Bacterial cell wall synthesis inhibitors

Question 1

Name 2 classes of bacterial cell wall synthesis inhibitors.

Answer 1

Beta-lactams, Glycopeptide

Question 2

Beta lactams bind to the active side of which enzyme?

Answer 2

Transpeptidase (penicillin binding protein)

Question 3

Name 4 types of beta lactams

Answer 3

Penicillins, cephalosporins, carbapenems, monobactam

Question 4

Name the 4 classes of penicillins

Answer 4

natural penicillins (Pen G and Pen V),
penicillinase resistant penicillins (cloxacillin),
aminopenicillins (amoxicillin, ampicillin),
antipseudomonal penicillins (piperacillin)

Question 5

Which natural penicillin is administered parenterally?

Answer 5

Penicillin G

Question 6

Syphilis caused by Treponema pallidum can be treated with which penicillin?

Answer 6

Penicillin G

Question 7

Which natural penicillin is administered orally?

Answer 7

Penicillin V (not IV)

Question 8

Which bacteria are natural penicillins effective against?

Answer 8

Mostly against Gram positive (streptococci and bacillus diphtheriae)
And some gram negative (meningococci and gonococci)
beta-lactamase negative strains

Question 9

What is cloxacillin effective against?

Answer 9

It is a Penicillinase-resistant Penicillin (anti-staphylococcal Penicillin)

effective against Penicillinase producing staphylococci and other gram positive.
Ineffective against Gram negative

Question 10

What are Ampicillin and amoxicillin effective against?

Answer 10

have additional hydrophilic group, allowing penetration into Gram-negative bacteria
Also effective against many beta-lactamase negative strains of Gram negative/positive microorganisms

Question 11

What are Ampicillin and amoxicillin ineffective against?

Answer 11

Pseudomonas and Klebsiella

Question 12

How is piperacillin administered?

Answer 12

Intravenously

Question 13

Which class of penicillins has coverage against Pseudomonas, Proteus and Klebsiella?

Answer 13

Anti-pseudomonal penicillins (piperacillin)

Question 14

How are penicillins cleared?

Answer 14

Renal excretion

Question 15

Which of the aminopenicillins (amoxicillin or ampicillin) has better oral absorption?

Answer 15

Amoxicillin

Question 16

Are aminopenicillins effective against beta lactamase producing strains of bacteria?

Answer 16

No

Question 17

Name the 2 aminopenicillins

Answer 17

Ampicillin, amoxicillin

Question 18

Which class of penicillin is commonly used against methicillin sensitive Staphylococcus aureus?

Answer 18

Penicillinase resistant penicillins

Question 19

How does methicillin sensitive Staphylococcus aureus acquire resistance against the natural penicillins?

Answer 19

They produce penicillinases

Question 20

Which bacteria is cloxacillin effective against?

Answer 20

Methicillin Sensitive Staphylococcus aureus (MSSA)

Question 21

How do beta-lactamase inhibitors work?

Answer 21

They either covalently bind at or near the active site of the β-lactamase and restructures it, permanently inactivating. In doing so, they protects other beta-lactam antibiotics from beta-lactamase catalysis.

Question 22

Name 3 beta lactams-beta-lactamase inhibitor combination drugs.

Answer 22

Augmentin (Amoxicillin + clavulanic acid)
Unasyn (ampicillin + sulbactam)
Zosyn (piperacillin + tazobactam)

Question 23

Which beta-lactamase combination drugs can be administered orally?

Answer 23

Augmentin (Amoxicillin + clavulanic acid)

Question 24

Name a microbe that commonly causes nosocomial infections and is resistant to all penicillins.

Answer 24

MRSA (methicillin resistant Staphylococcus aureus)

Question 25

Name at least 2 penicillins related life-threatening allergic reactions.

Answer 25

1.Anaphylaxis 2. Stevens Johnson syndrome 3. Toxic epidermal necrolysis

Question 26

Which generation of cephalosporins does cefazolin and cephalexin belong to?

Answer 26

First generation

Question 27

Which generation of cephalosporins are primarily administered orally? Any exceptions?

Answer 27

First and second generation cehalosporins. Cefazolin (first generation) is an exception.

Question 28

How are the 3rd, 4th and 5th generation cephalosporins administered?

Answer 28

Parenterally

Question 29

Name at least 3 types of microbes against which 1st -4th generation cephalosporins are ineffective?

Answer 29

LAME 1. Listeria monocytogenes, 2. Atypicals (Mycoplasma, Chlamydia, Legionella spp.), 3. MRSA, and 4. Enterococcus species

Question 30

Ceftriaxone belongs to which generation of cephalosporins?

