Week 10 - PCN, cephalosporins, glycopeptides

Question 1

Gram positive bacteria

Answer 1

Stains purple, thick layer/peptidoglycan wall

Examples: staph, clostridium, strep, enterococcus

Question 2

Gram negative bacteria

Answer 2

Stains pink, thin single layer/peptidoglycan wall

Examples: neisseria

Question 3

Bacteriostatic vs bactericidal

Answer 3

Bacteriostatic: prevents the growth of bacteria (keeps them in stationary phase of growth)

Bactericidal: kills bacteria

Question 4

Three ways providers can prescribe antibiotics

Answer 4

1) Empirically - based on evidence-based guidelines
2) Prophylactic - infection prevention (e.g. pretreating patient undergoing dental extractions, pretreatment to prevent TB)
3) Definitive - based on culture

Question 5

Three ways antibiotics interfere w/ bacteria proliferation

Answer 5

1) Effect cell wall synthesis
2) Alters DNA synthesis
3) Inhibits protein synthesis

Question 6

PCN: examples

Answer 6

Penicillin V, Penicillin G Benzathine (injection)

Amoxicillin, Amoxicillin/Clavulanic Acid

Question 7

PCN: activity

Answer 7

Aerobic, gram (+)

S. pneumonia, group A beta-hemolytic streptococci

Question 8

Amoxicillin (PCN): activity

Answer 8

Gram (+), greater activity against gram (-) bacteria

S. pneumonia, group A beta-hemolytic streptococci, enterococcus

Question 9

PCN: MOA

Answer 9

Prevents bacterial cell wall synthesis during active multiplication –> cell wall death

Bactericidal against susceptible bacteria

Question 10

PCN: caution and contraindications

Answer 10

• Hx of hypersensitivity reaction (e.g. Steven Johnsons)
• Caution in renal impairment
• Approved in pregnancy, lactation, pediatrics

Question 11

PCN: adverse effects

Answer 11

N/V/D, candidiasis, maculopapular rash, c. diff, anaphylaxis (rare)

Question 12

1st generation cephalosporins

Answer 12

Cefazolin, cephalexin

Question 13

1st generation cephalosporins: activity

Answer 13

Gram (+) Methicillin-sensitive s. aureus, s. epidermis, most strep, e. coli

Question 14

1st generation cephalosporin: indications

Answer 14

Cellulitis, uncomplicated cystitis, impetigo, group A beta hemolytic strep

Question 15

2nd generation cephalosporins

Answer 15

Cefuroxime, cefprozil, cefaclor

Question 16

2nd generation cephalosporin: activity

Answer 16

Gram (+)

Methicillin-sensitive s. aureus, s. epidermidis, strep e. coli

Increased activity against h. influenzae

Question 17

2nd generation cephalosporin: indications

Answer 17

Cellulitis, COPD, acute exacerbation, acute otitis media, GABHS, Lyme disease, uncomplicated UTI

Question 18

3rd generation cephalosporins

Answer 18

Ceftriaxone, cefdinir, cefpodoxime

Question 19

3rd generation cephalosporin: activity

Answer 19

Gram (+)

Methicillin-sensitive s. aureus, s. pneumoniae, gonorrhoeae, h. flu, meningitidis, e. coli

Question 20

Which 3rd generation cephalosporin should be avoided in neonates?

Answer 20

Ceftriaxone - increases risk for hyperbilirubinemia

Question 21

Cephalosporin: MOA (similar for all gens)

Answer 21

Prevents bacterial cell wall synthesis during active multiplication –> cell wall death

Bactericidal against susceptible bacteria

Question 22

Cephalosporin: ADR

Answer 22

N/V/D, maculopapular rash, c. diff, pain at injection site (ceftriaxone)

Rare: hypersensitivity reaction, hemolytic anemia

Question 23

Cephalosporin: caution and contraindications (1st and 3rd gens)

Answer 23

• Hx of hypersensitivity reactions
• Caution w/ hx of anaphylaxis or hypersensitivity reaction w/ PCN allergy
• Renal and hepatic impairment
• Approved in pregnancy, lactation, pediatrics

Question 24

Why is there cross-reactivity between cephalosporins and PCN?

Answer 24

Similar side chain

• More common w/ 1st generation cephalosporins

Question 25

Glycopeptides: example

Answer 25

Vancomycin

Question 26

Glycopeptide (Vancomycin): activity

Answer 26

Gram (+), bactericidal, given PO

C. diff, staph enterocolitis

Question 27

Glycopeptide (Vancomycin): MOA

Answer 27

Inhibits bacterial cell wall synthesis by blocking glycopeptide polymerization through binding tightly to D-A1a-D-A1a portion of cell wall precursor

Question 28

Glycopeptide (Vancomycin): caution and contraindications

Answer 28

• Approved in pregnancy, lactation, pediatrics
• PO vancomycin less nephrotoxic than IV

Question 29

Causes of antimicrobial drug resistance

Answer 29

• Recent use of abx (overuse of broad spectrum abx, over prescription of abx for viral illnesses, simple URIs, sinusitis, bronchitis)
• Age less than 2 years or greater than 65 years
• Daycare center attendence
• Exposure to young children
• Multiple medical comorbidities
• Immunosuppression

Question 30

What intervention has helped decrease antimicrobial drug resistance?

Answer 30

Pneumococcal vaccinations

Question 31

First line therapy for acute otitis media and sinusitis

Answer 31

Amoxicillin

Question 32

First line treatment for streptococcal pharyngitis

Answer 32

Penicillin

Question 33

First line therapy for infection following bites (including human bites)

Answer 33

Amoxicillin/clavulanate

Question 34

Which PCN used to treat UTIs during pregnancy?

Answer 34

Amoxicillin/clavulanate

Question 35

Which generations of cephalosporins are active against gram (+) vs gram (-)?

Answer 35

Gram (+) - 1st and 4th

Gram (-) - 2nd and 3rd

Question 36

When would 5th generation cephalosporins be prescribed?

Answer 36

More severe infections (IV only)

Question 37

Glycopeptide (Vancomycin): ADR

Answer 37

• Ototoxicity
• Nephrotoxicity
• Red Man syndrome if infused too fast

Question 38

Glycopeptide (Vancomycin): indications

Answer 38

PO vancomycin used to treat c. diff