Walters - Penicillins

Question 1

what is a beta lactam

Answer 1

4 membered cyclic amide; essential for activity of Penicillins

Question 2

what makes up Penicillin? is it static or cidal?

Answer 2

Thiazaolidine + beta lactam rings. It is cidal bc it disrupts cell wall synthesis causing lysis

Question 3

what does the side chain determine

Answer 3

the properties and spectrums of activity

Question 4

what is the mechanism of action of penicillin

Answer 4

inhibit transpeptidase (Pcn binding protein) which would normally help make cell wall of bacteria by removing D alanine

Question 5

What is peptidoglycan composed of?

Answer 5

1. N acetylglucosamine
2. N acetylmuramic acid
   * NAG and NAM

Question 6

penicillins are only effective against organisms that synthesize peptidoglycan. They are ineffective against ____ and protozoa

Answer 6

fungi

Question 7

what is the main mechanism of resistance

Answer 7

beta lactamase enzymes (Pcnases); break open the beta lactam ring which makes antibiotic ineffective

Question 8

What is penicillin G aka Benzyl Penicillin and how is it given?

Answer 8

Given parenterally, (IV or IM) not orally. Will enter CNS if meninges inflamed.

Question 9

What are the 3 forms of penicillin G?

Answer 9

1. Aqueous: solution; given via IV
2. Procaine: suspension; given via IM
3. benzathine: suspension; given via IM

Question 10

What is procaine

Answer 10

An ESTER that is a local anesthetic that combines with Penicillin and slows its absorption and helps numb the pain of injection. It is also available with benzathine as Bicillin C-R

Question 11

This form of Penicillin G is the longest acting

Answer 11

Benzathine

Question 12

How is pencillin eliminated

Answer 12

by tubular secretion.

Question 13

Penicillin is the only antibiotic that is not given in mg but in _____. 1 unit = 0.6 micro grams. 1 million units = _____mg. If given 2.4 million units of benzathine penicillin, how many mg is this?

Answer 13

units; 600;

1440 mg. (2.4 x 600)

Question 14

what organism causes syphillis?

Answer 14

Treponema pallidum

Question 15

What are characteristics of Penicillin V aka Phenoxymethyl PCN

Answer 15

• given orally!
• less active
• acid stable
• dosed in mgs!
• Food will decrease absorption. need to give 1 hour before/1 hour after meal

Question 16

What penicillins would you prescribe for microbes that don’t respond to penicillin G or V?
-Beta lactamase Resistance PCNs (DON)

Answer 16

1. Dicloxacillin: given orally
2. Oxacillin: given parenterally
3. Nafcillin: given parenterally

Question 17

How are beta lactamsae resistant pcn’s excreted

Answer 17

biliary and renal excretion

Question 18

Staph. areus that resist “DON” are called:

Answer 18

methicillin resistant (MRSA); although the drug methicillin was discontinued years ago due to nephrotoxicity

Question 19

What are aminopenicillins

Answer 19

extended spectrum PCN’s but with gram negative coverage. They are still susceptible to penicillinases. Strains that resist penicillin resist amino penicillins

Question 20

what are the type of aminopenicillins

Answer 20

1. Ampicillin

2. amoxicillin

Question 21

Ampicillin is available with _____ as Unasyn for IM/IV use which is a preferable form for peritonitis due to ____ fragilis; a gram negative rod that is part of the normal flora and is a big producer of beta lactamases

Answer 21

sulbactam; bacteroides

Question 22

what is a mechanism for sulbactam

Answer 22

inhibit beta lactamase and protects the drug from metabolism thus enhancing its activity.

Question 23

What are characteristics of amoxicillin

Answer 23

only available orally; better oral absorption and longer half life. Not used for initial treatment of peritonitis bc it can undergo absorption unike ampicillin which is given via IV

Question 24

what is amoxicillin available with

Answer 24

clavulanate; as augmentin

Question 25

what are other uses of amoxicillin

Answer 25

1. otitis media

2. prophylaxis before dental work for high risk patients (prosthetic valve, or cyanotic heart disease)

Question 26

What are Antipseudomonas Penicillins?

Answer 26

meant to target gram negative bacteria. They are still susceptible to Pcnases!

Question 27

What are the two types of Antipseudomonas Pcn’s

Answer 27

1. Ticarcillin with clavulanate (beta lactamase inhibitor)

2. Piperacillin with Tazobactam (beta lactamase inhibitor)

Question 28

What are general side effects of all penicillins

Answer 28

1. hypersensitivity: metabolites (mainly penicilloic acid) that act as haptens (immunogenic only if attached to proteins)
   - IgE mediated
   - fever, rash, bronchospasms, Stevens johnson, anaphylaxis
2. diarrhea: kill off normal gut flora that help maintain proper fluid and electrolyte balance in the intestinal fluid
3. superinfection: killing off certain organisms allows others to grow without competition for nutrients (as with C. difficile and pseudomembranous colitis).
4. Seizures; if penetrates BBB; dec in renal function

Question 29

what is common to all antibiotics? what is a potential risk with all antibiotics?

Answer 29

diarrhea; superinfection

Question 30

Penicillin is a ____ A antagonist

Answer 30

GABA; bodies primary inhibitory neurotransmitter

Question 31

What is the Jarisch Herxheimer Rxn

Answer 31

NOT an allergic reaction. only occurs with patients with secondary syphillis and occurs after first Penicillin injection. Supposed to give aspirin (asa). Possible that treponema endoxin gets released. Symptoms include flu like; fever, chills, headache, arthralgia

Question 32

What makes up a cephalosporin

Answer 32

dihydrothiazine + beta lactam ring + side chain

Question 33

What is the main advantage that they have vs penicillins

Answer 33

resist many beta lactamases

Question 34

what is the mechanism of action of cephalosporins

Answer 34

inhibits transpeptidase enzyme which prevents removeal of D alanine