Answer 30

Third generation

Question 31

Cefuroxime belongs to which generation of cephalosporins?

Answer 31

Second generation

Question 32

Name one cephalosporin from the third and fourth generation each which is effective against Pseudomonas aeruginosa.

Answer 32

Third generation – Ceftazidime Fourth generation - Cefepime

Question 33

Which generation of cephalosporins has coverage against MRSA?

Answer 33

Fifth generation (ceftaroline)

Question 34

How are most cephalosporins cleared? Any exceptions?

Answer 34

Renal clearance except ceftriaxone which is cleared hepatically

Question 35

Explain the mechanism of resistance underlying MRSA.

Answer 35

MRSA expresses an altered penicillin binding protein (PBP2a) with reduced affinity for the penicillins

Question 36

Name 3 advantages the third generation and fourth generation cephalosporins have over the first and second generations.

Answer 36

1. Higher activity against Gram-negative bacteria 2. Greater resistance against the beta-lactamase producing strains 3. Greater CSF penetration

Question 37

What are 2 adverse reaction to cephalosporins?

Answer 37

1. Hypersensitivity (CI with patients w penicillin allergy) 2. GI symptoms (broad spectrum antibiotics kill normal gut flora, allowing overgrowth of toxin producing Clostridioides difficile resulting in Clostridioides difficile-associated disease (CDAD)

Question 38

Name the class of antibiotics that are commonly used against extended spectrum beta-lactamase (ESBL) producing bacteria?

Answer 38

Carbapenems

Question 39

How are carbapenems administered?

Answer 39

Parenterally

Question 40

Name 3 carbapenems.

Answer 40

1. Imipenem, 2. meropenem, 3. ertapenem

Question 41

How are carbapenems administered?

Answer 41

Parenterally

Question 42

Imipenem is combined with __________, which works by __________.

Answer 42

cilastatin, inhibiting dehydropeptidase 1 (DHP1) found in the brush border of the proximal renal tubule. (DHP1 is necessary for the hydrolysis (breakdown) of imipenem--> increase active form of imipenem It is not a beta lactamase inhibitor.)

Question 43

Which carbapenems is ineffective against Pseudomonas and Enterococcus?

Answer 43

Ertapenem

Question 44

Can carbapenems be used to treat MRSA?

Answer 44

No

Question 45

How are carbapenems excreted?

Answer 45

Renal

Question 46

What are 3 adverse reaction to carbapenems?

Answer 46

1. Hypersensitivity (CI with patients w penicillin allergy) (new research suggest cross reactivity is quite low) 2. GI symptoms (broad spectrum antibiotics kill normal gut flora, allowing overgrowth of toxin producing Clostridioides difficile resulting in Clostridioides difficile-associated disease (CDAD) 3. Neurotoxity: seizures

Question 47

Which drug class does aztreonam belong to?

Answer 47

Monobactam

Question 48

Aztreonam is effective against Gram-

Answer 48

negative bacteria (no activity against Gram positive and anaerobic microbes)

Question 49

Does aztreonam have cross-sensitivity to penicillin?

Answer 49

No, suitable for treating Gram negative infections that normally would be treated with a beta lactam were it not for a prior allergic reaction

Question 50

How is aztreonam administered?

Answer 50

IM/IV

Question 51

Vancomycin is useful against Gram ___________

Answer 51

positives

Question 52

How is vancomycin commonly administered?

Answer 52

Intravenously

Question 53

When is oral vancomycin preferred instead of its usual IV form?

Answer 53

Clostridium difficile-associated diarrhea (CDAD) or the more severe antibiotic-associated pseudo-membranous colitis.

Question 54

What is the first line of antibiotics for CDAD?

Answer 54

Vancomycin

Question 55

Vancomycin interferes with cell wall synthesis by inhibiting ___________

Answer 55

transglycosylation

Question 56

How is vancomycin cleared?

Answer 56

Renal clearnace

Question 57

What must be noted before giving vancomycin?

Answer 57

whether patient has renal impairment; dose adjustment required

Question 58

Name 2 antibiotics that work by inhibiting bacterial cell wall synthesis, and are effective against MRSA?

Answer 58

1. ceftaroline (Fifth generation cephalosporins) 2. Vancomycin

Question 59

Name 3 adverse effects related to vancomycin

Answer 59

1.Nephrotoxicity, 2.Ototoxicity, 3.Red man syndrome due to histamine release; can be prevented by prolonging the duration of infusion to 1-2 hours.