = less infection)
• open vs laparoscopic procedure
• length of surgery
• instrument sterilization
• periop normothermia (cold = increased infection)
• appropriate antibiotic use and redosing as needed

Question 5

ATB resistant bugs:

Answer 5

1. Strep Pneumonia
2. Methicillin-resistant Staph Aureus (MRSA)
3. vancomycin-resistant enterococci (VRE)

Question 6

Narrow Spectrum ATBs are effective against?

Answer 6

OR

• only certain organisms
• either Gm+ OR Gm-, not both

Ex: clindamycin, vancomycin, bacitracin, metronidazole

Question 7

Extended Spectrum ATBs?

Answer 7

AND
-are effective against most Gm+ AND Gm- organisms

Ex: cephalospoins

Question 8

Broad Spectrum ATBs?

Answer 8

AND AND

• are effective against Gm +, Gm, AND many other organisms
• greater risk of superinfections

Question 9

Bactericidal

Answer 9

kills bacteria

MBC = minimal bactericidal concentration

Question 10

Bacteriostatic

Answer 10

inhibits bacterial growth

MIC = minimal inhibitory concentration

Question 11

Surgical prophylaxis requires ______? (bactericidal/bacteriostatic)

Answer 11

bacteriostatic

Question 12

Surgical ATB prophylaxis

Answer 12

• achieve necessary plasma concentration BEFORE incision (usually ATB given within 1 hr of incision)
• MBC or MIC must be met by surgical incision and maintained through closure
• redosed at intervals based on particular ATB
• continue for 24-48 hrs postop

Question 13

Cefazolin dose / redose

Answer 13

2g < 120 kg
3g > 120 kg

Q4

Question 14

Ciprofloxacin dose / redose

Answer 14

400 mg

N/A

Question 15

Vancomycin dose / redose

Answer 15

15mg/kg

N/A

Question 16

Clindamycin dose / redose

Answer 16

900 mg

Q6

Question 17

Gentamicin dose / redose

Answer 17

5 mg/kg

One dose

Question 18

Metronidazole dose / redose

Answer 18

1 g

N/A

Question 19

Ampicillin-Sulbactam dose / redose

Answer 19

3g (2g ampicillin, 1g sulbactam)

Q2

Question 20

Pipperacillin-Tazobactam dose / redose

Answer 20

3.375 g

Q2

Question 21

MOA of drugs commonly used for surgical prophylaxis?

Answer 21

Beta Lactams

• inhibit cell wall synthesis
• many services use cefazolin

-If beta-lactam allergy, alternatives: clindamycin, vancomycin, gentamicin

Question 22

MOA cell wall inhibitors

Answer 22

Inhibit cell wall biosynthesis: Beta-lactams
-PCNs, cephalosporins, carbapenems, monobactams

Interfere with the transport of cell wall building-blocks
Vancomycin
Bacitracin

Break up cell membranes
-polymyxins

Question 23

MOA Nucleic Acid Synthesis Inhibitors

Answer 23

Inhibit Folate synthesis

• sulfonamides
• trimethoprim

Interfere with DNA gyrase
-quinolones

Inhibits DNA-dependent RNA Polymerase
-rifampin

Question 24

MOA Protein Synthesis Inhibitors

Answer 24

Disrupt cell growth or proliferation by disrupting the generation of proteins

50S Subunit

• macrolides
• clindamycin
• linezolid
• chloramphenicol
• streptogramins

30S Subunit

• aminoglycosides
• tetracyclines